000 FXUS63 KGRR 040235 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1035 PM EDT FRI JUL 3 2009 LATEST UPDATE...SHORT TERM... .SYNOPSIS...(409 PM EDT FRI JUL 3 2009) LOW PRESSURE IN THE PLAINS THIS EVENING WILL SLIDE EAST INTO THE OHIO VALLEY ON SATURDAY. CLOUDS WILL SPREAD BACK INTO THE AREA LATE TONIGHT AND KEEP SKIES MOSTLY CLOUDY OVER SOUTHERN LOWER MICHIGAN ON THE FOURTH FOR A GOOD PORTION OF THE DAY. A FEW RAIN SHOWERS ARE EVEN POSSIBLE LATE TONIGHT AND ON THE FOURTH ALONG AND SOUTH OF INTERSTATE 94. HIGH PRESSURE WILL BUILD INTO THE AREA ON SUNDAY PROVIDING A GOOD DEAL OF SUNSHINE. && .SHORT TERM...(1035 PM EDT FRI JUL 3 2009) (TONIGHT THROUGH SUNDAY NIGHT) WILL ADD PATCHY FOG TO THE FORECAST. HAVE ALREADY SEEN SOME REPORTS OF IT AND ALSO SEEN ON WEB CAMS. THE CLOUD COVER THAT IS APPROACHING WILL REMAIN FAIRLY THIN...ESPECIALLY EAST...SO THE FOG WILL REMAIN. ANY SHOWERS THAT ARRIVE BY DAYBREAK SHOULD ONLY BE MAKING IT TO THE SHORELINE FROM MKG SOUTH...AND WILL STILL BE ISOLATED AND VERY LIGHT. HAVE TWEAK POPS SLIGHTLY. WEST NORTHWEST FLOW ALOFT WILL PUSH A SHORTWAVE IN OUR DIRECTION TONIGHT FROM THE PLAINS...PASSING INTO THE OHIO VALLEY TOMORROW. A SURFACE LOW WILL MOVE FROM MISSOURI INTO KENTUCKY. THE GRR FORECAST AREA WILL BE ON THE NORTHERN FRINGES OF THIS SYSTEM WITH CLOUDS BEING THE MAIN ISSUE. CLOUDS WILL INCREASE FROM THE WEST TONIGHT AND PUSH THROUGH LOWER MICHIGAN ON SATURDAY. SOUTHERN LOWER MICHIGAN MAY END UP WITH MOSTLY CLOUDY SKIES THE BULK OF THE DAY. SHOWERS ARE POSSIBLE...BUT IT APPEARS MOST OF THE RAIN WILL STAY TO OUR SOUTH. THE I-94 CORRIDOR STANDS THE BEST CHANCE AT SEEING A FEW RAIN SHOWERS. CLOUDS SHOULD BE ON THE DECREASE FROM NORTH TO SOUTH SATURDAY NIGHT AS THE SHORTWAVE AND SURFACE LOW MOVE SOUTH AND EAST OF THE REGION. SUNDAY SHOULD BE THE MOST SUMMER LIKE DAY OF THE LAST 5...WITH PLENTY OF SUNSHINE AND TEMPS IN THE UPPER 70S. AN UPPER LOW WILL DIG INTO THE EASTERN GREAT LAKES REGION SUNDAY NIGHT INTO MONDAY PUSHING A COLD FRONT INTO THE FORECAST AREA. AT THIS POINT MOISTURE LOOKS LACKING AND KEPT THE FORECAST DRY. && .LONG TERM...(409 PM EDT FRI JUL 3 2009) (MONDAY THROUGH FRIDAY) MAIN CONCERN IN THE LONG TERM PORTION OF THE FCST WILL BE DETERMINING RAIN CHCS THROUGH THE PERIOD WITH FRONTS TRYING TO MOVE INTO THE AREA. IN ADDITION TO THE RAIN CHANCES...THE DEGREE OF WARMING WILL HAVE TO BE DETERMINED. UPPER SYSTEM EXPECTED TO MOVE OUT THIS WEEKEND IS EXPECTED TO BE REPLACED TO SOME DEGREE BY ADDITIONAL ENERGY DIVING SE OUT OF CANADA. MODELS ARE DISAGREEING ON THE STRENGTH AND MOVEMENT OF THESE POTENTIAL FEATURES. THE