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Post by tornado on May 18, 2015 14:25:09 GMT -5
To see animated versions of some of the maps, here is the URL to this thread: wxobservers.freeforums.net/thread/752/lightning-projectLightning Data and LAWRS Sites
It has been suggested that LAWRS sites can rely on ALDARS to safely detect thunderstorms; or that LAWRS observers may be able to safely detect lightning and thunder when ALDARS is not representative. This paper will demonstrate that the above is not the case; and retaining contract weather observers at our nation’s largest (A and B level) airports will ensure the safest thunderstorm reporting.
First things first. Most lightning does not strike the ground!
Also, the first lightning a thunderstorm produces, is usually in-cloud:
The above article also states that the NLDN detects 90% of cloud-to-ground strikes. 10% of lightning is still at least 2 million of strokes per year!
From the UCAR Lightning FAQ page:
Source: www.ucar.edu/communications/infopack/lightning/faq.html
The article below states that annual lightning strikes in the United States alone, numbers about 25 million:
Global warming may increase frequency of lightning strikes
So lightning can strike below, within, or near a cumulonimbus cloud. By near, this sort of thing is meant:
Interconnected lightning can strike the ground in multiple places. This photo, from Wiesbaden in Germany (credit: Boris Jordan photography),
shows 11 lightning bolts striking the ground, while they are connected aloft:
Lightning strikes Freedom Tower, LTGICCACG
Airports need to get correct lightning information. Below is an archived lightning map, showing about 110 lightning strikes within a mile of
Sugar Land Regional Airport, near Houston Texas. The map shows lightning strikes in a 3-hour period on 26 May 2015:
Here are specific cases when ALDARS (based on the NLDN) missed lightning; or, in the absence of ALDARS (or if ALDARS is turned off), ATC missed the lightning: 1. La Crosse, Wisconsin, 7 May 2015:SPECI KLSE 072311Z 18017G24KT 10SM VCTS -RA BKN055 BKN080 BKN110 27/16 A2973 RMK AO2 LTG DSNT ALQDS RAB11 P0000 T02670156 The LAWRS site at La Crosse reported VCTS at 2311Z. TS was not reported until 0504Z the following day. But shortly before 2314Z, a lightning strike 5km from the airport was recorded. 5km is about 3.1 miles. This should have changed the VCTS to a TS; since that is SPECI criteria for ALDARS, a SPECI should have been recorded. But on the next METAR, there was no indication that a thunderstorm had occurred in the past hour: METAR KLSE 072353Z 18017G23KT 10SM -RA SCT039 BKN055 OVC100 24/18 A2975 RMK AO2 PK WND 19027/2340 LTG DSNT NW-E RAB11E23B39 SLP065 P0000 60000 T02390178 10289 20239 55009 Below are 2 charts showing the lightning strikes, the first, valid at 2314Z:   By 2342Z, a lightning strike occurred 4km to the north of KLSE, as shown in the above chart. 4km is about 2.5 miles. But not only did the 2353Z METAR not continue the VCTS, no TS was ever reported that hour at KLSE. Since the lightning data recorded 2 cloud-to-ground strikes within 3.1 miles of the airport, that was a missed thunderstorm.
2. Rochester, Minnesota, 7 May 2015:
METAR KRST 072354Z 18017KT 10SM FEW055 22/16 A2972 RMK AO2
PK WND 18031/2255 LTG DSNT SW-NW SLP059 60004
T02220161 10239 20206 56020
SPECI KRST 080020Z 19015KT 10SM VCTS SCT044 SCT055 22/16
A2974 RMK AO2 LTG DSNT SW-N T02170161
SPECI KRST 080050Z 24014KT 9SM -TSRA BKN039 BKN046 OVC060
21/17 A2976 RMK AO2 LTG DSNT ALQDS RAB33 TSB44
P0000
Rochester began a thunderstorm at 0044Z. However, the below lightning map shows a lightning strike less than 2 miles from KRST airport at 0009Z. The grey circle is the thunder display, with the thunder moving outward in all directions from the lightning strike. A second lightning bolt hit about 8.5 miles to the SEE of the airport, and a third bolt struck about 10 miles due west of the airport. All three bolts struck at 0009Z. Yet, KRST did not begin a VCTS until 0020Z, when it should have begun a TS as soon as possible after 0009Z. An on-site contract weather observer, with no other duties than to report the weather, would have picked up on this much sooner than did the LAWRS observer. Also, this demonstrates that ALDARS is not always reliable as it does not detect all cloud-to-ground strikes, nor properly measure their distance.
By 0031Z, there had been a cluster of lightning strikes 3-4 to the WNW of KRST:
Again, that was 13 minutes before KRST began a TS. A CWO would have picked up on that cluster as well.
3. Eau Claire, Wisconsin, 7(8) May 2015:
The LAWRS site at Chippewa Valley Regional Airport(KEAU) reported no lightning data at 2356Z. At 0056Z, KEAU reported lightning 10-30 miles from the site:
METAR KEAU 072356Z 18014KT 10SM BKN060 23/15 A2969 RMK AO2
PK WND 18028/2341 SLP051 T02330150 10267 20233 58016
METAR KEAU 080056Z 18017G28KT 10SM SCT110 22/15 A2970 RMK
AO2 PK WND 17028/0054 LTG DSNT W-N SLP053 T02220150
However, shortly before 0034Z, a lightning bolt struck about 7,000 feet from the north end of the runway. That was 1.32 miles:
Yet, ALDARS and the LAWRS observer somehow missed that bolt. By 0126Z, there were 3 other cloud-to-ground lightning bolts that struck 4-5 miles south of KEAU:
The most recent strike from the 0034Z chart, which appeared in yellow on that chart; had now darkened to brown as it was older, but still appeared on the 0126Z lightning map. Any and all of those 4 lightning strikes should have produced a TS at KEAU. Yet, all that was reported was lightning 10-30 miles away:
METAR KEAU 080156Z 18014G20KT 10SM SCT080 OVC100 21/16 A2972
RMK AO2 LTG DSNT SW-N SLP058 T02110156
4. Lawton, Oklahoma, 8 May 2015:
At 1912Z, 2 lightning bolts struck within 3 miles of the south end of the runway at Lawton-Fort Sill Regional Airport (KLAW):
Why this was not detected by ALDARS or LAWRS is unknown. But these were the 2 consecutive reports before and after 1912Z:
METAR KLAW 081853Z 09008KT 9SM BKN042 OVC049 23/20 A2988
RMK AO2 SLP112 T02330200
METAR KLAW 081953Z 13012KT 8SM FEW027 FEW060 SCT080 24/22
A2988 RMK AO2 RAB06E31 SLP109 P0001 T02440217
By 1923Z, there had been other nearby lightning strikes:
Yet, a TS was not reported that hour.
