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Post by weatheri on Apr 3, 2015 7:19:59 GMT -5
fu, Now that was funny!
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Post by wxmatrix on Apr 3, 2015 10:54:28 GMT -5
There is a lot of misinformation being posted on this forum.
Section 4.3.4 of the ASOS User's Guide is referring to the ASOS Single Site Lightning Sensor (ALS), NOT the ALDARS. As stated in Section 4.3.1 of the same manual, the ASOS ALS is installed at selected Service Level "D" sites that do not have the FAA's ALDARS. The ASOS ALS is separate and independent from ALDARS. So, in Section 4.3.4, the NWS is stating that the ASOS ALS can report 15-20% more valid thunderstorm minutes than an observer according to a 1997 field study due to an observer's ability to hear thunder being restricted due to local noise. They are not referring the to the ALDARS here.
Section 4.3.3 of the ASOS User's Guide discusses the ALDARS. It is a data processing architecture constructed by the FAA, not the NWS. However, the lightning data that is used by the ALDARS comes from the same source that the NWS uses for their lightning data: the National Lightning Detection Network (NLDN). Do not confuse the NLDN with the ASOS ALS. The ASOS ALS is not part of the NLDN. NWS offices that use lightning data from the NLDN include the Storm Prediction Center, Aviation Weather Center, National Hurricane Center, and the Weather Forecast Offices (WFOs). Each cloud-to-ground lightning strike detected by the NLDN sensors is assigned a precise latitude and longitude. Satellite communications then send the data to each FAA Air Route Traffic Control Center (ARTCC). The AWOS-ASOS Data Acquisition System (ADAS) at each ARTCC has programmed into it the latitude and longitude of all ASOSs within its airspace (via the Airport Reference Point, or ARP). The ADAS filters the data, and if it finds that a lightning strike is within 30 nautical miles of any ASOS within its airspace based on the latitude/longitude information, the ADAS sends that data to each ASOS meeting that criteria. The ASOS then processes and reports that lightning data in accordance with FAA JO 7900.5C paragraph 14.29.b. All polling between the ADAS and the ASOS updates once every minute.
There seems to be a lot of confusion about the automated lightning/thunderstorm reports generated by the ASOS via ALDARS. Carefully read FAA JO 7900.5C paragraph 14.29.b. It really isn't all that complicated.
If cloud-to-ground lightning is detected within 5 nautical miles of the ASOS and between 5-10 nautical miles of the ASOS, TS takes precedence and only TS will be reported.
An automated lightning remark (i.e. LTG DSNT xx, where xx is the direction from the ASOS) NEVER applies to TS or VCTS. Per FAA JO 7900.5C paragraph 14.29.b., the automated lightning remark is reported for lightning detected between 10-30 nautical miles of the ASOS. Automated reports of TS and VCTS do NOT generate associated automated lightning remarks, again per FAA JO 7900.5C paragraph 14.29.b. If you see TS and a LTG DSNT xx remark generated by the ASOS, it means that the ALDARS has detected cloud-to-ground lightning within 5 nautical miles of the ASOS (TS) and between 10-30 nautical miles of the ASOS (LTG DSNT xx). If you see VCTS and a LTG DSNT xx remark generated by the ASOS, it means that the ALDARS had detected cloud-to-ground lightning between 5-10 nautical miles of the ASOS (VCTS) and between 10-30 nautical miles of the ASOS (LTG DSNT xx).
Some have questioned why an automated report of VCTS does not generate begin/end times for thunder. Per NWS HQ, "A TS is considered to be occurring at the station when it is observed within 5 miles of the point of observation. This is according to the FMH-1, Section 8.5. No begin or end times are provided for activity "in the vicinity" of the station. Only those present weather events occurring at the station (e.g. TS) will be provided begin and end times. So, in this case ASOS is working as designed and in accordance with the FMH-1." This makes sense. If VCSH is reported, do you provide a begin/end time remark for the precipitation? No, of course not. It is not occurring at the station. The reference that has been made to the FAA JO 7900.5C is inconsistent with the FMH-1. The FMH-1 prescribes the standards for surface weather observing that are applicable to all Federal agencies. These agencies can and do issue orders and manuals to instruct their offices on procedures and practices to be followed to meet the Federal standards. The FAA does so via the 7900.5, of which JO 7900.5C is the current order. FAA JO 7900.5C paragraph 1.7.a. states "This order complements, but does not change the standards contained in FMH-1." Since FAA JO 7900.5C paragraph 10.29 says that thunder begins when "lightning is detected by an automated sensor within 10 miles of the airport", this is inconsistent with the FMH-1, and also with JO 7900.5C paragraph 14.29.b. The FAA will likely correct this when a new 7900.5 is issued.
