Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000 FXUS63 KGRR 220830 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 330 AM EST SAT NOV 22 2014 LATEST UPDATE... SYNOPSIS/SHORT TERM/LONG TERM/MARINE .SYNOPSIS... ISSUED AT 330 AM EST SAT NOV 22 2014 A LOW PRESSURE SYSTEM WILL EMERGE FROM THE PLAINS STATES THIS WEEKEND AND BRING WARMER AND WET CONDITIONS TO THE AREA. SOME FREEZING RAIN WILL OCCUR ACROSS THE AREA THIS MORNING AS THE LEADING EDGE OF THE PRECIPITATION MOVES IN. THE FREEZING RAIN WILL CHANGE OVER TO RAIN MID MORNING. RAIN WILL CONTINUE THROUGH THE WEEKEND AND TEMPERATURES WILL WARM WELL INTO THE 40S AND EVEN SOME 50S WILL BE POSSIBLE. COLDER AIR WILL MOVE BACK IN ACROSS THE AREA LATER ON MONDAY AND INTO TUESDAY. PRECIPITATION WILL CHANGE OVER FROM RAIN TO SNOW. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 330 AM EST SAT NOV 22 2014 THE BIGGEST IMPACT WEATHER EXPECTED IN THE SHORT TERM WILL BE THE FREEZING RAIN THAT IS EXPECTED THIS MORNING. SHOWERS HAVE BEEN EXPANDING IN COVERAGE ACROSS WI...IL...AND IN THIS MORNING...AND THEY ARE NOW STARTING TO MAKE THEIR WAY INTO SW LOWER. P-TYPES WITH THIS PCPN HAVE RANGED FROM RAIN TO FREEZING RAIN DEPENDING ON THE TEMP. TEMPS ARE COMING UP ACROSS THE CWFA THIS MORNING...HOWEVER EVERYWHERE AWAY FROM THE LAKESHORE IS STILL BELOW FREEZING AND DEW POINTS ARE IN THE TEENS. WE WILL SEE SOME EVAP COOLING TAKE PLACE INITIALLY AS PCPN BEGINS...HELPING THE CAUSE FOR SOME FREEZING RAIN. SOME SLEET AND SNOW WILL BE POSSIBLE ALSO. THE ADVECTION OF WARM AIR REMAINS STEADY THIS MORNING...AND ALL SITES LOOK TO BE ABOVE FREEZING BY NOON TODAY. THE SLICK ROADS MAY LAST A LITTLE LONGER THAN TEMPS RISING ABOVE FREEZING DUE TO ROAD TEMPS IN THE MID TO UPPER 20S. WE WILL SEE THE PCPN DIMINISH SOME THIS AFTERNOON AFTER THE INITIAL WAVE PASSES BY THE AREA TO THE E/NE. WE WILL SEE ONGOING WARM AND MOISTURE ADVECTION WHICH WILL HELP TO FORM AREAS OF DRIZZLE TO GO ALONG WITH RESIDUAL SHOWERS FLOATING THROUGH THE AREA. THIS WILL ESSENTIALLY CONTINUE THROUGH TONIGHT AND INTO THE FIRST HALF OF SUN. FOG IS ALSO EXPECTED TO BE PRESENT DUE TO THE SNOW PACK IN PLACE AND WITH THE COLD GROUND THAT IS PRESENT. WE WILL SEE THE RAIN PICK UP IN INTENSITY DURING THE AFTERNOON HOURS ON SUN AND ESPECIALLY ON SUN NIGHT. THIS OCCURS AS THE MAIN UPPER WAVE FOR OUR AREA WITH THIS SYSTEM THAT IS CURRENTLY ACROSS NRN MEXICO WILL LIFT UP TOWARD OUR AREA. IT WILL TAP MOISTURE DIRECTLY FROM THE GULF OF MEXICO AND BRING IT ALL OF THE WAY UP INTO THE AREA. THE CHCS OF THUNDER ARE NOT ZERO WITH THIS SYSTEM...HOWEVER THEY DO LOOK QUITE LOW WITH ELEVATED LI/S NOT QUITE GOING BELOW ZERO. WE WILL SEE THE COLDER AIR SWEEP BACK IN DURING THE DAY ON MON ACROSS THE AREA. THE SFC LOW WILL MOVE NORTH INTO CANADA...AND WE WILL SEE THE COLDER AIR ASSOCIATED WITH THE LONG WAVE TROUGH MOVE IN DURING THE DAY. IT DOES LOOK LIKE IT WILL TAKE UNTIL THE AFTERNOON ON MON FOR RAIN TO CHANGE OVER TO SNOW FOR THE AREA. .LONG TERM...