Lawton has ALDARS, according to the NWS AMSS website:
Lawton ATCT ought to place ASOS into AUTO mode, right before closing time. Looking at the observations, we see that KLAW placed ASOS into
AUTO/TSNO mode (which was level D service, by the way), sometime between 2054-2120Z:
METAR KLAW 072053Z 09009KT 10SM BKN085 OVC110 22/19 A2985 RMK AO2 SLP101 T02220194 58017
SPECI KLAW 072120Z AUTO 30014G20KT 9SM -RA SCT017 BKN027 OVC110 18/15 A2992 RMK AO2 RAB16 PRESRR P0001 T01830150 TSNO
2120Z was 4 p.m. Why would KLAW place ASOS into AUTO/TSNO mode, with a line of thunderstorms approaching from the west?
According to airvav.com. Lawton ATCT is open until 1900 local time:
1900 CDT was 0000Z on that date. Since KLAW placed ASOS into TSNO mode early, well before 2153Z, let's run a lightning map from 2200-0000Z, to see how much lightning was missed:
Well over 100 lightning strikes occurred within 10 miles of KLAW! Zooming in, many strikes were within 5 miles:
Not only that, lightning struck the airport, at about 2244Z:
Why would LAWRS leave ALDARS disabled, with that much lightning occurring? I had to go back and revisit this case, and update the data, once it was realized that it was much worse than first reported.
5. Flint, Michigan, 8 May 2015:
At Bishop International Airport (KFNT), a VCTS was begun at 1901Z, and VCTS appeared again on the next METAR at 1953Z:
SPECI KFNT 081901Z 27008KT 7SM VCTS FEW022 BKN070 OVC100
24/18 A2996 RMK AO2 LTG DSNT N RAE00 P0000 T02440178
SPECI KFNT 081929Z 21005KT 7SM -RA SCT060 SCT075 BKN095 24/19
A2996 RMK AO2 LTG DSNT N AND NE RAE00B07 P0002
T02390189
METAR KFNT 081953Z 18009KT 7SM VCTS FEW065 26/18 A2995 RMK
AO2 LTG DSNT NE-S RAE00B07E33 SLP139 P0002 T02560183
Yet, lightning data indicates that TS should have been reported, as 3 lightning strikes adjacent to the airport were recorded by 1920Z:
4 other nearby strikes were recorded as well. That was a total of 7 lightning strikes, any or all of which should have begun a TS; when all that was reported was VCTS.
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Post by fu on May 18, 2015 14:33:28 GMT -5
Very nice.
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Post by tornado on May 18, 2015 14:33:58 GMT -5
6. Decatur, Illinois, 8 May 2015:
At 1917Z, lightning data showed a strike 4 miles NW of KDEC:
A bit later, at 1932Z, more lightning strikes hit near KDEC:
ALDARS or the LAWRS observer detected those strikes, and issued a SPECI for TS:
SPECI KDEC 081939Z 25008KT 10SM -TSRA FEW012 BKN045 OVC110
20/18 A2998 RMK AO2 WSHFT 1900 RAB24 TSB33 P0000
T02000183
However, that should have been done as a result of the 1917Z lightning strike. So there was a delay of 16 minutes in getting a thunderstorm started, and a further delay of 6 minutes until the SPECI was issued.
7. Erie, Pennsylvania, 8 May 2015:
By 2247Z, there had been several lightning strikes between 5-10 miles from the Erie International Airport (KERI), that VCTS should have been reported.
It was not:
METAR KERI 082151Z 07003KT 10SM CLR 26/12 A3001 RMK AO2 SLP159 T02610117
METAR KERI 082251Z 05003KT 10SM BKN120 27/12 A3001 RMK AO2 SLP157 T02720117
8. Topeka, Kansas, 8 May 2015:
At 2304Z, a lightning bolt struck 4/5 of a mile from where the runways cross at Philip Billard Municipal Airport (KTOP) in Topeka:
Within 7 minutes, there had been another strike within 4 miles to the SE of KTOP:
The 2304Z LTG strike was turning orange in the above lightning map. But both lightning strikes can be measured within 5 miles of KTOP. However, lightning was not even reported that hour, making this a missed thunderstorm:
METAR KTOP 082253Z 03008KT 10SM OVC025 19/15 A2998 RMK AO2
SLP148 T01940150
METAR KTOP 082353Z 03007KT 10SM SCT022 BKN030 OVC036 19/14
A2998 RMK AO2 SLP148 T01890144 10206 20189 56003
9. Fort Smith, Arkansas, 9(10) May 2015:
At 0144Z, there had been a recent LTG strike 1 mile to the SE of KFSM Airport:
The above map shows that there had been other bolts strike within 5 miles as well. Yet, the SPECI at 0143Z showed heavy rain, but no lightning,
not even DSNT:
SPECI KFSM 100143Z 35009KT 1 3/4SM R25/5000VP6000FT +RA BR
FEW007 BKN024 OVC035 19/17 A2995 RMK AO2 WSHFT
0114 VIS 1V5 RAB12 P0026 T01890167
Thunder was finally reported after the METAR, at 0154Z:
SPECI KFSM 100149Z 04009KT 2 1/2SM R25/5000VP6000FT -RA BR
SCT022 BKN034 OVC050 19/17 A2995 RMK AO2 WSHFT
0114 RAB12 P0035
METAR KFSM 100153Z 07013KT 8SM -RA SCT026 BKN034 OVC055 19/17
A2994 RMK AO2 WSHFT 0114 RAB12 SLP135 P0035 T01890172
SPECI KFSM 100154Z 06014KT 9SM -TSRA SCT026 BKN034 OVC055
18/17 A2994 RMK AO2 TSB54 P0000 T01830172
That was a delay of at least 10 minutes from the time the LTG hit 1 mile SE of the airport.
10. Abilene, Texas, 9(10) May 2015:
Abilene had a LTG strike 4 miles to the east of the airport shortly before 0148Z:
Yet, the METAR a few minutes later, showed clear skies with no lightning:
METAR KABI 100152Z 11007KT 10SM CLR 26/19 A2974 RMK AO2 SLP047
T02560189
Storms continued to develop near Abilene the next hour. At 0220Z, a LTG strike was detected 4 miles SE of the airport. Previously that hour even closer lightning strikes had been detected:
Again, the next METAR reported clear skies, with no mention of lightning or thunder:
METAR KABI 100252Z 12005KT 10SM CLR 23/19 A2975 RMK AO2 SLP051
T02280189 51015
Those were 2 separate thunderstorms, that were not reported at all!
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Post by zoomthundersnow on May 18, 2015 14:35:14 GMT -5
Tornado, We were a test site for 3.10, they conducted the tests during the Winter Months when no TS activity was occurring to see if ALDARS was operating correctly to switch from VCTS to TS. Officials signed off on it with no real data from our site.
