Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 272021 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 415 PM EDT MON OCT 27 2008 LATEST UPDATE...ALL SECTIONS BUT AVIATION AND LONG TERM... .SYNOPSIS...(415 PM EDT MON OCT 27 2008) UNSEASONABLY COLD AIR AND SCATTERED LAKE EFFECT RAIN AND SNOW SHOWERS WILL LINGER ACROSS THE REGION THROUGH TUESDAY NIGHT. DRY WEATHER AND A WARMING TREND WILL BEGIN ON WEDNESDAY. && .SHORT TERM...(415 PM EDT MON OCT 27 2008) (TODAY THROUGH WEDNESDAY) LAKE ENHANCED OPEN CELL CONVECTION IS GETTING A DIURNAL BOOST THIS AFTERNOON... AND THERE HAVE BEEN SOME REPORTS OF HEAVIER SHOWERS MIXED WITH GRAUPEL. LATER TONIGHT AS THE DIURNAL EFFECTS ARE LOST AND THE FLOW BECOMES MORE NORTHERLY... THE LAKE EFFECT SHOWERS SHOULD BECOME RESTRICTED TO THE LAKE MICHIGAN SHORELINE COUNTIES. ONE DOMINATE BAND MAY EVOLVE... ESPECIALLY IF IT CLEARS INLAND AND AND BOUNDARY LAYER DECOUPLES. THIS SCENARIO APPEARS LIKELY. AS FAR AS PCPN TYPE TONIGHT... BELIEVE IT WILL PROBABLY REMAIN RAIN OR A MIX OF RAIN AND SNOW ALONG THE LAKESHORE SOUTH OF MKG DUE TO THE LENGTHY FETCH DOWN LK MI WHICH STILL HAS WATER TEMPS IN THE LOWER TO MID 50S. STILL CAN/T RULE OUT SOME LOCAL 1-2 INCH ACCUMULATIONS IN HEAVIER BANDS THAT ARE INLAND JUST ENOUGH FROM THE LK MI WARMING EFFECTS. PAW PAW FOR EXAMPLE WOULD BE A SPOT THAT COULD POTENTIALLY SEE THIS OCCUR. BACKING FLOW AND DIURNAL COMPONENT SHOULD ALLOW LAKE EFFECT SHOWERS TO SPREAD/DEVELOP INLAND AGAIN BY MID/LATE MORNING TUESDAY. PCPN SHOULD BE MIXY AGAIN BY AFTERNOON AS SFC TEMPS WARM TO AROUND 40... EXCEPT IN HIGHER ELEVATION AREAS IN THE FAR NRN CWFA. LITTLE OR NO SNOW ACCUMULATION EXPECTED. CYCLONIC FLOW WILL REMAIN ENTRENCHED OVER THE REGION TUESDAY NIGHT AND NW WINDS MAY ACTUALLY INCREASE AS DEEPENING LOW PRESSURE SYSTEM LIFTS NNW ACROSS NEW ENGLAND. WE SHOULD SEE A CONTINUATION OF LAKE EFFECT SNOW (OR MIXED RAIN AND SNOW SHOWERS)... AND THE STRONGER FLOW MAY KEEP THEM GOING INLAND MOST OF THE NIGHT. NO ACCUMS EXPECTED ATTM. DRIER AIR ARRIVES WEDNESDAY AND THE H8 THERMAL TROUGH BEGINS TO LIFT OUT. THUS A DECREASING CLOUD PATTERN IS EXPECTED ALONG WITH SLIGHTLY WARMER HIGH TEMPS. && .LONG TERM...