Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 030233 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
933 PM CDT WED SEP 2 2015

.UPDATE...
MINOR UPDATES TO TEMPS/SKY COVER BASED ON THE LATEST TRENDS.

&&

.DISCUSSION...
GENERAL WEAKNESS ALOFT OVER THE MID SOUTH REGION IS BEGINNING TO
TRANSLATE EWD...WITH SKIES CLEARING ACROSS WRN TN/NRN MS. LINGERING
RAINFALL ACROSS THE REGION FROM EARLIER HAS COME TO END WITH THE LOSS
OF DAYTIME HEATING...ALTHOUGH CONDITIONS REMAIN FAIRLY HUMID FOR THE
TIME BEING GIVEN WHAT LOW LEVEL MOISTURE REMAINS IN PLACE. SKIES OVER
THE CNTRL TN VALLEY SHOULD BEGIN TO SCT SOME OVERNIGHT FROM THE W
GIVEN THE EVOLVING PATTERN...WITH HIGH PRESSURE AT THE SFC REMAINING
FAIRLY STAGNANT ACROSS THE TN/OH VALLEY STATES. WITH DEW PTS ALSO IN
THE LOWER/MID 70S ACROSS MOST OF THE AREA...OVERNIGHT TEMPS MAY NOT
REACH THE 70F MARK UNTIL NEAR DAYBREAK THU. TEMP/SKY COVER GRIDS HAVE
BEEN UPDATED BASED ON THESE LATEST WX TRENDS...BUT OVERALL A FAIRLY
QUIET NIGHT REMAINS IN THE FORECAST HEADING INTO THE MORNING HRS.

09

&&

.AVIATION...
/ISSUED 635 PM CDT WED SEP 2 2015/
FOR 00Z TAFS...
A BROAD AREA OF HIGH PRESSURE SITUATED ACROSS THE APPALACHIANS WILL
PROVIDE A LIGHT NORTHERLY FLOW ACROSS THE AREA THIS FORECAST PERIOD.
EXTENSIVE MID AND HIGH ALTITUDE CLOUDS SHOULD INHIBIT FOG FORMATION
DURING THE LATE NIGHT.

RSB

&&

.PREV DISCUSSION...
/ISSUED 146 PM CDT WED SEP 2 2015/
WATER VAPOR AND VISIBLE IMAGERY COUPLED WITH SHORT RANGE MODEL
ANALYSIS INDICATES A DISTINCT TROF/WAVE AT UPPER LEVELS OVER MS. THIS
IS FORECAST TO TRANSLATE NEWD THRU THE HUN FORECAST AREA THIS
EVENING, THEN BACK SE INTO GA ON THURSDAY. THE BEST UVM ASSOCIATED
WITH THIS FEATURES WILL RESIDE JUST TO OUR S, AND AN ABUNDANCE OF DRY
AIR ALOFT SHOULD PRECLUDE PRECIP ACTIVITY. WE ARE WATCHING A FEW VERY
SMALL PULSE -SHRA THAT DEVELOP AND DIE VERY QUICKLY. THUS ATTM, WILL
KEEP A DRY FORECAST INTO TONIGHT. MUGGY DEW POINTS IN THE U60S-L70S
ARE PUSHING HEAT INDEX VALUES INTO THE L-M90S THIS AFTN. WILL FOLLOW
NAM SFC DEW POINT VALUES CLOSELY AS COMPARED TO THE SPURIOUS LOOKING
GFS VALUES WHICH ARE FAR TOO LOW. HIGH CLOUDS ARE FORECAST TO SHIFT
E-SE OF OUR AREA VERY LATE TONIGHT, SO AM HESITANT TO ADD FOG IN JUST
YET DESPITE THE HIGH AMOUNT OF BL RH EXPECTED.

SUMMERTIME WARM/MUGGY WX IS AHEAD FOR THURSDAY AND FRIDAY AS OUR AREA
RESIDES IN SUBSIDENT NNWLY FLOW AT 500 MB AND IN THE SERN QUADRANT OF
A LARGE 850 MB ANTICYCLONE THAT WILL BE CENTERED IN THE LOWER OH
VALLEY. WE WILL CONTINUE TO FORECAST MAX TEMPS IN VALLEYS IN THE
L-M90S (80S ON THE PLATEAUS/MTNS). RAIN CHANCES SHOULD REMAIN ABOUT
10 PERCENT OR LESS BOTH DAYS. THIS MAY CHANGE AS EARLY AS LATE
SATURDAY AND INTO SUNDAY WITH A BACKDOOR COLD FRONT SLIDES DOWN SE OF
THE SPINE OF THE APPALACHIANS. THE FRONT WILL APPROACH OUR EASTERN
COUNTIES LATE SATURDAY AFTERNOON WITH MODELS SHOWING SOME CONVECTIVE
ACTIVITY POTENTIAL. MLCAPE VALUES WILL BE ~1000-1500 J/KG RANGE AND
CONVERGENCE ALONG THIS BOUNDARY SUPPORTS THIS IDEA. WILL MAINTAIN LOW
AFTN POPS E OF I-65 SATURDAY AFTERNOON, AND AREAWIDE LOW POPS ON
SATURDAY NIGHT AND SUNDAY. THE UPPER TROF AXIS WILL BEGIN TO SHIFT
INTO THE GULF OF MEXICO NEWD INTO THE CAROLINAS, KEEPING OUR AREA IN
A MAINLY SUBSIDENT REGION. WILL OPT TO STAY BELOW SCHC POP LEVELS AT
THIS POINT INTO NEXT WEEK.

&&

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

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.



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