DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251632
SWODY1
SPC AC 251630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT FRI MAY 25 2012

VALID 251630Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NY AND NRN NEW
ENGLAND...

...THERE IS A SLGT RISK OF SVR TSTMS OVER THE PARTS OF THE OH
VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE GREAT
PLAINS...

...NORTHEAST...
A VIGOROUS SHORT WAVE TROUGH ACROSS SRN ONTARIO IS FORECAST TO
CONTINUE TO LIFT RAPIDLY NEWD ACROSS JAMES BAY AND OVER QUEBEC
THROUGH THE DAY. COLD FRONT ASSOCIATED WITH THIS DISTURBANCE IS
CLEARLY EVIDENT IN SURFACE AND SATL DATA AND WILL CONTINUE TO SPREAD
EAST ACROSS LAKES ERIE AND ONTARIO...AND TO NRN NY LATER THIS
AFTERNOON/EARLY EVENING. THE FRONT WILL THEN SETTLE ACROSS NRN NEW
ENGLAND THROUGH TONIGHT. STRONGEST FORCING FOR ASCENT ALONG THE COLD
FRONT WILL EXIST NORTH OF THE BORDER IN QUEBEC WHERE SEVERE STORMS
APPEAR MORE LIKELY. WHILE LOW LEVEL CONVERGENCE AND LIFT ALONG THE
FRONT WITH SWD/SWWD EXTENT WILL BE WEAKER...LATEST GUIDANCE DEPICTS
AREAS OF WEAK TO MODEST DESTABILIZATION FROM NY ACROSS NRN VT BY
LATER TODAY. MLCAPE VALUES IN THESE AREAS SHOULD REACH THE 500-1000
J PER KG RANGE WHERE FORECAST SOUNDINGS FROM NAM AND WRF-ARW MODELS
DEPICT PRONOUNCED LOW LEVEL VERTICAL SHEAR. ANY STORMS THAT CAN
DEVELOP WILL EXIST IN AN ENVIRONMENT WITH SUFFICIENT VERTICAL SHEAR
FOR UPDRAFT PERSISTENCE AND ROTATION. GREATEST UNCERTAINTY EXISTS
WITH REGARD TO STORM COVERAGE GIVEN THE RAPID TRANSLATION OF THE
UPPER TROUGH AWAY FROM THE AXIS OF STRONGER POTENTIAL INSTABILITY
LATER TODAY. LATEST INDICATIONS CONTINUE TO SUPPORT THE DEVELOPMENT
OF AT MOST SCATTERED TSTMS ALONG THE FRONT DURING A RELATIVELY
NARROW WINDOW IN SPACE/TIME FROM LATE AFTERNOON INTO THE EVENING.
GIVEN INSTABILITY AND SHEAR FORECAST OVER UPSTATE NY INTO NRN VT...A
FEW ROTATING STORMS MAY EVOLVE IN THIS PERIOD AND POSE SOME THREAT
OF DAMAGING WINDS OR PERHAPS A TORNADO. SPC HAIL MODEL GUIDANCE
INDICATES ONLY ISOLATED HAIL PERHAPS TO AROUND 1 INCH IN DIAMETER.

...OH VALLEY...
FARTHER SW AHEAD OF THE COLD FRONT...SCATTERED LESS-ORGANIZED STORMS
APPEAR LIKELY AS A MOIST AND INCREASINGLY UNSTABLE AIRMASS FUELS
DEVELOPMENT FROM OH WWD ACROSS IND/IL. THE BULK OF THIS ACTIVITY
WILL OCCUR BENEATH WEAK MID LEVEL HEIGHT RISES AND ON THE SRN
PERIPHERY OF STRONGER MID LEVEL FLOW ACROSS THE GREAT LAKES.
MAGNITUDE OF INSTABILITY AND SUFFICIENT LIFT ALONG THE FRONT
SETTLING INTO THIS REGION SHOULD CONTRIBUTE TO NUMEROUS STORMS...A
FEW OF WHICH MAY BE CAPABLE OF SEVERE HAIL/WIND EVENTS THROUGH LATE
TODAY.

...WRN KS TO ERN TX PANHANDLE/WRN OK REGION...
ISOLATED TO WIDELY SCATTERED TSTMS ARE POSSIBLE ALONG DRYLINE DURING
21Z-00Z TIME FRAME...DURING PERIOD OF MOST INTENSE BOUNDARY-LAYER
WARMTH/MIXING. CONVECTION NEAR TRIPLE POINT AND ADJOINING
WARM-FRONTAL SEGMENT MAY PERSIST NOCTURNALLY...LEADING TO UPSCALE
GROWTH/MERGER WITH ELEVATED CONVECTION FARTHER NE OVER CENTRAL
PLAINS.