(247 PM EDT MON OCT 27 2008) (THURSDAY THROUGH MONDAY) LONG WAVE RIDGING WILL BE IN CONTROL OF THE WX FOR THE STATE AT THE BEGINNING OF THE LONG TERM ON THU MORNING. STRONG RETURN FLOW WILL DEVELOP ACROSS THE AREA AS SFC RIDGE MOVES SE AND AS THE NEXT LOW BEGINS TO APPROACH THE AREA FROM THE NW. THIS RETURN FLOW WILL SEND H850 TEMPS UP INTO THE LOW TO MID TEENS C. THIS WILL ALLOW TEMPS TO MAKE A RUN AND POTENTIALLY EXCEED 60F ON THU. THIS FRONT WILL DROP SOUTH THROUGH THE AREA DURING THE AFTERNOON TO EVENING HOURS ON FRI. DEPENDING ON HOW FAST THE FRONT MOVES THROUGH...WE COULD SEE ONE MORE MILD DAY. THE FRONT CONTINUES TO LOOK LIKE IT WILL BE MOISTURE STARVED AND THE SUPPORTING UPPER WAVE IS EXPECTED TO REMAIN NORTH OF THE AREA. TEMPS WILL PLUMMET FOR SAT AS COLD AIR ADVECTS IN FROM THE NNE WITH THE HIGH REMAINING TO OUR NW. MODELS ARE INDICATING THAT IT MAY NOT BE AS COLD AS PREVIOUS RUNS HAVE SHOWN. THE RIDGE WILL MOVE ACROSS THE AREA SAT NIGHT...AND RETURN FLOW WILL SET UP FOR SUN. THIS WILL OCCUR AS AN UPPER TROUGH DIGS OVER THE WRN U.S. AND UPPER HEIGHTS WILL BUILD A BIT OVER THE EAST. MILDER AIR WILL RETURN FOR SUN...AND ESPECIALLY ON MON WITH A LOW THREAT OF PCPN. && .MARINE...(415 PM EDT MON OCT 27 2008) GALE WARNING AS BEEN ALLOWED TO EXPIRE BUT THE NW FLOW REMAIN AS HIGH AS 30 KNOTS THROUGH AT LEAST WEDNESDAY MORNING. THUS WAVES GREATER THAN 4 FEET...HAZARDOUS TO SMALL CRAFT...WILL CONTINUE. && .AVIATION...(136 PM EDT MON OCT 27 2008) BANDS OF LAKE EFFECT SHOWERS CONTINUE TO AFFECT THE AREA THIS AFTERNOON AS COLD AIR MOVES OVER THE LAKE. THE MOST WIDESPREAD COVERAGE AND INTENSE SHOWER ACTIVITY IS AT THE KAZO AND KBTL TERMINALS AS THE FLOW REMAINS FROM ROUGHLY 320 OR NW. ELSEWHERE DIURNAL SHOWERS ARE DEVELOPING UNDER THE COLD POOL OF AIR ALOFT. PCPN HAS BEEN MAINLY RAINFALL WITH TEMPS IN THE 40S...HOWEVER CAN NOT RULE OUT SOME SNOW/HAIL/GRAUPEL MIXING IN WITH SOME OF THE MORE INTENSE SHOWERS. THIS TREND WILL CONTINUE THROUGH THE AFTERNOON AS WILL THE WIND GUSTS TO 25 KNOTS. WINDS WILL DIMINISH AROUND SUNSET THIS EVENING...AND DIURNAL SHOWER ACTIVITY WILL DIE OFF. LAKE EFFECT WILL SHIFT TO ALONG THE IMMEDIATE LAKESHORE AS THE FLOW BECOMES ALMOST DUE NORTHERLY. SKIES SHOULD IN FACT SCATTER OUT AT MOST TERMINALS. LAKE EFFECT WILL SHIFT BACK ONSHORE DURING THE MORNING HOURS ON TUE AS THE FLOW BECOMES NW ONCE AGAIN. ANY SHOWERS EARLY WILL LIKELY BE SNOW...TRANSITIONING TO RAIN AS THE SFC WARMS. FOR NOW...WE HAVE GONE WITH VCSH TO COVER THIS. WINDS SHOULD BE A LESS GUSTY ON TUE. && .HYDROLOGY...(415 PM EDT MON OCT 27 2008) NO HYDRO CONCERNS AS PCPN NEXT 72 HOURS WILL BE GENERALLY SCATTERED IN NATURE WITH QPF AMOUNTS BELOW HALF INCH. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY IN EFFECT THROUGH 15Z WED FROM ST. JOSEPH TO MANISTEE. && $$ SYNOPSIS: MEADE SHORT TERM: MEADE LONG TERM: NJJ MARINE: MEADE AVIATION: NJJ HYDROLOGY: MEADE