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Post by tornado on Jul 6, 2016 11:31:26 GMT -5
Bush Field, Augusta, Georgia, Tue 5 Jul 2016: At 4:30 p.m. (2030Z), an area of thunderstorms was moving towards Bush Field (KAGS). By 4:50 p.m., they had moved generally east, and were even closer to the airport:
METAR KAGS 052053Z 29010G20KT 10SM CLR 34/21 A3001 RMK AO2 PK WND 28036/2000 WSHFT 1954 LTG DSNT ALQDS RAB11E26 SLP161 P0000 60000 T03440211 55001
While LTG DSNT ALQDS was recorded in remarks, the sky condition surely wasn't clear. A remark of CB DSNT W MOV E would have alerted pilots and users on the ground, of the approaching hazards. Then this happened:
SPECI KAGS 052115Z 27030G50KT 10SM SQ FEW047 SCT055 BKN070 29/19 A3005 RMK AO2 PK WND 26050/2109 LTG DSNT SW-NW T02940194
A squall to 50 knots struck the airport at 2109Z! Here was the radar a minute later:
The rain had not yet reached Bush Field by 2110Z. The worst of the area of "weather" was to the NW at about 10 miles, and to the SW by about 15 miles. The nearest cloud-to-ground lightning before 2109Z, was 18 miles away:
So this area of thunderstorms, produced a gust front well out ahead of it, that struck a level C airport. There was more lightning after the gust to 50 knots, than before:
Thunderstorms can produce strong wind gusts, well out ahead of the cells. KAGS didn't even report a thunderstorm until 2128Z:
SPECI KAGS 052128Z 27019G35KT 10SM VCTS -RA FEW049 BKN085 OVC100 28/21 A3007 RMK AO2 PK WND 26050/2109 LTG DSNT ALQDS RAB18 P0000 T02780206
Yet, a remark of CB DSNT W MOV E at 2053Z, would have provided 16 minutes worth of lead time of the wind event. Forbes Field, Topeka, Kansas, Thu 7 Jul 2016: METAR KFOE 070853Z 17005KT 10SM CLR 28/24 A2973 RMK AO2 SLP054 T02780239 55015 SPECI KFOE 070937Z 24011G17KT 10SM VCTS SCT065 SCT085 28/24 A2978 RMK AO2 LTG DSNT SW-N PRESRR T02780239 SPECI KFOE 070946Z 35030G63KT 6SM VCTS -RA SQ SCT023 SCT034 BKN065 24/19 A2985 RMK AO2 PK WND 33063/0940 LTG DSNT ALQDS RAB42 PRESRR P0000 T02440189 SPECI KFOE 070951Z 35021G39KT 2SM R31/4500VP6000FT +TSRA FEW015 BKN030 OVC080 21/18 A2986 RMK AO2 PK WND 33063/0940 WSHFT 0937 LTG DSNT ALQDS RAB42 TSB50 PRESRR P0010
The official start time of the thunderstorm, was 0950Z. A wind gust to 63 knots occurred at 0940Z, and wasn't reported
in a SPECI until 0946Z. The strong gust was during the VCTS, 10 minutes before the start of the TS.
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Post by tornado on Aug 8, 2016 12:07:59 GMT -5
Gwinnett County-Briscoe Field Airport, Lawrenceville, Georgia, Sat 6 Aug 2016:
Lawrenceville (KLZU) is a D level site. As such, it provided a very basic weather observation at 2230Z on the 6th:
SPECI KLZU 062230Z 22008KT 10SM SCT060 31/22 A2988 RMK ATIS G, RWY 25 SU
The radar showed a rain shower over the airport at that time:
It's unclear why rain wasn't reported. Perhaps it hadn't reached either the ASOS, or the control tower, by the time the report transmitted. In any event, by 2250Z, the radar still showed heavy rain over the airport, a level 6 cell:
But that time, the report showed a severe thunderstorm:
METAR KLZU 062250Z 23030G54KT 1/2SM +TSRAFG OVC010 26/21 A2990 RMK ATIS H, RWY 25 SU
In essence, the lead time of that thunderstorm was zero. It could have been negative, as no TSB nor PK WND times were reported. A severe thunderstorm struck the small airport with little or no warning. Hutchinson, Kansas, Sun 7 Aug 2016:METAR KHUT 070852Z AUTO 27011KT 8SM VCTS RA SCT031 BKN110 22/20 A3004 SPECI KHUT 070903Z AUTO 27022G58KT 2 1/2SM R13/6000VP6000FT VCTS +RA SQ FEW011 BKN030 BKN043 22/19 A3008 RMK AO2 PK WND 26058/0900 LTG DSNT SW-N PRESRR P0011 T02220189 SPECI KHUT 070912Z AUTO 27007KT 1SM R13/4500VP6000FT +TSRA BR FEW011 BKN025 OVC032 21/19 A3006 RMK AO2 PK WND 26058/0900 WSHFT 0852 LTG DSNT ALQDS TSB12 P0034 T02110194 There was a "severe thunderstorm in the vicinity". TSB and TSE times ought to be programmed to include VCTS.
