000 FXUS63 KAPX 261509 AFDAPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1109 AM EDT THU MAR 26 2009 .SYNOPSIS.../ISSUED AT 444 AM/ WEAK HIGH PRESSURE BUILT OVER THE GREAT LAKES REGION OVERNIGHT WHILE A STORM SYSTEM MOVED WEST OF LAKE SUPERIOR INTO JAMES BAY ONTARIO. THE AREA OF LOW CLOUDS ACROSS NORTHERN MICHIGAN THIS MORNING...WILL GRADUALLY BREAK UP THIS AFTERNOON AS HIGH PRESSURE CONTINUES TO BUILD OVER THE GREAT LAKES. HIGH PRESSURE OVER THE UPPER MIDWEST AND GREAT LAKES...WILL BECOME CENTERED JUST NORTH OF LAKE SUPERIOR FRIDAY...KEEPING DRY CONDITIONS OVER NORTHERN MICHIGAN THROUGH FRIDAY NIGHT. HOWEVER A DEVELOPING STORM SYSTEM OVER THE SOUTHERN PLAINS...WILL BEGIN TO PUSH TOWARD THE GREAT LAKES THIS WEEKEND. THIS STORM SYSTEM WILL GENERATE A ROUND OF MIXED RAIN/SNOW SATURDAY WITH SNOW SHOWERS SUNDAY. TEMPERATURES WILL BE RUNNING A FEW DEGREES ABOVE NORMAL TODAY AND FRIDAY...THEN RUNNING BELOW NORMAL THIS WEEKEND. SWR && .SHORT TERM.../ISSUED AT 1109 AM/...THIS AFTERNOON CURRENT FCST LOOKS GREAT...WITH ONLY SOME MINOR TWEAKS MADE TO CLOUD COVER TRENDS/TIMING AND TEMP RESPONSE WITH CLOUDS BREAKING A BIT FASTER ACRS THE SOUTH. STILL APPEARS AFTN MIXING SHOULD DO ITS THING AND ERODE PESKY LOW STRATUS DECK (ALREADY UNDERWAY PER LATEST SATELLITE PICS)...WITH THE EXCEPTION OF EASTERN UPR WHERE LOW CLOUD MAY WELL TAKE INTO THE LATE AFTN TO BREAK GIVEN WEAK PERSISTENT LOW LEVEL CONVERGENCE WITH DIFFUSE BOUNDARY LAID OUT NEAR THE ST MARYS RIVER. OTHERWISE...NUDGED AFTN HIGHS UP JUST A TOUCH FAR SOUTH GIVEN EXPECTED BETTER SUNSHINE. LAWRENCE PREVIOUS DISCUSSION BELOW: LONG WAVE TROUGH PATTERN CONTINUES TO DEVELOP ACROSS THE CONUS WITH THE MAIN CIRCULATION ALONG THE U.S./CENTRAL CANADIAN BORDER...AND A MYRIAD OF EMBEDDED WAVES TRAVERSING THE COUNTRY. ONE WAVE MOVING NORTHEASTWARD THROUGH THE MID MISSISSIPPI RIVER VALLEY PUSHING THICKER MID-HIGH CLOUD COVER INTO LOWER MICHIGAN AS WELL AS PRODUCING SOME SOME SHOWER ACTIVITY ACROSS THE MIDWEST. ANOTHER MORE POTENT WAVE NOW DIVING SE THROUGH THE ROCKIES WHICH MAY ULTIMATELY EVOLVE INTO A WINTRY MESS FOR THE GREAT LAKES THIS WEEKEND (MORE BELOW). ACROSS THE GREAT LAKES...SUBSTANTIAL LOW CLOUD COVER SPANS THE NRN PLAINS INTO NRN MICHIGAN CURRENTLY. SFC LOW PRESSURE (PART OF THE PARENT TROUGH OVER NOAM) REMAINS SITUATED OVER SW ONTARIO WITH A COLD FRONT STRETCHING THROUGH MINNESOTA INTO NEBRASKA WHILE SPOTTY PRECIP CAN BE FOUND FROM THE CENTRAL AND NRN PLAINS BACK INTO THE ROCKIES. IN ALL...A CONVOLUTED WEATHER PATTERN SHAPING UP FOR NRN MICHIGAN OVER THE NEXT COUPLE DAYS...WITH FORECAST ISSUES ALONG THE LINES OF NUISANCE CLOUD COVER...A DIFFUSE FRONT/COLDER AIR SLIPPING THROUGH THE REGION AND LOW END PRECIP CHANCES. BIGGER ISSUES ARRIVE THIS WEEKEND HOWEVER AS A POTENT EARLY SPRING STORM SYSTEM LOOKING TO TAKE AIM ON THE GREAT LAKES. TODAY...MID LEVEL SHORT WAVE WILL MOVE FROM THE MID MISSISSIPPI RIVER VALLEY UP THROUGH LOWER MICHIGAN BY EVENING. NOT A GREAT DEAL OF FORCING WITH THIS WAVE AND OVERALL AVAILABLE MOISTURE IS LACKING. SO...NOT ANTICIPATING ANY PRECIP