MESOSCALE DISCUSSION 2310 NWS STORM PREDICTION CENTER NORMAN OK 0441 AM CST WED NOV 09 2011 AREAS AFFECTED...PARTS OF NERN IA/SERN MN NORTHEASTWARD THRU MUCH OF CNTRL WI CONCERNING...HEAVY SNOW VALID 091041Z - 091415Z HEAVY WET SNOW AND GUSTY STRENGTHENING WINDS ARE EXPECTED TO DEVELOP ACROSS THE REGION THROUGH MID MORNING. AS A VIGOROUS SHORT WAVE IMPULSE AND ASSOCIATED MID/UPPER JET STREAK LIFT NORTHEASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY TOWARD THE UPPER GREAT LAKES...RAPID DEEPENING OF AN ASSOCIATED SURFACE CYCLONE IS NOW UNDERWAY. LATEST SURFACE DATA SUGGEST THAT THIS IS OCCURRING FASTER THAN PERHAPS MOST MODEL GUIDANCE HAS INDICATED...AND FURTHER INTENSIFICATION IS EXPECTED AS THE LOW TRACKS FROM WEST CENTRAL ILLINOIS INTO THE VICINITY OF SOUTHERN LAKE MICHIGAN BY 18Z. LATEST RUC GUIDANCE SUGGESTS THE DEVELOPMENT OF A NEW DEFORMATION ZONE...WITH SUBSTANTIAL STRENGTHENING OF MID-LEVEL FRONTOGENETIC FORCING EXPECTED DURING THE 12-16Z TIME FRAME ALONG AN AXIS NEAR OR JUST NORTH OF NORTHEASTERN IOWA TOWARD CENTRAL UPPER MICHIGAN. THERMODYNAMIC PROFILES ACROSS THIS REGION ARE ALREADY MOSTLY BELOW FREEZING...AND MELTING OF SNOW IS EXPECTED TO CONTRIBUTE TO COOLING OF THE BOUNDARY LAYER CLOSER TO FREEZING. COUPLED WITH INCREASING LIFT IN THE FAVORABLE MIXED PHASE LAYER FOR DENDRITIC ICE CRYSTAL GROWTH...HEAVY SNOW RATES IN EXCESS OF 1 INCH PER HOUR APPEAR POSSIBLE IN THE PRESENCE OF RELATIVELY HIGH PRECIPITABLE WATER VALUES AROUND OR ABOVE .5 INCHES.
No comments:
Post a Comment