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Post by tornado on Sept 14, 2016 13:27:19 GMT -5
Cedar Rapids, Iowa, Fri 9 Sep 2016: METAR KCID 092252Z 00000KT 10SM BKN060 23/21 A2986 RMK AO2 SLP107 T02330206 SPECI KCID 092327Z 33019G25KT 8SM -TSRA FEW021 BKN033 OVC050 20/19 A2992 RMK AO2 PK WND 32035/2316 WSHFT 2309 LTG DSNT W AND NW RAB25 TSB27 P0001 T02000189
While calm winds were on the ATIS, a wind gust to 35 knots struck the airport at 2316Z. That was even before the thunderstorm began at 2327Z.
Salina, Kansas, Fri 9 Sep 2016: METAR KSLN 092153Z 34009KT 10SM OVC044 31/22 A2985 RMK AO2 SLP094 T03060222 SPECI KSLN 092250Z 35021G30KT 10SM VCTS FEW028 FEW038 OVC046 28/22 A2988 RMK AO2 PK WND 33030/2248 LTG DSNT E-SW
A VCTS wasn’t reported until 2250Z. That was after the gust to 30 knots, while winds of 34009KT were still on the ATIS. If there was a 6-minute lag time to begin the VCTS, ASOS missed having a positive lead time of the wind gust.
Redbird Airport, Dallas, Texas, Sat 10 Sep 2016: METAR KRBD 100953Z 33007KT 10SM FEW019 BKN043 26/23 A3006 RMK AO2 LTG DSNT W-N SLP167 T02560233 SPECI KRBD 101005Z 36017G34KT 10SM TS BKN021 OVC043 24/19 A3007 RMK AO2 PK WND 34034/0959 LTG DSNT W-N TSB05 PRESRR T02390189
The worst of the wind, struck before the thunderstorm began.
Denton, Texas, Sat 10 Sep 2016: METAR KDTO 100853Z AUTO 01030G40KT 10SM VCTS SCT025 BKN030 OVC050 22/18 A3009 RMK AO2 PK WND 01040/0846 LTG DSNT W-NE SLP178 T02220178 53043 SPECI KDTO 100906Z AUTO 01022G35KT 4SM +TSRA BR BKN030 BKN038 OVC048 20/18 A3009 RMK AO2 PK WND 36038/0855 LTG DSNT W-NE RAB0858 TSB00 P0002 T02000183
The VCTS produced a wind gust to 40 knots at 0846Z, and 38 knots at 0855Z; the TS did not produce winds as strong.
Meacham International Airport, Fort Worth, Texas, Sat 10 Sep 2016: SPECI KFTW 100924Z 36012KT 10SM FEW021 BKN039 OVC120 27/22 A3005 RMK AO2 WSHFT 0904 LTG DSNT W-NE T02720217 SPECI KFTW 100929Z 36024G40KT 10SM VCTS SQ BKN021 BKN039 OVC120 25/19 A3006 RMK AO2 PK WND 35040/0927 WSHFT 0904 LTG DSNT W-NE T02500189 SPECI KFTW 100944Z 02026G44KT 4SM TSRA BKN021 BKN028 OVC037 22/18 A3007 RMK AO2 PK WND 02044/0935 WSHFT 0904 LTG DSNT W-NE RAB39 TSB38 P0002 T02170183
The strongest wind gust, was during the VCTS, at 0935Z.
