000 FXUS63 KGRR 100847 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 346 AM EST FRI FEB 10 2012 LATEST UPDATE...ALL BUT AVIATION... .SYNOPSIS...(346 AM EST FRI FEB 10 2012) AN ARCTIC COLD FRONT WILL MOVE ACROSS LOWER MICHIGAN TODAY BRINGING A BURST OF SNOW AND MUCH COLDER TEMPERATURES. DRIVING CONDITIONS WILL LIKELY BE IMPACTED THIS AFTERNOON. COLDER WEATHER WILL LINGER THROUGH THE WEEKEND BEFORE TEMPERATURES BEGIN CLIMBING BACK TO 40 MIDWEEK. && .SHORT TERM...(346 AM EST FRI FEB 10 2012) (TODAY THROUGH SUNDAY) WE/RE RUNNING WITH A WINTER WX ADVISORY THIS AFTERNOON/EVENING FOR ALL BUT THE NRN 2 ROWS OF COUNTIES. THIS WILL BE AN IMPACT DRIVEN EVENT FEATURING 1-3 INCHES OF SNOW ALONG WITH RAPIDLY FALLING TEMPS THIS AFTERNOON. OF PARTICULAR CONCERN WILL BE TRAVEL CONDITIONS ALONG THE INTERSTATES 96/94 AS THE HEAVIEST SNOW WILL COMMENCE IN THOSE LOCATIONS AROUND MID AFTERNOON...AROUND THE TIME SCHOOLS ARE LETTING OUT AND PEOPLE BEGIN TO HEAD HOME FROM WORK FOR THE WEEKEND. TEMPS WILL BE IN THE 30S AHEAD OF THE FRONT. LATEST HRRR INDICATES THAT SOME LIGHT SNOW MAY BEGIN PRIOR TO FROPA. THIS WILL RESULT IN SOME MELTING ON ROADWAYS WHICH WILL QUICKLY FREEZE BEHIND THE FRONT. ADDITIONALLY...MUCH OF THE OMEGA IS JUST BELOW THE DGZ SUGGESTING THAT FLAKE SIZE WILL BE SMALL. SMALL FLAKES COMBINED WITH A FREEZING ROAD SFC WILL CREATE ICY CONDITIONS. NORTH WINDS GUSTING TO 25-30 MPH WILL ALSO CREATE STRONG CROSS WINDS ON THE E/W INTERSTATES FURTHER REDUCING VSBYS. ALL OF THESE FACTORS COMBINED WITH THE TRANQUIL WX WE/VE SEEN RECENTLY MAY CATCH PEOPLE OFF GUARD AND RESULT IN NUMEROUS SLIDE OFFS. THUS WE FELT IT PRUDENT TO HIGHLIGHT THIS EVENT WITH AN ADVISORY. THE SNOW WILL DIMINISH A FEW HOURS AFTER FROPA. THIS DOES/T LOOK LIKE A BIG LAKE EFFECT PRODUCER FOR US. BOUNDARY LAYER WINDS BECOME NNE TONIGHT RESULTING IN A DOMINANT BAND FROM JUST OFF SHORE LUDINGTON SSW TO NEAR CHICAGO. IT REMAINS POSSIBLE THAT THE MAIN BAND COULD CLIP THE POINTS AND WE/LL KEEP AN EYE ON THAT. INLAND...NORTH WINDS SHOULD LEAD TO SOME CLEARING. WINDS BEGIN TO BACK TO THE NW SATURDAY AS WARM AIR ADVECTION BEGINS. THIS WILL CAUSE SHSN OVER THE LAKE TO MOVE INLAND. THE LAKESHORE AREAS SOUTH OF GRAND HAVEN HAVE THE BEST CHANCE AT SEEING UP TO AN INCH. PCPN WILL DIMININSH SATURDAY NIGHT AND SUNDAY LOOKS DRY AS TEMPS CLIMB BACK UP TO 30. && .LONG TERM...