(MONDAY NIGHT THROUGH FRIDAY) ISSUED AT 330 AM EST SAT NOV 22 2014 SLIPPERY TRAVEL IS EXPECTED TO DEVELOP MONDAY NIGHT AND CONTINUE INTO TUESDAY AS COLD AIR AND LAKE ENHANCED SNOW SHOWERS IMPACT THE AREA ON THE BACK SIDE OF THE DEPARTING LOW. DEEP MOISTURE AND CYCLONIC FLOW DURING THIS TIME SHOULD LEAD SOME SNOW ACCUMULATIONS... WITH THE PROGGED WESTERLY LOW LEVEL FLOW FAVORING OTTAWA...KENT...ALLEGAN AND BARRY COUNTIES. SURFACE RIDGING AND WARM ADVECTION SHOULD BRING A DIMINISHING TREND TO SNOW SHOWERS ON TUESDAY NIGHT. WEDNESDAY THE BIG TRAVEL DAY CURRENTLY LOOKS RELATIVELY TRANQUIL WITH A SOUTHERLY LOW LEVEL FLOW PROGGED AHEAD OF A SFC LOW DEVELOPING TO OUR WEST ALONG A SHARPENING BAROCLINIC ZONE. MODEL CONSENSUS IS FOR MORE COLD AIR AND LAKE EFFECT SNOW SHOWERS TO RETURN FOR THANKSGIVING DAY INTO FRIDAY. HOWEVER CONFIDENCE IS LOW WITH RESPECT TO THE TIMING OF THE PASSAGE OF THE COLD FRONT... THE STRENGTH OF THE COLD ADVECTION BEHIND IT... AND THE LOW LEVEL FLOW PATTERN THAT SETS UP. THIS LEADS TO UNCERTAINTIES REGARDING ANY POTENTIAL SNOW ACCUMULATIONS OVER THE HOLIDAY PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1148 PM EST FRI NOV 21 2014 STRATUS CLOUDS WITH CEILINGS OF 2000 TO 300 FEET AGL WILL BE SPREADING INTO LOWER MICHIGAN FROM THE SOUTHWEST BETWEEN 09Z AND 11Z. SOME FREEZING RAIN IS EXPECTED BY 12Z BUT SHOULD ONLY LAST FOR 1 TO 3 HOURS BEFORE TEMPERATURES RISE ABOVE FREEZING. CEILINGS AND VISIBILITY WILL LOWER QUICKLY AFTER THAT AS IFR IS EXPECTED IN LOW CLOUDS AND FOG THROUGH SATURDAY AFTERNOON. && .MARINE... ISSUED AT 330 AM EST SAT NOV 22 2014 WE WILL BE MAINTAINING THE MARINE HEADLINES AS IS WITH THIS FCST PACKAGE. WE ARE LIKELY SEEING THE PEAK WINDS OCCURRING RIGHT NOW...OR THEY WILL PEAK VERY SOON. IT APPEARED EARLIER THAT THE NRN HALF OF THE NEARSHORE WOULD LIKELY HIT GALES...HOWEVER GALE REPORTS HAVE BEEN VERY ISOLATED THUS FAR WITH THE STABLE CONDITIONS OVER THE LAKE. WE WILL CONTINUE TO MONITOR THE SITUATION. IT DOES LOOK LIKE WE WILL HOLD IN SMALL CRAFT ADVISORY CONDITIONS ALL WEEKEND AND INTO EARLY NEXT WEEK. IT WILL BE POSSIBLE WE SEE GALES ON MON IN THE WAKE OF THE FRONT. && .HYDROLOGY... ISSUED AT 330 PM EST FRI NOV 21 2014 COMPLICATED FORECAST FROM A HYDROLOGY FORECAST. AT THIS TIME IT APPEARS THAT HYDRO LOGIC IMPACTS WILL BE MINIMAL...BUT WE WILL NEED TO MONITOR TRENDS CLOSELY. SNOW WATER EQUIVALENT VALUES RANGE FROM LESS THAN A HALF INCH INLAND AROUND LANSING AND JACKSON TO AN INCH AROUND GRAND RAPIDS TO JUST UNDER AN INCH FOR MUCH OF THE LAKESHORE. BASED ON RAIN FORECASTS AND WARMER TEMPERATURES...WE SHOULD LOSE A CONSIDERABLE AMOUNT OF THIS SNOW PACK. AFTER PUTTING IN ROUGHLY AND INCH TO AN INCH AND A HALF OF RAIN...FACTORING IN MELTING MOST OF THE SNOW PACK...ALL THE RIVERS SHOW A CONSIDERABLE RISE. HOWEVER VERY LITTLE IF ANY FLOODING SHOWED UP IN THE HYDROGRAPHS. THIS IS SUPPORTED BY THE RIVER ENSEMBLE FORECASTS. THE PORTAGE RIVER NEAR VICKSBURG WAS ON OF THE SITES THAT WAS SHOWN TO APPROACH FLOOD STAGE ON MONDAY. ANOTHER POTENTIAL FLOODING FACTOR IS THAT SOME OF THE RIVERS HAVE ICE IN THEM. THIS INCLUDES THE GRAND AND MUSKEGON RIVERS. HOWEVER THE ICE DOES NOT APPEAR TO BE THICK...GENERALLY LESS THAN 4 INCHES. HOWEVER WE ARE TRYING TO GAIN A BETTER HANDLE ON HOW THICK THE ICE IS. IF THE ICE IS THICKER THAN 4 INCHES...THAT COULD POTENTIALLY LEAD TO PROBLEMS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...FREEZING RAIN ADVISORY UNTIL 9 AM EST THIS MORNING FOR MIZ037>040-043>046-050>052-056>059-064>067-071>074. LM...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 4 AM EST SUNDAY FOR LMZ847>849. GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ847>849. SMALL CRAFT ADVISORY UNTIL 4 AM EST SUNDAY FOR LMZ844>846. && $$ SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...MEADE AVIATION...OSTUNO HYDROLOGY...MJS MARINE...NJJ

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