Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 311143 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 732 AM EDT FRI OCT 31 2008 LATEST UPDATE...AVIATION .SYNOPSIS...(322 AM EDT FRI OCT 31 2008) A COLD FRONT THAT CURRENTLY STRETCHES FROM NORTHEAST ONTARIO TO SOUTHWEST MINNESOTA WILL MOVE SOUTH THROUGH LOWER MICHIGAN THIS AFTERNOON. THE FRONT WILL NOT PRODUCE ANY PRECIPITATION AS IT MOVES THROUGH. FAIR SKIES ARE EXPECTED TODAY WITH HIGHS IN THE 60S. COOLER WEATHER...AND MORE SUNSHINE...WILL ARRIVE FOR THE WEEKEND. && .SHORT TERM...(322 AM EDT FRI OCT 31 2008) (TODAY THROUGH SUNDAY) FORECAST CONCERNS ARE FEW TODAY AND MAINLY DEAL WITH A COLD FRONT MOVING THROUGH THE CWA. LATEST IR LOOP SHOWS A SHORT WAVE MOVING THROUGH SRN IA/NRN MO. THIS WAVE HAS A VERY SMALL AREA OF CLOUDS ASSOCIATED WITH IT ALONG WITH A FEW SHOWERS...BUT WILL MOVE SOUTH OF THE CWA. NORTHWEST UPPER FLOW WILL MEAN DRY WX ACROSS THE CWA THROUGH SUNDAY. QUITE A BIT OF SUNSHINE IS EXPECTED TODAY AND SATURDAY WITH CLEAR SKIES TONIGHT. EXPECT SOME HIGH CLOUDS TO INCREASE SATURDAY NIGHT INTO SUNDAY AHEAD OF THE NEXT SHORT WAVE THAT WILL MOVE INTO THE GREAT LAKES SUNDAY NIGHT. && .LONG TERM...(322 AM EDT FRI OCT 31 2008) (SUNDAY NIGHT THROUGH THURSDAY) THE MAIN CHALLENGE IN THE LONG TERM PERIOD DEALS WITH THE TIMING AND STRENGTH OF THE LOW PRESSURE SYSTEM AND ITS ASSOCIATED PRECIPITATION FIELDS. THE MODELS DO AGREE THAT A LOW WILL DEVELOP IN THE WRN PLAINS AND TRACK THROUGH THE WRN GREAT LAKES REGION FOR THE MIDDLE TO END OF NEXT WEEK. THE CANADIAN GLOBAL IS WEAKEST WITH THE STORM AND TRACKS THE ASSOCIATED COLD FRONT THROUGH LATER WEDNESDAY. THE GFS IS THE SLOWEST WITH THE SYSTEM...NOT BRINGING IT IN UNTIL LATER THU WITH A WAVE RIDING UP THE FRONT. THE ECMWF IS BETWEEN THE TWO AND TRACKS THE FRONT THROUGH AROUND THU AM. WHILE IT IS DIFFICULT TO SAY WHICH MODEL IS RIGHT...I PREFER THE ECMWF AS IT IS BETWEEN THE CANADIAN GLOBAL AND GFS. INDICATIONS ARE THAT THIS SYSTEM WILL BE RATHER DYNAMIC AS THE NEGATIVE TILT UPPER FLOW EVOLVES INTO A DEEPENING CLOSED LOW. THIS COULD RESULT IN SOME STRONGER STORMS. I DID MOVE UP THE MENTION OF THUNDER TO WED NIGHT GIVEN THE ARRIVAL OF PREFRONTAL CONVECTION. MODELS SHOW WARMER AIR STREAMING INTO THE GREAT LAKES REGION MON THROUGH WED. WILL MAINTAIN THE WELL ABOVE NORMAL TEMPERATURES FOR THAT TIMEFRAME. && .MARINE...(322 AM EDT FRI OCT 31 2008) WE ENDED THE GALE WARNING DUE TO WINDS LESS THAN GALES. SCA HAS BEEN EXTENDED IN TIME THROUGH THE AFTERNOON AND INCLUDES THE ENTIRE NEARSHORE. && .AVIATION...(732 AM EDT FRI OCT 31 2008) WILL KEEP THE TAFS FEATURING VFR WEATHER THROUGH 12Z SAT. WE WILL BE MONITORING A COLD FRONT THAT WILL DROP SOUTHWARD THROUGH THE TAF SITES THIS AFTERNOON AND EVENING. THERE IS A SMALL RISK FOR LOWER CLOUDS TO FORM ALONG THIS FRONT. CONSIDERING THE FRONT CURRENTLY CONTAINS FEWER LOW CLOUDS THAN FORECASTED...I WILL KEEP THEM OUT OF THE FORECAST. THE CORE OF STRONGER LOW LEVEL WINDS WAS PULLING EAST THIS AM...SO THE WIND SHEAR THREAT IS DIMINISHING. && .HYDROLOGY...(322 AM EDT FRI OCT 31 2008) NO HYDRO CONCERNS DUE TO DRY WX REGIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT TODAY FROM ST JOSEPH TO MANISTEE. && $$ SYNOPSIS: 93 SHORT TERM: 93 LONG TERM: MJS MARINE: 93 AVIATION: DUKE HYDROLOGY: 93