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Post by tornado on Nov 2, 2016 8:11:25 GMT -5
From late October:
Sikorsky Memorial Airport, Bridgeport, Connecticut: SPECI KBDR 302005Z 33009G28KT 1 3/4SM +RA FEW017 SCT033 OVC040 18/14 A2983 RMK AO2 PK WND 32028/2002 RAB1953 PRESRR P0002 T01780139 SPECI KBDR 302050Z 01007KT 5SM VCTS -RA OVC042 18/14 A2982 RMK AO2 PK WND 32028/2002 LTG DSNT SW-NW RAB1953 P0034 METAR KBDR 302052Z NIL SPECI KBDR 302106Z 04003KT 2 1/2SM TSRA FEW031 BKN040 OVC055 18/14 A2982 RMK AO2 VIS 1 3/4V4 LTG DSNT SW P0006 T01830144
In this case, the strongest wind was before the VCTS, let alone the TS.
Idaho Falls, Idaho: SPECI KIDA 310240Z AUTO 19013KT 10SM VCTS -RA SCT060 BKN080 OVC100 16/08 A2962 RMK AO2 LTG DSNT SW-N P0001 T01560083 METAR KIDA 310253Z AUTO 25029G55KT 2 1/2SM VCTS +RA FEW023 BKN060 OVC080 13/09 A2968 RMK AO2 PK WND 21055/0250 VIS 1V5 LTG DSNT ALQDS PRESRR SLP035 P0009 60012 T01280094 55013 SPECI KIDA 310301Z AUTO 25021G38KT 2 1/2SM RA BR FEW022 BKN043 OVC090 11/08 A2971 RMK AO2 PK WND 26038/0254 WSHFT 0243 LTG DSNT S PRESRR P0002 T01060083
ALDARS did not record lightning within 5 miles for that storm. Instead, lightning was detected 5-10 miles away from the airport, so VCTS was recorded. Said VCTS still produced a wind gust that met severe criteria.
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Post by skobie on Nov 2, 2016 12:06:47 GMT -5
That's because ALDARS (and ASOS) are not meant to run by themselves, Tornado. They're a guide, at best. Of course, we both know that (along with about a million other weather people), but some in a particular department within the FAA who run this show probably wouldn't know their ass from a hole in the ground either.....
skobie
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Post by tornado on Nov 2, 2016 12:22:58 GMT -5
Well, we've had several cases this year, of severe thunderstorms that were classified as VCTS; also a severe rain shower (Idaho Falls, May 14th); and severe wind gust after a VCTS had ended (Hobbs, New Mexico, May 31st). Yet, the current programming (ASOS version 3.10) records only TSB and TSE times for TS- meaning VCTS doesn't count as a true thunderstorm. We know that not to be the case. Of course, that contradicts the 7900.5C, which states on page 76:
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Post by tornado on Nov 3, 2016 15:25:35 GMT -5
Springfield, Illinois, Wed 2 Nov 2016:METAR KSPI 022152Z 23011G18KT 10SM CLR 27/18 A3009 RMK AO2 LTG DSNT W-N PRESRR SLP185 T02720178 SPECI KSPI 022200Z 31029G41KT 10SM VCTS SQ SCT046 24/17 A3015 RMK AO2 PK WND 31041/2158 LTG DSNT W-N PRESRR T02440167 SPECI KSPI 022222Z 31013G18KT 6SM -TSRA FEW017 SCT046 OVC065 18/16 A3017 RMK AO2 PK WND 31041/2158 WSHFT 2150 LTG DSNT ALQDS RAB02 TSB16 P0000 T01830156 In 6 minutes, conditions went from clear skies, with lightning in the distance; to a squall of 41 knots striking the airport. Officially, a thunderstorm did not begin at the airport until 2216Z. How many contract weather observers would report clear skies, with this on radar 2 minutes prior to the METAR?
