DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 301952
SWODY1
SPC AC 301950

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0250 PM CDT SAT JUN 30 2012

VALID 302000Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM CNTRL IL/IND EWD INTO THE
NC/VA COAST....

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN KS INTO THE DAKOTAS...

...OH VALLEY INTO THE MID ATLANTIC...
REDUCED SEVERE PROBABILITIES TO A BROAD 15% MINIMAL SLIGHT FOR THE
REGION. THE AIR MASS OVER MUCH OF THE AREA FROM PA INTO ERN VA...MD
AND DE HAS NOT YET RECOVERED FROM THE PREVIOUS MCS. THE 18Z IAD
SOUNDING HAD VERY LITTLE INSTABILITY...ALTHOUGH MIDLEVEL FLOW WAS
STRONG. STRONGER HEATING WAS OCCURRING JUST SW OF THE AREA OVER
CNTRL VA...AND CU WAS INCREASING NEAR AN OLD BOUNDARY FROM ERN KY
INTO WRN VA. IF STORMS FORM HERE...THEY COULD GROW UPSCALE ACROSS
SRN VA...ERN TN AND NRN/WRN NC.

OTHER STORMS WERE LINGERING OVER CNTRL IL INTO IND...AND MAY
EVENTUALLY GROW UPSCALE AS STRONG INSTABILITY REMAINS OVER THE
REGION.

...SRN APPALACHIANS...
EXTREMELY HOT TEMPERATURES HAVE MIXED MOISTURE VERTICALLY AND ALSO
REDUCED CAPPING. VISIBLE IMAGERY SHOWS CU ALONG AND S OF THE OLD
OUTFLOW BOUNDARY FROM ERN KY INTO WRN VA...AND ALSO SWD ACROSS ERN
TN...WRN NC...AND NRN GA. WITH CONTINUED HEATING...ISOLATED STORMS
WILL BE POSSIBLE. LOW TO MIDLEVEL LAPSE RATES ARE VERY STEEP...AND
WITH WEAK WINDS ALOFT...THIS WOULD SUPPORT VERY STRONG BUT LIKELY
SHORT LIVED UPDRAFTS CAPABLE OF DAMAGING DOWNBURSTS AND MARGINAL
HAIL.

...WRN NEB/NERN CO...
SHUNTED WRN EDGE OF SLIGHT RISK EWD TO ACCOUNT FOR DRYING FROM THE
W.

..JEWELL.. 06/30/2012

.PREV DISCUSSION... /ISSUED 1141 AM CDT SAT JUN 30 2012/

...OH VALLEY TO THE MID ATLANTIC THROUGH EARLY TONIGHT...
THE SEVERE MCS LAST NIGHT OVERTURNED MUCH OF THE AREA FROM OH TO
VA...AS EVIDENCED BY ROUGHLY 3500 J/KG REDUCTIONS IN MOST-UNSTABLE
CAPE AT ILN AND IAD FROM 29/12Z TO 12Z THIS MORNING. SOME RECOVERY
IS EXPECTED THIS AFTERNOON GIVEN THE STRONG SURFACE HEATING THAT IS
UNDERWAY FROM THE OH VALLEY INTO THE MID ATLANTIC...WHERE MLCAPE
SHOULD RANGE FROM 1500-2000 J/KG ACROSS VA TO 2500 J/KG FROM
CENTRAL/SRN IL TO THE OH/KY BORDER. MEANWHILE...WATER VAPOR IMAGERY
AND MORNING UPPER AIR PLOTS SHOW A SERIES OF EMBEDDED VORTICITY
MAXIMA FROM IA TO WRN PA. THESE WAVES WILL INTERACT WITH THE MEAN
BAROCLINIC ZONE FROM CENTRAL IL TO SRN OH...AND SHOULD SUPPORT THE
DEVELOPMENT OF ONE OR MORE THUNDERSTORM CLUSTERS THIS AFTERNOON.