WITH THIS SYSTEM WITH THE MAIN IMPACT BRINGING THICKER MID AN HIGH CLOUD COVER UP THROUGH THE REGION. DAYTIME HEATING AND AN OVERALL LOW LEVEL DRYING TREND MAY EVENTUALLY MIX OUT THE LOW STUFF BUT ONLY TO BE REPLACED BY THICKER MID AND HIGH CLOUD COVER. SO WILL KEEP THINGS ON THE MOSTLY CLOUDY SIDE. ADAM && .LONG TERM.../ISSUED AT 444 AM/...TONIGHT AND BEYOND TONIGHT THROUGH FRIDAY...STACKED LOW OVER ONTARIO SLATED TO SLIP EASTWARD TONIGHT DRAGGING DIFFUSE SFC COLD FRONT THROUGH NRN MICHIGAN BY FRIDAY MORNING. AGAIN...NOT MUCH TO THIS SYSTEM FROM A MOISTURE/FORCING STANDPOINT. BUT WEAKISH LOW LEVEL CONVERGENCE COUPLED WITH INCREASING OVER LAKE INSTABILITY OVER SUPERIOR AND MICHIGAN (H8 TEMPS COOLING TO -10C TO -12C) ENOUGH TO WARRANT CHANCY POPS FOR SNOW SHOWERS AND FLURRIES FOR EASTERN UPPER MICHIGAN OVERNIGHT...DOWN INTO NW LOWER MICHIGAN FRIDAY MORNING. NOT A BIG DEAL...BUT HIGH TEMPS FRIDAY WILL DROP BACK OFF A BIT COOLER THAN WHAT WE/VE SEEN THE LAST FEW DAYS FOLLOWED UP BY A FAIRLY COOL NIGHT FRIDAY NIGHT. SATURDAY THROUGH SUNDAY...AFOREMENTIONED SHORT WAVE DIVING THROUGH THE ROCKIES TODAY FORECAST TO MOVE THROUGH THE SRN PLAINS BEFORE ROUNDING THE CORNER SATURDAY AND LIFTING INTO THE OHIO VALLEY... POSSIBLY PHASING WITH NRN STREAM ENERGY OVER THE GREAT LAKES. STRONG SFC LOW EXPECTED TO SPIN UP OVER THE GULF STATES AIDED BY A WIDE OPEN GULF AND COUPLED JET STRUCTURE DEVELOPMENT ALONG THE EASTERN EDGE OF THE LONG WAVE TROUGH...THEN LIFT INTO THE REGION LATER SATURDAY INTO SUNDAY. SOME SIGNIFICANT MODEL DIFFERENCES TO NOTE...WITH THE GFS SOLUTION FASTER AND FURTHER NORTH/WEST WITH THE SYSTEM TRACK AS COMPARED TO A SLOWER NAM/ECMWF SOLUTION. BUT GIVEN THE TENDENCY FOR DEEPENING/PHASING/NEGATIVELY TILTED STORM SYSTEMS TO TRACK FURTHER NORTH/WEST THAN GUIDANCE DEPICTS A FEW DAYS OUT...TEND TO BUY MORE INTO THE GFS IDEA WHICH DEVELOPS A SWATH OF HEAVIER (F-GEN DRIVEN) PRECIP INTO THE GREAT LAKES AS EARLY AS SATURDAY AFTERNOON BUT ALSO DRAWS WARMER AIR INTO THE REGION LEADING TO BIGGER P-TYPE ISSUES WITH MAINLY RAIN OR A RAIN/SNOW MIX ACROSS NRN LOWER MICHIGAN. STILL SOME TIME TO SORT THROUGH THE DETAILS. IN ANY EVENT...SHAPING UP TO BE A BIG MESS DURING THE WEEKEND WITH SEVERAL INCHES OF SNOW A POSSIBILITY FOR A PORTION OF THE CWA. WINTER WEATHER HEADLINES A DISTINCT POSSIBILITY BUT STILL TOO EARLY WITH TOO MUCH UNCERTAINTY TO PUT ANYTHING UP. ADAM && .AVIATION.../ISSUED AT 617 AM/...VALID FOR 12Z TAFS MVFR CIGS WILL PERSIST AT THE TERMINAL SITES THROUGH MID MORNING. HOWEVER...DAYTIME HEATING COMBINED WITH LOW LEVEL DRYING SHOULD ERODE/MIX OUT THE MVFR CIGS BETWEEN 15Z AND 18Z LEAVING SCT-BKN MID AND HIGH CLOUD FOR THE DURATION OF THE DAY THROUGH A GOOD PORTION OF TONIGHT. DIFFUSE COLD FRONT EXPECTED TO SLIP THROUGH NRN MICHIGAN LATE TONIGHT INTO FRIDAY WITH COOLER AIR THEN SLIDING INTO THE REGION. THIS WILL RESULT IN ANOTHER ROUND OF LOW CLOUD DEVELOPMENT BEHIND THE FRONT TOWARD FRIDAY MORNING...WITH A FEW FLURRIES OFF LAKE MICHIGAN POSSIBLE AT PLN. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... NONE. && $$