All CWO offices should have received a memorandum from FAA HQ via their vendor dated September 24, 2013. This memorandum instructs that "once the controllers/observers complete the ASOS 3.10 briefing and the local National Weather Service ASOS technicians install the ASOS 3.10 software upgrade, controllers/observers must enable ALDARS service 24-hours per day." Sites with ASOS software version 3.10 installed that do not enable ALDARS service 24 hours per day are in violation of FAA policy and the vendor is in default under the terms of their contract.
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Post by fu on Apr 3, 2015 11:35:15 GMT -5
All CWO offices should have received a memorandum from FAA HQ via their vendor dated September 24, 2013. This memorandum instructs that "once the controllers/observers complete the ASOS 3.10 briefing and the local National Weather Service ASOS technicians install the ASOS 3.10 software upgrade, controllers/observers must enable ALDARS service 24-hours per day." Sites with ASOS software version 3.10 installed that do not enable ALDARS service 24 hours per day are in violation of FAA policy and the vendor is in default under the terms of their contract. That same memorandum also states that the CWO is still responsible for the backup of ASOS in accordance with FAA Order 7900.5 Chapter 6 Table 6-6. "Thunderstorm reporting is produced via backup if ALDARS should become inoperative or is unrepresentative" Since ALDARS is only representative when no LTG is occurring nobody would be in default if they turned it off.
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Post by Little Miss Sunshine on Apr 3, 2015 11:39:26 GMT -5
" Sites with ASOS software version 3.10 installed that do not enable ALDARS service 24 hours per day are in violation of FAA policy and the vendor is in default under the terms of their contract. However, based on the memo below a site can disable if the observer feels that ALDARS is unrepresentative ... and would not be in violation of FAA policy and the vendor would not be in default under terms of their contract, yes? ASOS 3.10 Software Upgrade 9.pdf (373.64 KB)
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Post by fu on Apr 3, 2015 11:48:43 GMT -5
Some have questioned why an automated report of VCTS does not generate begin/end times for thunder. Per NWS HQ, "A TS is considered to be occurring at the station when it is observed within 5 miles of the point of observation. This is according to the FMH-1, Section 8.5. No begin or end times are provided for activity "in the vicinity" of the station. Only those present weather events occurring at the station (e.g. TS) will be provided begin and end times. So, in this case ASOS is working as designed and in accordance with the FMH-1." This makes sense. If VCSH is reported, do you provide a begin/end time remark for the precipitation? No, of course not. It is not occurring at the station. The reference that has been made to the FAA JO 7900.5C is inconsistent with the FMH-1. The FMH-1 prescribes the standards for surface weather observing that are applicable to all Federal agencies. These agencies can and do issue orders and manuals to instruct their offices on procedures and practices to be followed to meet the Federal standards. The FAA does so via the 7900.5, of which JO 7900.5C is the current order. FAA JO 7900.5C paragraph 1.7.a. states "This order complements, but does not change the standards contained in FMH-1." Since FAA JO 7900.5C paragraph 10.29 says that thunder begins when "lightning is detected by an automated sensor within 10 miles of the airport", this is inconsistent with the FMH-1, and also with JO 7900.5C paragraph 14.29.b. The FAA will likely correct this when a new 7900.5 is issued. A And until the FAA corrects it we are still required to follow the 7900.5C which states a TS is considered to begin when lightning is detected by an automated sensor within 10 miles of the airport. Doesn't that make ALDARS unrepresentative. Doesn't that allow us to turn it off and provide backup TS reporting (Table 6-6 footnote 4).
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Post by fu on Apr 3, 2015 11:54:03 GMT -5
The main reason the FAA wants to force ALDARS into operation at manned stations is so that they can proceed with the new service standards that remove TS data from a sites bad weather score.
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Post by Little Miss Sunshine on Apr 3, 2015 12:18:57 GMT -5
The reference that has been made to the FAA JO 7900.5C is inconsistent with the FMH-1. The FMH-1 prescribes the standards for surface weather observing that are applicable to all Federal agencies. These agencies can and do issue orders and manuals to instruct their offices on procedures and practices to be followed to meet the Federal standards. The FAA does so via the 7900.5, of which JO 7900.5C is the current order. FAA JO 7900.5C paragraph 1.7.a. states "This order complements, but does not change the standards contained in FMH-1." September 2005 is the latest version we see online of the FMH. Is there a later version? Odd thing is the FMH is not required to be on site and is not listed on the FAA inspection checklist.
