National Weather Service Weather Forecast Office

Area Forecast Discussion

139
FXUS64 KHUN 220523 AAC
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1223 AM CDT WED MAY 22 2013

.UPDATE...
FOR 06Z TAFS

&&

.DISCUSSION...
/ISSUED 852 PM CDT TUE MAY 21 2013/
A LINE OF THUNDERSTORMS IS APPROACHING (AND ACCELERATING SOMEWHAT)
THE AREA FROM THE WEST OVER N MS/W TN. MESOSCALE ANALYSIS (VIA
RAP/NAM) OF THE ENVIRONMENT AHEAD OF THIS FRONT INDICATES A DECREASE
IN SB INSTABILITY WHILE ELEVATED INSTABILITY REMAINS. HOWEVER, EVEN
THEN CURRENT BMX SOUNDING DOES INDICATE A STEEP LAPSE RATE BTWN
891-500 MB WHICH COULD MEAN SOME ELEVATED REDEVELOPMENT LATER
TONIGHT. WIND SHEAR IS WEAK AHEAD OF THE LINE, BUT HAVE NOTICED SOME
BRIEF PERIODS OF ROTATION THAT DID NOT LAST FOR MORE THAN A VOLUME
SCAN OR TWO FURTHER WEST A COUPLE OF HOURS AGO. MOST OF THE MORE
SEVERE AND MORE ORGANIZED PORTIONS OF THE LINE APPEAR TO BE
CONCENTRATED FURTHER SOUTH OVER CENTRAL MS. LIGHTNING HAS FALLEN OFF
WITH THE PORTION OF THE LINE CLOSER TO NW AL, WITH THE LINE BREAKING
UP. THUS, HAVE INCREASED POPS TO LIKELY MAINLY FOR NW AL WITH CHANCE
OF THUNDERSTORMS FURTHER EAST. THERE IS AN OUTFLOW BOUNDARY
PROPAGATING SOUTHEAST FROM THE LINE WHICH COULD RESULT IN ADDITIONAL
DEVELOPMENT AHEAD OF THE LINE WHICH IS ANOTHER REASON FOR HIGHER POPS
OVER NORTH CENTRAL AL INTO NE AL.

IN ADDITION, MADE SOME ADJUSTMENTS TO DEWPOINT AND SKY COVER GRIDS
BASED ON THE CURRENT TRENDS.

SL.77

&&

.AVIATION...
FOR 06Z TAFS...
A SLOW MOVING LINE OF -TSRA IS EXPECTED TO IMPACT THE TERMINALS OVER
THE NEXT 3-6 HOURS. HAVE INCLUDED A POSSIBLE DROP TO `ADDITIONAL FUEL
REQUIRED` CATEGORY FOR 08-15Z WITH THE HEAVIER TSRA. THIS LINE OF
TSRA IS EXPECTED TO CONTINUE AFTER 15Z THROUGH THE REST OF N AL/S
MIDDLE TN UNTIL 00Z WHEN TSRA SHOULD DIMINISH. SW WIND SPEEDS ARE
EXPECTED TO INCREASE AFTER 14-15Z TO 12G20KTS AS THE SFC COLD FRONT
APPROACHES.

SL.77

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

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