05/24/11 UPDATE: SPC Now Has A HIGH Risk For Severe Thunderstorms on Tuesday, May 24, 2011

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT MON MAY 23 2011


VALID 241200Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS LATE TUE AFTN INTO TUE NIGHT
ACROSS CENTRAL AND EASTERN OKLAHOMA...MUCH OF CENTRAL AND EASTERN
KANSAS...PARTS OF SOUTHWEST MISSOURI...NORTHWEST ARKANSAS AND NORTH
CENTRAL TEXAS...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
AREA ACROSS MUCH OF THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI
VALLEY...EASTWARD THROUGH PARTS OF THE LOWER OHIO AND TENNESSEE
VALLEYS...AND NORTHEASTWARD THROUGH THE NORTHERN MID ATLANTIC COAST
STATES AND HUDSON VALLEY...


...AN OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES IS POSSIBLE
LATE TUESDAY AFTERNOON AND EVENING...


...SYNOPSIS...
MODELS INDICATE THAT THE LARGE-SCALE TROUGH...NOW DEVELOPING INTO
THE WESTERN U.S...GRADUALLY SPLITS...WITH A SIGNIFICANT SOUTHERN
PORTION SLOWLY LIFTING EAST NORTHEASTWARD OUT OF THE SOUTHERN
PLATEAU BY EARLY TUESDAY...AS ANOTHER LARGE AND STRONG IMPULSE
APPROACHES THE PACIFIC COAST. THE LEAD TROUGH...WITH AT LEAST A
COUPLE OF SIGNIFICANT EMBEDDED SMALLER SCALE IMPULSES...IS PROGGED
TO EVOLVE INTO A CLOSED LOW AS IT MIGRATES ACROSS THE SOUTHERN
ROCKIES INTO THE CENTRAL PLAINS LATER TUESDAY AND TUESDAY NIGHT.
ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION APPEARS LIKELY TO
CONTRIBUTE TO FURTHER DEEPENING OF A SURFACE CYCLONE OVER THE SOUTH
CENTRAL PLAINS. THIS IS EXPECTED TO BE ACCOMPANIED BY A
STRENGTHENING SOUTHERLY LOW-LEVEL JET IN EXCESS OF 50 KT AT 850 MB
BY EARLY TUESDAY EVENING...FROM NORTH CENTRAL TEXAS INTO EASTERN
KANSAS...AS A CYCLONIC AND GENERALLY WESTERLY 70 KT 500 MB JET
STREAK NOSES INTO AND THROUGH THE SOUTHERN PLAINS RED RIVER VALLEY
REGION.

AT THE SAME TIME...A LARGE COLD UPPER VORTEX WITH SEVERAL STRONG
EMBEDDED SHORT WAVE IMPULSES WILL LINGER OVER MUCH OF EASTERN
CANADA. AN ASSOCIATED SIGNIFICANT COLD FRONT APPEARS LIKELY TO
ADVANCE SOUTHEAST OF THE GREAT LAKES THROUGH MUCH OF THE
NORTHEAST...AS ANOTHER IMPULSE...PERHAPS CONVECTIVELY
ENHANCED...WITHIN THE SOUTHERN BRANCH OF THE SPLIT UPPER
FLOW...LIFTS OUT OF THE OHIO VALLEY THROUGH SOUTHERN NEW ENGLAND BY
12Z WEDNESDAY.

GIVEN THE CONTINUING PRESENCE OF A SEASONABLY MOIST BOUNDARY LAYER
AIR MASS IN THE WARM SECTOR OF THE PLAINS CYCLONE...AND ALONG AND
AHEAD OF THE EASTERN COLD FRONT...DESTABILIZATION PROBABLY WILL
BECOME SUFFICIENT TO SUPPORT CONSIDERABLE STRONG/SEVERE STORM
DEVELOPMENT DURING THIS PERIOD. ASIDE FROM SOME SEA BREEZE STORMS
IN THE SOUTHEAST...THIS WILL MOSTLY REMAIN WEST AND NORTH OF
PERSISTENT SUBTROPICAL RIDGING CENTERED JUST EAST OF THE SOUTH
ATLANTIC COAST.

