Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 290744 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 344 AM EDT WED OCT 29 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(344 AM EDT WED OCT 29 2008) A WARMING TREND WILL DEVELOP OVER THE AREA FOR THE NEXT SEVERAL DAYS. HIGH TEMPERATURES TODAY WILL BE IN THE 40S...BUT WARM INTO THE LOWER 60S BY HALLOWEEN. THE WEATHER WILL ALSO REMAIN DRY THROUGH AT LEAST THURSDAY NIGHT. A WEAK COLD FRONT WILL MOVE OVER LOWER MICHIGAN ON FRIDAY. AT THIS POINT IT APPEARS THIS FRONT WILL NOT PRODUCE ANY PRECIPITATION. && .SHORT TERM...(344 AM EDT WED OCT 29 2008) (TODAY THROUGH FRIDAY) A SHORT WAVE TROUGH WAS MOVING SOUTHEAST OVER SAGINAW BAY THIS MORNING. AS THIS FEATURE PASSES BY IT WILL TAKE MUCH OF THE LOW LEVEL MOISTURE WITH IT. THERE WAS ALREADY SEVERAL HOLES IN THE CLOUD COVER THIS MORNING...SO WILL CALL IT PARTLY SUNNY EARLY... BECOMING MOSTLY SUNNY INTO EARLY AFTERNOON. A SURFACE RIDGE SETTLES IN TONIGHT. THE WINDS WILL DECOUPLE EARLY TONIGHT AND TEMPS WILL QUICKLY DROP BELOW FREEZING. HOWEVER...A LIGHT SOUTHERLY WIND SHOULD DEVELOP AFTER MIDNIGHT WHICH SHOULD HOLD TEMPS NEARLY STEADY FOR THE REMAINDER OF THE OVERNIGHT PERIOD. LOWS SHOULD BOTTOM OUT FROM 25 TO 30 IN MOST LOCALES. WE WILL BE MUCH WARMER THURSDAY AND THURSDAY NIGHT WITH ABOVE NORMAL TEMPS AS SSW WINDS PULL IN AN AIR MASS FROM THE SOUTHERN PLAINS. HIGHS WILL BE WELL INTO THE 50S WITH LOWS MAINLY IN THE 40S. THE MODELS ARE IN VERY GOOD AGREEMENT SHOWING A WEAK COLD FRONT DROPPING ACROSS THE UPPER MIDWEST AND INTO LOWER MICHIGAN BY LATE IN THE DAY. THE CHANCES OF PCPN WILL NOT BE ZERO AS THERE IS A SLIGHT WEAKNESS IN THE INSTABILITY. HOWEVER...THE FRONT WILL LACK MOISTURE AND THE INSTABILITY APPEARS TOO BORDERLINE TO ADD POPS TO THE NORTHERN CWA. WITH THE FRONT NOT MOVING IN UNTIL CLOSE TO EVENING WE WILL BE ABLE TO WARM INTO THE 60 TO 65 DEGREE RANGE. && .LONG TERM...(344 AM EDT WED OCT 29 2008) (FRIDAY NIGHT THROUGH TUESDAY) SHALLOW COLD AIR ADVECTION ARRIVES FRIDAY EVENING AND LASTS INTO SATURDAY. THE NORTHEASTERLY FLOW WILL DRAW DOWN A STABLE AIRMASS FROM ONTARIO. LIMITED MIXING HEIGHTS ON SATURDAY SHOULD KEEP OUR TEMPERATURES SLIGHTLY BELOW NORMAL. TROUGHING DEVELOPS IN THE WRN U.S. FOR SUN INTO TUE...AND THAT WILL LEAD TO RIDGING EAST OF THE ROCKIES. THE DEVELOPING SOUTHERLY FLOW WILL WARM UP OUR TEMPERATURES...TO WELL ABOVE NORMAL LEVELS. AS FOR RAIN...WILL NEED TO MONITOR SUN EVENING WITH A WARM FRONT LIFTING THROUGH THE REGION. THE RECENT RUN OF THE HI RES EURO SHOWS A RATHER MOIST PROFILE WITH THE FRONT. THE GFS IS CONSIDERABLY DRIER. AT THIS POINT I WILL MAINTAIN A DRY FORECAST. && .MARINE...(344 AM EDT WED OCT 29 2008) BRISK NORTHWEST WINDS WILL CONTINUE TODAY KEEPING THE LAKE CHURNED UP. THE WINDS AND WAVES WILL DIMINISH THIS EVENING AS THE SURFACE RIDGE MOVES IN. HAVE EXTENDED THE SMALL CRAFT ADVISORY BY A FEW HOURS TO ACCOUNT FOR THE DELAYED REACTION IN THE WAVES ACTION SUBSIDING. THIS BREAK IN LOWER WAVES WILL ONLY LAST ABOUT 12 HOURS AS SOUTHERLY WINDS ON THE BACKSIDE OF THE HIGH BEGIN TO STIR UP THE LAKE ONCE AGAIN BY THURSDAY AFTERNOON. IN FACT IT APPEARS THAT WINDS MAY APPROACH GALE FORCE ACROSS CENTRAL LAKE MICHIGAN BY MID AFTERNOON INTO EARLY THURSDAY NIGHT. && .AVIATION...(1112 PM EDT TUE OCT 28 2008) IT WOULD SEEM THE SHORTWAVE ASSOCIATED WITH THE POLAR JET STREAK HAS LEAD TO DEEPER MIXING AND IS MIXING OUT THE LOWER CLOUD DECK AS I WRITE THIS AT 11 PM. ACTUALLY THERE IS A SURFACE TROUGH WITH THIS FEATURE THAT IS ROTATING SOUTHWARD THROUGH LOWER MICHIGAN. AT 03Z IT WAS FROM OSC TO CAD. AS THAT TROUGH MOVES SOUTH THE LOW CLOUDS WILL FOLLOW. THESE LOW CLOUDS WILL LAST INTO MID AFTERNOON ON WEDNESDAY. AT THAT POINT...2 AM TO 4 AM WEDNESDAY... THE POLAR JET WILL START TO SHIFT TO THE EAST AND THAT WILL BRING SURFACE RIDGING. THAT WILL IN TURN BRING CLEARING SKIES AND LIGHT WINDS BY SUNSET. && .HYDROLOGY...(344 AM EDT WED OCT 29 2008) LITTLE OR NO MEASURABLE PCPN IS EXPECTED THE NEXT 7 DAYS SO THERE ARE NO HYDRO ISSUES/CONCERNS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH THIS EVENING FROM ST. JOSEPH TO MANISTEE. && $$ SYNOPSIS: JK SHORT TERM: JK LONG TERM: MJS MARINE: JK AVIATION: WDM HYDROLOGY: JK