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Post by tornado on May 18, 2015 14:44:30 GMT -5
11. Fort Worth, Texas, 9(10) May 2015:
Meacham International Airport in Fort Worth, Texas, had a lightning strike just before 0149Z, that was about 6 miles away to the SW:
A VCTS should have been reported at that point. Instead, this was the METAR a few minutes later:
METAR KFTW 100153Z 15013KT 10SM CLR 26/22 A2976 RMK AO2 LTG
DSNT S-W SLP070 T02610217
The lightning maps can be overlaid with radar data. At 0202Z, such a map showed the FTW area was not clear, as there was much rainfall over the entire area:
A new lightning strike was detected to the NW of KFTW at 0202Z as well. Yet, pilots and other users had to wait until 0230Z for VCTS to be reported:
SPECI KFTW 100230Z 14016G26KT 10SM VCTS -RA BKN100 BKN110
26/22 A2976 RMK AO2 PK WND 16028/0217 LTG DSNT
S AND SW RAB09 P0000 T02610217
Since a VCTS should have begun at 0149Z, that was a 41 minute delay in properly reporting a thunderstorm at Meacham Intl that evening.
At 0239Z, a LTG bolt struck 4 miles S of KFTW:
Yet, despite that meeting the criteria for TS, only VCTS was reported:
METAR KFTW 100253Z 14025G31KT 10SM VCTS -RA SCT095 26/19
A2975 RMK AO2 PK WND 15031/0251 LTG DSNT SE-SW
RAB09 SLP064 P0000 60000 T02560194 50001
Also note that just before 0239Z, a bolt had struck about 4 miles to the NE of Meacham; yet, ALDARS reported LTG DSNT SE-SW. A contract weather observer, especially with access to live lightning data, would have been able to detect more lightning than did ALDARS or the busy LAWRS observers.
12. Sioux City, Iowa, 10 May 2015:
The Sioux Gateway Airport had this report at 1952Z:
METAR KSUX 101952Z 16031G45KT 10SM -RA SQ SCT020 SCT024 BKN030 19/14 A2972 RMK AO2 PK WND 15045/1949 LTG DSNT ALQDS RAB52 SLP058 P0000 T01940144
Wind gusts to 45 knots are thunderstorm-type winds, even near-severe. Should a thunderstorm have been reported at that time? Lightning data suggests yes:
The above chart is valid at 1953Z. A lightning strike occurred about 7 miles to the east of the airport. Since the circle is orange, it is several minutes old; i.e., before the METAR time. The present weather code should have been –VCTSRA SQ. A thunderstorm was begun at 2001Z, but more lead time for aircraft could have been provided by reporting VCTS on the 1952Z METAR.
13. Erie, Pennsylvania, 10 May 2015:
The METAR at 2151Z showed moderate rain, and a poor RVR:
METAR KERI 102151Z 17007KT 4SM R06/5000VP6000FT RA FEW045 BKN060 BKN090 24/17 A3003 RMK AO2 RAB45 SLP165 P0002 T02390167
Yet, lightning data indicated strikes that would justify a VCTS as early as 2131Z:
By 2151Z, several lightning bolts had struck within 5 miles of the airport:
The METAR posted above, had moderate rain, but no mention of lightning or thunder, not even distant lightning in remarks! At 2211Z, many lightning strikes were recorded that very minute:
Those strikes could have resulted in a SPECI for a TS becoming a VCTS. But again, no lightning or thunder was reported on the previous METAR- or the next:
METAR KERI 102251Z 17007KT 10SM BKN065 BKN090 24/18 A3004 RMK AO2 RAE18 SLP168 P0000 T02440178
That thunderstorm was completely missed somehow, by both ALDARS and the LAWRS observer. It was still putting out a lot of lightning as of 2225Z:
All of those yellow, orange, and brown dots represent lightning strikes within the past hour, the darker dots being older strikes. The dots drop off the live lightning map after one hour. So the Erie area was covered in lightning strikes, during an hour when KERI did not even report lightning!
Erie also missed a thunderstorm, between 1615-1715Z:
METAR KERI 101651Z VRB06KT 2SM R06/4000VP6000FT RA FEW044 BKN095 OVC110 22/17 A3009 RMK AO2 RAB40 SLP184 P0002 T02220172
METAR KERI 101751Z 33007KT 10SM SCT120 24/19 A3007 RMK AO2 RAE05 SLP179 P0005 60007 T02440189 10278 20206 58007
14. Decatur, Illinois, 10(11) May 2015:
The Decatur Airport was reporting VCTS as early as 2354Z:
METAR KDEC 102354Z 18007KT 10SM VCTS CLR 26/18 A2994 RMK
AO2 SLP133 T02560178 10272 20250 55009
At 0037Z, a lightning bolt struck 3-4 miles SW of the airport:
That should have triggered a SPECI to change the VCTS to a TS, but it did not. Then, heavy rain and a squall to 41 knots hit the airport:
SPECI KDEC 110043Z 21025G41KT 2 1/2SM VCTS +RA BR SQ FEW023
SCT039 BKN060 19/17 A3001 RMK AO2 PK WND 22041/0037
RAB39 PRESRR P0014 T01940172
Even at 0050Z, VCTS was being reported instead of TS:
SPECI KDEC 110050Z 23014G34KT 1 1/4SM VCTS +RA BR BKN029
BKN041 OVC085 18/17 A3001 RMK AO2 PK WND 22041/0037
RAB39 P0029
That was despite 4-6 lightning bolts striking within 1 mile of the airport, depending on the reference point, at or right before 0045Z:
The METAR did not record a TS within 5 miles:
METAR KDEC 110054Z 22014KT 2SM VCTS RA BR BKN036 BKN060 OVC085
18/17 A3000 RMK AO2 PK WND 22041/0037 RAB39 SLP156
P0030 T01830167
Is this what we really want? Lightning strikes 1 mile away from an airport, that are reported as being 5-10 miles away?
Late edit:
Despite VCTS beginning at 2354Z, with a gust to 41 knots soon after; the VCTS ended at 0220Z, without ever being changed to TS.
Setting a lightning map to encompass that period, showed this:
There were over 2 dozen lightning strikes within the red 5-mile range ring! All of those bolts met TS criteria, when only VCTS was
recorded. Lightning possibly struck the airport, or very close to it:
15. Myrtle Beach, South Carolina, 11 May 2015:
This site should have begun a TS or at least a VCTS, as early as 1907Z, for a LTG strike SW of the airport, along the beach:
Sometime between 1919Z and 1923Z, there was a lightning strike at the edge of the airport, just east of Ardmore Ave.:
By zooming in a few minutes later, the position of the strike can be seen better:
However, the Grand Strand Airport did not report a VCTS until 1933Z:
METAR KCRE 111853Z 20013G21KT 2SM HZ BKN005 25/22 A3011 RMK
AO1 LTG DSNT NE AND SW CIG 002V007 SLP196 T02500222
SPECI KCRE 111933Z AUTO 20014G20KT 2SM VCTS -RA BR SCT005
BKN033 OVC060 24/22 A3011 RMK AO1 LTG DSNT NE
AND SW AND W RAB11 P0000 T02390217
Of course, KCRE should have been reporting TS, instead of VCTS! Lightning was able to be pinpointed to a location either at or just off airport property, as noted in the chart above.
That was the 15th level C weather observing site in a survey period of just 5 days, that had issues reporting thunderstorms. Certainly,
retaining weather observers at our nation’s level A and B airports, adds another level of safety regarding thunderstorms; does not detract from ATC duties by increasing controller workload; and is part of the pro-active culture the FAA seeks.
