DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 251253
SWODY1
SPC AC 251251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT FRI MAY 25 2012

VALID 251300Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
FROM THE MID-MO VALLEY SWD INTO THE SRN PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EVENING
ACROSS PARTS OF THE LOWER GREAT LAKES...

...SYNOPSIS...

LARGE-SCALE PATTERN WILL UNDERGO AMPLIFICATION THIS PERIOD OWING TO
THE SEWD DEVELOPMENT OF UPPER TROUGH THROUGH THE GREAT BASIN INTO
LOWER CO VALLEY...AND SUBSEQUENT NWD/NEWD EXPANSION OF SUBTROPICAL
RIDGE INTO MID-MS AND OH VALLEYS. WITHIN THIS BROADER-SCALE
PATTERN...SHORT-WAVE TROUGH OVER THE UPPER GREAT LAKES INTO WRN
ONTARIO WILL DE-AMPLIFY WHILE TRANSLATING ENEWD INTO QUEBEC.

AT THE SURFACE...COLD FRONT ATTENDANT TO THE GREAT LAKES SHORT-WAVE
TROUGH WILL ADVANCE EWD TO THE LEE OF LAKE ERIE/ONTARIO BY LATE
AFTERNOON/EARLY EVENING WITH THE BOUNDARY TRAILING WSWWD INTO THE
CNTRL PLAINS WHERE IT WILL BE LIFTING NWD AS A WARM FRONT. A
DRYLINE WILL EXTEND FROM THE WARM FRONT OVER WRN KS SWD TO ALONG THE
TX/OK BORDER AND INTO THE PECOS RIVER VALLEY DURING THE PEAK OF THE
DIURNAL HEATING CYCLE.

...MID-MO VALLEY INTO THE SRN PLAINS...

SURFACE-BASED TSTM DEVELOPMENT REMAINS UNCERTAIN ALONG THE WARM
FRONT AND DRYLINE THIS AFTERNOON/EVENING OWING TO THE RISING
MIDLEVEL HEIGHTS DOWNSTREAM FROM WRN U.S. TROUGH. HOWEVER...SOME
MESOSCALE AND CONVECTION-ALLOWING MODEL GUIDANCE DOES SUGGEST THAT
STRONG DIABATIC WARMING WITHIN AIR MASS W OF DRYLINE FROM SWRN KS
INTO W-CNTRL TX MAY BE SUFFICIENT TO INITIATE ISOLATED TSTMS BY LATE
AFTERNOON/EARLY EVENING. AS SUCH...HIGHER SEVERE PROBABILITIES AND
A CATEGORICAL SLIGHT RISK HAVE BEEN EXTENDED SWD INTO THE ERN TX
PNHDL/WRN OK.

12Z OBSERVED SOUNDINGS WITHIN THE WARM SECTOR INDICATE THE POTENTIAL
FOR STRONG AIR MASS DESTABILIZATION TODAY /MLCAPE OF 2000-4000 J PER
KG/ OWING TO THE COLLOCATION OF A MOIST BOUNDARY LAYER WITH STEEP
MIDLEVEL LAPSE RATES ATTENDANT TO EML. THE STRONGEST DEEP-LAYER
SHEAR /50-60 KT/ WILL RESIDE ACROSS WARM FRONT WITH A GENERAL
DECREASE WITH SWD EXTENT ALONG DRYLINE. IN AREAS WHERE THE VERTICAL
SHEAR IS WEAKER...THE STRONG INSTABILITY WILL COMPENSATE WITH
SUPERCELLS LIKELY ANYWHERE SURFACE-BASED STORMS CAN INITIATE AND
BECOME SUSTAINED. LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH
THE THREAT FOR TORNADOES WILL INCREASE THIS EVENING ACROSS NRN
EXTENSION OF DRYLINE AND WARM FRONT WHERE LOW-LEVEL SHEAR IS
ENHANCED.

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.

...MO THIS MORNING...

A CLUSTER OF ELEVATED TSTMS IS ONGOING THIS MORNING INVOF OF MKC
WITHIN A ZONE OF WEAK LOW-LEVEL WAA N OF SURFACE FRONT. 12Z SGF
SOUNDING SUGGESTS THAT ENVIRONMENT IS MODERATELY UNSTABLE FOR
PARCELS ORIGINATING ABOVE STABLE SURFACE LAYER WITH MUCAPE OF
2000-2500 J/KG. ISOLATED OCCURRENCES OF MARGINALLY SEVERE HAIL ARE
POSSIBLE THIS MORNING BEFORE STORMS GRADUALLY WEAKEN LATER TODAY.

...LOWER GREAT LAKES...

STRONG FORCING FOR ASCENT/HEIGHT FALLS ATTENDANT TO DE-AMPLIFYING
SHORT-WAVE TROUGH WILL REMAIN N OF REGION TODAY WITH CONVERGENCE
ALONG THE COLD FRONT AND/OR DEVELOPING LAKE BREEZE CIRCULATION
SERVING AS THE FOCUS FOR DIURNAL STORM INITIATION. DAYTIME HEATING
COUPLED WITH DEWPOINTS IN THE LOWER 60S WILL CONTRIBUTE TO A
MODERATELY UNSTABLE AIR MASS BY AFTERNOON WITH MLCAPE VALUES
APPROACHING 1000-2000 J/KG. THIS INSTABILITY WILL COINCIDE WITH A
GRADUALLY STRENGTHENING DEEP-LAYER WIND FIELD ALONG SRN PERIPHERY OF
SHORT-WAVE TROUGH WITH ENVIRONMENT BECOMING SUPPORTIVE OF
ORGANIZED/ROTATING STORMS CAPABLE OF DAMAGING WINDS...LARGE HAIL AND
PERHAPS A TORNADO.

..MEAD/ROGERS.. 05/25/2012

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