MOST FAVORABLE LOW-LEVEL HODOGRAPHS AND DEEP-SHEAR PROFILES FOR
SUPERCELLS WILL BE NEAR W-CENTRAL KS TRIPLE POINT...DECREASING BUT
REMAINING AT LEAST MRGLLY FAVORABLE WITH SWD EXTENT WRN OK. KS
JUXTAPOSITION OF BOUNDARIES WILL YIELD RELATIVELY MAXIMIZED
JUXTAPOSITION OF FAVORABLE SHEAR AND LOW-LEVEL CONVERGENCE.
ENHANCED LOW-LEVEL VORTICITY AND SRH ALSO WILL ACCOMPANY BACKED SFC
WINDS ALONG WARM FRONT...FOR ANY CONVECTION THAT CAN DEVELOP AT
TRIPLE POINT OR NEARBY DRYLINE SEGMENT AND MOVE DEVIANTLY RIGHTWARD
IN THAT PART OF WARM-FRONTAL ZONE WHERE CAPE REMAINS SFC-BASED. FCST
HODOGRAPHS SUGGEST SMALL AREA OF 200-400 J/KG 0-1 KM AGL SRH
ACCOMPANYING WARM FRONT...DECREASING SWD. THESE FACTORS SHOULD FOCUS
TORNADO POTENTIAL NEAR TRIPLE POINT AND WARM FRONT. LARGE HAIL ALSO
IS LIKELY WITH ANY SUPERCELLS.

SPECIFIC FOCI FOR CONVECTIVE INITIATION FARTHER S ACROSS WRN OK/ERN
TX PANHANDLE REGION ARE RATHER NEBULOUS. HOWEVER...SOME
CONVECTION-ALLOWING PROGS INDICATE DEVELOPMENT IN THIS REGION
BETWEEN 21Z-00Z. FCST SOUNDINGS SUGGEST SFC TEMPS 90S F AND DEW
POINTS 60S E OF DRYLINE WITH RESULTING MLCAPE 2000-3000 J/KG... AND
30-40 KT EFFECTIVE SHEAR MAGNITUDES. HODOGRAPHS ENLARGE AFTER DARK
AS CINH STRENGTHENS CONSIDERABLY...BUT WITH SOME OVERLAPPING TIME
WINDOW WHERE SFC PARCELS STILL ARE ACCESSIBLE WITH AID OF INTERNALLY
FORCED STORM DYNAMICS.

...NW TX TO RIO GRANDE...
VERTICAL SHEAR WILL WEAKEN OVER THIS REGION SWD FROM SWRN OK...WHILE
INITIATION POTENTIAL REMAINS VERY CONDITIONAL/ISOLATED IN NATURE.
ACTIVITY OVER THIS REGION GENERALLY SHOULD BE MORE PURELY DIURNALLY
DRIVEN AND SHORT-LIVED AS WELL...GIVEN PRESENCE OF VERY STG CAPPING
AND WARM 700-850 MB LAYER IN MORNING RAOBS THAT PERSISTS THROUGH
AFTERNOON. THEREFORE...UNCONDITIONAL SVR PROBABILITIES ARE KEPT AT
MRGL/5% LEVELS. HOWEVER...ANY TSTMS THAT DO FORM AWAY FROM EXISTING
CLOUD COVER WILL BE HIGH-BASED...ATOP INTENSELY HEATED/WELL-MIXED
BOUNDARY LAYER...AND CAPABLE OF STG-SVR DOWNBURSTS AND ISOLATED
LARGE HAIL. MOST PROBABLE AREA FOR DEVELOPMENT MAY BE OVER REGION
FROM PERMIAN BASIN SWD OVER LOWER PECOS/RIO GRANDE REGIONS. MOISTURE
CHANNEL IMAGERY INDICATES SUBTLE/MID-UPPER LEVEL
PERTURBATIONS MOVING NNEWD ACROSS BIG-BEND REGION AND OVER
CENTRAL/N-CENTRAL MEX NNE OF PAC HURRICANE BUD. EACH MAY ENHANCE
LARGE-SCALE ASCENT AND THERMODYNAMIC ENVIRONMENT ALOFT FOR
LATE-AFTERNOON TSTM POTENTIAL OVER THIS CORRIDOR.

...CNTRL PLAINS/MISSOURI VALLEY...
THE NOCTURNAL ENHANCEMENT TO THE LLJ WILL LIKELY GIVE RISE TO AN
INCREASE IN ELEVATED TSTMS ACROSS THE MID-MO VALLEY TONIGHT WHERE
THE PRESENCE OF MODERATE-STRONG INSTABILITY WILL PROMOTE EMBEDDED
SUPERCELLS CAPABLE OF MAINLY LARGE HAIL.

...FL...
SCATTERED STRONG TO ISOLATED SEVERE STORMS WITH WINDS AND PERHAPS
SOME HAIL APPEAR LIKELY ACROSS PARTS OF S FL LATER THIS AFTERNOON.
FLOW REGIME SHOULD CONTRIBUTE TO SWD/SWWD MOVING MULTICELL STORMS
OCCASIONALLY STRENGTHENING NEAR BOUNDARY INTERSECTIONS AND/OR CELL
MERGERS.

..CARBIN/EDWARDS/PETERS.. 05/25/2012

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