THE MORE PROBABLE AREAS FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON
SHOULD BE ALONG THE DIFFUSE FRONT ACROSS CENTRAL IL/INDIANA...AND
ALONG THE SRN FLANK OF THE REMNANT MCV CROSSING WRN PA AS OF LATE
MORNING. THOUGH BUOYANCY WILL BE REDUCED COMPARED TO
YESTERDAY...VERTICAL SHEAR WILL BE STRONGER BENEATH A BELT OF 50-60
KT MIDLEVEL FLOW THAT WILL OVERSPREAD WV/NRN VA/MD THIS AFTERNOON.
THUS...AN ORGANIZED CLUSTER OR TWO OF STORMS WILL BE POSSIBLE THIS
AFTERNOON/EVENING...AND DAMAGING WINDS SHOULD BE THE PRIMARY SEVERE
CONCERN.

...CENTRAL/NRN PLAINS THROUGH EARLY TONIGHT...
SEVERAL WEAK VORTICITY MAXIMA WILL CREST THE RIDGE OVER THE
DAKOTAS/NEB...WHILE A SEPARATE CYCLONIC SHEAR AXIS PERSISTS NEAR THE
CO/KS BORDER. MORNING ELEVATED STORMS HAVE WEAKENED OVER ND...BUT
ADDITIONAL DEVELOPMENT IS EXPECTED THIS AFTERNOON IN SEVERAL
CLUSTERS ACROSS SD/NEB/KS IN ASSOCIATION WITH THE VORTICITY MAXIMA
AND THE STALLED SURFACE FRONT NEAR THE NEB/KS BORDER. DEEP-LAYER
VERTICAL SHEAR WILL BE SUFFICIENT FOR SOME SUPERCELL STRUCTURES
ACROSS SRN ND/SD...WHILE WEAKER VERTICAL SHEAR AND WARMER SURFACE
TEMPERATURES/DEEPER MIXED LAYERS WILL SUPPORT HIGHER-BASED MULTICELL
STORMS FARTHER S INTO NEB/KS. DAMAGING OUTFLOW GUSTS AND LARGE HAIL
WILL BE THE MAIN THREATS LATER THIS AFTERNOON INTO EARLY TONIGHT.

...NRN MAINE THIS AFTERNOON...
LOW-LEVEL MOISTURE HAS DECREASED A LITTLE SINCE YESTERDAY ACROSS THE
SAINT LAWRENCE VALLEY...AND THIS WILL LIKELY RESULT IN SOMEWHAT
WEAKER BUOYANCY. DEEP-LAYER VERTICAL SHEAR WILL STILL BE SUFFICIENT
FOR ORGANIZED/PERSISTENT STORMS...AND CONVECTIVE DEVELOPMENT IS
ALREADY UNDERWAY IN ERN QUEBEC IN ADVANCE OF A MIDLEVEL TROUGH
APPROACHING SRN QUEBEC. SOME OF THESE STORMS COULD SPREAD INTO
NW/NRN MAINE THIS AFTERNOON...WITH AN ACCOMPANYING RISK FOR ISOLATED
DAMAGING GUSTS AND MARGINALLY SEVERE HAIL.

...INTERIOR PAC NW THIS AFTERNOON/EVENING...
A MIDLEVEL TROUGH WILL PROGRESS INLAND TODAY OVER NRN CA/ORE/WA.
REGIONAL 12Z SOUNDINGS SHOWED POOR LAPSE RATES ALOFT WITH MOIST
PROFILES...AND LOW-LEVEL MOISTURE WILL BE LIMITED IN AREAS
IMMEDIATELY E OF THE ASSOCIATED CLOUD BAND WHERE SURFACE HEATING
WILL BE STRONGER. THE NET RESULT WILL BE AN ENVIRONMENT THAT IS
ONLY WEAKLY UNSTABLE. ASSUMING A FEW STORMS CAN DEVELOP THIS
AFTERNOON/EVENING ALONG THE E EDGE OF THE CLOUD BAND...DEEP-LAYER
VERTICAL SHEAR WILL SUPPORT ORGANIZED STORMS WITH SOME POTENTIAL FOR
STRONG OUTFLOW GUSTS.

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