FXUS63 KGRR 112348 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 648 PM EST THU MAR 11 2010 LATEST UPDATE...AVIATION... .SYNOPSIS...(420 PM EST THU MAR 11 2010) SEVERAL BANDS OF RAIN SHOWERS ROTATING AROUND A SLOW MOVING LOW PRESSURE SYSTEM WILL IMPACT SOUTHWEST MICHIGAN THROUGH THE WEEKEND. THE RAIN FALLING ON ALREADY SATURATED GROUNDS FROM RECENT SNOW MELT MAY RESULT IN SOME MINOR FLOODING ISSUES. UNSEASONABLY MILD TEMPERATURES WILL CONTINUE THROUGH FRIDAY BEFORE COOLING JUST A BIT THIS WEEKEND. && .SHORT TERM...(420 PM EST THU MAR 11 2010) (TONIGHT THROUGH SATURDAY NIGHT) BANDS OF HEAVIER RAIN SHOWERS WITH EMBEDDED TSTMS ASSOCIATED WITH H8 THETA-E RIDGE AXIS WILL LIFT NORTH THROUGH THE AREA TONIGHT. HEAVIEST RAIN WILL FALL OVER THE SOUTHWEST HALF OF THE CWFA WHERE ONE HALF TO ONE INCH OF QPF IS EXPECTED. PRECIPTABLE WATER VALUES ARE AROUND 1.0 IN THIS AREA. QPF MORE LIKE ONE QUARTER TO ONE HALF INCH ARE EXPECTED IN THE NORTHEAST CWFA TONIGHT. UNLESS SOME SFC BASED INSTABILITY CAN DEVELOP SOON IN THE EXTREME SW CORNER OF THE CWFA... SVR WX THREAT IS ALMOST NIL. SHOULD THAT HAPPEN (EVEN JUST A FEW HUNDRED JOULES OF SFC BASED CAPE)... FEEL A LOW RISK FOR CELL ROTATION EXISTS THROUGH ABOUT 02Z AROUND VAN BUREN COUNTY WITH 0-1KM HELICITY VALUES CURRENTLY AROUND 150 M2/S2. DENSE FOG MAY REFORM TONIGHT DUE TO VERY MOIST BOUNDARY LAYER CONDITIONS... AND LINGER THROUGH MID MORNING FRIDAY. BAND OF RAIN WHICH IMPACTS THE AREA TONIGHT IS EXPECTED TO LIFT NORTH OF THE AREA BY DAYBREAK FRIDAY... LEAVING A PREDOMINATELY DRY DAY IN IT/S WAKE WITH MILD TEMPS NEAR 60 (ONCE ANY FOG/STRATUS BURNS OFF). NEXT IMPULSE CURLING AROUND THE UPPER LOW IS PROGGED TO IMPACT MOSTLY THE SRN CWFA FRIDAY NIGHT THROUGH SATURDAY NIGHT AND WILL CARRY LIKELY POPS DURING THAT TIME. && .LONG TERM...(420 PM EST THU MAR 11 2010) (SUNDAY THROUGH THURSDAY) FORECAST CONCERNS DURING THE EXTENDED PERIOD ARE MINIMAL. THE LARGE CUTOFF LOW MOVING THROUGH THE GREAT LAKES WILL BE MOVING OVER THE ATLANTIC BY SUNDAY. PCPN WILL BE ENDING SUNDAY AFTERNOON. THIS WILL BE FOLLOWED BY SEVERAL DAYS OF DRY WX. TEMPS WILL BE A LITTLE COOLER THAN THE PAST FEW DAYS...BUT NOT MUCH. H8 TEMPS GENERALLY REMAIN AOA 0C THROUGH THE PERIOD WHICH SHOULD RESULT IN THE LOWER 50S...SEVERAL DEGREES ABOVE AVERAGE. && .AVIATION...