966
NOUS41 KWBC 161933
PNSNMC
NATIONAL TECHNICAL INFORMATION MESSAGE 95-22
NATIONAL WEATHER SERVICE HEADQUARTERS
0330 PM EDT FRI JUN 16 1995
TO: USERS OF AFOS GRAPHICS
FROM: PAUL DALLAVALLE
CHIEF... SYNOPTIC-SCALE TECHNIQUES BRANCH
SUBJECT: NGM-BASED THUNDERSTORM AND SEVERE LOCAL STORM
PROBABILITY FORECASTS FOR THE CONUS
EFFECTIVE WITH THE 1200 UTC CYCLE ON JUNE 21... 1995... THE
NATIONAL WEATHER SERVICE WILL OPERATIONALLY IMPLEMENT NEW
GRAPHICS PRODUCTS THAT CONTAIN NGM-BASED MOS PROBABILITY
FORECASTS OF THUNDERSTORMS AND SEVERE LOCAL STORMS FOR THE
CONTERMINOUS U.S. THESE PRODUCTS WILL BE DISTRIBUTED ON AFOS
WITH THE FOLLOWING IDENTIFIERS...
1200 UTC
NMCGPH02G - 6-24 H UNCONDITIONAL THUNDERSTORM PROBABILITY
NMCGPH02O - 6-24 H CONDITIONAL SEVERE LOCAL STORM PROBABILITY
NMCGPH03G - 24-48 H UNCONDITIONAL THUNDERSTORM PROBABILITY
NMCGPH03O - 24-48 H CONDITIONAL SEVERE LOCAL STORM PROBABILITY
0000 UTC
NMCGPH0TG - 12-36 H UNCONDITIONAL THUNDERSTORM PROBABILITY
NMCGPH0TO - 12-36 H CONDITIONAL SEVERE LOCAL STORM PROBABILITY
NMCGPH05G - 36-60 H UNCONDITIONAL THUNDERSTORM PROBABILITY
NMCGPH05O - 36-60 H CONDITIONAL SEVERE LOCAL STORM PROBABILITY
THE THUNDERSTORM FORECASTS GIVE THE UNCONDITIONAL
PROBABILITY OF TWO OR MORE CLOUD-TO-GROUND LIGHTNING FLASHES
OCCURRING IN GRID BLOCKS THAT ARE 48-KM ON A SIDE. IN
CONTRAST... THE SEVERE LOCAL STORM EQUATIONS GIVE THE CONDITIONAL
PROBABILITY OF TORNADOES... LARGE HAIL... AND/OR DAMAGING WINDS
GIVEN THE OCCURRENCE OF A THUNDERSTORM (DEFINED AS TWO OR MORE
CLOUD-TO-GROUND LIGHTNING FLASHES IN A GRID BLOCK).
TECHNICAL PROCEDURES BULLETIN #419 DESCRIBES THE NEW NGM-
BASED THUNDERSTORM AND SEVERE LOCAL STORM PRODUCTS. IF YOU NEED
FURTHER INFORMATION ON THE PRODUCTS... PLEASE CALL RON REAP OF
THE TECHNIQUES DEVELOPMENT LABORATORY AT (301) 713-1772... OR
WRITE TO HIM AT...
NOAA/NATIONAL WEATHER SERVICE
TECHNIQUES DEVELOPMENT LABORATORY... W/OSD21
1325 EAST-WEST HWY 10380
SILVER SPRING... MD 20910
END