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Post by tornado on May 18, 2015 14:51:06 GMT -5
Tornado, We were a test site for 3.10, they conducted the tests during the Winter Months when no TS activity was occurring to see if ALDARS was operating correctly to switch from VCTS to TS. Officials signed off on it with no real data from our site.
Well I have data that I didn't post, that shows ALDARS working fairly decently at times. But this site has a disclaimer that it doesn't catch all
the lightning strikes. It also says it is for entertainment purposes only, but that disclaimer appears to be so they aren't held liable for the data. From what I've seen, the data is very good.
I sent this report to my contractor, and he said he made copies to pass out at the meeting last week. I'm just now posting this because I was out of town Thursday and Friday. But this is another area I'm going to be watching closely. It's just better to have the real-time lightning data, than archived lightning data, because users can zoom in down to street level with the live lightning data.
That's just this site. If there's a contractor or observer out there that has purchased zoomable archived lightning data, that would be even better!
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Post by tornado on May 18, 2015 18:56:38 GMT -5
16. North Las Vegas, Nevada, 18 May 2015:METAR KVGT 181953Z 33012KT 10SM -RA BKN065 OVC080 16/08 A2996 RMK AO2 RAB1855 SLP148 P0000 T01560083 No lightning remarks to indicate LTG 10-30 miles away; nor VCTS, nor TS. But the chart below arguably shows 2 lightning strikes within 4 miles:  The scale on the chart is 1 mile. 17. Santa Fe, New Mexico, 18 May 2015:For whatever reason, ATC logged off ASOS, and let ALDARS handle what turned out to be thunderstorm activity: METAR KSAF 181953Z 16014G22KT 10SM FEW080 SCT100 22/00 A3020 RMK AO2 PK WND 14030/1941 SLP155 T02170000 METAR KSAF 182053Z AUTO 14022G32KT 10SM SCT080 22/00 A3017 RMK AO2 PK WND 11033/2007 SLP144 T02220000 58017 METAR KSAF 182153Z AUTO 13025G54KT 7SM -RA FEW050 BKN070 18/04 A3015 RMK AO2 PK WND 14054/2145 RAB47 SLP146 P0000 T01780039 METAR KSAF 182253Z 14020G26KT 10SM -RA SCT055 OVC070 17/05 A3016 RMK AO2 PK WND 13037/2226 SLP153 P0000 T01720050 There was a wind gust to 54 knots at 2145Z. What could have caused that?  I didn't see that until quite awhile after the strong wind gust, but I did notice the lightning nearby. The above lightning map shows a strike within about 6 miles. But not only was VCTS not reported, DSNT LTG (10-30 miles away) was not even reported, at either 2053Z, 2153Z or 2253Z. The next chart shows another bolt struck about 6 miles to the north, and another closer strike about 3 miles to the SW:  TS would have been warranted for that lightning strike 3 miles away; VCTS should have begun for either of the 2 bolts striking about 6 miles away. But no TS, VCTS, nor DSNT LTG was reported! The best explanation for that 54 knot wind gust, is that a thunderstorm produced it- a thunderstorm that ALDARS at KSAF missed! Edit: case study:Here was the radar from northern New Mexico at 2119Z;  There was some shower activity near KSAF. Below is the audio archive from KSAF TWR beginning at 2130Z on May 18th. KSAF-ZAB-May-18-2015-2130Z.mp3 (3.6 MB) At 14:28 into the audio file, a controller gave the wind as 12020G30. There were 2 gliders that had just landed. The only reference by a controller to the 54 knot wind gust, began at 18:34 into the audio file. You can hear a female controller say, “Winds 170 at 10… it’s showing gust to 54, but does not appear to be gusting that much right now.” Fortunately there was very little traffic at KSAF at that moment. That much wind could flip a glider though. I did not hear any references to lightning or thunderstorms during that half hour on the audio. The controllers seemed to be more concerned about dogs near the runway, than the weather.
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Post by tornado on May 18, 2015 21:19:58 GMT -5
18. San Angelo, Texas, 18 (19) May 2015:
The LAWRS site at San Angelo (KSJT) had this sequence this past hour:
METAR KSJT 190051Z 09012KT 10SM CLR 29/16 A2997 RMK AO2 LTG
DSNT S AND SW SLP125 T02940161
SPECI KSJT 190144Z 09013KT 10SM VCTS FEW060 SCT080 28/17
A2998 RMK AO2 LTG DSNT S-W T02830167
METAR KSJT 190151Z 10013KT 10SM TS SCT060 28/17 A2997 RMK
AO2 LTG DSNT S-W TSB50 SLP125 T02830167
But the first lightning map shows a lightning strike about 17,000 feet (just over 3 miles) to the
northeast of KSJT at 0132Z:
That lightning strike should have registered on ALDARS to start a TS. Users had to wait 18 minutes
for ALDARS to catch up (TSB50).
The second chart (below) showed a lightning strike about 2 miles west of KSJT just before 0143Z:
If that strike had been the one to trigger the TS on ALDARS at KSJT, it would have shown up as
TSB43 or TSB44. It didn't.
So which lightning bolt did trigger ALDARS to begin reporting TS within 5 miles? It appears this
one did:
So ALDARS missed a TS for the first two lightning bolts, and started a thunderstorm as a result of the third strike.
Later, at 0229Z, there was a cluster of 3 lightning strikes 3-5 miles away, to the southwest:
Yet, KSJT ended the thunderstorm, only to restart it 2 minutes later:
METAR KSJT 190251Z 10014G19KT 10SM -TSRA FEW036 BKN046 OVC110
26/19 A2998 RMK AO2 LTG DSNT ALQDS RAB05 TSE31B33
PRESFR SLP130 P0001 60001 T02560189 55002
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Post by tornado on May 18, 2015 22:18:35 GMT -5
19. Ithaca, New York, 18 (19) May 2015:
This entire past hour, or at least from 0157Z-0256Z, Ithaca (KITH) reported VCTS:
METAR KITH 190156Z 18009KT 10SM BKN050 21/19 A3001 RMK AO2
T02050188 SLP154
SPECI KITH 190203Z AUTO 17011KT 9SM VCTS BKN100 21/19 A3000
RMK AO2 BKN V SCT LTG DSNT ALQDS TSB0157
SPECI KITH 190238Z AUTO 32015KT 2 1/2SM R32/2400VP6000FT
+VCTSRA BR SCT012 BKN029 OVC045 19/18 A3003 RMK
AO2 BKN V SCT LTG DSNT ALQDS TSB0157RAB25 P0048
SPECI KITH 190241Z AUTO 33013KT 1 3/4SM R32/2200VP6000FT
+VCTSRA BR FEW008 BKN014 OVC045 19/18 A3003 RMK
AO2 OVC V BKN LTG DSNT ALQDS TSB0157RAB25 P0084
SPECI KITH 190247Z AUTO 34007KT 1 3/4SM R32/2200V4500FT +VCTSRA
BR SCT008 BKN016 OVC045 19/18 A3004 RMK AO2 LTG
DSNT NE-S TSB0157RAB25 P0123 WSHFT 0228
METAR KITH 190256Z AUTO 26006KT 3SM +RA BR SCT008 BKN016
OVC022 18/18 A3004 RMK AO2 53008 60140 T01830177
LTG DSNT NE-SE TSB0157E56RAB25 P0143 WSHFT 0228
SLP166
After 0244Z, I expected the VCTS to turn into a TS, based on the closeness of 2 lightning strikes, to both the
north and south of the airport:
But the ASOS, now on AUTO mode after ATC went home for the evening; either did not detect those 2 strikes
via ALDARS, or improperly ranged them. At 0251Z, another bolt clearly struck within 5 miles to the NE of KITH:
5 minutes after that bolt struck, KITH ended the VCTS! It should have reported a TS for 10 more minutes.