MODELS DO AGREE WITH KEEPING THE ACTIVE PORTION OF THE JET NORTH AND EAST OF THE AREA...WHICH SHOULD KEEP THE PCPN OUT OF THE AREA FOR THE MOST PART THROUGH THU. CHC OF RAIN IS NOT ZERO...BUT IT IS TOO LOW AT THIS TIME TO MENTION IN THE FCST. BEST THREAT OF RAIN WOULD BE ON FRI AS A WAVE LOOKS TO BREAK DOWN THE RIDGE...BUT THERE IS LOW CONFIDENCE EVEN WITH THIS SYSTEM. UPPER HEIGHTS BUILDING INTO THE AREA AND STRENGTHENING LOW LEVEL SW FLOW IS EXPECTED TO RESULT IN A WARMING TREND THROUGH THE PERIOD. ECMWF KEEPS H850 TEMPS A LITTLE COOLER INITIALLY WITH THE UPPER LOW A LITTLE CLOSER...HOWEVER ALL MODELS WARM H850 TEMPS INTO THE UPPER TEENS TO AROUND 20C BY NEXT FRI. THIS WOULD SUPPORT TEMPS WELL INTO THE 80S AND APPROACHING 90...IF NOT WARMER. && .AVIATION...(708 PM EDT THU JUL 2 2009) AS I SUGGESTED YESTERDAY...THE AXIS OF THE POLAR JET MOVED EAST OF THE GRAND RAPIDS CWA DURING THE MID AFTERNOON TODAY. WITH THAT WENT THE LOW CLOUD COVER. THUS I EXPECT MOSTLY CLEAR SKIES EARLY TONIGHT. HOWEVER... THE LEFT ENTRANCE REGION OF THAT SAME JET WILL COME OVER SOUTHWEST MICHIGAN EARLY SATURDAY MORNING. THAT WILL BRING SOME MID AND HIGH CLOUDS IN TOWARD MORNING. I BELIEVE THE RAIN WILL STAY SOUTH OF MICHIGAN WITH THIS EVENT...CLOSER TO I-80 SATURDAY. EVEN SO... I ALLOWED VCSH IN THE I-94 TAFS FOR THE MID MORNING HOURS OF SATURDAY. DUE TO THE LAYERED MID AND HIGH CLOUDS I DO NOT BELIEVE FOG IS MUCH OF A THREAT OVERNIGHT. && .MARINE...(835 PM EDT FRI JUL 3 2009) WILL ADD PATCHY FOG TO THE NEARSHORE WATERS FOR TONIGHT. WEB CAMS WERE SHOWING FOG ALONG THE SHORELINE AT MUSKEGON AND GRAND HAVEN. GIVEN THE LIGHT WINDS AND POCKETS OF COOLER WATER THIS FOG IS LIABLE TO PERSIST IN SPOTS. OVERALL LIGHT WINDS AND SMALL WAVES ARE EXPECTED THE NEXT 48 HOURS. A WEAK LOW PRESSURE SYSTEM WILL SLIDE ACROSS THE OHIO VALLEY ON SATURDAY WITH HIGH PRESSURE IN PLACE NORTH OF THE LOW ACROSS THE GREAT LAKES. WINDS SHOULD ESSENTIALLY BE 10-12 KNOTS OR LESS THROUGH SUNDAY EVENING. CORRESPONDINGLY...WAVES SHOULD BE 1-2 FEET OR LESS THIS WEEKEND. CLOUDS WILL BE FAIRLY PREVALENT ACROSS THE SOUTHERN HALF OF THE LAKE ON SATURDAY WITH SHOWERS IN THE FAR SOUTH. SUNDAY SHOULD BE A SUNNIER DAY. && .HYDROLOGY...(409 PM EDT FRI JUL 3 2009) NO HYDROLOGY ISSUES EXPECTED. DRY WEATHER IS EXPECTED FOR MUCH OF THE NEXT SEVERAL DAYS AND ALL SITES REMAIN WITHIN BANK. ANY RAIN ACROSS THE SOUTHWEST CORNER OF THE STATE LATE TONIGHT INTO SATURDAY SHOULD LIGHT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. && $$ SYNOPSIS: DUKE SHORT TERM: DUKE JK LONG TERM: NJJ AVIATION: WDM MARINE: DUKE JK HYDROLOGY: DUKE