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[GEMPAK #HFP-442517]: Problem decoding TOR/SVR from previous month



Hi Dan-

> I started playing with the dcwarn decoder to ingest/decode/create a
> nationwide polygon map of TOR/SVR/FFW's and came across what appears to
> be a bug in the dcwarn decoder.  I downloaded and decoded all SVR's and
> TOR's for all NWS offices in the lower 48, in some cases this meant that
> I was downloading and decoding warnings that had been issued last month
> or even earlier. These older warnings were decoded and placed in gempak
> files corresponding to the present month when this was clearly not the
> case. I am attaching an example from NWS Buffalo, a Tornado warning from
> the end of last month (June) being placed in a file for July 29th
> instead of June 29. While this doesn't present an immediate problem, it
> will on July 29th around 2145Z since this warning will show up with the
> "then present" other warnings in effect across the CONUS.
> 
> Any idea why this might be happening? I'm assuming dcwarn just grabs the
> UGC start/expire times and assumes the current month? What type of
> workaround I can incorporate so that I don't place past warnings in
> future gempak files?

dcwarn uses the WMO header to determine the day and month, not the UGC
start/expire time.  Since that only has the day, it assumes the current month.  
You can use the -c option (try dcwarn -h for help) to set the "current" time.  
So, if you change your invocation to:

dcwarn -v 10 -d - -c 080615/0000 YYYYMMDDHH_warn.gem < BUF

you will get them decoded in June.  I picked the 15th because if you
go too close to the start of the month (e.g. 080601), it'll end up decoding it 
as
May since the May 29th is closer to June 1 than June 29.

Don Murray

> dcwarn -v 10 -d - YYYYMMDDHH_warn.gem <BUF
> [9503] 080713/0932[DC 3]  Starting up. Version 5.11.1
> [9503] 080713/0932[DC 2]  read 1524/102399 bytes strt 0 newstrt 1524
> [9503] 080713/0932[DC 2]  read 0/100876 bytes strt 1524 newstrt 1524
> [9503] 080713/0932[DC 5]  Normal termination.
> [9503] 080713/0932[DC 2]  Number of bulletins read and processed: 1
> [9503] 080713/0932[DC 6]  Shutting down.
> 
> [daniel.leins@******* warn]$ more 2008072921_warn.gem
> |TOR|080729/2141|080729/2230|KBUF|1
> 4200 7917 4199 7933 4200 7933 4206 7933 4224 7876 4200 7871 4199 7917
> NYC009    36009 Cattaraugus                      NY US     42.25
> -78.68      0.00  0  BUF
> NYC013    36013 Chautauqua                       NY US     42.23
> -79.36      0.00  0  BUF
> 
> [daniel.leins@****** warn]$ cat BUF
> 
> 000
> WFUS51 KBUF 292141 CCA
> TORBUF
> NYC009-013-292230-
> /O.COR.KBUF.TO.W.0001.080629T2139Z-080629T2230Z/
> BULLETIN - EAS ACTIVATION REQUESTED
> TORNADO WARNING...CORRECTED
> NATIONAL WEATHER SERVICE BUFFALO NY
> 539 PM EDT SUN JUN 29 2008
> THE NATIONAL WEATHER SERVICE IN BUFFALO HAS ISSUED A
> * TORNADO WARNING FOR...
> EXTREME SOUTHEAST CHAUTAUQUA COUNTY
> SOUTHWEST CATTARAUGUS COUNTY
> * UNTIL 630 PM EDT
> * AT 537 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
> SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 6 MILES
> SOUTHWEST OF FREWSBURG...OR 6 MILES SOUTH OF JAMESTOWN...MOVING
> EAST AT 37 MPH.
> * THE TORNADO WILL BE NEAR...
> FREWSBURG BY 545 PM EDT...
> ALLEGHENY RESERVOIR BY 605 PM EDT...
> ALLEGANY STATE PARK BY 615 PM EDT...
> THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A
> WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS
> AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN
> INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO
> COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.
> IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
> SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
> NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
> A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM EDT SUNDAY
> EVENING FOR WESTERN NEW YORK.
> LAT...LON 4200 7917 4199 7933 4200 7933 4206 7933
> 4224 7876 4200 7871 4199 7917
> TIME...MOT...LOC 2139Z 250DEG 32KT 4202 7925
> $$
> HITCHCOCK
> 
> 
> 
> 
> 
> 


Ticket Details
===================
Ticket ID: HFP-442517
Department: Support GEMPAK
Priority: Normal
Status: Open