Late edit: does this look like a TS, or a VCTS?
20. Garden City, Kansas, 19 May 2015:
For part of the past hour, Garden City (KGCK) reported VCTS:
METAR KGCK 191454Z 07020G28KT 3/4SM VCTS +RA BR SCT008 BKN019
OVC085 06/06 A3014 RMK AO2 PK WND 07028/1448 LTG
DSNT SE SLP204 P0050 60094 T00610056 56018
SPECI KGCK 191500Z 08015KT 1 3/4SM VCTS -RA BR SCT008 BKN022
OVC055 06/06 A3017 RMK AO2 WSHFT 1446 LTG DSNT
SE P0000 T00610056
SPECI KGCK 191503Z 09013KT 3SM VCTS RA BR SCT008 BKN026 OVC060
06/06 A3018 RMK AO2 WSHFT 1446 LTG DSNT E AND
SE P0001 T00610056
That was despite having lightning strikes about 1 and 3 miles to the northeast, at 1452Z:
Instead of VCTS, KGCK should have reported TS during the early part of that hour. Again, ALDARS did not properly measure
the distance to those lightning strikes.
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Post by tornado on May 19, 2015 11:45:49 GMT -5
21. Montgomery, Alabama, 19 May 2015:
Here's a case of when ALDARS began a VCTS, when it shouldn't have. The lightning map below
has a scale of 5 miles. 3 lightning strikes to the NW can be seen, all of which were outside 10 miles:
The valid time of the map is 1620Z. The colored circles are orange, because the lightning strikes were
several minutes old. Those lightning strikes appeared to be 18-21 miles away. The sequence of METARs and SPECIs from Montgomery (KMGM) was as follows:
METAR KMGM 191553Z 00000KT 10SM FEW110 28/21 A3012 RMK AO2
LTG DSNT N AND NW SLP195 T02830211
SPECI KMGM 191605Z 00000KT 10SM VCTS FEW023 SCT110 28/20
A3012 RMK AO2 LTG DSNT N TSB1559=
SPECI KMGM 191612Z 33004KT 10SM FEW023 29/21 A3011 RMK AO2
TSB1559E06
ALDARS began a VCTS at 1559Z, but ended it at 1606Z. The data shows that it shouldn't have begun
as VCTS at all. Something was not right with ALDARS, since there can't be a 7-minute thunderstorm.
22. David Wayne Hooks Arpt, Houston, Texas, 19 May 2015:
Firstly, this airport (KDWH) did report a thunderstorm between 1805Z-1811Z:
SPECI KDWH 191811Z VRB03KT 10SM BKN032 BKN045 OVC090 29/23
A3004 RMK AO2 TSB05E11
METAR KDWH 191853Z 10006KT 10SM SCT034 27/21 A3003 RMK AO2
TSB05E11 SLP166 T02720211
Since that was a 6-minute thunderstorm that ended as soon as the SPECI to report it transmitted,
users weren't sure if that was supposed to be a VCTS or a TS. At 1836Z, this was the situation:
That certainly was a TS within 5 miles! But by 1843Z, there had been a whole bunch of younger lightning strikes
within 10 miles:
Still, those 6 minutes, TSB05E11, was all the thunderstorm activity that was reported at KDWH that hour.
Late edit:
Between 1815-1900Z, after the thunderstorm officially ended, this was the archive of lightning strike data around KDWH:
Zooming in, there had been plenty of lightning striking nearby, even after KDWH reported TSE11:
Did KDWH end the thunderstorm, just because the cell had moved off to the east?
The radar image above is valid at 1820Z. Yet at 1819Z, lightning struck the airport!
Compare the above image, to the position of the control tower on the airport diagram:
The control tower is the little white spot on the 1819Z zoomed image, just below the "or" in the word airport. Based on that, the
best-resolved distance to the lightning strike, from the control tower, would be about 1,000 feet, or 1/5 of a mile. That would
place the lightning strike at or next to taxiway E, just south of the tower. How is it that thunder could not be heard? Or if heard, how is it that thunder wasn't reported after that nearby strike? Did the LAWRS observer get complacent, because the rain had moved off to the east? This is a case when the closest lightning strike, occurred outside of the core of the thunderstorm rain shaft.
Also, recall that this was the SPECI, prior to lightning striking the airport:
SPECI KDWH 191811Z VRB03KT 10SM BKN032 BKN045 OVC090 29/23
A3004 RMK AO2 TSB05E11
By rule, in aviation weather reporting (according to FAA Order 7900.5C) a thunderstorm cannot last less than 15 minutes. Recording
TSB05E11 was an error; a 6-minute thunderstorm is not permissible by the rules. Therefore, a thunderstorm that began at 1805Z, could not legally have ended before 1820Z. Yet, lightning struck the airport at 1819Z. If the thunderstorm had been reported correctly, the LTGCG AT AP would have struck while TS was already being reported. However, TSE11 gave an "all clear" to ground crews, that lightning was no longer within 5 miles. Obviously, the all clear was given too soon!
23. Grand Junction, Colorado, 19 May 2015
Grand Junction Walker Field (KGJT) did report a thunderstorm in the vicinity this past hour:
METAR KGJT 192253Z 00000KT 10SM SCT085 16/02 A2996 RMK AO2
LTG DSNT SW RAB11E39 SLP108 P0000 T01610022
SPECI KGJT 192341Z 14009KT 10SM VCTS SCT100 16/03 A2997 RMK
AO2 LTG DSNT SE-W TS S-W MOV LTL OCNL LTGCG VCSH
T01610028
METAR KGJT 192353Z 14010KT 10SM VCTS BKN090 16/03 A2997 RMK
AO2 LTG DSNT S AND NW SLP112 TS S-W MOV LTL OCNL
LTGCG VCSH 60002 T01610033 10172 20122 55004
SPECI KGJT 200010Z 18009KT 9SM -RA SCT060 BKN075 OVC090 14/06
A2997 RMK AO2 LTG DSNT SW AND W RAB09 P0000 T01440061
However, their remarks indicated that the thunderstorm was within 5 miles, by the lack of "VC"
as a descriptor (i.e. TS VC S-W). So was ALDARS right, or was it ATC?
Looking at the above map, there were 2 lightning strikes about 3-4 miles to the southwest of KGJT.
