Issued by NWS Grand Rapids, MI
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000 FXUS63 KGRR 261125 AFDGRR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 725 AM EDT SUN OCT 26 2008 LATEST UPDATE...AVIATION... .SYNOPSIS...(425 AM EDT SUN OCT 26 2008) A COLD FRONT WILL PUSH ACROSS THE REGION THIS MORNING BRINGING WINDY CONDITIONS...FALLING AFTERNOON TEMPERATURES AND SCATTERED SHOWERS. A SECOND COLD FRONT WILL PLOW INTO THE AREA LATE TONIGHT WITH EVEN COLDER AIR. SOME AREAS MAY SEE A RAIN AND SNOW MIX TONIGHT...BUT ALL AREAS IN SOUTHWEST LOWER MICHIGAN WILL SEE SNOW BY MONDAY AS THE COLDEST AIR OF THE SEASON ARRIVES. LIGHT SNOW ACCUMULATIONS ON GRASSY AREAS WILL BE POSSIBLE MONDAY THROUGH TUESDAY. && .SHORT TERM...(425 AM EDT SUN OCT 26 2008) (TODAY THROUGH TUESDAY) WILL TWEAK THE FORECAST SOMEWHAT THIS MORNING...MAINLY DEALING WITH PCPN TYPE. THE COLDEST AIR DOES NOT ARRIVE UNTIL MONDAY WITH A SECONDARY COLD FRONT. UNTIL THEN THE BULK OF THE PCPN WILL REMAIN RAIN. WILL MAINTAIN WIND HEADLINES AS IS...ALTHOUGH WITH THE FRONT MOVING IN A BIT SLOWER IT APPEARS THE STRONGEST WINDS WILL NOT ARRIVE UNTIL AFTERNOON. HAVE TRIMMED BACK A LITTLE ON THE SPEEDS TOO...AS INLAND AREAS SHOULD OCCASIONALLY SEE AFTERNOON GUSTS AROUND 45 MPH...AND AROUND 50 MPH ALONG THE LAKE SHORE. A BAND OF LIGHT SHOWERS WERE LIFTING THROUGH THE CWA THIS MORNING WITH THE FIRST COLD FRONT. THERE WAS SOME SURFACE BASED INSTABILITY...SO WILL MAINTAIN THE MENTION OF THUNDER. WE MAY SEE A QUICK BURST OF LAKE EFFECT RAIN SHOWERS BEHIND THE FRONT. THEN SOMEWHAT DRIER AIR WILL MOVE INTO THE REGION SOUTH OF I96 WHERE SOME AFTERNOON SUNSHINE WILL BE POSSIBLE. HOWEVER...TO THE NORTH THE STRONGER SECONDARY FRONT WILL BE APPROACHING AND RAIN SHOWERS WILL INCREASE BY LATE DAY ACROSS CENTRAL LOWER. A CORE OF COLDER H8 TEMPS THAT WAS NEAR LAKE WINNIPEG THIS MORNING WILL PIVOT SOUTHEAST AHEAD OF THE SECOND FRONT AND SHOULD CLIP SOUTHERN LOWER. THIS WILL RESULT IN THE SOUTH SEEING A BETTER CHANCE OF A RAIN/SNOW MIX TONIGHT THEN THE NORTHERN CWA. ALL IN ALL...FEEL HIGHLY CONFIDENT THAT THERE WILL BE A FAIRLY SOLID BAND OF SHOWERS WITH THIS FRONT AND WILL CARRY HIGH POPS FOR LATE TONIGHT ACROSS THE CWA. THE REAL COLD AIR ARRIVES BEHIND THE SECOND FRONT ON MONDAY AND HOLDS OVER LOWER MICHIGAN INTO TUESDAY. ALL AREAS WILL SEE ANY RAIN CHANGE OVER TO SNOW FROM WEST TO EAST THROUGH THE DAY ON MONDAY. THE LAKE EFFECT SHOULD ALSO BE GOING STRONG THROUGH THIS PERIOD AS WE MAINTAIN CYCLONIC FLOW...H8 TEMPS OF -8 TO -10C AND DEEP MOISTURE. RIGHT NOW THE THINKING IS THAT MOST AREAS WILL SEE AT LEAST A LIGHT DUSTING OF SNOW THROUGH THIS PERIOD...WITH LOCALIZED 2-3 INCHES POSSIBLE IF A PERSISTENT LAKE EFFECT BAND IS ESTABLISHED. OVERALL NOTHING TOO SEVERE...BUT A TASTE OF WINTER FOR SURE. && .LONG TERM...(425 AM EDT SUN OCT 26 2008) (TUESDAY NIGHT THROUGH SATURDAY) SFC RIDGING BUILDING IN AT THE BEGINNING OF THE PERIOD ALONG WITH HEIGHT RISES AS UPPER TROUGH MOVES EAST. THIS WILL MEAN FAIR WEATHER WITH MODERATING TEMPERATURES FOR WEDNESDAY THROUGH FRIDAY. THE ONLY POTENTIAL FORECAST ISSUE IS THE TIMING OF A SHORTWAVE TROUGH AND COLD FROPA AND THE RESULTING PRECIPITATION CHANCES TOWARDS THE END OF THE PERIOD. THE 00Z ECMWF IS ABOUT 24 HOURS SLOWER THAN THE 00Z GFS WITH THE FROPA. POPS MAY BE NEEDED FOR EITHER FRIDAY OR SATURDAY DEPENDING ON WHICH MODEL VERIFIES. LEFT THINGS DRY FOR NOW PENDING BETTER MODEL AGREEMENT. && .MARINE...(425 AM EDT SUN OCT 26 2008) A GALE WARNING WILL BE CONTINUED TODAY INTO THE FIRST HALF OF MONDAY. WIND FIELDS LOOK SLIGHTLY LESS...THEREFORE WILL CALL FOR 40 KNOT GALES. WAVES WILL EXCEED 10 FEET AT TIMES. && .AVIATION...(725 AM EDT SUN OCT 26 2008) EXPECT SOME SCATTERED RAIN SHOWERS TODAY WITH CEILINGS OCCASIONALLY FALLING TO 2500 FEET AS THE RAIN SHOWERS MOVES THROUGH. CONDITIONS WILL GET WORSE TONIGHT AS COLDER AIR WILL GENERATE LAKE EFFECT RAIN SHOWERS WITH CEILINGS FALLING TO 1500 TO 2000 FEET AND ENOUGH LOW LEVEL MOISTURE TO RESTRICT VISIBILITY TO 5 OR 6 MILES. && .HYDROLOGY...(425 AM EDT SUN OCT 26 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...WIND ADVISORY TODAY...ENTIRE CWA. LM...GALE WARNING IN EFFECT ST. JOE TO MANISTEE TODAY THROUGH MONDAY AFTERNOON. && $$ SYNOPSIS: JK SHORT TERM: JK LONG TERM: OSTUNO MARINE: JK AVIATION: OSTUNO HYDROLOGY: JK
