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000
FXUS64 KHUN 171009
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
509 AM CDT MON JUN 17 2013

.DISCUSSION...
WATER VAPOR SATELLITE ANIMATION AND ANALYSIS OF UPPER-AIR DATA
INDICATE THAT A MODERATELY STRONG WEST-NORTHWEST FLOW REGIME ALOFT
HAS BECOME ESTABLISHED ACROSS THE TENNESSEE VALLEY...TO THE NORTH OF
A ZONALLY ORIENTED SUBTROPICAL RIDGE POSITIONED ALONG 25N LATITUDE.
THE FIRST IN A SERIES OF MID-LEVEL WAVES...WHICH AIDED IN THE
DEVELOPMENT OF CONVECTION YESTERDAY AFTERNOON...HAS NOW PUSHED TO THE
EAST OF THE SOUTHERN APPALACHIANS...WITH ANOTHER WEAK DISTURBANCE
CURRENTLY INITIATING NEW CONVECTIVE DEVELOPMENT IN THE WARM/MOIST AND
UNSTABLE AIRMASS ACROSS THE LOCAL AREA. ALTHOUGH MESOSCALE DETAILS
ARE DIFFICULT TO PINPOINT EVEN WITHIN THE NEXT 6-12 HOURS...ALL
PARAMETERS SUGGEST THAT THE AREAL COVERAGE OF CONVECTION TODAY WILL
BE SIMILAR TO WHAT WAS EXPERIENCED YESTERDAY AND WILL HOLD POPS IN
THE 50-60 PERCENT RANGE. THIS IS SUPPORTED BY RECENT GUIDANCE FROM
THE NSSL WRF/WRF-NMM AND HRRR. GUIDANCE FROM GLOBAL MODELS...
INCLUDING THE GFS/GEM/UKMET/ECMWF...ALL INDICATE THAT ENVIRONMENTAL
CONDITIONS WILL BECOME MUCH MORE FAVORABLE FOR A WIDESPREAD
CONVECTIVE EVENT BEGINNING EARLY TUESDAY MORNING IN NORTHWEST AND
NORTH CENTRAL ALABAMA...AND LINGERING OVER THE ENTIRE REGION FOR MOST
OF TUESDAY MORNING -- BEFORE DIMINISHING FROM WEST-TO-EAST DURING THE
AFTERNOON. ESSENTIALLY...WE ARE EXPECTING ONE OR MORE ORGANIZED
CONVECTIVE COMPLEXES TO DEVELOP LATER THIS EVENING ALONG A WEAK COLD
FRONT DRIFTING SOUTHWARD INTO THE OZARKS/SOUTHERN PLAINS. THIS
ACTIVITY IS EXPECTED TO SHIFT EAST-SOUTHEASTWARD INTO THE REGION
EARLY TUESDAY MORNING...WITH WIDESPREAD SHOWERS AND STORMS CONTINUING
THROUGH THE MORNING AS A SLIGHTLY STRONGER MID-LEVEL WAVE INDUCES THE
DEVELOPMENT OF A WEAK SURFACE LOW ALONG THE FRONT. ALTHOUGH A MODEST
INCREASE IN MID-LEVEL FLOW MAY RESULT IN A GREATER THREAT FOR STRONG
STORMS FROM LATE TONIGHT THROUGH TUESDAY MORNING...DEEP-LAYER
VERTICAL WIND SHEAR DOES NOT APPEAR TO BE FAVORABLE FOR SEVERE
THUNDERSTORMS. HOWEVER...MULTIPLE EPISODES OF RAIN/THUNDERSTORMS MAY
LEAD TO A HEIGHTENED RISK OF FLASH FLOODING DURING THIS PERIOD.

THE SYNOPTIC PATTERN WILL BEGIN TO CHANGE BY TUESDAY NIGHT AND
WEDNESDAY...AS THE MID-LEVEL WAVE RESPONSIBLE FOR OUR CONVECTION
SHIFTS EASTWARD INTO THE CAROLINAS/GEORGIA. A STRONGER VORT MAX --
PROGGED TO DIG SOUTHEASTWARD ACROSS THE UPPER MIDWEST ON TUESDAY AND
LOWER GREAT LAKES/UPPER OHIO VALLEY ON TUESDAY NIGHT -- WILL COMBINE
WITH PRONOUNCED HEIGHT RISES ACROSS THE SOUTHERN PLAINS TO INDUCE
MORE OF A NORTHWEST FLOW REGIME ACROSS THE LOCAL REGION...AND THIS
WILL EFFECTIVELY ALLOW THE SURFACE COLD FRONT TO DRIFT SOUTHWARD. THE
ADVECTION OF A DRIER AIRMASS FROM THE NORTHEAST AND WEAK DEEP-LAYER
FORCING FOR UVM WILL LIMIT RAIN CHANCES FROM TUESDAY NIGHT INTO
WEDNESDAY.

THE PATTERN IN PLACE AT THE END OF THE SHORT TERM PERIOD WILL
CONTINUE IN THE EXTENDED...ALTHOUGH OUR LOCAL WEATHER REGIME WILL
BECOME INCREASINGLY INFLUENCED BY A STRONG MID-TROPOSPHERIC
ANTICYCLONE BECOMING ESTABLISHED ACROSS THE SOUTHERN PLAINS. A COUPLE
OF WEAK DISTURBANCES WILL TRANSLATE SOUTH-SOUTHEASTWARD ON FRIDAY AND
SATURDAY...PERHAPS BRINGING ISOLATED SHOWERS AND STORMS TO THE
REGION. HOWEVER...WE STILL ANTICIPATE MORE OF A DIURNAL CONVECTIVE
CYCLE TO EVOLVE EARLY NEXT WEEK...AS THE SOUTHERN PLAINS RIDGE BEGINS
TO EXPAND EASTWARD INTO THE REGION.

70/DD

&&

.AVIATION...
/ISSUED 1143 PM CDT SUN JUN 16 2013/
FOR 06Z TAFS...PATCHY FOG WILL DEVELOP THIS MORNING AND WILL REDUCE
VSBY INTO THE MVFR CATEGORY AT TIMES. IFR CONDS CANNOT BE RULED
OUT, BUT CONFIDENCE IS NOT HIGH ENOUGH GIVEN A SOLID DECK OF MID
LEVEL CLOUDS EXPECTED TO BE IN PLACE THROUGH DAYBREAK. REDEVELOPMENT
OF SHRA OR TSRA IS POSSIBLE, BUT THE GREATER THREAT WILL BE SOUTH OF
KMSL AND KHSV THRU MORNING. ADDITIONAL DEVELOPMENT OF SHRA AND TSRA
IS ANTICIPATED AGAIN ON MONDAY, ESPECIALLY DURING THE AFTERNOON
HOURS. WILL MAINTAIN A CB LAYER TO ACCOUNT FOR THIS POTENTIAL UNTIL
BETTER COVERAGE AND TIMING DETAILS CAN BE DETERMINED.

AK

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    88  70  83  68 /  60  80  90  40
SHOALS        89  71  85  67 /  60  80  90  20
VINEMONT      86  68  82  66 /  60  80  90  40
FAYETTEVILLE  84  69  82  66 /  60  80  90  40
ALBERTVILLE   86  67  81  66 /  60  70  90  40
FORT PAYNE    84  66  81  65 /  60  60  90  40

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...NONE.

TN...NONE.

&&

$$

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