Severe Threat Tomorrow Afternoon

Source: SPC

Tomorrow afternoon, the Storm Prediction Center out of Norman, OK does include the Stateline in a slight risk for severe weather. We will have a cold front pushing into the area from the west late tomorrow afternoon and evening that could trigger some thunderstorms. However, we will have a lot of warm air aloft tomorrow which will be an inhibiting factor to the vertical development of any storms. For that reason, I'm cautiously optimistic that severe weather will avoid the area tomorrow. Still, the FirstWarn Weather team will be on top of the situation tomorrow. Happy Memorial Day!

Here's the synopsis by the SPC:

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT MON MAY 30 2011
VALID 311200Z - 011200Z
...THERE IS A SLGT RISK OF SVR TSTMS TUE ACROSS PARTS OF THE UPPER
MIDWEST/GREAT LAKES REGION...

...SYNOPSIS...
MID-LEVEL SUBTROPICAL RIDGING NOW PRESENT ACROSS MUCH OF THE EASTERN U.S...SOUTHWESTWARD INTO THE MEXICAN PLATEAU...APPEARS LIKELY TO REMAIN GENERALLY STRONG THROUGH THIS FORECAST PERIOD. HOWEVER...MODELS STILL INDICATE THAT ONE IN A SERIES OF CLOSED
LOWS/SHORT WAVE TROUGHS WILL CONTINUE PROGRESSING WITHIN SEASONABLY STRONGER FLOW AROUND ITS WESTERN AND NORTHERN PERIPHERY.

THE CYCLONIC CIRCULATION CENTER ASSOCIATED WITH THIS LATTER FEATURE IS PROGGED TO SHIFT INTO AREAS NEAR OR JUST NORTH OF THE NORTH DAKOTA/SASKATCHEWAN BORDER AREA AT 12Z TUESDAY...BEFORE
WEAKENING/BROADENING AND ACCELERATING EAST NORTHEASTWARD INTO NORTHERN ONTARIO BY 12Z WEDNESDAY. THIS IS EXPECTED TO OCCUR AS A SMALLER SCALE SHORT WAVE IMPULSE PIVOTS AROUND ITS SOUTHERN/ EASTERN PERIPHERY...THROUGH THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION DURING THE DAY TUESDAY...INTO WESTERN QUEBEC BY THE END OF THE PERIOD.
SOUTH OF A BROAD DEEP SURFACE CYCLONE ACCOMPANYING THE UPPER LOW...A COLD FRONT WILL ADVANCE THROUGH MUCH OF THE UPPER MIDWEST/GREAT LAKES/OHIO AND MIDDLE MISSISSIPPI VALLEY REGION. HOWEVER...THE FRONT/PRE-FRONTAL DRY LINE ACROSS THE CENTRAL AND SOUTHERN PLAINS LIKELY WILL WEAKEN AND LIFT NORTHWARD/RETREAT WESTWARD...AS THE CENTER OF RIDGING ALOFT SHIFTS WEST OF THE LOWER MISSISSIPPI VALLEY...AND ANOTHER CLOSED LOW/SHORT WAVE TROUGH DIGS INTO THE PACIFIC COAST.

..UPPER MIDWEST/GREAT LAKES REGION...
REMNANTS OF CONSIDERABLE DAY 1 CONVECTIVE DEVELOPMENT MAY BE IN THE PROCESS OF SPREADING ACROSS MUCH OF THE UPPER HALF OF THE
MISSISSIPPI VALLEY EARLY TUESDAY. AND THE INFLUENCE OF ASSOCIATED
CLOUD COVER AND PRECIPITATION ON SUBSEQUENT DOWNSTREAM PRE-FRONTAL DESTABILIZATION REMAINS UNCLEAR. STRONGER LOW-LEVEL CONVERGENCE ALSO APPEARS LIKELY TO REMAIN FOCUSED NORTH OF THE INTERNATIONAL BORDER AREA THROUGH THE PERIOD...WHICH MAY ALSO SUBSTANTIALLY IMPACT THE CONVECTIVE POTENTIAL.

HOWEVER...THE WARM SECTOR BOUNDARY LAYER SHOULD BE SEASONABLY MOIST /UPPER 60S NEAR 70F SURFACE DEW POINTS/...AND INSOLATION PROBABLY WILL BE SUFFICIENT TO CONTRIBUTE TO MODERATE CAPE BY THE AFTERNOON. COUPLED WITH FAVORABLE MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION EXPECTED TO SPREAD ACROSS EASTERN WISCONSIN AND MICHIGAN NEAR AND AFTER PEAK HEATING...THIS SHOULD BE SUFFICIENT TO INITIATE NEW CONVECTIVE DEVELOPMENT. IN THE PRESENCE OF SHEARED 40+ KT WESTERLY
DEEP LAYER MEAN FLOW FIELDS /STRONGEST NEAR AND NORTH OF THE
INTERNATIONAL BORDER/...ISOLATED SUPERCELLS WILL BE POSSIBLE BEFORE UPSCALE CONVECTIVE GROWTH INTO ONE OR MORE ORGANIZED CONVECTIVE LINES OR CLUSTERS OCCURS. DAMAGING WIND GUSTS AND HAIL APPEAR THE PRIMARY SEVERE THREATS...BUT TORNADOES WILL BE POSSIBLE...BEFORE THE THREAT DIMINISHES/SPREADS INTO ONTARIO TUESDAY EVENING.

...LEE OF THE LWR GREAT LAKES/OH VLY INTO S ATLC COAST STATES...
DAYTIME HEATING OF A VERY MOIST BOUNDARY LAYER IS EXPECTED TO YIELD MODERATE TO STRONG CAPE BY TUESDAY AFTERNOON BENEATH UPPER RIDGING.  ALTHOUGH FORCING REMAINS UNCERTAIN...AND SHEAR WILL BE WEAK...THERMODYNAMIC PROFILES SHOULD BE SUPPORTIVE OF AT LEAST LOW SEVERE PROBABILITIES...WITH THE BEST CHANCE FOR SCATTERED STORM DEVELOPMENT ON THE PERIPHERY OF THE WEAKENING MID-LEVEL HIGH CENTER.



..KERR.. 05/30/2011