Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 212321
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
521 PM CST FRI NOV 21 2014

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 228 PM CST FRI NOV 21 2014/
LOW TO MID LEVEL CLOUDS PRESENT TO THE WEST AS OF 20Z SHOULD STAY TO
THE WEST OF OUR AREA OR MAYBE MAKE IT BRIEFLY INTO THE WESTERN
COUNTIES. THE HIGH PRESSURE TO THE EAST WILL BUILD ALOFT TOWARDS THE
WEST AND HELP KEEP THE CLOUDS OUT OF THE AREA AND KEEP WINDS LIGHT.

FOR THE NEXT SYSTEM...THE UPPER LOW IS DIGGING THROUGH SOUTHERN
CALIFORNIA AND INTO ARIZONA AS OF 18Z. SURFACE LOW IS TRYING TO
DEVELOP AHEAD OF IT IN CENTRAL TEXAS AND WILL CONTINUE TO DEVELOP
AND MOVE EAST THROUGH SATURDAY. TEMPS ON SAT WILL WARM INTO THE
UPPER 50S TO LOWER 60S THANKS TO A WARM SOUTHWESTERLY FLOW.

AS FAR AS SUNDAY IS CONCERNED...ONLY NOTICEABLE CHANGE FROM PREVIOUS
FORECASTS IS THE TIMING SHIFTED VERY SLIGHTLY IN THE SLOWER
DIRECTION BUT THIS DOES NOT LOOK TO HAVE ANY MAJOR IMPACTS ON THE
FORECAST. IT ALSO LOOKS LIKE THAT SECONDARY LOW THAT DEVELOPS ALONG
THE WARM FRONT TO THE SOUTH WILL MOVE MORE NORTHEAST AWAY FROM THE
LOCAL AREA. THIS SUPPORTS EVEN MORE OF A LACK OF INSTABILITY FOR
NORTH ALABAMA AS WELL AS POSSIBLY LESS RAINFALL.

BROUGHT SUNDAY TEMPERATURES DOWN A FEW DEGREES. WITH THE MODELS
SLOWING DOWN ON THE PROGRESSION OF THE PRECIP SUNDAY...EXPECT
CLEARING SKIES TO HAPPEN LATER THAN PREVIOUSLY THOUGHT.
THEREFORE...TEMPS WILL NOT WARM AS MUCH AS EXPECTED. STILL
FORECASTING SLIGHTLY ABOVE NORMAL VALUES THANKS TO THE SOUTHWESTERLY
FLOW.

THERE IS STILL NO INSTABILITY PRESENT UNTIL SUNDAY EVENING AND EVEN
THEN IT IS VERY LOW. EVEN WITH THE SLOWER FORECAST IT WILL STILL NOT
BE ENOUGH TO FORCE ANY STRONGER STORMS AND PRECIP WILL LIKELY BE
DONE BY THAT TIME. THE STRONG LOW LEVEL INVERSION HOLDS IN PLACE IN
BOTH THE GFS/NAM FOR MUCH OF THE DAY...SEVERELY LIMITING ANY
CONVECTION POTENTIAL. HOWEVER...0-6KM SHEAR IS STILL 50-60KT AND 0-1
KM SHEAR IS STILL 30-40KT. BUT WITH NO INSTABILITY THE ATMOSPHERE
WILL LIKELY NOT REALIZE THIS SHEAR TO CREATE STRONG THUNDERSTORMS.

THE MAIN CONCERN LOOKS TO BE THE MODERATE TO HEAVY RAINFALL IN THE
AFTERNOON WITH A VERY MOIST ATMOSPHERE AND A STRONG LLJ HELPING IT.
AS WELL...WITH 50-60KT OF WIND RIGHT ABOVE THE INVERSION...ANY
CONVECTION THAT DOES DEVELOP MAY DRAG THIS WIND DOWN RESULTING IN
LOCALLY STRONG WIND GUSTS. WILL NOT MAKE MAJOR CHANGES TO THE
POPS/WX...LEAVING JUST A CHANCE OF THUNDERSTORMS.

TIMING LOOKS AS IF RAINFALL WILL START AS LIGHT RAIN/DRIZZLE COMING
FROM THE SW BETWEEN 3-6 AM SUNDAY FOR THE WESTERN AREAS WITH LIGHT
RAIN CONTINUING THROUGH THE MORNING AND TRACKING E-NE. HEAVIEST
RAINFALL WILL BE BETWEEN ABOUT NOON AND 5 PM WITH LIGHT RAIN
TAPERING OFF IN THE EVENING. WITH THE SURFACE LOW STRENGTHENING AND
QUICKLY MOVING OFF TO THE NORTH...DRY AIR WRAPPING AROUND WILL
ENTRAIN THE AREA BETWEEN 21-00Z. THIS SHOULD QUICKLY SHUT OFF ANY
RAINFALL.

A DRY COLD FRONT IS STILL EXPECTED TO MOVE THROUGH BY MONDAY
AFTERNOON BRING IN A COOLER NW WIND AND COOLER TEMPS FOR THE REST OF
THE WEEK.

LN

&&

.AVIATION...
FOR 00Z TAFS...
LOW AND MID LEVEL CLOUDS LOCATED OVER MISSISSIPPI THIS EVENING WILL
GRADUALLY WORK INTO NORTHERN ALABAMA OVERNIGHT. CIGS BETWEEN 6 TO 7
KFT EXPECTED WITH THESE CLOUDS...BUT VFR CONDITIONS CONTINUE THROUGH
THE PERIOD. A STRONG LOW PRESSURE SYSTEM CURRENTLY LOCATED OVER AZ/NM
AREA WILL MOVE INTO CENTRAL TX SATURDAY. SOUTHEAST WINDS PICKUP
DURING THE DAY AHEAD OF THIS SYSTEM WITH SPEEDS BETWEEN 10 AND 15
KTS.

STUMPF

&&

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

$$

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


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