SWODY2
SPC AC 311726
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT TUE MAY 31 2011
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS WEDNESDAY ACROSS PARTS OF THE
MIDDLE AND NORTHERN ATLANTIC COAST STATES...
...THERE IS A SLGT RISK OF SVR TSTMS WEDNESDAY AFTERNOON AND EVENING
ACROSS PARTS OF THE CENTRAL PLAINS AND MIDDLE MISSOURI VALLEY...
...SYNOPSIS...
SUBTROPICAL RIDGING...CENTERED AT MID-LEVELS ROUGHLY ALONG AN AXIS
ACROSS THE MEXICAN PLATEAU INTO THE SOUTHERN PLAINS AND LOWER
MISSISSIPPI VALLEY...MAY BEGIN TO WEAKEN DURING THIS FORECAST
PERIOD...AS A COUPLE OF SIGNIFICANT SHORT WAVE TROUGHS PROGRESS
THROUGH SEASONABLY STRONG FLOW ON ITS NORTHERN PERIPHERY. MODELS
INDICATE THAT ONE TROUGH WILL GRADUALLY DIG FROM ONTARIO/QUEBEC AND
THE UPPER GREAT LAKES REGION INTO THE NORTHEAST...WHILE ANOTHER
LIFTS INLAND ACROSS THE PACIFIC COAST INTO THE INTERMOUNTAIN WEST.
IN BETWEEN...SHORT WAVE RIDGING IS EXPECTED TO BUILD ALONG AN AXIS
THROUGH THE CENTRAL AND NORTHERN PLAINS.
IN RESPONSE TO THESE DEVELOPMENTS...A SIGNIFICANT COLD FRONT IS
EXPECTED TO ADVANCE SOUTHEASTWARD THROUGH MUCH OF THE GREAT LAKES/
OHIO VALLEY/NORTHEAST AND MID ATLANTIC STATES BY 12Z THURSDAY...
WHILE RETURN FLOW RESULTS IN SIGNIFICANT MOISTENING FROM THE CENTRAL
PLAINS INTO THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY. AT
THE SAME TIME...SEASONABLY WARM AND MOIST CONDITIONS WILL PERSIST
ACROSS MUCH OF THE SOUTHEAST...WHILE MUCH OF THE WEST BEGINS TO
COOL.
...EASTERN STATES...
DEEP LAYER WESTERLY FLOW AND SHEAR WILL BE STRONGEST NEAR THE COLD
FRONT AS IT ADVANCES ACROSS PENNSYLVANIA AND NEW YORK INTO NEW
ENGLAND DURING THE DAYTIME HOURS...BUT STRONGEST DESTABILIZATION
PROBABLY WILL OCCUR WITHIN THE PRE-FRONTAL LEE SURFACE TROUGH FROM
VIRGINIA INTO NORTHERN MID ATLANTIC COASTAL AREAS AND SOUTHERN NEW
ENGLAND. CONDITIONS NEAR THESE SURFACE FEATURES MAY BECOME THE
FOCUS FOR SCATTERED STRONG/SEVERE STORM DEVELOPMENT CAPABLE OF
PRODUCING DAMAGING WIND GUSTS AND LARGE HAIL WEDNESDAY...AND
CATEGORICAL/PROBABILITY LINES HAVE BEEN ADJUSTED TO ACCOUNT FOR
THIS...AS WELL AS FAVORABLE OROGRAPHIC FORCING ALONG AND EAST OF THE
BLUE RIDGE MOUNTAINS.
...CENTRAL PLAINS INTO THE MID MISSOURI VALLEY...
MODELS SUGGEST THAT VERY WARM ELEVATED MIXED LAYER AIR WILL ADVECT
NORTHEAST OF THE PLATEAU/ROCKIES REGION THROUGH THE PLAINS DURING
THIS PERIOD...AND INCREASING INHIBITION CONTRIBUTES TO UNCERTAIN
CONVECTIVE POTENTIAL. IT APPEARS POSSIBLE THAT VIGOROUS STORM
DEVELOPMENT COULD OCCUR WEDNESDAY MORNING WITHIN A LOWER/MID
TROPOSPHERIC WARM ADVECTION ZONE...NEAR THE NOSE OF A STRENGTHENING
LOW-LEVEL JET ACROSS PARTS OF SOUTH CENTRAL SOUTH DAKOTA/CENTRAL
NEBRASKA...BEFORE SLOWLY SPREADING NORTHEASTWARD THROUGH THE PERIOD.
OTHERWISE...GUIDANCE IS SUGGESTIVE THAT A WEAK SMALLER SCALE
IMPULSE MIGRATING AROUND THE SUBTROPICAL RIDGE COULD CONTRIBUTE TO
THE INITIATION OF STORMS ACROSS PARTS OF THE CENTRAL HIGH PLAINS
NEAR/SHORTLY AFTER PEAK HEATING. IN THE PRESENCE OF STEEP LAPSE
RATES...MODERATELY LARGE CAPE AND MODEST SHEAR...ENHANCED BY
PRONOUNCED VEERING OF WIND FIELDS WITH HEIGHT...ISOLATED SUPERCELLS
ARE POSSIBLE...WITH PERHAPS UPSCALE GROWTH INTO A ORGANIZED STORM
CLUSTER OR TWO DURING THE EVENING HOURS.
..KERR.. 05/31/2011
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