...CENTRAL/SOUTHERN PLAINS...
LINGERING VARIABILITY AMONG THE MODELS AND ENSEMBLES CONCERNING THE
TIMING AND TRACK OF THE TROUGH EMERGING FROM THE SOUTHWEST CONTINUES
TO COMPLICATE THE FORECAST. BUT IT APPEARS THAT THIS WILL ONLY
IMPACT THE EXACT PLACEMENT OF THE HIGHEST SEVERE PROBABILITIES...AS
THE EVOLVING LARGE-SCALE PATTERN SEEMS SUPPORTIVE OF A FAIRLY
CLASSIC SEVERE WEATHER OUTBREAK. AND ENOUGH COMMON GROUND APPEARS
TO EXIST TO JUSTIFY AN UPGRADE TO MODERATE RISK SEVERE PROBABILITIES
ACROSS MUCH OF CENTRAL/EASTERN KANSAS AND OKLAHOMA...PORTIONS OF
NORTH CENTRAL TEXAS...NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI.

SURFACE DEW POINTS AROUND 70F ARE PROGGED IN THE WARM SECTOR OF THE
DEEPENING CYCLONE...ALONG AND EAST OF A SHARPENING DRY LINE DURING
THE LATE AFTERNOON HOURS...WHEN PEAK AFTERNOON HEATING AND
STEEPENING LAPSE RATES ASSOCIATED WITH MID-LEVEL COOLING PROBABLY
WILL CONTRIBUTE TO MIXED LAYER CAPE OF 2000-4000 J/KG. AS THE
MID-LEVEL JET NOSES INTO THE RED RIVER VALLEY...THE DRY LINE IS
EXPECTED TO BECOME THE FOCUS FOR THE PRIMARY STORM DEVELOPMENT AS IT
SURGES NORTHEASTWARD OUT OF SOUTH CENTRAL KANSAS...AND EASTWARD OUT
OF CENTRAL OKLAHOMA...THROUGH MUCH OF EASTERN KANSAS AND OKLAHOMA BY
LATE EVENING. GIVEN THE ANTICIPATED WIND PROFILES...EXHIBITING
STRONG DEEP LAYER SHEAR AND LARGE CLOCKWISE CURVED LOW-LEVEL
HODOGRAPHS...THE ENVIRONMENT IS EXPECTED TO BECOME CONDUCIVE TO
LONG-LIVED SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND
STRONG TORNADOES. THIS THREAT MAY CONTINUE THROUGH MUCH OF THE
EVENING...PERHAPS INTO THE 06-09Z TIME FRAME...GRADUALLY SPREADING
TOWARD THE LOWER MISSOURI VALLEY AND OZARKS...BEFORE DIMINISHING IN
THE PRESENCE OF A MORE STABLE OR STABILIZING BOUNDARY LAYER.

...NORTHERN MID ATLANTIC STATES INTO THE LOWER HUDSON VALLEY...
WEAK TO MODERATE DESTABILIZATION ALONG AND AHEAD OF THE
SOUTHEASTWARD ADVANCING COLD FRONT...AND WITHIN THE PRE-FRONTAL LEE
SURFACE TROUGH...IS EXPECTED TO PROVIDE THE FOCUS FOR VIGOROUS
CONVECTIVE DEVELOPMENT WITH THE APPROACHING UPPER IMPULSE TUESDAY
AFTERNOON. MODELS ARE A BIT MORE UNCLEAR CONCERNING THE STRENGTH OF
THE VERTICAL SHEAR...BUT IT SHOULD BE ENOUGH TO SUPPORT POTENTIAL
FOR ORGANIZED STORM CLUSTERS...AND ISOLATED SUPERCELLS MAY NOT BE
OUT OF THE QUESTION. THIS COULD IMPACT MUCH OF THE URBAN
CORRIDOR...FROM WASHINGTON D.C./BALTIMORE TO NEW YORK CITY...BEFORE
CONVECTION DIMINISHING/SPREADS OFFSHORE WITH UPPER FORCING BY
TUESDAY EVENING.

..KERR.. 05/23/2011


[link to www.spc.noaa.gov]

Last Edited by Cell Therapy on 05/24/2011 02:57 AM