So why didn't ATC edit the VCTS in present weather, to make it TS? Apparently they were relying
on the reliability of the automation of ALDARS. But in this case, ALDARS failed to measure
the range to the lightning strikes properly.
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Post by tornado on May 19, 2015 13:20:32 GMT -5
The real-time aspect of this project came about, because I couldn't find any free street-level mapping of lightning data elsewhere.
The lightningmaps.org site has data going back 5 years, but it isn't zoomable. Still, I did find some obvious issues with ALDARS.
Philadelphia-Northeast PA, 3 Jul 2014:
METAR KPNE 032254Z 21013G21KT 10SM BKN035 OVC047 32/22 A2989
RMK AO2 SLP121 T03170222
SPECI KPNE 032318Z 28033G57KT 2 1/2SM RA SQ FEW012 BKN033 OVC065 29/22 A2991
RMK AO2 PK WND 25057/2317 RAB18 P0000 T02940222
Another severe rain shower? Or was thunder missed at this site? That gust to 57 knots would qualify a thunderstorm as severe, but none was reported.
The TAF included thunderstorms. There were level 6 echoes within 2 miles NW of the airport at 2320Z. The map below, has a valid time of 2300Z
on 3 Jul 2014:
That's fairly close to when the gust to 57 knots occurred. The KPNE area was covered in lightning, albeit we can't tell how close it was to the airport
at specific times. The next chart compiled all the lightning strikes between 1800Z-2400Z on 3 Jul 2014:
Notice that the Philadelphia area was covered with lightning strikes! Yet, KPNE did not record thunderstorms or lightning at all that day, according to
archived METAR data: www.wunderground.com/history/airport/KPNE/2014/7/3/DailyHistory.html?req_city=Philadelphia&req_state=PA&req_statename=&reqdb.zip=19114&reqdb.magic=4&reqdb.wmo=99999
Edit: Now that lightningmaps.org has detailed archived lightning data, I will add this to the queue of cases. It will be case 109.
Here is the archived lightning display around KPNE, for the half hour of 2300Z-2330Z on 3 Jul 2014:
There were 11 lightning strikes within the red 5-mile range ring around KPNE; and perhaps 2 dozen more within the green 10-mile range ring.
Both TS and VCTS criteria were met, without this site reporting lightning nor thunder that hour!
Rome NY, 8 Jul 2014:
METAR KRME 082253Z 32032G50KT 1/2SM RA SQ FEW014 BKN080 OVC100
24/20 A2954 RMK AO2 PK WND 30050/2251 RAB52 SLP999 P0018 T02390200 RVRNO
Here was another “severe rain shower”. Thunder was not reported at this site on the 8th.
4 people were killed in upstate New York, from severe thunderstorms.
From nearby Syracuse, a contract weather site:
SPECI KSYR 082203Z 22026G36KT 1SM R28/2000VP6000FT +TSRA SQ SCT030CB BKN050 OVC075 27/21 A2956 RMK AO2 PK WND 23036/2202 TSB03
PRESRR OCNL LTGCGIC SW TS SW MOV NE P0002
Are we to believe it didn’t thunder yesterday in Rome, New York? According to the METAR archives on Weather Underground, it did not: www.wunderground.com/history/airport/KRME/2014/7/8/DailyHistory.html?req_city=Rome&req_state=NY&req_statename=&reqdb.zip=13440&reqdb.magic=1&reqdb.wmo=99999
However, a look at archived lightning data, shows dense lightning coverage over the entire region southeast of Lake Ontario, where Rome NY is located:
The above chart covers the period 1800Z-2400Z on 8 Jul 2014. Yet, KRME did not report thunder during that time. Nor were there any TSNO nor LTG remarks at all!
Fort Smith AR, 23 Jul 2014:
METAR KFSM 231953Z 31035G57KT 5SM -RA SQ FEW034 BKN055 OVC070 27/23 A3001 RMK AO2 PK WND 30057/1949 RAB50 PRESRR SLP156 P0000 T02720228
SPECI KFSM 231956Z 30025G57KT 1 3/4SM RA SQ FEW016 BKN035 OVC065 24/21 A3000 RMK AO2 PK WND 31037/1954 VIS 1/2V5 P0000 T02390211
Despite the fact that there was a wind gust to 57 knots, this supposedly occurred without thunder. This goes down as another "severe rain shower"! Yet, the Storm Prediction Center
had info on that event on their Storm Reports page. It was listed as:
1949 66 FORT SMITH SEBASTIAN AR 3539 9440 THUNDERSTORM WIND GUSTS TO 66 MPH AT THE FORT SMITH REGIONAL AIPORT.
www.wunderground.com/history/airport/KFSM/2014/7/23/DailyHistory.html?req_city=KFSM&req_state=AR&req_statename=Arkansas&reqdb.zip=72903&reqdb.magic=4&reqdb.wmo=99999
But according to the Weather Underground link above, it wasn't reported as a thunderstorm in a METAR or SPECI at KFSM! The archived data on the lightningmaps.org site, has a higher resolution map of Oklahoma/Kansas (also Texas and Florida). Fort Smith is located right where the Oklahoma-Arkansas border bends. But if you click on the map to enlarge it, you'll see the Fort Smith area covered in lightning:
That chart compiled all the lightning strikes between 1800Z-2400Z on 23 Jul 2014. The color of the strikes can show the time of day, with the reds and
purples being late in the day. So we can surmise that ALDARS was not working properly because:
- the archived lightning data shows a lot of lightning in the Fort Smith area at that time
- a squall to 57 knots was more indicative of a thunderstorm than a rain shower
- the Storm Prediction Center reported the wind gust (66 mph) as being from a thunderstorm. The SPC surely has high-resolution archived and live lightning data
Texarkana, AR, 23 Jul 2014:
As with Ft. Smith, a mesoscale convective complex with a lot of lightning, moved south along the western Arkansas border. Referring back to the map above, the 6-hourly lightning archive clearly showed Texarkana covered in lightning strikes. Yet, KTXK was another site that did not report thunder at all on the 23rd:
www.wunderground.com/history/airport/KTXK/2014/7/23/DailyHistory.html?req_city=KTXK&req_state=AR&req_statename=Arkansas&reqdb.zip=71854&reqdb.magic=4&reqdb.wmo=99999
The daily sequence of METARs included another near-severe rain shower:
METAR KTXK 232253Z 01022G45KT 5SM -RA SQ SCT017 BKN034 BKN085 23/20 A3009 RMK AO2 PK WND 01045/2246 RAB46 SLP186 P0002 T02330200
It very much appears that ALDARS failed at Texarkana, as well as Fort Smith, on that date.
Considering that lightning data shows all 4 of the above sites with many lightning strikes in the area, which is more likely: that rain showers were producing wind gusts of 45-57 knots? Or that ALDARS failed to detect lightning strikes?