(648 PM EST THU MAR 11 2010) THE PRECIPITATION BAND ASSOCIATED WITH THE OCCLUDED FRONT WILL MOVE THROUGH THE CWA BETWEEN NOW AND MIDNIGHT. THERE IS SOME ELEVATED INSTABILITY BUT THUNDERSTORMS SEEM UNLIKELY. SEVERAL STATIONS HAVE HAD 2SM RA OVC025...LDM WAS 1 1/2SM +RA AT 636 PM THIS EVENING SO I PUT A TEMPO GROUP IN TO ALLOW FOR LOWER VSBY IN HEAVY SHOWERS (PUT CB WITH CIGS TO IMPLY CONVECTION). ONCE THE RAIN BAND IS THROUGH (AROUND MIDNIGHT) LOW CLOUDS WILL DOMINATED INTO LATE MORNING. WINDS DECREASE SOME LATER TONIGHT SO I CONTINUED THE 1/2SM FG THAT WAS IN THE PREVIOUS TAF FORECASTS AROUND 05 AM FRIDAY MORNING. SOME IMPROVEMENT TO VFR VSBY / CIGS ARE POSSIBLE BY MID AFTERNOON AHEAD OF THE NEXT SHORTWAVE. && .MARINE...(420 PM EST THU MAR 11 2010) OFFSHORE FLOW WILL KEEP WAVE HEIGHTS IN CHECK. SPEEDS/GUSTS OUT OF THE EAST COULD APPROACH SMALL CRAFT ADVISORY AT TIMES... BUT NOT CONSISTENTLY ENOUGH TO WARRANT MARINE HEADLINES ATTM. && .HYDROLOGY...(420 PM EST THU MAR 11 2010) HAVE ISSUED AN AREAL FLOOD ADVISORY FOR ABOUT THE SOUTHWEST ONE HALF OF THE CWFA THROUGH FRIDAY 230 PM TO ACCOUNT FOR ONE HALF TO ONE INCH OF RAIN FALLING ON TOP OF ALREADY SATURATED SOILS AND SWOLLEN CREEKS AND STREAMS FROM RECENT SNOW MELT. ADDITIONAL MINOR AREAL NUISANCE FLOODING IS POSSIBLE FRIDAY NIGHT THROUGH SATURDAY NIGHT AS THE NEXT BAND OF PERSISTENT RAIN IMPACTS THE AREA. QPF DURING THIS TIME COULD BE ANOTHER ONE HALF TO ONE INCH. CONCERNING RIVER FORECAST POINTS... SOUTHWEST LOWER MICHIGAN HAS SEEN WARM WEATHER OVER THE COURSE OF THE LAST WEEK...WHICH HAS RESULTED IN LOSING MUCH OF OUR SNOW PACK. THE MELT WATER HAS MADE ITS WAY INTO AREA RIVERS AND RIVER STAGES HAVE BEEN ON THE RISE THE LAST COUPLE DAYS. RAINFALL ON THE ORDER OF A HALF INCH IS EXPECTED THIS EVENING AND TONIGHT. THE EVENING RAINFALL COMBINED WITH FURTHER SNOW MELTWATER WORKING ITS WAY INTO RIVERS WILL RESULT IN SOME RIVER STAGES EXCEEDING BANKFULL. WE HAVE ISSUED A FLOOD ADVISORY FOR SIX SITES THAT ARE EXPECTED TO REACH/EXCEED BANKFULL. THEY ARE...MAPLE RAPIDS...IONIA... SMYRNA...HASTINGS...BURLINGTON AND HOLT. PLEASE SEE THE LATEST FLSGRR AND RVSGRR PRODUCTS FOR FURTHER INFORMATION. && .GRR WATCHES/WARNINGS/ADVISORIES... MI....NONE. LM....NONE. && $$ SYNOPSIS: MEADE SHORT TERM: MEADE LONG TERM: 93 AVIATION: WDM MARINE: MEADE HYDROLOGY: MEADE/DUKE WWWW