Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 221444 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
944 AM CDT FRI AUG 22 2014

.UPDATE...
MORNING UPDATE.

&&

.DISCUSSION...
ANOTHER HOT AND HUMID DAY IS UNDERWAY ACROSS THE TENNESSEE VALLEY.
WITH AN UPPER LEVEL RIDGE PARKED OVER THE TX/LA STATE LINES,
CONVECTION CAN BE SEEN ON VISIBLE/WV IMAGERY ROTATING CLOCKWISE
AROUND THE PERIPHERY OF THIS FEATURE (MOST NOTABLY OVER THE SOUTHERN
GREAT LAKES). CIRRUS CLOUDS FROM THIS CONVECTION ADVECTING TO THE
SOUTH WILL STREAM OVERHEAD THE AREA THROUGH THE AFTERNOON. SFC HIGH
PRESSURE IS LOCATED OVER THE GOLDEN TRIANGLE IN EAST CENTRAL MS, WITH
LIGHT SW TO NW WINDS IN PLACE ACROSS THE REGION.

9AM TEMPERATURES ARE ALREADY IN THE LOWER/MIDDLE 80S IN MANY
LOCATIONS. DEWPOINTS ACROSS THE CWFA ARE EXPECTED TO REMAIN IN THE
LOWER/MIDDLE 70S THROUGH THE AFTERNOON, PRODUCING HEAT INDEX VALUES
AROUND/EXCEEDING 105 DEGREES. AS SUCH, WILL KEEP THE HEAT ADVISORY
GOING. MINOR ADJUSTMENTS WERE MADE TO THE DEWPOINT GRIDS FOR THE
REMAINDER OF THE AFTERNOON, BUT ALL OTHER WX ELEMENTS WERE ON TRACK.
AFTN HIGHS WILL TOP OUT IN THE MID/UPPER 90S, WITH THE WARMEST
TEMPS/HIGHEST HEAT INDEX VALUES OCCURRING OVER NW AL.

UPDATED PRODUCTS WILL BE SENT SHORTLY.

12

&&

.AVIATION...
/ISSUED 658 AM CDT FRI AUG 22 2014/
FOR 12Z TAFS...EXCEPT FOR MVFR FOG AT KMSL UNTIL 13Z...MAINLY VFR
CONDITIONS ARE EXPECTED THRU THE FCST PERIOD...DUE TO HIGH PRESSURE
ACROSS THE AREA.

07

&&

.PREV DISCUSSION...
/ISSUED 527 AM CDT FRI AUG 22 2014/
CURRENT SFC OBS SHOW LIGHT FOG DEVELOPMENT ACROSS THE HUN CWA WITH
MORE FOG DEVELOPING IN THE VALLEYS. DEWPOINTS HAVE ONLY DROPPED DOWN
INTO THE LOWER 70S OVERNIGHT. HIGH PRESSURE WILL CONTINUE TO STAY
ANCHORED OVER THE REGION FOR THE NEXT FEW DAYS. WITH HIGH
TEMPS/DEWPOINTS ACROSS THE TN VALLEY OVER THE NEXT TWO DAYS...WENT
AHEAD AND EXTENDED THE HEAT ADVISORY UNTIL SATURDAY AT 9PM. THE HEAT
INDEX WILL RISE UP TO VALUES RANGING FROM 100-107 DEGREES ACROSS THE
HUN CWA FRIDAY AND SATURDAY.

THE GFS MAY BE TOO WARM WITH TEMPS AND TOO LOW ON DEWPOINTS. WHERE AS
THE NAM LOOKED MORE REASONABLE WITH TEMPS AND DEWPOINTS. BECAUSE OF
RECENT RAINFALL /AND VEGETATION STILL GREEN/ WE SHOULD NOT WARM UP
AS MUCH AS THE GFS IS EXPECTING. TEMPS WILL RANGE IN THE MID TO UPPER
90S OVER THE NEXT FEW DAYS.

OVERALL WENT WITH A BLEND OF THE ECMWF AND GFS BUT LEANED MORE
TOWARDS THE GFS. A CHANCE OF SHOWERS AND THUNDERSTORMS WILL RETURN
SUNDAY INTO MONDAY WITH A BACK DOOR COLD FRONT. WITH LOW LEVEL
CONVERGENCE AND A SLIGHT INCREASE IN DEWPOINTS...INCREASED THE POPS
AND CLOUD COVER FOR SUNDAY AND MONDAY. BUT WITH THE EXPECTED INCREASE
IN CLOUDS AND PRECIP...MAY NOT REACH THE HEAT ADVISORY CRITERIA
SUNDAY SO WILL HOLD OFF AT THIS TIME. BY MONDAY NIGHT INTO
TUESDAY...THE SFC HIGH PRESSURE IN THE NORTHEASTERN US WILL PULL
DRIER AIR WILL INTO THE TN VALLEY. HOWEVER WILL MAINTAIN A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY DUE TO THE LINGERING
EFFECT OF THE BACK DOOR COLD FRONT. ALTHOUGH LATER SHIFTS MAY WANT TO
REMOVE THIS SMALL CHANCE OF PRECIP FROM THIS TIME FRAME.

BY WEDNESDAY AND THURSDAY...MODELS ARE SHOWING A COLD FRONT
APPROACHING THE REGION. THE GFS IS MUCH QUICKER WITH THE FRONT THAN
THE ECMWF...THUS WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON WEDNESDAY AND THURSDAY.

JMS

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...HEAT ADVISORY UNTIL 9 PM CDT SATURDAY FOR ALZ001>010-016.

TN...HEAT ADVISORY UNTIL 9 PM CDT SATURDAY FOR TNZ076-096-097.

&&

$$

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



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