FXUS63 KMQT 201137 AAA AFDMQT AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 737 AM EDT SAT SEP 20 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .DISCUSSION... ISSUED AT 420 AM EDT SHOWERS HAVE DEVELOPED AHEAD OF THE FRONTAL SYSTEM MOVING THROUGH THE AREA. THESE SHOWERS ARE LIKELY DUE TO INCREASED FRONTAL CONVERGENCE AS A WAVE DEVELOPED ALONG THE LOW OVER LAKE SUPERIOR EARLY THIS MORNING. ALTHOUGH THIS PCPN WILL BE CONFINED TO THE EARLY MORNING HOURS...THE FORECAST WILL NEED TO KEEP SMALL CHANCE POPS IN EARLY TO ACCT FOR THE LEFTOVER PCPN. OTHERWISE...THE COLD FRONT WILL MOVE THROUGH THE REMAINDER OF THE AREA THIS MORNING. STRONG HIGH PRESSURE BEHIND THE FRONT WILL MOVE ACROSS THE UPPER LAKES TODAY. NORTH-NORTHEAST WINDS BEHIND THE FRONT WILL ALLOW FOR A SIGNIFICANT COOLDOWN FROM FRIDAY WITH CALENDAR DAY HIGH TEMPERATURES LIKELY ALREADY OCCURRING AT MOST LOCATIONS. THE HIGH WILL QUICKLY BUILD ACROSS LAKE SUPERIOR THIS AFTERNOON...THEN MOVE EAST OF THE REGION TONIGHT. UPSLOPE FLOW INITIALLY THIS MORNING INTO EARLY THIS AFTERNOON WILL KEEP CLOUD COVER ACROSS MUCH OF NORTH CENTRAL UPPER MICHIGAN DESPITE THE STRONG SUBSIDENCE AND DRY AIR ASSOCIATED WITH THE HIGH. IN FACT...THE CLOUD COVER AND THE STRONG COLD ADVECTION MAY ALLOW TEMPS TO REMAIN NEARLY STEADY FOR MUCH OF THE DAY. HOWEVER...AS THE HIGH BUILDS ACROSS THE AREA LATER TODAY...THE UPSLOPE FLOW WILL DIMINISH AND THE CLOUDS SHOULD ALSO DECREASE. WITH THE COLD TEMPS ALOFT...WILL LIKELY KEEP STRATOCUMULUS ALL DAY ACROSS THE AREA HOWEVER THESE SHOULD DISSIPATE SOON AFTER DARK. ONCE TEMPS SETTLE DOWN THIS MORNING...THEY SHOULD REMAIN IN THE UPPER 50S NORTH AND MIDDLE 60S SOUTH. MENOMINEE MAY STILL REACH 70 IF THAT AREA CAN SEE SOME SUNSHINE THIS MORNING. MAIN CONCERN REVOLVES THE POTENTIAL FOR FREEZING TEMPS TONIGHT. TRICKY FORECAST FOR FREEZING TEMPS AS THE MODELS ARE IN EXCELLENT AGREEMENT IN SHOWING THE CENTER OF THE HIGH JUST PASSING EAST OF THE REGION BY SUNDAY MORNING. MEANWHILE...UPPER HEIGHTS BUILD ACROSS THE WESTERN U.P. AND THERE IS A HINT OF WARM ADVECTION LATE ACROSS THE FAR WEST. IN FACT...STATISTICAL GUIDANCE SUGGESTS SOME CLOUDS WITH THE WARM ADVECTION LATE TONIGHT...ALTHOUGH THIS DOES NOT SEEM LIKELY GIVEN THE DRY AIRMASS ASSOCIATED WITH THE HIGH. ALL OF THIS WOULD POINT TO A FREEZE BEING UNLIKELY. HOWEVER...OBJECTIVE AND STATISTICAL GUIDANCE POINT TO DEW POINTS DROPPING INTO THE UPPER 20S-LOWER 30S ACROSS INLAND WEST CENTRAL UPPER MICHIGAN TONIGHT. THIS DRY AIR COMBINED WITH LIGHT WINDS SHOULD ALLOW FOR FREEZING TEMPS IN THE NORMALLY COLDER LOCATIONS IN BARAGA/SRN HOUGHTON AND IRON COUNTIES. WITH THIS IN MIND...WILL UPGRADE THE FREEZE WATCH TO A FREEZE WARNING WITH THIS ISSUANCE FOR THOSE AREAS. DO NOT EXPECT A HARD FREEZE AT THIS TIME...BUT IT SEEMS REASONABLE FOR SOME LOCATIONS IN THE WARNED AREA TO GET AS LOW AS 30F TONIGHT. AS FOR SURROUNDING COUNTIES...IT LOOKS LIKE THESE AREAS WILL STAY SLIGHTLY WARMER BUT A FROST ADVISORY WILL BE ORDER. MARQUETTE COUNTY WILL STAY WARMER SIMPLY DUE TO THE LAKE INFLUENCE AND GOGEBIC/ONTONAGON