Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 071152 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 650 AM EST FRI NOV 7 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(513 AM EST FRI NOV 7 2008) THE WARM WEATHER IS COMING TO AN END AS A COLD FRONT PUSHES EAST OF THE AREA TODAY. GRADUALLY COOLER AIR WILL FILTER INTO THE REGION INTO THE WEEKEND. TODAY WILL FEATURE A MIX OF SUN AND CLOUDS...WITH SOME MORNING FOG. CLOUDS AND SHOWERS WILL DEVELOP TONIGHT...AS COOLER AIR MOVING OVER LAKE MICHIGAN GENERATES PRECIPITATION. THE RAIN SHOWERS MAY MIX AT TIMES WITH SOME SNOW FRIDAY NIGHT INTO SATURDAY. EVEN COLDER AIR WILL SETTLE IN FOR SATURDAY NIGHT AND SUNDAY MAKING A MIX OF RAIN AND SNOW SHOWERS LIKELY. HIGH TEMPERATURES OVER THE WEEKEND WILL NOT MAKE IT OUT OF THE 40S. && .SHORT TERM...(513 AM EST FRI NOV 7 2008) (TODAY THROUGH SUNDAY) BAND OF CLOUDS AND RAIN SHOWERS AHEAD OF THE COLD FRONT IS PROGRESSING INTO EASTERN LOWER MICHIGAN THIS MORNING. CLEARING IS DEVELOPING OVER WESTERN LOWER...WITH AREAS OF FOG FORMING. FOG WILL BE THE FIRST CONCERN AND WILL BE MONITORED THIS MORNING. SO FAR...FOG HAS BEEN LIMITED TO THE IMMEDIATE COAST AT SOUTH HAVEN AND HOLLAND. A MIX OF SUN AND CLOUDS CAN BE EXPECTED TODAY AS THE DRY SLOT MOVES THROUGH LOWER MICHIGAN. 850MB TEMPS WILL BECOME COLD ENOUGH THIS EVENING FOR LAKE GENERATED PRECIPITATION. RAIN SHOWERS SHOULD DEVELOP THIS EVENING. THE RAIN MAY MIX AT TIMES WITH SNOW OVERNIGHT INTO SATURDAY MORNING...AS 850MB TEMPS ARE PROGD TO BE NEAR -6 C (WHICH WILL PRODUCE DELTA T/S NEAR 17/18 DEGREES). THE -12 TO -18 C LAYER BECOMES SATURATED VIA BOTH THE NAM AND THE GFS MODELS. WET BULB ZERO HEIGHTS OFF BOTH MODELS DROP TO AROUND 1000 FT AS WELL. THE SREF P/TYPE GUIDANCE INDICATES THE CHANCE FOR SOME SNOW TO MIX IN LATE TONIGHT AND TOMORROW MORNING. NOT EXPECTING ANY ACCUMULATION...BUT THERE MAY BE A MIX NONETHELESS. THE LAKE WILL CONTINUE TO GENERATE PRECIPITATION RIGHT THROUGH THE REMAINDER OF THE SHORT TERM INTO SUNDAY. EVEN COLDER AIR FILTERS IN FOR SATURDAY NIGHT AND SUNDAY WITH 850MB TEMPS DROPPING TO AROUND -8 C. A SHORTWAVE DROPPING INTO THE BACKSIDE OF THE UPPER TROUGH WILL LIKELY ADD A BOOST TO THE RAIN AND SNOW DURING THIS TIME FRAME. THERE COULD BE SOME LIGHT ACCUMULATION OF SNOW SATURDAY NIGHT AND SUNDAY ESPECIALLY IF THE SHORTWAVE COMES IN A BIT QUICKER (SATURDAY NIGHT). DIURNAL AFFECTS THIS TIME OF YEAR TEND TO PUSH P/TYPE MORE TOWARD RAIN DURING THE DAYTIME HOURS. BEST CHANCE AT ANY ACCUMS WILL BE AWAY FROM THE IMMEDIATE COAST GIVEN THE WARM LAKE BOUNDARY LAYER. WINDS OF 20-30 KNOTS AT 850MB/S WILL LIKELY PLACE THE EASTERN HALF OF THE LAKESHORE COUNTIES AND THEN EAST TOWARD HIGHWAY 131 AS THE LOCATIONS WITH THE BEST CHANCE AT SEEING SOME ACCUMS. && .LONG TERM...