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Post by hlsto2 on Apr 3, 2015 12:35:31 GMT -5
we just save ourselves any hassle with ALDARS and leave it OFF!
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Post by fu on Apr 3, 2015 13:10:51 GMT -5
The reference that has been made to the FAA JO 7900.5C is inconsistent with the FMH-1. The FMH-1 prescribes the standards for surface weather observing that are applicable to all Federal agencies. These agencies can and do issue orders and manuals to instruct their offices on procedures and practices to be followed to meet the Federal standards. The FAA does so via the 7900.5, of which JO 7900.5C is the current order. FAA JO 7900.5C paragraph 1.7.a. states "This order complements, but does not change the standards contained in FMH-1." September 2005 is the latest version we see online of the FMH. Is there a later version? Odd thing is the FMH is not required to be on site and is not listed on the FAA inspection checklist. That's true the FMH-1 is not required to be kept on site. The paragraph from the FMH that wxmatrix quoted is also true (1.7.a). However there is also a paragraph 1.8.b which gives is guidance in case of conflicting info. 1.8. Applicability of Procedures and Practices a. Applicability. The procedures and practices in this order apply to all facilities that have the capability to comply with the stated procedure or practice. Some procedures and practices vary at LAWRS sites. LAWRS requirements are contained in Appendix C, LAWRS Requirements. At sites ranked as Service Level C, the basic weather observing requirements are the same as a LAWRS observation. LAWRS observers are not required to back up the observation if measuring or observing equipment is not available. b. Conflicting Information. In case of conflicting information, the procedures and practices in this order take precedence. However, any applicable FAA air traffic orders take precedence over any procedures or practices in this order that are in conflict. Such conflicts should be brought to the attention of the originator of this order.
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Post by fu on Apr 3, 2015 13:37:34 GMT -5
Since ALDARS does not follow the guidelines given in the 7900 for reporting TSB time (inside 10 miles) and since the 7900 takes precedence over the FMH in cases of conflicting info the observer would have reason to believe the accuracy or validity of ALDARS was questionable. The 7900 provides guidance on what to do in that case as well. Observers should discontinue the use of such equipment.
Wxmatrix can you tell us why you think sites that turn ALDARS are off are in violation of the FAA policy?
3.11. Evaluating Weather Sensor Accuracy Sensor Evaluations. When the observer has reason to believe that the accuracy or validity of indications from meteorological sensors is questionable, the use of such equipment should be discontinued until necessary corrective maintenance has been accomplished. If the use of such equipment is discontinued, any required back-up procedures or practices must be initiated. FAA personnel and NF-OBS providers must make appropriate maintenance notifications in the event of any equipment outages. .
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aero0
New Member
Posts: 29
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Post by aero0 on Apr 3, 2015 14:32:41 GMT -5
In my 50 years of taking Weather Obs I have never seen a software program that was so difficult to use and produces so many critical errors such as the location of the Thunder or Lightning, and movement. I think it is a bigger problem in the West where there are many small Thunderstorm Cells to track as these weak cells form and dissipate quickly and move in and out of the 10 mile radius. It is clear that whoever wrote this program didn't understand the enormous problems that would evolve and are not solvable because of the nature of convective weather.
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Post by tornado on Apr 6, 2015 8:32:43 GMT -5
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Post by weatheri on Apr 6, 2015 10:23:37 GMT -5
Absolutely! I even thought about building one of the detectors.
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Post by wxmatrix on Apr 7, 2015 11:00:57 GMT -5
About LightningMaps.org"Important notice We are not liable for the completeness, timeliness, quality and accuracy of the information on our website. We are not responsible for damages, resulting from trusting the content of our website or its use. Blitzortung.org is not a commercial information service for lightning data. The data of Blitzortung.org is not suitable for a plausibility check in insurance matters and it is not intended for protection of life and property! You must use a commercial lightning location provider in such cases! The data provided by Blitzortung.org is only for entertainment purposes." Read that last sentence again, folks. "The data provided by Blitzortung.org is only for entertainment purposes." I don't think that the FAA has contracted for CWO services for "entertainment purposes." The commercial lightning location provider that the FAA has approved and purchased data from for use (as has the NWS) is the NLDN and Global Lightning Data Set GLD360 operated by Vaisala. Press releases: FAA Chooses Vaisala to Supply Real-Time Lightning Data
Vaisala Signs Lightning Contract with US National Weather Service
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Post by weatheri on Apr 7, 2015 12:06:27 GMT -5
OK, I'll clarify. I absolutely use it for entertainment purposes only. I can sit at home see the strike on the screen and follow the thunder sound wave circle right to my house and it entertains me. Misses a bunch as do all of them.
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