WILL STAY WARMER DUE TO THE STRONG WARM ADVECTION AND HIGH RISES. MARKED WARM ADVECTION WILL OCCUR ACROSS THE ENTIRE REGION ON SUNDAY ALTHOUGH THE 850MB RIDGE AXIS WILL STILL BE SW OF THE AREA. ALTHOUGH UPPER MICHIGAN WILL LIKELY STAY DRY ON SUNDAY DUE TO THE DRY AIRMASS...IT WOULD NOT BE SURPRISING IF A SHOWER WOULD POP UP SUNDAY DUE TO THE STRONG WARM ADVECTION. OF EVEN GREATER INTEREST IS THE DEFORMATION AREA MOVING OUT OF MANITOBA AND INTO ONTARIO/NORTHERN LAKE SUPERIOR SUNDAY NIGHT. THIS DEFORMATION AREA WILL ACT ON THE ALREADY TIGHT TEMPERATURE GRADIENT ACROSS THE LAKE LATE SUNDAY NIGHT AND ALLOW FOR A VERY NARROW BUT INTENSE AREA OF FRONTOGENESIS TO DEVELOP. THIS IN TURN WILL LIKELY CAUSE A BAND OF SHOWERS TO MOVE NW-SE ACROSS FAR EASTERN LAKE SUPERIOR. THE NAM AND GFS SUGGEST THAT THIS AREA WILL STAY OVER THE LAKE AND INTO ONTARIO...ALTHOUGH THIS WILL HAVE TO BE WATCHED GIVEN THAT EASTERN UPPER MICHIGAN WILL BE ON THE WARM SIDE OF THE FRONTOGENETICAL CIRCULATION. FOR NOW...WILL JUST BRING IN SLIGHT CHANCE POPS INTO THE LAKE SUNDAY NIGHT. QUIET WEATHER MONDAY...WITH MODELS SPEEDING UP THE SYSTEM ON TUESDAY NIGHT. WILL BRING SOME SHOWER CHANCES INTO THE FAR WEST TUE AFTN AND SPREAD ACROSS THE ENTIRE REGION BY WEDNESDAY. AFTER THE WEEKEND...TEMPERATURES WILL RISE ABOVE NORMAL ONCE AGAIN FOR MOST OF THE WEEK. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... IN THE WAKE OF A COLD FRONT THAT HAS MOVED S OF KCMX/KSAW...AIRMASS IS NOT PARTICULARLY MOIST PER 00Z CYPL/KINL SOUNDINGS AND SFC OBS. SO...EXPECT A BKN STRATOCU DECK/MVFR CONDITIONS TO DEVELOP ONLY AT KSAW WHERE N WINDS ARE MORE DIRECTLY UPSLOPING AS MUCH COOLER AIR ARRIVES ON THE HEELS OF GUSTY WINDS. DIURNAL HEATING WILL SCT OUT THE MVFR DECK AT KSAW IN THE AFTN. VFR CONDITIONS WILL PREVAIL THEREAFTER. AT KCMX...EXPECT VFR CONDITIONS THRU THIS FCST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A PERIOD OF 20-30KT N TO NE WINDS EXPECTED THIS MORNING AS PRES RISE MAX DROPS SE ACROSS LAKE SUPERIOR BEHIND COLD FRONT USHERING IN SHALLOW COLD AIRMASS. FOR A FEW HRS EARLY THIS MORNING...MAY SEE A FEW GUSTS TO 35 KT. OTHERWISE...HIGH PRES OVER NRN MANITOBA WILL NOSE SE TO LAKE SUPERIOR LATE THIS AFTN... CAUSING WINDS TO DIMINISH TO UNDER 20 KT BY EVENING. OUTSIDE OF LOCAL EFFECTS...A LIGHT WIND REGIME GENERALLY IN THE SUSTAINED 10-15KT RANGE IS EXPECTED TONIGHT/SUN AS HIGH PRES PASSES JUST N AND E OF LAKE SUPERIOR. SE TO S WINDS WILL BEGIN TO PICK UP SUN NIGHT/MON AS THE HIGH SLIPS TO THE E. A COLD FRONT MOVING E ACROSS THE PLAINS WILL LIKELY BRING ANOTHER PERIOD OF SRLY 20-30KT WINDS FOR TUE INTO PART OF WED OVER THE E HALF OF LAKE SUPERIOR WHICH IS FAVORED FOR STRONGER WINDS THAN THE W HALF IN SRLY FLOW. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FREEZE WARNING FROM 2 AM EDT /1 AM CDT/ TO 9 AM EDT /8 AM CDT/ SUNDAY FOR MIZ004-010-084. FROST ADVISORY FROM 2 AM EDT /1 AM CDT/ TO 9 AM EDT /8 AM CDT/ SUNDAY FOR MIZ002-005-009-011. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ DISCUSSION...MRD AVIATION...ROLFSON MARINE...ROLFSON