May 21, 2013
AS THE COLD FRONT NEARS THE REGION..THE MAIN UPPER TROF AND SURFACE LOW WILL MOVE NORTHEAST INTO THE UPPER GREAT LAKES. THIS WILL BEGIN TO STRETCH OUT THE SOUTHERN END OF THE SYSTEM AND SLOW ITS EASTWARD PROGRESS. THE NAM GUIDANCE IS COMPLETELY DEVOID OF POPS FOR OUR CWA AT THIS TIME...BUT WILL INCLUDE A SLIGHT CHANCE POP IN THE WEST AS A COMPROMISE SOLUTION WITH THE GFS. ANY PRECIPITATION SATURDAY NIGHT SHOULD BE WELL AFTER MIDNIGHT...AND PROBABLY CLOSER TO DAYBREAK. SUNDAY...WITH THE UPPER LEVEL ENERGY CONTINUING TO DEPART RAPIDLY NORTHEAST...THE FRONTAL BOUNDARY WILL SLOW TO A CRAWL. THE NAM IS MUCH MORE DRAMATIC WITH THIS SLOWING...BUT SEEMS TO BE GENERALLY WITHIN 6 HOURS OR SO OF THE GFS FORECAST. FOR THIS REASON...WILL BE ABLE TO INCREASE POPS TO THE LIKELY CATEGORY IN OUR WESTERN ZONES AS THERE IS HIGHER CONFIDENCE IT WILL RAIN IN THE 12Z SUNDAY TO 00Z MONDAY TIME PERIOD...ALTHOUGH WE CAN`T BE AS CONFIDENT AT THE 6 HOURLY TIME STEPS. WITH LIMITED LIFT AND INSTABILITY...WILL ONLY INCLUDE ISOLATED THUNDER WORDING OVER THE INLAND AREAS. SUNDAY NIGHT...A WEAK WAVE IS EXPECTED TO DEVELOP ALONG THE FRONTAL BOUNDARY IN RESPONSE TO A WEAK UPPER TROF MOVING ACROSS THE SOUTHEAST. THIS WILL HELP BEGIN THE PUSH TO CLEAR THE FRONT FROM OUR REGION...BUT ALSO ENHANCE PRECIPITATION OVERNIGHT. WILL KEEP AN AREA OF 40 TO 50 PERCENT POPS IN THE GRIDS FOR NOW.
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