Now, since we know that lightning hasn't downed a commercial airliner in the U.S. since December 1963, lightning is actually not the biggest hazard during thunderstorms. Hail, icing, heavy rain, tornadoes, etc., can all cause worse problems for pilots. But perhaps the biggest issue is wind: wind shear, microbursts, etc. Properly identifying thunder- storms is one of the first lines of defense for a pilot to have information about tricky winds near convective cells. In all 4 cases above though, pilots could have been surprised by wind shear, because the cells were not identified as thunder- storms. If ALDARS isn't always reliable, how does the FAA know their LLWAS is always reliable?
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Post by weatheri on May 19, 2015 16:33:29 GMT -5
Just a quick note to say THANK YOU! I know this takes a lot of time and your hard work is appreciated.
Regards.
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Post by tornado on May 20, 2015 14:21:43 GMT -5
24. Gulfport-Biloxi Regional Airport, Mississippi, 20 May 2015:2 consecutive observations out of Gulfport (KGPT) showed no lightning activity: METAR KGPT 201753Z 19008KT 180V240 10SM SCT031 31/22 A3000 RMK AO2 SLP159 T03060217 10306 20228 58006= METAR KGPT 201853Z 19008KT 10SM CLR 31/22 A2999 RMK AO2 RAB12E22 SLP153 P0000 T03060217 Yet, lightning strikes were measured within 10 miles:  The above chart was valid at 1842Z. One can see a recent cluster of 5 lightning strikes to the northeast. There was also a lightning bolt that struck to the south, clearly within 5 miles.  Measuring the distance from the KGPT airport, to the lightning bolt that struck along interstate 10, yielded a distance of 6.24 miles. That's clearly close enough to generate a VCTS. Not only that, measuring the distance from the KGPT airport, to the lightning bolt that struck along E. Pass Rd., yielded a distance of 1.74 miles. That's clearly close enough to generate a TS. However, both ALDARS and ATC missed those 6 bolts of lightning; not only was TS nor VCTS reported, LTG
didn't even appear in remarks! If ALDARS is not representative, out of service, or not installed; it falls to ATC to identify thunderstorms. Somehow, that didn't happen this past hour. How do we know that data obtained from lightningmaps.org is accurate? Well, I was watching KECP this hour, which is the NW Florida Beaches Intl Airport. Their METAR this past hour, showed distant lightning: METAR KECP 201853Z 21014G20KT 10SM SCT044 33/21 A2995 RMK AO2 LTG DSNT N AND NW SLP154 T03280211 At 1923Z, lightningmaps.org stations recorded a bolt striking just over a mile to the east of KECP:  3 minutes later, KECP took a SPECI: SPECI KECP 201926Z 21014G18KT 10SM TS BKN044 BKN055 32/21 A2996 RMK AO2 FRQ LTGCG W-E TS W-E MOV LTL T03170206 So the data on lightningmaps.org is good, because one can anticipate a site taking a SPECI for TS or VCTS activity. It's when that doesn't happen, that there seems to be problems with ALDARS. Late edit:This is an upgrade of the case; upon revisiting the archived data, this case was found to be worse than originally described.
Gulfport (KGPT) had a thunderstorm during the late afternoon on the 20th:
METAR KGPT 201853Z COR 19008KT 10SM SCT038 31/22 A2999 RMK AO2 RAB12E22 SLP153 P0000 T03060217
METAR KGPT 201953Z 19006KT 10SM SCT038 29/22 A2999 RMK AO2 SLP154 T02890217
SPECI KGPT 201954Z COR 19006KT 10SM SCT039 29/22 A2999 TS RMK LTGAO2 T02890217
METAR KGPT 201958Z 20009KT 10SM CLR 29/22 A2998 RMK AO2 TS 5N MOV E OCNL LTGICCCCG T02890217
SPECI KGPT 202012Z VRB05KT 10SM TS SCT039 29/22 A3000 RMK AO2 TSB06 TS 5N MOV E OCNL LTGICCCCG T02940217
But the thunderstorm wasn’t properly reported during that time. First, a SPECI was sent to include the thunderstorm at 1954Z, but had to be corrected. Even then, an error was made; TS RMK LTGAO2 was run together in the wrong place. TS should have gone after the visibility. By 1958Z, it was decided that the TS was 5 miles to the north- even with clear skies, and no thunderstorm recorded in present weather. At 2012Z, the thunderstorm was again said to be 5N- more on that shortly.
The first problem, is that setting the lightning display to end at 1940Z (14 minutes before any mention of thunder), shows that there had already been plenty of lightning striking within 10 miles of KGPT:
The oldest lightning bolt plotted, is the bolt about 5 miles to the NE, north of Interstate 10 near the intersection of Jordon Rd. with Lorraine Rd. That bolt struck about 1729Z, well before any thunder was reported by KGPT. A couple of strikes were about a mile from the runways:
So, well before 1954Z, there should have been a thunderstorm reported. But once one was reported, it was mentioned as being 5 miles to the north. That was at 1958Z. But looking at the period from 1950-1955Z, lightning very nearly struck the airport:
The distance from that strike, to the control tower, can best be estimated as 1.15 miles away:
The control tower is on the south side of KGPT, while the lightning hit just north of airport property, north of Airport Rd. Why was the thunderstorm described as 5 miles to the north, when lightning had just struck 1.15 miles north of the control tower? The distance from the lightning strike, to the Airport Reference Point (ARP), would be even less; while the distance from the lightning strike to the terminal, would be even less than that to the ARP. Could it be because of the radar signature?
At 1955Z, the airport was still well outside the main rain shaft produced by the thunderstorm. It wasn’t outside the area where lightning was striking. This is another case when lightning struck outside the main rain shaft, and didn’t get reported properly. After not reporting the thunderstorm soon enough; LAWRS didn’t have enough time to measure the distance to the nearest lightning strike in the 1958Z and 2012Z SPECIs. Was that a problem?
While the thunderstorm was reported as 5N, lightning twice struck the airport! Hopefully, ground crews were alerted to the lightning danger, once TS was reported. But since TS wasn’t recorded in the body of a SPECI until 2012Z, did ground crews get the word in time? How is such a thing not hazardous to personnel and property at an airport?
