FXUS63 KAPX 091953 AFDAPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 352 PM EDT SAT MAY 9 2009 .SYNOPSIS.../ISSUED AT 158 PM/ HIGH PRESSURE ACROSS THE NORTHERN THIRD OF THE COUNTRY...WILL BUILD INTO THE STATE TONIGHT. THIS AREA OF HIGH PRESSURE...WILL GENERATE DRY AND COOL CONDITIONS...OVER NORTHERN MICHIGAN SUNDAY THROUGH MONDAY. WARMER WEATHER WILL RETURN TUESDAY THROUGH THURSDAY...AS WINDS TURN SOUTHERLY...IN ADVANCE OF A STORM SYSTEM DEVELOPING OVER THE UPPER MIDWEST. MSB && .SHORT TERM.../ISSUED AT 352 PM/...TONIGHT COMPACT LOW PRESSURE SYSTEM CONTINUES TO EXIT TO THE EAST WITH INCREASING NORTHERLY FLOW DRAGGING COOL AIR INTO THE STATE AND LEAVING A SUBSTANTIAL AMOUNT OF CLOUD COVER ACROSS THE FORECAST AREA. SOME CLEARING HAS DEVELOPED ACROSS EASTERN UPPER MICHIGAN AND DOWN INTO THE TIP OF THE MITT COUNTIES. UPSTREAM HOWEVER...A COUPLE SMALLER SCALE CIRCULATIONS NOTED ON WATER VAPOR/VISIBLE SATELLITE IMAGERY DROPPING DOWN ACROSS LAKE SUPERIOR BEGINNING TO PUSH ALONG ANOTHER LARGE AREA OF SYNOPTIC AND DIRUNAL CLOUD COVER (AND A FEW SPRINKLES ON KAPX RADAR) INTO THE FORECAST AREA. TONIGHT...BIGGEST FORECAST CHALLENGE IS CLOUD COVER. PER SATELLITE TRENDS...APPEARS ANOTHER ROUND OF UPSTREAM CLOUD COVER WILL SPREAD INTO THE REGION THIS EVENING...FILLING IN WHATEVER HOLES WE DO MANAGE TO GET LATE THIS AFTERNOON. IN ADDITION...POCKET OF FAIRLY COOL AIR (H8 TEMPS -4C TO -6C) ACROSS WESTERN UPPER MICHIGAN (NOTE WEAK LAKE INDUCED PRECIP STREAMERS EARLIER IN THE DAY IN THE WESTERN U.P.) FORECAST TO SLIP INTO NRN LAKE MICHIGAN LATER THIS EVENING AND OVERNIGHT. ENOUGH LAKE INSTABILITY FOR POSSIBLE LAKE CLOUD CONTRIBUTIONS IN ADDITION TO THE SYNOPTIC CLOUD COVER. SO...PLAN TO KEEP MAINLY CLOUDY SKIES GOING FOR MOST AREAS TONIGHT. EVEN WITH THE CLOUDS HOWEVER...COLD ADVECTION REGIME SHOULD PUSH NIGHTTIME TEMPS HANDILY INTO THE LOWER 30S FOR MOST AREAS. ADAM && .LONG TERM.../ISSUED AT 352 PM/...SUNDAY AND BEYOND SUNDAY THROUGH NEXT SATURDAY...UNSEASONABLY COOL NORTHWEST FLOW ALOFT WILL SLOWLY MODIFY SUNDAY INTO EARLY NEXT WEEK. ANOTHER LESS AMPLIFIED TROUGH THEN APPEARS LIKE IT WILL DIG IN LATE NEXT WEEK. OVERALL...TEMPERATURES APPEAR LIKE THEY WILL BE BELOW AVERAGE OVER THE NEXT SEVERAL DAYS FOR THE MOST PART. THE MAIN LONG TERM FORECAST CONCERNS REVOLVE AROUND DAILY TEMPERATURES AND THE POTENTIAL FOR FROST FOR SUNDAY AND MONDAY NIGHTS. SUNDAY...WEAK SURFACE RIDGING WITH TIME BUT A CONTINUED TROUGH IN PLACE ALOFT. MODEL SOUNDINGS/CROSS SECTIONS INDICATE LOW/MID LEVELS SLOWLY DRY OUT (MEAN 1000-500 MB RH FALLS FROM 80-90 