Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 291215
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
715 AM CDT WED JUL 29 2015

.UPDATE...
FOR 12Z TAFS

&&

.DISCUSSION...
/ISSUED 439 AM CDT WED JUL 29 2015/
AS OF 09Z OUTFLOW FROM EARLIER STORMS IS MAKING ITS WAY EAST THROUGH
NORTH CENTRAL AL AND SOUTHERN MIDDLE TN AND HAS GENERATED A FEW
SHOWERS. THESE SHOULD CONTINUE MOVING EAST FOR ABOUT ANOTHER HOUR OR
TWO AND WILL BE MAINLY CONFINED TO THE OUTFLOW BOUNDARY. MORE
DEVELOPMENT IS POSSIBLE THIS MORNING ACROSS NW ALABAMA AS SATELLITE
IMAGERY SHOWS SOME REMNANT BOUNDARY EXTENDING FROM CENTRAL AL INTO SE
MO. IN ADDITION TO THIS A CU FIELD WAS BEGINNING TO DEVELOP ACROSS
WESTERN TN ALONG AND AHEAD OF ANOTHER OUTFLOW BOUNDARY. THIS HAS
BEEN WELL REPRESENTED IN THE LAST FEW RUNS OF THE HRRR AND OTHER
HIRES GUIDANCE WHICH ALL SHOW ACTIVITY BEGINNING BETWEEN 09-12Z THIS
MORNING.

FOR TODAY...IT WILL BE ANOTHER HOT AND HUMID DAY WITH TEMPS PEAKING
IN THE MID 90S WITH A FEW UPPER 90S LIKELY IN SPOTS. HEAT INDEX
VALUES WILL BE GREATEST FROM ALONG THE I-65 CORRIDOR WESTWARD AND BE
BETWEEN 104-107. A HEAT ADVISORY REMAINS IN EFFECT THROUGH THIS
EVENING FOR THESE AREAS. SHORT RANGE MODELS INDICATE A WEAK SHORTWAVE
DROPPING SOUTH THROUGH THE AREA TODAY AS WELL AS A 25 TO 30 KT LOW
LEVEL JET AND THESE WILL HELP TO INITIATE CONVECTION ACROSS THE
REGION TODAY. WITH CAPE VALUES AROUND 2000 J/KG AND THE SLIGHTLY
INCREASED SHEAR FROM THE LOW LEVEL JET...WE COULD SEE A FEW ISOLATED
STRONG TO SEVERE STORMS THIS AFTERNOON EVENING WITH WIND THE PRIMARY
THREAT.

THE PERSISTENT HIGH PRESSURE BEGINS TO BREAK DOWN TODAY/THURSDAY AND
SHIFT FURTHER WESTWARD. AS THIS HAPPENS...A LOW PRESSURE SYSTEM
TRAVELING THROUGH THE GREAT LAKES REGION WILL SEND A COLD FRONT SOUTH
ACROSS THE AREA THURSDAY. MODELS SHOW SOME SLIGHT DIFFERENCES IN THE
TIMING OF THIS FRONT THROUGH THE AREA BUT ALL HAVE IT SOUTH BY
THURSDAY NIGHT. THE HIGH TEMPS ON THURSDAY WILL DEPEND ON THE
ARRIVAL OF THE FRONT BUT ARE NOT EXPECTED TO MAKE IT MUCH ABOVE 90
DEGREES DUE TO INCREASED CLOUD COVER. SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP ALONG AND AHEAD OF THE FRONT WITH A FEW STRONG TO
SEVERE STORMS POSSIBLE.

FINALLY SOME RELIEF FROM THE HEAT ARRIVES BEHIND THE FRONT WITH TEMPS
FORECAST TO REMAIN AROUND 90 DEGREES THROUGH THE WEEKEND. NORTHERLY
WINDS BEHIND THE FRONT WILL BRING DRIER AIR SOUTHWARD AND SEND
DEWPOINTS INTO THE LOWER 60S WHICH ARE EXPECTED TO CONTINUE THROUGH
EARLY NEXT WEEK. THESE DRIER CONDITIONS WILL ALSO ALLOW FOR OVERNIGHT
LOWS TO DROP INTO THE MID TO UPPER 60S FRIDAY THROUGH MONDAY.

FOR THE EXTENDED PERIOD...500MB HEIGHTS INCREASE AND WINDS BEGIN TO
SHIFT BACK TO THE S/SW TOWARDS THE MIDDLE OF NEXT WEEK...WHICH WILL
SEND TEMPS BACK INTO THE MID TO UPPER 90S. MODELS ARE IN DECENT
AGREEMENT IN SENDING A FEW SYSTEMS THROUGH THE GREAT LAKES REGION AND
BRINGING WEAK FRONTS TOWARDS THE AREA. HOWEVER...MOISTURE WILL BE
SLOW TO RETURN TO THE AREA AND WE LIKELY WONT SEE MUCH OUT OF ANY OF
THESE WEAK FRONTS AND KEPT POPS AT SLIGHT CHANCE.

STUMPF

&&

.AVIATION...
FOR 12Z TAFS...INITIAL ROUND OF EARLY MORNING SHRA ACTIVITY HAS
PUSHED SOUTH OF THE REGION...WITH BKN/OVC MID AND HIGH LEVEL CIGS
IN PLACE AT BOTH TERMINALS. ADDITIONAL SHRA ARE CURRENTLY DEVELOPING
IMMEDIATELY E OF HSV BUT WILL LIKELY MISS THE TERMINAL. IR SATELLITE
IMAGERY SUGGESTS A FAIRLY RAPID EROSION OF AS/CS CLOUDS WILL OCCUR
FROM THE NE EARLY IN TAF PERIOD...ALLOWING AN INCREASINGLY UNSTABLE
AIRMASS TO SUPPORT HIGHER THREAT FOR TSRA BTWN 15-00Z. AFTER A BREAK
THIS EVENING...ANOTHER ROUND OF SHRA/TSRA IS EXPECTED TO DEVELOP
ALONG COLD FRONT ADVANCING SEWD THRU MID TN. SOME OF THIS ACTIVITY
MAY APPROACH THE TERMINALS BY END OF TAF PERIOD...BUT UNCERTAINTY TOO
GREAT TO INCLUDE VCTS ATTM. OUTSIDE OF CONVECTION...EXPECT A
CONTINUATION OF SCT CU BENEATH BKN MID/HIGH CLOUDS. SFC WINDS WILL
REMAIN FROM THE NW AT 5-10 KTS TODAY...BUT WILL VEER TO NNE
OVERNIGHT.

70/DD

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ALZ001>007-016.

TN...NONE.

&&

$$

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



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