25. Key Field, Meridian, Mississippi, 20 May 2015:At Key Field, a thunderstorm was reported between 1914Z-1931Z, after which time VCTS was reported: SPECI KMEI 201914Z 27019G28KT 10SM TS SCT041 28/21 A2999 RMK AO2 PK WND 27028/1914 TSB14 T02830211 SPECI KMEI 201923Z 28017G34KT 1 1/2SM R01/2600VP6000FT TS HZ FEW021 SCT041 BKN048 22/19 A2999 RMK AO2 PK WND 26034/1916 TSB14 FRQ LTGICCCCG W TS W MOV E P0001 T02170189 SPECI KMEI 201931Z 30005KT 1 1/4SM R01/4000VP6000FT VCTS BR SCT031 BKN043 BKN100 22/19 A3000 RMK AO2 PK WND 26034/1916 TSB14E31 FRQ LTGICCCCG W TS W MOV E P0018 T02170194 The first note about that sequence, is that a CWO would include the lightning frequency, type, and thunderstorm location and movement, even on the first report (1914Z). Also, it does not appear that the remarks were updated. In any event, the VCTS was soon ended: SPECI KMEI 201938Z 00000KT 6SM VCTS BR FEW029 BKN042 BKN100 22/20 A3002 RMK AO2 PK WND 26034/1916 TSB14E31 PRESRR FRQ LTGICCCCG E TS E MOV E P0018 T02220200 SPECI KMEI 201947Z 07006KT 10SM -RA SCT029 BKN036 OVC110 22/21 A3001 RMK AO2 PK WND 26034/1916 RAB47 TSB14E31 P0018 T02220206 METAR KMEI 201958Z 06004KT 10SM -RA FEW028 SCT050 BKN110 22/21 A3000 RMK AO2 PK WND 26034/1916 RAB47 TSB14E31 SLP154 P0018 T02220206 However, the thunderstorm within 10 miles (VCTS) should have continued, which KMEI did not report. Here was the situation at 1943Z:  2 lightning bolts had just struck in Bonita Lakes Park. The following chart shows the distance to one of the bolts:  One of the lightning strikes was 5.89 miles away. More lightning bolts were recorded at 1947Z:  That bolt was even closer. Since it struck inside the bend in state route 145, it measured at 3.56 miles from Key Field:  That should have restarted the thunderstorm; instead; KMEI dropped any mention of thunder in the 1958Z report, except for mentioning the thunderstorm ended at 1931Z. So ALDARS was accurate to a point, and then missed later lightning strikes that should have continued the VCTS, then restarted the TS. Attachments:
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Post by skobie on May 20, 2015 14:59:17 GMT -5
Wow Tornado, that's really in-depth. Excellent job! Another place to direct unknowing User Groups.
skobie
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Post by tornado on May 20, 2015 17:25:14 GMT -5
26. Florence Regional Airport, South Carolina, 20 May 2015:
This past hour, Florence (KFLO) had heavy rain:
METAR KFLO 202053Z AUTO 10007KT 10SM FEW065 BKN110 28/21
A2988 RMK AO2 RAB10E36 SLP113 P0000 60000 T02780206
56012 TSNO
SPECI KFLO 202134Z 26003KT 2SM -RA BKN060 BKN070 OVC095 27/21
A2990 RMK AO2 RAB24 PRESRR P0006 T02670211
SPECI KFLO 202146Z 29013G22KT 3/4SM +RA SCT037 BKN060 OVC075
25/21 A2991 RMK AO2 RAB24 P0026 T02500211
METAR KFLO 202153Z 28010G22KT 1SM +RA BR BKN041 OVC060 24/22
A2991 RMK AO2 RAB24 SLP126 P0036 T02390217
I monitored the lightning data, and there should have been a VCTS reported this past hour:
That lightning bolt was 5.37 miles to the west of Florence.
There were other lightning bolts that struck further north, some of which were less than 10 miles from the airport.
For example, a bolt struck between Pisgah Road and Stokes Road. That bolt was exactly 6 miles from the airport:
So we see that during the hour from 2053Z-2153Z, ALDARS at KFLO missed reporting a VCTS.
Pensacola, Florida:
METAR KPNS 202153Z 23012G18KT 10SM TS CLR 31/22 A2994 RMK
AO2 LTG DSNT NW-NE TSB50 SLP138 T03060217
TS? Yes. CLR? No.
Montgomery, Alabama:
METAR KMGM 202153Z 29007KT 10SM VCTS FEW055 32/19 A2994 RMK
AO2 LTG DSNT W-N TSB48 SLP136 T03170189
SPECI KMGM 202236Z 28024G32KT 1 3/4SM VCTS -RA FEW029 BKN055
OVC110 23/19 A2999 RMK AO2 PK WND 28038/2223 LTG
DSNT ALQDS RAB35 P0001
SPECI KMGM 202241Z 29018G31KT 3/4SM +TSRA BR SCT029 BKN042
OVC070 21/19 A3000 RMK AO2 PK WND 28038/2223 LTG
DSNT ALQDS RAB35 P0014
Note that the strongest winds, were during the VCTS, before heavy rain made the airfield IFR.
Wouldn't pilots have been helped by a remark of TS VC W MOV E (or SE) on the 2153Z METAR?
That's the value of having a CWO, giving the pilots extra information about hazards, ahead of time!
A CWO (Contract Weather Observer) has the time to study movement of storms.
27. Monroe, Louisiana, 20 May 2015:
Monroe Regional Airport (KMLU) reported a VCTS this past hour:
METAR KMLU 202153Z 27010KT 10SM BKN047 BKN065 32/20 A2995
SPECI KMLU 202212Z 29008KT 10SM VCTS FEW050 SCT075 32/21
A2994 RMK AO2 LTG DSNT SW T03170206
SPECI KMLU 202251Z 30009KT 10SM FEW050 31/21 A2994 RMK AO2
LTG DSNT S AND SW
METAR KMLU 202253Z 31008KT 10SM FEW050 31/20 A2994 RMK AO2
LTG DSNT S SLP138 T03110200
However, lightning data showed some close strikes to the airport. 2 of those bolts were just before 2241Z:
Measuring the bolt that struck near Highway 15 and S. 6th Street, we find a distance from the airport of 3.6 miles:
But another bolt struck even closer. Measuring the one that hit between Nutland and Parker Roads, near the
Best Western, we find a distance of 1.94 miles to the airport:
Any or all of those 4 lightning strikes in that cluster, should have triggered ALDARS to take a SPECI for VCTS
becoming TS. But that didn't happen.
Late edit:
Archived data shows a total of 8 lightning strikes within 5 miles, that met TS criteria.
There were 5 strikes in that cluster to the SW.
28. Pensacola, Florida, 20 May 2015:
The Pensacola Intl Airport (KPNS) had a thunderstorm at 2153Z:
METAR KPNS 202153Z 23012G18KT 10SM TS CLR 31/22 A2994 RMK
AO2 LTG DSNT NW-NE TSB50 SLP138 T03060217
Already posted was a lightning map, with a radar overlay, to demonstrate that it was not clear. KPNS
ended the TS by transitioning it to a VCTS (thunderstorm 5-10 miles away) at 2226Z, and kept the
VCTS for the 2253Z METAR:
SPECI KPNS 202232Z 25014G21KT 10SM VCTS BKN043 BKN110 31/22
A2994 RMK AO2 LTG DSNT N AND NE TSE26 T03060217
METAR KPNS 202253Z 27012KT 10SM VCTS SCT043 OVC050 29/21
A2996 RMK AO2 LTG DSNT N AND NE TSE26 SLP145 T02940211
However, the TS should have either been kept, or restarted. By 2250Z, there had been several
lightning strikes in adjoining Escambia Bay, just to the east of the airport:
Measuring the most recent lightning strike, produced a distance of 3.34 miles from the airport:
That was not even the closest recent lightning strike! There was a cluster of 5 bolts that struck
within 5 miles of the airport, not long before 2250Z. But ALDARS claimed there had been no
lightning bolts within that distance since 2211Z (since it ended the TS at 2226Z). So ALDARS
did not detect nearby lightning bolts after the thunderstorm had ended; failing to restart a TS. |
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