New Day Two Severe Weather Outlook

Issued within the hour from SPC… full details on the afternoon Weather Xtreme video here by 3:30…

SPC AC 011730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT WED APR 01 2009

VALID 021200Z – 031200Z

…THERE IS A MDT RISK OF SVR TSTMS FROM PARTS OF SWRN TN…MS AL
AND WRN GA…

…THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MS VALLEY…SRN
PARTS OF THE OH VALLEY AND MUCH OF THE SERN STATES…

…SYNOPSIS…

SHORTWAVE TROUGH NOW OVER THE CNTRL ROCKIES WILL MOVE SE INTO THE
SRN PLAINS TONIGHT BEFORE EJECTING ENEWD THROUGH THE SERN STATES
THURSDAY. ATTENDANT LEE CYCLONE OVER OK EARLY THURSDAY WILL LIFT
ENEWD THROUGH THE LOWER MS AND TN VALLEYS…REACHING THE OH VALLEY
OVERNIGHT. TRAILING PACIFIC FRONT WILL ADVANCE EAST AND EXTEND FROM
THE WRN CAROLINAS SWWD THROUGH THE WRN FL PANHANDLE BY THE END OF
THE PERIOD. WARM FRONT OVER THE NRN GULF WILL LIKELY LIFT NWD INTO
THE GULF COASTAL STATES…BUT NWD PROGRESSION OF THIS BOUNDARY MAY
BE LIMITED TO SOME DEGREE BY THE POTENTIAL FOR ONGOING CONVECTION.

…LOWER MS VALLEY THROUGH SERN STATES AND TN VALLEY…

THREAT STILL EXISTS FOR A SIGNIFICANT SEVERE EVENT OVER A PORTION OF
THE SERN STATES. HOWEVER POTENTIAL LIMITING FACTORS DO EXIST. THE
RICH LOW LEVEL MOISTURE WITH DEWPOINTS IN THE UPPER 60S TO AROUND 70
HAS BEEN SHUNTED SWD INTO THE NRN GULF SOUTH OF A CONVECTIVELY
ENHANCED FRONTAL BOUNDARY. POTENTIAL COMPLICATING FACTORS INVOLVE
IMPULSES EMBEDDED WITHIN THE SUBTROPICAL JET STREAM. ONE SUCH
IMPULSE IS FORECAST TO EJECT NEWD THROUGH THE NRN GULF REGION EARLY
THURSDAY WITH A CORRESPONDING INCREASE IN THE LOW LEVEL JET. THIS
WILL LIKELY ENHANCE LIFT IN VICINITY OF THE BOUNDARY OVER THE NRN
GULF…RESULTING IN THE DEVELOPMENT OF STORMS. CONCERN IS THAT THIS
ACTIVITY MAY LIMIT THE NWD RETURN OF THE RICH GULF MOISTURE TO SOME
EXTENT WITH LOW TO MID 60S MORE LIKELY OVER THE SERN STATES THAN
UPPER 60S INLAND FROM COASTAL AREAS. REMNANT EML WILL LIKELY ADVECT
EWD ABOVE THE RETURNING MOIST AXIS…AND IN ADDITION TO POTENTIAL
FOR EARLY STRATUS COULD RESULT IN A CAP IN MUCH OF THE WARM SECTOR.
THE ATMOSPHERE WILL LIKELY UNDERGO SOME DESTABILIZATION DURING THE
DAY AS MOISTURE RETURNS NWD AND LOW CLOUDS BEGIN TO MIX OUT…WITH
MLCAPE FROM 1000-1500 J/KG.

STORMS WILL LIKELY BE ONGOING WITHIN ZONE OF FORCING/DPVA ALONG AND
JUST AHEAD OF THE FRONT AND ATTENDANT SHORTWAVE TROUGH FROM ERN TX
INTO AR. THIS ACTIVITY WILL LIKELY CONTINUE EAST DURING THE DAY AND
GROW UPSCALE INTO AN MCS. ACTIVITY WILL BE EMBEDDED WITHIN STRONG
VERTICAL SHEAR WITH HODOGRAPHS SUFFICIENT FOR EMBEDDED SUPERCELLS
AND LEWP STRUCTURES. THE STORMS WILL LIKELY INTENSIFY AS THE
ATMOSPHERE DESTABILIZES DOWNSTREAM. DAMAGING WIND…LARGE HAIL AND
TORNADOES WILL BE POSSIBLE WITH THIS ACTIVITY.

FARTHER EAST IN THE WARM SECTOR ACROSS AL…LOW LEVEL HODOGRAPHS
WILL INITIALLY NOT BE PARTICULARLY LARGE DUE TO THE SPLIT LOW LEVEL
JET STRUCTURE WITH ONE BRANCH FARTHER WEST IN ASSOCIATION WITH THE
PROGRESSIVE SHORTWAVE TROUGH…AND ANOTHER BRANCH FARTHER SWD ALONG
THE GULF COAST. DISCRETE INITIATION AWAY FROM THE FRONTAL BOUNDARY
IS POSSIBLE BUT IS MORE UNCERTAIN DUE TO POTENTIAL FOR AT LEAST A
MODEST CAP AND PRESENCE OF LOW CLOUDS. HOWEVER…IF SUFFICIENT
BREAKS OCCUR A FEW DISCRETE STORMS MAY DEVELOP DURING THE AFTERNOON.
THE LOW LEVEL JET WILL LIKELY STRENGTHEN WITH TIME IN THIS REGION AS
THE UPPER TROUGH CONTINUES EAST. IF DISCRETE MODES CAN DEVELOP AND
BE MAINTAINED AS THE LOW LEVEL JET STRENGTHENS…THE THE TORNADO
THREAT WOULD CORRESPONDINGLY BE HIGHER.

OTHER SEVERE STORMS WILL BE LIKELY WITH CONVECTION DEVELOPING IN
VICINITY OF THE BOUNDARY ALONG THE GULF COASTAL REGION.

…SE GA INTO CAROLINAS…

THE UPPER TROUGH AND STRONGER LOW-MID LEVEL FLOW WILL SHIFT ENEWD
THROUGH SRN GA AND THE CAROLINAS OVERNIGHT. SOME INLAND RECOVERY IS
POSSIBLE…ESPECIALLY FROM SRN GA INTO THE ERN CAROLINAS AS THE
BOUNDARY LAYER FLOW STRENGTHENS. THREAT WILL EXIST FOR ORGANIZED
STORMS INCLUDING SUPERCELLS WITH DAMAGING WIND…ISOLATED TORNADOES
AND LARGE HAIL POSSIBLE.

..DIAL.. 04/01/2009

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