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Post by tornado on Feb 14, 2017 9:10:06 GMT -5
New Braunfels, Texas, Tue 14 Feb 2017: SPECI KBAZ 141013Z AUTO 01010G19KT 3SM RA BR SCT014 BKN020 OVC027 11/09 A2984 RMK AO2 LTG DSNT SW-N P0018 T01060094 SPECI KBAZ 141029Z AUTO 36037G50KT 2SM VCTS +RA BR FEW013 OVC028 12/10 A2979 RMK AO2 PK WND 35050/1025 VIS 1V4 LTG DSNT SW-N PRESFR P0031 T01170100 SPECI KBAZ 141045Z AUTO 35023G34KT 1 3/4SM +TSRA BR BKN027 OVC039 11/11 A2981 RMK AO2 PK WND 35050/1025 LTG DSNT ALQDS TSB45 P0054
VCTS conditions produced a wind gust to 50 knots. That was a "severe thunderstorm in the vicinity." Officially, the thunderstorm began at 1045Z. How wacky is the rule that a thunderstorm is not a thunderstorm, until it is within 5 miles of the reporting site?
Arlington, Texas, Mon 20 Feb 2017: SPECI KGKY 200618Z AUTO 28017G37KT 10SM VCTS -RA BKN021 BKN027 OVC032 16/12 A2990 RMK AO2 PK WND 28037/0609 WSHFT 0602 LTG DSNT SW AND NW RAB12 P0000 T01610122 SPECI KGKY 200644Z AUTO 29016G25KT 6SM TSRA BR FEW030 BKN038 OVC047 15/13 A2990 RMK AO2 PK WND 28037/0609 WSHFT 0602 LTG DSNT ALQDS RAB12 TSB38 P0007 T01500128
The VCTS produced the peak wind that hour, a gust to 37 knots. That was 29 minutes before the thunderstorm had its official start time!
Redbird Airport, Dallas, Texas, Mon 20 Feb 2017: SPECI KRBD 200642Z AUTO 29016G33KT 2 1/2SM VCTS +RA BR OVC018 16/13 A2991 RMK AO2 PK WND 28033/0638 LTG DSNT ALQDS RAB34 PRESRR P0008 T01560133 SPECI KRBD 200648Z AUTO 31011G32KT 1 3/4SM +TSRA BR FEW008 SCT012 OVC018 14/13 A2990 RMK AO2 PK WND 28033/0638 WSHFT 0631 LTG DSNT ALQDS RAB34 TSB48 P0015
The peak wind was produced during the VCTS, 10 minutes before the official time of beginning of the thunderstorm.
Tyler, Texas, Mon 20 Feb 2017: SPECI KTYR 200918Z AUTO 26026G48KT 4SM VCTS -RA BR SQ OVC012 18/16 A2995 RMK AO2 PK WND 25048/0916 LTG DSNT ALQDS RAB17 PRESRR P0004 T01780156 SPECI KTYR 200931Z AUTO 30016G29KT 1 1/2SM +TSRA BR FEW007 SCT010 OVC015 15/14 A2997 RMK AO2 PK WND 25048/0916 WSHFT 0912 LTG DSNT ALQDS RAB17 TSB30 P0032 T01500139
Officially, the thunderstorm began at 0930Z (TSB30). Yet, when it was producing lightning between 5-10 miles from the airport (VCTS), it also produced the peak wind gust to 48 knots. That was 14 minutes before the thunderstorm officially started! TSB and TSE times should incorporate VCTS.
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Post by tornado on Mar 1, 2017 23:43:51 GMT -5
Athens, Georgia, Wed 1 Mar 2017: METAR KAHN 020051Z 25007KT 10SM SCT060 SCT075 23/16 A2987 RMK AO2 LTG DSNT W-NE SLP112 T02330161 SPECI KAHN 020105Z AUTO 30023G47KT 4SM VCTS -RA BKN043 BKN055 19/13 A2993 RMK AO2 PK WND 31047/0101 LTG DSNT W-NE RAB02 PRESRR P0000 T01940133 SPECI KAHN 020108Z AUTO 30021G47KT 1 3/4SM -TSRA FEW022 SCT041 BKN048 18/14 A2994 RMK AO2 PK WND 31047/0101 WSHFT 0054 VIS 1/2V5 LTG DSNT W-NE RAB02 TSB08 PRESRR P0000 T01780144
Well that deteriorated in a hurry! The peak wind of 47 knots, struck during the VCTS, 7 minutes before the thunderstorm within 5 miles began. Not only that, it took 4 minutes after the peak gust, just to get the VCTS started! In the meantime, the latest information pilots had was LTG DSNT W-NE. In other words, a near-severe thunderstorm struck the airport, with the only warning in a weather report being the distant lightning remark. Fulton County Airport, Atlanta, Georgia, Wed 1 Mar 2017:SPECI KFTY 020005Z 28011G17KT 10SM VCTS FEW046 BKN080 OVC110 23/16 A2990 RMK AO2 LTG DSNT ALQDS PRESRR T02330156 SPECI KFTY 020011Z 29022G46KT 2SM VCTS +RA SQ FEW013 BKN060 OVC110 20/14 A2993 RMK AO2 PK WND 33046/0007 LTG DSNT ALQDS RAB07 PRESRR P0015 T02000139 SPECI KFTY 020018Z 28015G41KT 2SM +TSRA BKN026 BKN045 OVC110 17/14 A2993 RMK AO2 PK WND 33046/0007 LTG DSNT ALQDS RAB07 TSB16 P0031 T01670139 Another site where VCTS produced the peak gust. This time, the wind gusted to 46 knots, 9 minutes before the VCTS became TS.
