Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 280816 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 416 AM EDT TUE OCT 28 2008 LATEST UPDATE...ALL SECTIONS EXCEPT AVIATION... .SYNOPSIS...(416 AM EDT TUE OCT 28 2008) THE COLD AIR AND LAKE EFFECT RAIN AND SNOW SHOWERS WILL CONTINUE OVER THE NEXT 24 HOURS. TEMPERATURES WILL WARM BY WEDNESDAY AND THE LAKE EFFECT PRECIPITATION WILL END...WITH SUNSHINE DEVELOPING. AFTER A CHILLY WEDNESDAY NIGHT...THURSDAY WILL WARM WELL INTO THE 50S. && .SHORT TERM...(416 AM EDT TUE OCT 28 2008) (TODAY THROUGH THURSDAY) LAKE EFFECT RAIN AND SNOW SHOWERS WILL CONTINUE TODAY AS CHILLY CYCLONIC FLOW IS MAINTAINED OVER THE LAKE. THERE WILL BE A SHORT WAVE THAT WILL BE DROPPING DOWN OVER THE SUPERIOR REGION BY LATE IN THE DAY AND THIS MAY HELP PERK UP THE LAKE EFFECT ACTIVITY TOWARD EVENING. IT WILL ALSO BACK WINDS MORE TO THE NW...VERSUS NNW THIS MORNING...SO THE PRECIPITATION WILL MOVE INLAND A BIT MORE. STILL EXPECTING LITTLE ACCUMULATION AS THE DIURNAL IMPACT WILL CAUSE OPEN CELLS. BY TONIGHT THE SUPERIOR SHORT WAVE MOVES SOUTHEAST. WE WILL BEGIN TO ADVECT SOMEWHAT WARMER AIR IN THE MID LEVELS THAT DRIVES THICKNESS LEVELS UPWARD. THEREFORE THE LAKE EFFECT WILL LARGELY STAY A RAIN/SNOW MIX OVERNIGHT. AS THE SHORT WAVE DEPARTS THE MOISTURE DEPTH BEGINS TO WANE OVERNIGHT...LEADING TO LESS INTENSE SHOWERS. WILL ADD SPRINKLES AND FLURRIES TO WEDNESDAY MORNING AS THE LAKE EFFECT ACTIVITY WILL BE IN THE DWINDLING MODE TOWARD 12Z AS THE FLOW BECOMES ANTICYCLONIC AND THE LOW LEVEL MOISTURE EXITS. SKIES SHOULD GRADUALLY BECOME MOSTLY SUNNY INTO THE AFTERNOON. A SURFACE AND UPPER LEVEL RIDGE APPROACHES THE AREA WEDNESDAY NIGHT AND THURSDAY LEADING TO FAIR WEATHER. WITH THE CLEARING SKIES LOWS WILL GET INTO THE 20S IN MANY AREAS WEDNESDAY NIGHT...BUT IT WILL REBOUND NICELY TO 55 TO 60 ON THURSDAY AS SOUTHERLY WINDS KICK IN. && .LONG TERM...(416 AM EDT TUE OCT 28 2008) (THURSDAY NIGHT THROUGH MONDAY) THE TREND OF THE MODELS INDICATE THAT THE HIGH PRESSURE SYSTEM WHICH ARRIVES IN THE GREAT LAKES REGION ON SATURDAY WILL NOT BE AS STRONG AS INDICATED EARLIER. THUS THE SURGE OF SHALLOW COOLER AIR AHEAD OF IT WILL NOT BE AS COLD AS THOUGHT IN PREVIOUS FORECASTS. AS A RESULT...WHILE SATURDAY COULD STILL END UP COOLER THAN NORMAL...AT OR ABOVE NORMAL HIGHS WILL ARRIVE FOR SUNDAY INTO MONDAY. A SOUTHWESTERLY FLOW OF WARMER AIR WILL BE DEVELOPING FOR EARLY NEXT WEEK. OUR WEATHER IS EXPECTED TO REMAIN DRY FOR THE EXTENDED PERIOD. WE WILL BE MONITORING THE COLD FRONTAL PASSAGE FRI EVENING FOR PERHAPS SOME DRIZZLE...BUT I AM NOT CONFIDENT ENOUGH TO ADD IT TO THE FORECAST AT THIS POINT. LOOKING FURTHER OUT...NO MAJOR COOLING TRENDS ARE SEEN FOR NEXT WEEK. && .MARINE...(416 AM EDT TUE OCT 28 2008) THE SMALL CRAFT ADVISORY HAS BEEN EXTENDED TO ALL DAY WEDNESDAY AS WAVES WILL REMAIN HIGH THROUGH THIS PERIOD. WINDS AND WAVES WILL DIMINISH WEDNESDAY NIGHT AS THE SURFACE HIGH APPROACHES. && .AVIATION...(1145 PM EDT MON OCT 27 2008) SKIES HAVE CLEARED AS EXPECTED. THE CLOUDS ARE STAYING VERY CLOSE TO THE LAKE SHORE AS WINDS FROM 925 MB TO 850 MB HAVE BECOME MORE NORTHERLY. WE STILL HAVE AN ISSUE WITH THE SNOW BAND FROM GRAND TRAVERSE BAY EXTENDING DOWN INTO THE AREAS NEAR AND WEST OF ROUTE 131. THE NAM SHOWS THE 925 MB RH TRAILING SOUTH TO GRR BY 05 AM. CAD HAD CLEARED OUT BUT SINCE 10 AM HAS HAD OCCASIONAL SNOW SHOWERS. SO I DID BRING THOSE CLOUDS TO GRR BY 09Z. I DO NOT BELIEVE AZO OR BTL WILL HAVE PROBLEMS WITH THIS LOW CLOUD DECK THROUGH. MY THINKING FOR TUESDAY REMAINS AS IT WAS EARLIER THIS EVENING. DAY TIME HEATING COMBINED WITH THE AID OF A 7000 FT INVERSION WILL STILL ALLOW FOR SHOWERS AND MOSTLY CLOUDY SKIES. IT WILL BE COLD ENOUGH FOR MOSTLY SNOW SHOWERS IN THE MID TO LATE MORNING BUT IF ANY HAPPEN THEY WOULD BE BRIEF AND LIGHT (SO I DID NOT PUT THEM IN THE TAFS). DAY TIME HEATING WOULD CHANGE THE SNOW SHOWERS TO MIXED RAIN AND SNOW BY EARLY AFTERNOON. SOME MID CLOUDS FROM THE EASTERN STORM COULD ROTATE INTO THE CWA BY 8 AM TUESDAY EVENING. && .HYDROLOGY...(416 AM EDT TUE OCT 28 2008) THE SCATTERED NATURE OF THE PCPN OVER THE NEXT 24 HOURS WILL NOT LEAD TO ANY HYDRO CONCERNS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH WEDNESDAY FROM ST. JOSEPH TO MANISTEE. && $$ SYNOPSIS: JK SHORT TERM: JK LONG TERM: MJS MARINE: JK AVIATION: WDM HYDROLOGY: JK