PERCENT AT 12Z TO ABOUT 50 PERCENT AT 00Z). SO EXPECT MOSTLY CLOUDY CONDITIONS TO START WITH CLOUDS EVENTUALLY SCATTERING OUT IN THE AFTERNOON. STILL CHILLY WITH HIGHS ONLY RANGING FROM THE UPPER 40S TO MIDDLE 50S. SUNDAY NIGHT...WEAK SURFACE RIDGE CONTINUES TO BUILD INTO THE REGION LEADING TO MOSTLY CLEAR SKIES AND LIGHT WINDS. THIS EXCELLENT RADIATIONAL COOLING SETUP WILL LIKELY LEAD TO AREAS OF FROST FORMATION. LOWS IN THE UPPER 20S AND LOWER 30S. MONDAY AND TUESDAY...SLOWLY BUILDING HEIGHTS ALOFT AS A LOW AMPLITUDE RIDGE BUILDS IN FROM THE WEST. THIS SHOULD CONTINUE THE STRETCH OF DRY WEATHER WITH TEMPERATURES SLOWLY REBOUNDING (BUT STILL BELOW NORMAL). HIGHS MAINLY IN THE 50S MONDAY AND THE UPPER 50S AND LOWER 60S TUESDAY. THERE WILL PROBABLY BE SOME MORE AREAS OF FROST MONDAY NIGHT. WEDNESDAY...LOW PRESSURE MOVES INTO CENTRAL CANADA AND DRAGS A COLD FRONT ACROSS THE AREA WEDNESDAY NIGHT. THIS WILL LIKELY BRING A DECENT CHANCE OF SHOWERS. HIGHS IN THE 60S. THURSDAY THROUGH SATURDAY...ANOTHER TROUGH ALOFT MOVES IN FOR THURSDAY AND FRIDAY LEADING TO COOLER TEMPERATURES. HIGHS IN THE 50S TO LOWER 60S. LOW PRESSURE IN THE PLAINS FRIDAY LOOKS TO TRACK TO OUR WEST OVER THE WEEKEND BRINGING ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY (MODEL TIMING OF FRONTS THIS FAR OUT IS OF COURSE SUBJECT TO CHANGE AND COULD SEE IT BEING DELAYED TOWARD THE END OF THE WEEKEND INSTEAD). SULLIVAN && .MARINE.../ISSUED AT 352 PM/ GUSTY NORTH TO NORTHWEST WINDS WILL CONTINUE TO PRODUCE SMALL CRAFT WINDS AND WAVES ON THE NEARSHORE AREAS THIS EVENING...BEFORE SUBSIDING OVERNIGHT. WINDS WILL BE NEAR THE SMALL CRAFT ADVISORY THRESHOLD SUNDAY. LATER SHIFTS MAY HAVE TO HOIST AN ADVISORY. WINDS WILL THEN DIMINISH SUNDAY NIGHT THROUGH THE REST OF THE FORECAST AS A WEAK AREA OF HIGH PRESSURE BUILDS IN FROM THE WEST. && .AVIATION.../ISSUED AT 158 PM/...VALID FOR 18Z TAFS RAINFALL HAS ENDED AT ALL THREE TAF SITES AND EXPECT CIGS TO SLOWLY INCREASE TO MVFR THROUGH THE AFTERNOON. PLN WILL BE THE EXCEPTION WHERE SKIES ARE LOOKING TO SCATTERED OUT FOR A TIME. TONIGHT... POCKET OF COOLER AIR WILL DESCEND INTO NRN LOWER MICHIGAN... POTENTIALLY COOL ENOUGH TO GENERATE SOME MVFR LAKE CLOUDS OFF LAKE MICHIGAN IMPACTING PLN/TVC. BUT HIGH PRESSURE AND DRIER AIR BUILDING INTO THE REGION IS EXPECTED TO PRODUCE VFR CONDITIONS ON SUNDAY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LMZ323-341- 342-344>346. LH...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LHZ345>349. LS...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LSZ321-322. && $$