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Post by tornado on Mar 31, 2017 15:07:44 GMT -5
Flagstaff, Arizona, Thu 30 Mar (31 Mar UTC) 2017: METAR KFLG 310257Z AUTO 20030G46KT 10SM VCTS BKN080 OVC095 10/M08 A2948 RMK AO2 PK WND 21054/0240 SLP919 T01001078 56038 SPECI KFLG 310308Z AUTO 21030G57KT 10SM BKN075 OVC095 10/M08 A2948 RMK AO2 PK WND 22057/0259 T01001078 METAR KFLG 310357Z AUTO 29016G27KT 3SM -TSSN BKN044 OVC065 02/M02 A2957 RMK AO2 PK WND 22057/0259 WSHFT 0340 LTG DSNT N RAB38E56SNB56 TSB56 PRESRR SLP963 P0000 T00221017
The VCTS produced a wind gust of 57 knots. The TS produced a wind gust of 27 knots.
Alexandria, Louisiana, Wed 29 Mar (30 Mar UTC) 2017 : SPECI KAEX 300041Z 15019G25KT 7SM VCTS -RA SCT050 BKN080 OVC110 22/20 A2975 RMK AO2 PK WND 13027/0022 LTG DSNT ALQDS P0005 T02220200 METAR KAEX 300053Z 14037G45KT 4SM RA BR SCT048 BKN075 OVC120 22/20 A2977 RMK AO2 PK WND 14045/0052 LTG DSNT SE-SW PRESRR SLP084 P0008 T02170200 SPECI KAEX 300106Z 12032G41KT 6SM -TSRA BR FEW042 SCT075 OVC110 22/20 A2971 RMK AO2 PK WND 15042/0055 LTG DSNT ALQDS TSB00 PRESFR P0002 T02170200 METAR KAEX 300153Z 13041G51KT 7SM VCTS RA FEW075 FEW100 BKN120 21/19 A2971 RMK AO2 PK WND 14051/0152 LTG DSNT ALQDS TSB00E17 SLP063 P0004 T02110194
A thunderstorm ended at 0117Z. That is, lightning ceased to be detected within 5 miles, after 0102Z- and by rule, a thunderstorm ends after 15 minutes has passed from the LOL (Last Observed Lightning) when detected by an automated system (ALDARS). However, the wind gust at 0152Z, met severe criteria for thunderstorms. It is suggested that ASOS/ALDARS be reprogrammed to include VCTS in TSB/TSE times, for liability purposes. VCTS can produce more hazardous conditions than TS!
Elko, Nevada, Thu 30 Mar 2017: METAR KEKO 301656Z AUTO 19007KT 10SM SCT035 BKN048 OVC065 07/03 A2963 RMK AO2 LTG DSNT W RAE44 SLP012 P0005 T00670033 SPECI KEKO 301744Z AUTO 31032G43KT 2 1/2SM VCTS +RA FEW016 BKN025 OVC060 05/02 A2962 RMK AO2 PK WND 25043/1741 LTG DSNT SW RAB41 PRESRR P0000 T00500017 METAR KEKO 301756Z AUTO 31024G38KT 1/2SM TSSN FG BKN016 OVC060 01/M01 A2964 RMK AO2 PK WND 25043/1741 WSHFT 1738 LTG DSNT S RAB41E49SNB49 TSB52 SLP026 P0002 60013 T00111011 10089 20011 55012
Small airport, experienced its strongest wind gust during the VCTS, not the TS.
