DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 091631
SWODY1
SPC AC 091629

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT FRI AUG 09 2013

VALID 091630Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DELMARVA INTO SERN PA
AND NJ...

...DELMARVA INTO SERN PA/NJ...
VISIBLE IMAGERY SHOWS LIMITED CLOUDS FROM SRN/ERN VA INTO THE
DELMARVA PENINSULA...WITH BREAKS IN CLOUDS NWD INTO NJ. STRONGER
DIABATIC HEATING HAS OCCURRED AHEAD OF AN ADVANCING CLOUD SHIELD
WITH SURFACE TEMPERATURES RANGING FROM NEAR 90 IN VA TO LOW 80S IN
NJ. DESPITE MODEST LAPSE RATES...AMPLE MOISTURE /DEW POINTS IN
LOW/MID 70S AND PW AOA 2 IN/ IS CONTRIBUTING TO CAPE VALUES AROUND
1500 J/KG...AND WEAK CIN SHOULD RESULT IN CONVECTION INITIATION
OCCURRING DURING EARLY/MID AFTERNOON HOURS CONSISTENT WITH CONSENSUS
OF MULTIPLE CONVECTION-ALLOWING MODEL FORECASTS.

12Z AREA SOUNDINGS AND LATEST VAD WIND PROFILES INDICATE 30-40 KT OF
WLY FLOW ABOVE 1-2 KM AGL WHICH WILL SUPPORT PRIMARILY ORGANIZED
MULTICELL CONVECTIVE STRUCTURES. AS STORMS MOVE EWD DURING THE
AFTERNOON AND EARLY EVENING HOURS...DOWNWARD TRANSFER OF HORIZONTAL
MOMENTUM AUGMENTED BY PRECIPITATION-LOADING EFFECTS SHOULD SUPPORT
DEVELOPMENT OF A FEW WET MICROBURSTS CAPABLE OF PRODUCING LOCALIZED
DAMAGING WIND GUSTS.

...PARTS OF NEW ENGLAND...
AN EXTENSIVE AREA OF CLOUDS AND PRECIPITATION MOVING ACROSS THIS
REGION IS INHIBITING STRONGER DIURNAL HEATING AND DESTABILIZATION.
WIND PROFILES EXHIBIT STRONGER LOW LEVEL FLOW THAT VEERS WITH HEIGHT
WITH RESULTANT VERTICAL SHEAR THAT IS FAVORABLE FOR ORGANIZED
CONVECTIVE STRUCTURES INCLUDING POSSIBLE SUPERCELLS. HOWEVER...THE
WIDESPREAD PRECIPITATION IS LIKELY TO LIMIT OVERALL SEVERE POTENTIAL
ALTHOUGH AN EMBEDDED STORM OR TWO MAY BE CAPABLE OF PRODUCING
MARGINAL SEVERE WIND OR A BRIEF TORNADO DURING THE AFTERNOON.

...ERN OK TO WRN KY/TN...
A CONVECTIVELY-ENHANCED MID LEVEL TROUGH OVER NRN OK IS FORECAST TO
DRIFT ENEWD TO THE SE KS/SW MO BORDER REGION BY TONIGHT. A WEAK
COLD FRONT IS EXPECTED TO BEGIN MOVING SWD FROM KY/MO TO
TN/AR...MODIFIED BY ONGOING CONVECTION. WEAK CONVERGENCE ALONG THE
FRONT WILL SUPPORT ADDITIONAL THUNDERSTORM DEVELOPMENT THIS
AFTERNOON AS THE MOIST BOUNDARY LAYER HEATS ALONG AND S OF THE
EFFECTIVE FRONT. MODERATE INSTABILITY IS EXPECTED ALONG THE
FRONT/DIFFERENTIAL HEATING ZONE...AND VERTICAL SHEAR WILL BE MORE
FAVORABLE FOR ORGANIZED STORM CLUSTERS IN THE WEAK NELY FLOW ON THE
IMMEDIATE COOL SIDE OF THE FRONT. A FEW DAMAGING GUSTS WILL BE
POSSIBLE FROM ERN OK ACROSS NRN AR TO WRN TN...WHERE THE STRONGER
INSTABILITY COINCIDES WITH A BELT OF SOMEWHAT ENHANCED MID LEVEL
FLOW ON THE IMMEDIATE SE SIDE OF THE WEAK MID LEVEL TROUGH.

...ERN NM AREA...
A DEPARTING MID LEVEL TROUGH OVER THE PLAINS WILL LEAVE LITTLE
LARGE-SCALE FOCUS FOR ASCENT ACROSS THIS AREA. STILL...LINGERING
LOW-LEVEL MOISTURE AS A WEAK UPSLOPE FLOW REGIME DEVELOPS THIS
AFTERNOON SHOULD SUPPORT AT LEAST WIDELY SCATTERED THUNDERSTORM
DEVELOPMENT ALONG THE E SLOPES OF THE HIGHER TERRAIN. STORMS SHOULD
SUBSEQUENTLY MOVE SLOWLY SEWD THROUGH THE EVENING...WITH SOME
POTENTIAL FOR ISOLATED LARGE HAIL AND STRONG GUSTS GIVEN MLCAPE OF
1000-1500 J/KG AND EFFECTIVE BULK SHEAR OF 25-30 KT.

...SE MT/NE WY/SW SD...
PATTERN OF WEAK LOW-LEVEL FRONTOGENESIS IS EXPECTED TO PERSIST ALONG
FROM NERN WY ACROSS SWRN SD AND ADDITIONAL THUNDERSTORM DEVELOPMENT
IS EXPECTED THIS AFTERNOON. RESIDUAL LOW-LEVEL MOISTURE BENEATH THE
NE EDGE OF THE STEEPER MIDLEVEL LAPSE RATES WILL CONTRIBUTE TO
WEAK-MODERATE INSTABILITY...WHILE DEEP-LAYER VERTICAL SHEAR WILL BE
AT LEAST MARGINALLY FAVORABLE FOR ORGANIZED MULTICELLS AND/OR
SUPERCELLS. ISOLATED LARGE HAIL AND DAMAGING GUSTS WILL BE THE MAIN
THREATS FOR A FEW HOURS THIS AFTERNOON/EVENING.

...NRN CA TO CENTRAL ORE THIS AFTERNOON/EVENING...
SUFFICIENT DEEP LAYER MOISTURE AND ASCENT NE OF THE QUASI-STATIONARY
UPPER LOW OVER THE NRN CA COAST IS SUPPORTING THUNDERSTORMS OVER
NERN CA ATTM...AND ADDITIONAL CONVECTION IS LIKELY TO SPREAD/DEVELOP
INTO PARTS OF OREGON THIS AFTERNOON/EVENING. MODEST INSTABILITY AND
DEEP-LAYER SELY SHEAR WILL SUPPORT A FEW ORGANIZED CLUSTERS CAPABLE
OF PRODUCING ISOLATED STRONG/DAMAGING GUSTS AND MARGINALLY SEVERE
HAIL.

..WEISS/BUNTING.. 08/09/2013

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