000
FXUS64 KHUN 212336 AAA
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
636 PM CDT TUE MAY 21 2013

.UPDATE...
FOR 00Z TAFS

&&

.DISCUSSION...
/ISSUED 305 PM CDT TUE MAY 21 2013/
PRE-FRONTAL TROUGH AXIS IS CURRENTLY MAKING ITS WAY EWD ACROSS WRN TN
LEADING INTO NRN MS...WITH A BROKEN LINE OF CONVECTION ONGOING WELL
AHEAD OF THE SFC BOUNDARY. THE BULK OF THE CONVECTIVE LINE WAS
GENERALLY LIFTING TO THE ENE ACROSS MID/ERN TN...ALTHOUGH SOME
TRAILING SHOWERS/TSTMS ALONG THE SRN END WAS TRYING TO SPREAD INTO
EXTREME NW AL/SRN MID TN. ABUNDANT LATENT HEATING EFFECTS/LOW LEVEL
INSTABILITY MAY BE SUFFICIENT ENOUGH TO WARRANT THE THREAT OF A FEW
STRONG/MARGINALLY SVR TSTMS EARLY THIS AFTERNOON...CAPABLE OF BRIEF
DAMAGING WIND GUSTS AND LARGE HAIL. ANY TRAILING SHOWERS/TSTMS ALONG
THE SRN FRINGE OF THIS LINE SHOULD THEN GRADUALLY DIMINISH AS THIS
ACTIVITY MERGES WITH DRIER LOW/MID LEVEL AIR EMBEDDED WITHIN THE
EXITING UPPER RIDGE AXIS TO THE E EARLY THIS EVENING. THE COLD FRONT
ITSELF HELPING TO DRIVE MUCH OF THIS CONVECTION WAS GRADUALLY MOVING
EWD INTO THE LOWER MS VALLEY. THIS ONCOMING FRONT WILL BE THE MAIN
PLAYER AS FAR AS ANY ADDITIONAL CONVECTION GOING INTO MID WEEK.

IN THE SHORT TERM...THE PRE-FRONTAL AXIS SHOULD CONTINUE TO LIFT NE
AS THE SRN STREAM GRADUALLY APPROACHES FROM THE W. THE POTENT UPPER
LOW/VORTEX RESPONSIBLE FOR MUCH OF THE SVR WX ACROSS THE MID PLAINS
THE PAST FEW DAYS FINALLY LOOKS TO WEAKEN AND TRANSLATE EWD LATER
TONIGHT/INTO WED. TRAILING UPPER TROUGH AXIS ACROSS THE LOWER MS
VALLEY WILL ALSO BEGIN TO OVERSPREAD THE AREA LATER TONIGHT...WITH
THE ATTENDANT COLD FRONT LAGGING ACROSS THE MID SOUTH REGION. ANY
ADDITIONAL CONVECTIVE ACTIVITY LOOKS TO BECOME MORE CONFINED ALONG
THE APPROACHING FRONT...WITH ISO/SCT SHOWERS/TSTMS MOVING PREDOM INTO
THE CNTRL/WRN HALF OF THE AREA AFTER MIDNIGHT. PRIOR TO THE ARRIVAL
OF THE NEXT ROUND OF PRECIP...UNSEASONABLY WARM AND HUMID CONDITIONS
WILL LINGER INTO WED.

WHILE SOME DISCREPANCIES REMAIN BETWEEN THE LATEST MODELS WITH THE
COVERAGE/EXTENT OF CONVECTIVE DEVELOPMENT WED...GENERAL CONSENSUS
HAS THE FRONT GRADUALLY MOVING THROUGH THE AREA DURING THE DAY AND
WEAKENING. ABUNDANT LOW LEVEL ENERGY/MOISTURE COUPLED WITH MARGINAL
UPPER DYNAMICS/FORCING WILL TRANSLATE INTO SOME THREAT FOR ADDITIONAL
STRONG/LOCALLY SVR TSTMS...MAINLY DURING THE FIRST HALF OF THE DAY
WITH THE ONSET OF THE FRONT. ANY SUBSEQUENT THREAT FOR STRONGER TSTMS
WILL THEN BE DEPENDENT ON ANY CLEARING IN CLOUD COVER HEADING INTO
THE AFTERNOON PERIOD...COUPLED WITH WEAK UPPER WAVES TRAVERSING EWD
AHEAD OF THE SFC FRONT.

PRECIP IS STILL XPCTED TO TAPER OFF FROM W TO E WED NIGHT WITH THE
EXITING/WEAKENING FRONT TO THE NE AND INFLUX OF SLIGHTLY DRIER AIR.
SOME VARIATIONS WITH THE LATEST MODELS THOUGH STILL EXISTS WITH ANY
CONVECTIVE REDEVELOPMENT ON THU. IN ANY CASE...LINGERING MOISTURE
COUPLED WITH ANY FURTHER PASSING UPPER WAVES MAY ALLOW FOR SOME
ADDITIONAL SHOWERS/TSTMS DURING THE DAY THU. STRONG HIGH PRESSURE
BUILDING SWD ACROSS THE MIDWEST/OH VALLEY AREAS WILL THEN USHER MOD
POLAR AIR INTO THE REGION...WITH QUIET AND MORE SEASONAL LIKE WX
CONDITIONS XPCTED THIS WEEKEND. THE QUIET WX PATTERN LOOKS TO
CONTINUE INTO THE NEW WORK WEEK AS THE SFC HIGH BECOMES ENTRENCHED
ACROSS THE SRN ATLANTIC BASIN...ALTHOUGH THE UPPER FLOW PATTERN MAY
BECOME A BIT MORE ACTIVE OUT OF THE NW.

09

&&

.AVIATION...
FOR 00Z TAFS...

VFR CONDITIONS SHOULD PREVAIL ACROSS N AL/S MIDDLE TN AT LEAST FOR
THE NEXT 9-11 HOURS. A LINE OF STRONG THUNDERSTORMS IS APPROACHING NW
AL AND SHOULD ARRIVE BTWN 08-10Z AFFECTING KMSL BY 09Z. THUS, HAVE
INCLUDED THE ONSET OF TSRA FOR KMSL AT 09Z/KHSV AT 11Z, BUT HAVE ONLY
INCLUDED A FEW-SCT020 CLOUD GROUP AT THIS TIME DUE TO SOME
UNCERTAINTY ON ITS STRENGTH/CIGS AS IT ARRIVES. ADDITIONAL -TSRA AND
INCREASE IN WIND SPEEDS ARE THEN POSSIBLE AFTER 15Z AS ANOTHER LINE
OF -TSRA CROSSES N AL/S MIDDLE TN.

SL.77

&&

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

$$

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