(346 AM EST FRI FEB 10 2012) (SUNDAY NIGHT THROUGH THURSDAY) THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE SNOW AMOUNTS FOR MONDAY INTO TUESDAY. MODELS ARE TRENDING TOWARD A FASTER AND WEAKER SYSTEM FOR THIS TIME FRAME. MODELS ARE IN DECENT AGREEMENT IN SHOWING WEAK LIFT BUT DECENT MOISTURE DEPTH ESPECIALLY MON NIGHT. AT THIS POINT WILL KEEP POPS UNDER LIKELY AS THE TREND HAS BEEN FOR A WEAKER SYSTEM. THE DGZ BECOMES UNSATURATED TUESDAY...THUS THE POTENTIAL FOR MEASURABLE AMOUNTS DROPS OFF. HIGH PRESSURE MOVES IN FOR WED. THAT WILL LIMIT THE RISK FOR PRECIPITATION. HOWEVER ANOTHER STORM SYSTEM WILL RIDE UP THE OH VALLEY ON THU. THIS COULD LEAD SOME SNOW FOR SW LOWER MI. && .AVIATION...(1158 PM EST THU FEB 9 2012) EXPECT 3 TO 5 HOURS OF LIFR CIGS/VSBY WITH SNOW AT ALL TAF SITES DURING FROM LATE MORNING INTO EARLY EVENING FRIDAY. THE LOW CLOUDS (MVFR CIGS STREAMED IN FROM LAKE MICHIGAN EARLIER THAN EXPECTED SO I UPDATED THE TAFS ALREADY TO ACCOUNT FOR THAT AND BELIEVE THEY WILL REMAIN ALL NIGHT INTO FRIDAY. THE NEXT ISSUE IS WILL THERE BE LAKE ENHANCED SOUTHWEST FLOW SNOW SHOWERS AHEAD OF THE ARCTIC FRONT AT MKG...GRR AND AZO BTW 12Z AND 16Z? THE 950 TO 850 RH IS MARGINALLY HIGH ENOUGH AND THERE IS SOME LIFT IN THE DGZ TOO. THE HRRR SHOWS THIS ALSO BUT THE RH BECOMES LOWER AS ONE IS FARTHER SOUTH FROM THE PRIMARY COLD FRONT SO I HAVE THE SNOW STARTING EARLY AT MKG BUT NOT SO MUCH AT GRR AND AZO. THAT WILL HAVE TO BE WATCHED. THE BIGGEST CHANGE IS THAT THE NAM AND GFS ARE MUCH STRONGER ON THE SURFACE LOW FOR FRIDAY AFTERNOON. THIS CREATES A SIGNIFICANTLY LONGER PERIOD OF SNOW AND IT THE SNOW WOULD CONTINUE PAST SUNSET AT LOCATIONS EAST OF GRR. LIFR CONDITIONS WOULD SEEM LIKELY AT MOST TAF SITES FRIDAY AFTERNOON DUE TO SNOW AND MAYBE EVEN BLOWING SNOW AS THE COLD AIR BECOMES MORE ENTRENCHED WHILE THE LOW LEVEL WINDS KICK UP AFTER 21Z. WE WILL HAVE TO MONITOR THIS TOO. CONDITIONS WOULD NOT IMPROVE MUCH UNTIL AFTER 03Z AT MOST TAF SITES. && .MARINE...(346 AM EST FRI FEB 10 2012) WE/LL SEE AN ABRUPT WIND SHIFT TODAY AS A STRONG COLD FRONT MOVES THROUGH. WINDS WILL GUST FROM THE NORTH BEHIND THE FRONT TO JUST UNDER GALE FORCE AND THEN DIMINISH OVERNIGHT. AS TEMPS FALL BELOW FREEZING LATER THIS AFTERNOON AND TONIGHT...THE GUSTY WINDS MAY RESULT IN FREEZING SPRAY. && .HYDROLOGY...(346 AM EST FRI FEB 10 2012) MINIMAL HYDRO CONCERNS. A COUPLE OF INCHES OF SNOW IS EXPECTED WITH THE STRONG FRONT TODAY BUT THAT WILL HAVE A LIMITED IMPACT ON AREA RIVERS. THE ARCTIC AIR THAT OVERSPREADS THE REGION THIS WEEKEND LIKELY WON/T LAST LONG ENOUGH TO CREATE ICE JAM ISSUES. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY THIS AFTERNOON AND EVENING FOR ALL BUT THE NORTHERN TWO ROWS OF COUNTIES. LM...SMALL CRAFT ADVISORY THROUGH SATURDAY. && $$ SYNOPSIS: 93 SHORT TERM: 93 LONG TERM: MJS AVIATION: WDM MARINE: 93 HYDROLOGY: 93