FXUS63 KGRR 191956 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 350 PM EDT FRI MAR 19 2010 LATEST UPDATE...ALL BUT AVIATION... .SYNOPSIS...(350 PM EDT FRI MAR 19 2010) A STRONG COLD FRONT WILL SLIP SOUTHEAST THROUGH THE GREAT LAKES REGION TONIGHT. PRECIPITATION WILL DEVELOP ALONG THE FRONT AS IT TRACKS THROUGH LOWER MICHIGAN. MUCH COLDER AIR WILL FILTER IN BEHIND THE FRONT...RESULTING IN UNSEASONABLY COLD TEMPERATURES DURING THE DAY SATURDAY. && .SHORT TERM...(350 PM EDT FRI MAR 19 2010) (TONIGHT THROUGH SUNDAY NIGHT) THE MAIN CONCERN WITH THE FORECAST DEALS WITH THE PRECIPITATION TYPE AND AMOUNT FOR LATER TONIGHT INTO SATURDAY. MODELS ARE SHOWING A TREND TOWARD LESS PRECIPITATION WITH THIS SYSTEM. HOWEVER THE SYSTEM IS STILL STRENGTHENING UPSTREAM ACROSS THE LOWER TO CENTRAL PLAINS. THE STRONG COLD FRONT WILL PUSH THROUGH TONIGHT. SOME FGEN WILL CAUSE THE PRECIPITATION TO EXPAND ALONG THE FRONT AS IT COMES THROUGH. THIS OCCURS AFTER THE FRONT PUSHES THROUGH. THUS THE MAIN PRECIPITATION TYPE SHOULD BE SNOW. FORECAST SOUNDINGS SUPPORT THIS. AT 12Z SAT SOUNDINGS FOR BTL SHOW SNOW FROM THE GFS...NAM AND LOCAL WRF...ALTHOUGH THE NEW HIGH RES EURO SUGGESTS SOME RAIN THEN. THROUGH 06Z TONIGHT...MAINLY DRY WEATHER IS EXPECTED. I WILL KEEP POPS AT OR BELOW 30 PERCENT THROUGH 06Z TONIGHT. HOWEVER LATER TONIGHT AND MORE SO SATURDAY MORNING IS THE MOST LIKELY TIMEFRAME FOR PRECIPITATION. UP AROUND ROUTE 10 AND NORTH...ALMOST NO PRECIPITATION IS EXPECTED AND THE SUN COULD COME OUT SATURDAY AFTERNOON. I DO NOT SEE TEMPERATURES CLIMBING MUCH ON SATURDAY...MANY LOCATIONS TO STAY IN THE 30S. QUITE A CHANGE FROM THE PAST COUPLE OF DAYS. THE GFS SUGGESTED SOME ZL POSSIBLE ON SUN. NOT READY TO JUMP ON THIS TREND...BUT IT NEEDS MONITORING. THE NAM KEPT US DRY. FAIRLY DECENT AGREEMENT IN THE MODELS IN KEEPING THE UPPER LOW FAR ENOUGH SOUTH OF THE AREA THROUGH SUNDAY NIGHT TO LIMIT THE RISK FOR PRECIPITATION. THUS I WILL KEEP IT DRY. CLOSE CALL THOUGH FOR AREAS SOUTH OF INTERSTATE 94. && .LONG TERM...(350 PM EDT FRI MAR 19 2010) (MONDAY THROUGH FRIDAY) MEDIUM RANGE MODELS CONTINUE TO SHOW A JAMES BAY HIGH PRESSURE CENTER WILL BE STRONG ENOUGH TO KEEP THE SOUTHERN STREAM LOW TO OUR SOUTH. IT SHOULD HEAD FOR THE MID ATLANTIC COAST...A STORM PATH THAT HAS BEEN FAIRLY COMMON THIS EL NINO SEASON. THE DRY NE FLOW AROUND THE HIGH SHOULD HELP TO BRING US SUNSHINE ON MONDAY...SO HAVE GONE MORE OPTIMISTIC ON THE SKIES FOR MONDAY...AND ALSO...WITH THE ADDITIONAL SUNSHINE...HAVE RAISED TEMPS ABOUT 5 DEGREES. THE HIGH PRESSURE RIDGE WILL LINGER OVER THE GREAT LAKES AS THE MID ATLANTIC SYSTEM MOVES SLOWLY OFF SHORE. THEREFORE DRY CONDITIONS ARE EXPECTED FOR THE FIRST HALF OF THE WORK WEEK. BY WED A WEAK COLD FRONT MOVES IN AND MAY BRIEFLY STALL...OR AT LEAST SLOW...AS IT DRIFTS OVER THE AREA. THE FRONT APPEARS TO BE MOISTURE STARVED...SO NOT EXPECTING MUCH PCPN WITH IT...ALTHOUGH THE ECMWF IS A BIT WETTER. ANOTHER SURGE OF ARCTIC AIR GRAZES THE REGION BY THE END OF THE WEEK. AT THIS POINT THE CORE OF THIS COLD AIR APPEARS TO STAY TO OUR NORTH. && .AVIATION...(131 PM EDT FRI MAR 19 2010) A COLD FRONT WAS ACROSS CENTRAL LOWER MICHIGAN AS OF 17Z AND IT CONTINUES TO MOVE SOUTHWARD. AS IT CROSSES THE TAF SITES THEY WILL SEE A WIND SHIFT TO THE NW OR N AND VFR CEILINGS OF 4-5K FT WILL SETTLE IN. A WAVE OF ENERGY WILL MOVE ALONG THE FRONT ON SAT AND BEGIN TO SPREAD LIGHT PCPN INTO SOUTHERN LOWER MICHIGAN LATE TONIGHT. THE PCPN SHOULD START AS RAIN IN MOST AREAS...BUT AS THE COLDER AIR CONTINUES TO FILTER IN IT WILL CHANGE TO SNOW EARLY SATURDAY MORNING. FOR THE MOST PART THIS APPEARS TO BE A VERY LIGHT SNOW AND VSBYS SHOULD BE MOSTLY MVFR. HOWEVER...AS THE SYSTEM BECOMES BETTER ORGANIZED TOWARD MID DAY ON SATURDAY A BURST OF STEADIER SNOW MAY DEVELOP OVER THE SOUTHERN TAF SITES. HAVE PUT IN SOME IFR CONDITIONS AT AZO AND BTL. MOST OF THE SNOW SHOULD QUICKLY MELT ON RUNWAYS DUE TO THE WARM GROUND. && .MARINE...(350 PM EDT FRI MAR 19 2010) WINDS WILL INCREASE BEHIND THE FRONT TONIGHT...AND COULD TOP 25 KNOTS...ESPECIALLY NEAR LITTLE AND BIG SABLE POINTS. WAVES WILL BUILD TO NEAR SMALL CRAFT ADVISORY CRITERIA FOR A FEW HOURS. && .HYDROLOGY...(350 PM EDT FRI MAR 19 2010) WATER LEVELS WILL CONTINUE TO RECEDE THROUGH THE WEEKEND. PRECIPITATION FROM THIS NEXT SYSTEM IS EXPECTED TO REMAIN UNDER A QUARTER INCH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI....NONE. LM....NONE. && $$ SYNOPSIS: MJS SHORT TERM: MJS LONG TERM: JK AVIATION: JK MARINE: MJS HYDROLOGY: MJS