000 FXUS63 KGRR 111919 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 300 PM EDT SUN MAY 11 2008 LATEST UPDATE...SHOT TERM SYNOPSIS MARINE HYDROLOGY... .SYNOPSIS...(300 PM EDT SUN MAY 11 2008) A STRONG AREA OF LOW PRESSURE OVER INDIANA WILL TRACK SLOWLY EAST TONIGHT TAKING MOST OF THE RAIN WITH IT. HIGH PRESSURE WILL BUILD INTO THE GREAT LAKES REGION FOR MONDAY AND PERSIST INTO TUESDAY PROVIDING MAINLY DRY WEATHER. A COLD FRONT WILL MOVE INTO MICHIGAN TUESDAY NIGHT AND WEDNESDAY BRINGING SOME SHOWERS TO THE REGION. && .SHORT TERM...(300 PM EDT SUN MAY 11 2008) (TONIGHT THROUGH TUESDAY NIGHT) THE DEEP LOW PRESSURE SYSTEM OVER INDIANA WAS TRACKING SLOWLY EAST. A LARGE BAND OF RAIN PIVOTING AROUND THIS SYSTEM WAS LOCATED OVER SOUTHWEST LOWER MICHIGAN. AS THE STORM PULLS EAST TONIGHT THE RAIN WILL BE TAPERING OFF FROM THE NORTHWEST. UP TO THIS POINT ABOUT A HALF INCH OF RAIN HAS FALLEN ACROSS VAN BUREN ALLEGAN AND KALAMAZOO COUNTIES BASED ON SURFACE OBSERVATIONS. RADAR HAS BEEN OVERESTIMATING THE RAINFALL AMOUNTS. ANOTHER QUARTER TO LOCALLY A HALF INCH COULD FALL IN THE NEXT COUPLE OF HOURS. ACROSS MY NORTHWEST COUNTIES ONLY A COUPLE HUNDRETHS MAY END UP FALLING AS THE PRECIPITATION WAS BATTLING SOME DRIER AIR. OVERNIGHT THE RAIN WILL BE TAPERING OFF FROM WEST TO EAST. THE WEATHER LOOKS MAINLY DRY MON THROUGH TUE. CLOUDS WILL PERSIST FOR MUCH OF MON...WHICH WILL LIKELY HOLD BACK TEMPERATURES WELL UNDER NORMAL LEVELS. A COLD FRONT WILL BE REACHING THE WRN GREAT LAKES AREA LATER TUE AFTERNOON. OUR WINDS WILL SHIFT TO THE SOUTH AND THAT WILL BRING UP SOME WARMER AIR. MANY LOCATIONS WILL SEE HIGHS NEAR 70 DEGREES. THE NAM DID TREND FASTER WITH THE COLD FRONT AND IS COMING IN LINE WITH THE GFS. THIS SUPPORTS SOME LOW POPS FOR TUE NIGHT. WITH ELEVATED INSTABILITY ARRIVING WILL INCLUDE SOME THUNDER. && .LONG TERM...(1215 PM EDT SUN MAY 11 2008) (WEDNESDAY THROUGH SUNDAY) SHOWERS ARE LIKELY WEDNESDAY ALONG AND OUT AHEAD OF THE COLD FRONT. WE CONSIDERED ADDING A MENTION OF CONVECTION INTO THE FCST BETWEEN 12Z AND 18Z WED. HOWEVER IT STILL APPEARS THAT THE MOST VIGOROUS PVA WILL STAY WELL NORTH OF OUR CWFA. FRONTAL TIMING IS ALSO NOT THE MOST CONDUCIVE FOR CONVECTIVE DEVELOPMENT. THEREFORE WE WILL ONLY MENTION SHOWERS AT THIS POINT (BEST CHC BETWEEN 12Z AND 18Z WED). DRY WX WILL RETURN FROM LATE WEDNESDAY THROUGH THURSDAY NIGHT. WE WILL HAVE A CHC FOR SHOWERS FROM FRIDAY THROUGH THE WEEKEND AS THE H5 TROF AXIS DIGS INTO THE EASTERN CONUS. WE HAVE RAMPED UP POPS FOR SHOWERS NEXT WEEKEND AS A FAIRLY STRONG NORTHERN STREAM SYSTEM DIVES DOWN FROM THE NNW ON SATURDAY. MEX GUIDANCE MAX TEMPS ARE BEING SKEWED TOO HIGH FOR NEXT WEEKEND BY CLIMO VALUES. GIVEN THE EVOLVING SFC/UPPER LEVEL PATTERN FOR NEXT WEEKEND FEATURING A DEEP H5 TROF DIGGING IN... WE WILL UNDERCUT MEX GUIDANCE MAX TEMPS FOR SAT/SUN. MAX TEMPS WILL ONLY REACH THE 50S BOTH DAYS. && .MARINE...(300 PM EDT SUN MAY 11 2008) WILL MAINTAIN THE SMALL CRAFT ADVISORY INTO MONDAY. STRONG GUSTY WINDS OVER THE NEARSHORE WATERS WILL CONTINUE TO BACK THROUGH THE NIGHT. THIS WILL ALLOW FOR BUILDING WAVES TO OVER 4 FEET. WIND GUSTS THIS EVENING MAY BRIEFLY TOUCH GALE CRITERIA NEAR SOUTH HAVEN..BUT PREVAILING CONDITIONS ARE EXPECTED TO BE AT SMALL CRAFT ADVISORY LEVELS. && .AVIATION...(115 PM EDT SUN MAY 11 2008) PRIMARILY MVFR CONDITIONS ARE ANTICIPATED AT ALL TAF SITES THIS AFTN WITH REDUCTIONS INTO THE IFR CATEGORY LIKELY FROM MID AFTERNOON THROUGH 06Z TONIGHT DUE TO LOWERING CIGS. RAIN WILL GRADUALLY EXIT THE AREA FROM NW TO SE BETWEEN 00Z AND 06Z FOLLOWED BY MVFR CONDITIONS BETWEEN 06Z AND 12Z. A RETURN TO VFR CONDITIONS IS ANTICIPATED AT ALL TAF SITES BY 14Z MON. && .HYDROLOGY...(300 PM EDT SUN MAY 11 2008) RAINFALL WILL STILL BE LOCALLY HEAVY INTO THE EARLY EVENING HOURS. AT THIS POINT IT LOOKS LIKE MOST LOCATIONS WILL STAY UNDER AN INCH FOR QPF. RISES ARE EXPECTED ON SOME RIVERS...BUT FLOODING IS NOT EXPECTED AT THIS TIME. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT FROM ST JOSEPH TO MANISTEE THROUGH MONDAY. && $$ SYNOPSIS: MJS SHORT TERM: MJS LONG TERM: LAURENS MARINE MJS AVIATION: LAURENS HYDROLOGY: MJS