(513 AM EST FRI NOV 7 2008) (SUNDAY NIGHT THROUGH THURSDAY) A STRONG LOW PRESSURE SYSTEM WILL MOVE SLOWLY TO THE NORTHEAST FROM JUST SOUTH OF HUDSON BAY. WAVES TRAVELING AROUND THE LOW WILL BRING WRAP AROUND PRECIPITATION AND PULSES OF COLDER AIR TO THE GREAT LAKES REGION. THE PRECIPITATION SUNDAY NIGHT INTO MONDAY WILL BE ALL SNOW AS THE PRECIPITATION WINDS DOWN AND HIGH PRESSURE BEGINS TO NUDGE IN. TUESDAY THROUGH WEDNESDAY ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE UP THE OHIO VALLEY SOUTH OF THE AREA. FEEL CLOUD COVER IN THE GRIDS IS SUFFICIENT AT THIS TIME. THE LOW TEMPERATURES THROUGH THE EXTENDED PERIOD WILL BE NEAR NORMAL FOR THIS TIME OF YEAR IN THE MID 20S TO THE MID 30S. THE HIGHS WILL RANGE FROM THE UPPER 30S TO THE LOWER 40S MONDAY... WHICH IS A LITTLE COLDER THAN NORMAL. THE HIGHS WILL SLOWLY WARM INTO THE MID TO UPPER 40S BY THURSDAY... WHICH IS NEAR NORMAL. && .MARINE...(513 AM EST FRI NOV 7 2008) WINDS AND WAVES WILL BE ON THE INCREASE TODAY AND TONIGHT AS LOW PRESSURE DRIFTS FROM THE PLAINS INTO THE NORTHERN GREAT LAKES. WAVES WILL BUILD INTO THE 3 TO 5 FOOT RANGE THIS AFTERNOON...AND GRADUALLY INCREASE INTO SATURDAY NIGHT AS A TIGHT PRESSURE GRADIENT MOVES ACROSS LAKE MICHIGAN. A SMALL CRAFT ADVISORY IS IN EFFECT FROM THIS MORNING THROUGH SATURDAY. WAVES SATURDAY NIGHT COULD APPROACH 10 FEET...AS WESTERLY WINDS INCREASE TO NEAR 30 KNOTS IN COLD AIR ADVECTION. && .AVIATION...(650 AM EST FRI NOV 7 2008) COLD FRONT IS MOVING ACROSS THE FORECAST AREA THIS MORNING...WITH CLOUDS AND PRECIPITATION EXITING THE EASTERN TAF SITES AT KLAN AND KJXN. IN THE WEST...SOME FOG AS DEVELOPED IN AREAS THAT CLEARED OVERNIGHT TOWARD LAKE MICHIGAN. EXPECT THE FOG TO LIFT THROUGH THE COURSE OF THE MORNING...WITH VFR CONDITIONS THE BULK OF THE DAY. AN UPPER LOW OFF TO THE WEST WILL MOVE TOWARD LOWER MICHIGAN TODAY...SPREADING CLOUDS INTO THE AREA TOWARD SUNSET AS WELL AS COLDER AIR. MVFR CEILINGS SHOULD OVERSPREAD THE AREA BETWEEN 21Z AND 01Z THIS EVENING. THE COLD AIR MOVING OVER LAKE MICHIGAN WILL GENERATE RAIN SHOWERS TONIGHT OFF THE LAKE...ESPECIALLY AT KMKG AND KGRR. && .HYDROLOGY...(513 AM EST FRI NOV 7 2008) RAINFALL AMOUNTS WERE ON THE LIGHT SIDE THE LAST 12-18 HOURS...GENERALLY BETWEEN A TRACE AND A QUARTER OF AN INCH. WITH RIVERS ALL WITHIN BANK...THE LIGHT PRECIPITATION WILL HAVE LITTLE AFFECT. PRECIPITATION OVER THE NEXT COUPLE OF DAYS WILL BE LAKE GENERATED AND NOT VERY HEAVY. SO...HYDRO CONCERNS ARE NOT EXPECTED. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY THIS MORNING THROUGH SATURDAY FROM ST JOSEPH TO MANISTEE. && $$ SYNOPSIS: DUKE SHORT TERM: DUKE LONG TERM: IOD MARINE: DUKE AVIATION: DUKE HYDROLOGY: DUKE