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Post by tornado on May 9, 2018 10:16:42 GMT -5
Pendleton, Oregon, 8 May (9th UTC) 2018: METAR KPDT 090253Z 26038G48KT 3SM +TSRA FEW050 OVC085 15/12 A2991 RMK AO2 PK WND 27054/0234 WSHFT 0222 LTG DSNT ALQDS RAB25 TSB52 SLP118 P0002 60002 T01500122 53015 SPECI KPDT 090237Z 26038G54KT 6SM VCTS -RA BKN085 BKN110 17/12 A2985 RMK AO2 PK WND 27054/0234 WSHFT 0222 LTG DSNT ALQDS RAB25 PRESRR P0000 T01670117 METAR KPDT 090153Z 36009KT 10SM SCT110 25/11 A2979 RMK AO2 LTG DSNT SW SLP076 T02500106
The severe thunderstorm with a wind gust to 54 knots occurred while the thunderstorm was still classified as a VCTS. What relevance does TSB52 have? If it is to legally warn airport workers of “lightning within 5 miles”, what about the other thunderstorm hazards, such as wind? Also, the wind gust to 54 knots occurred at 0234Z; the VCTS wasn’t reported until 0237Z.
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Post by hlsto2 on May 9, 2018 11:37:14 GMT -5
I have found using weathertap live lightning that ALDARS can at times be 5-10 minutes late in reporting a VCTS or TS. It appears wxtap reports more IC and CC strikes than ALDARS
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Post by tornado on May 29, 2018 11:11:54 GMT -5
Goodland, Kansas, 28 (29th UTC) May 2018: SPECI KGLD 290148Z AUTO 11029G46KT 8SM -TSRA FEW070 FEW110 17/15 A2983 RMK AO2 PK WND 12050/0104 LTG DSNT ALQDS RAB0055E10B45 TSB42 P0000 $ METAR KGLD 290053Z AUTO 13028G54KT 7SM FEW010 17/15 A2984 RMK AO2 PK WND 12054/0051 LTG DSNT E AND SE SLP069 T01720150 PWINO $ SPECI KGLD 290033Z AUTO 11029G42KT 10SM SCT009 17/15 A2978 RMK AO2 PK WND 11042/0031 LTG DSNT E-S T01720150
Lightning/thunderstorm activity was 10-30 miles away when the peak wind gust of 54 knots struck the airport. A reportable thunderstorm at the station didn't begin for another 51 minutes.
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Post by tornado on Jun 12, 2018 8:12:19 GMT -5
Fort Smith, Arkansas, 12 Jun 2018: SPECI KFSM 121242Z 36026G37KT 7SM TSRA FEW032 BKN055 OVC100 23/18 A3003 RMK AO2 PK WND 34043/1228 LTG DSNT W-NE RAB34 TSB36 P0000 T02280183 METAR KFSM 121153Z 01005KT 10SM CLR 26/23 A2995 RMK AO2 LTG DSNT N AND NW SLP137 T02560233 10267 20244 53037 A wind group of 01005KT was on the ATIS until the 1242Z SPECI. In the meantime, a wind gust of 43 knots occurred at 1228Z- even before the thunderstorm began at 1236Z.
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Post by tornado on Aug 8, 2018 13:47:15 GMT -5
Pueblo, Colorado, 8 Aug 2018: SPECI KPUB 081832Z 09013G30KT 10SM VCTS SCT031 SCT038 BKN045 22/14 A3025 RMK AO2 PK WND 04045/1801 LTG DSNT NW-E T02170139 SPECI KPUB 081808Z 05024G45KT 8SM SQ BKN033 BKN039 OVC050 22/13 A3025 RMK AO2 PK WND 04045/1801 LTG DSNT NW-E T02170133 The peak wind gust to 45 knots occurred 31 minutes before the thunderstorm entered VCTS phase. Since LTG DSNT is such a common remark, how does a pilot know which LTG/TS is moving towards the airport, based on the SPECI alone? An observer could have reported CB movement remarks… but radar would have to be used.
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