FXUS63 KAPX 241126
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
626 AM EST THU DEC 24 2009
.SYNOPSIS.../ISSUED AT 434 AM/
HIGH PRESSURE WILL LIFT OUT OF THE NORTH WOODS TODAY WHILE A STORM
SYSTEM STRENGTHENS IN THE MISSISSIPPI VALLEY. CLOUDS WILL THICKEN
OVER THE ENTIRE REGION...WHILE A LIGHT WINTRY MIX OF PRECIPITATION
WORKS INTO THE GRAND TRAVERSE BAY REGION TONIGHT. THIS WINTRY MIX
SPREADS OVER ALL OF NORTHERN MICHIGAN ON CHRISTMAS DAY...BEFORE
CHANGING TO PERIODS OF LIGHT SNOW...DRIZZLE AND FREEZING DRIZZLE
CHRISTMAS NIGHT.
ADDITIONAL SNOWS ARE POSSIBLE SATURDAY NIGHT AND INTO EARLY NEXT
WORK WEEK...AS THE LAKE EFFECT MACHINE WILL AT LEAST TRY AND GET
STARTED AGAIN.
SMD
&&
.SHORT TERM.../ISSUED AT 434 AM/...TODAY
ON THE LATEST SURFACE WEATHER MAP...1038 MB HIGH PRESSURE WAS
CENTERED OVER NORTHERN ONTARIO WITH 998 MB LOW PRESSURE OVER EAST
TEXAS. SATELLITE PRODUCTS AND SURFACE OBSERVATIONS INDICATE THAT LOW
CLOUDS ENSHROUD ALL OF NORTHERN LOWER WITH JUST HIGH CLOUDINESS
ACROSS EASTERN UPPER. APX AND SURROUNDING RADARS CONTINUE TO SHOW
LOTS OF MID AND UPPER LEVEL RETURNS MOVING INTO SOUTHWESTERN PORTION
OF THE FORECAST AREA (THIS IS NOT REACHING THE GROUND). THE MAIN
SHORT TERM FORECAST CONCERN REVOLVES AROUND POPS AND THE FORM OF
PRECIPITATION (IF ANY) TODAY.
THE WELL ADVERTISED WINTER STORM SYSTEM GATHERING STRENGTH ACROSS
EAST TEXAS EARLY THIS MORNING WILL TRACK NORTHEASTWARD INTO THE
LOWER MISSISSIPPI VALLEY TODAY. AN INITIAL ISENTROPICALLY DRIVEN
(I285-295) BAND OF MOISTURE WILL CONTINUE TO SURGE INTO SOUTHWESTERN
FORECAST AREA...ESPECIALLY EARLY THIS MORNING. HOWEVER...ABUNDANT
DRY AIR AT LOW LEVELS WILL MAKE IT TOUGH TO ACTUALLY GET
PRECIPITATION DOWN TO THE SURFACE. BEST CHANCE IS ACROSS SOUTHWEST
ZONES. MODEL SOUNDINGS/CROSS SECTIONS APPEAR COLD ENOUGH FOR THE
FORM OF PRECIPITATION TO BE LIGHT SNOW OR FLURRIES THIS MORNING.
OTHERWISE...LOW LEVEL WARM NOSE WORKS ITS WAY INTO THE REGION
LATER TODAY LEADING TO PRECIPITATION TYPE ISSUES.
THEREFORE...THERE COULD BE A MIXTURE OF LIGHT SNOW AND FREEZING
RAIN ACROSS SOUTHWEST ZONES LATER THIS AFTERNOON. ELSEWHERE IT
WILL BE CLOUDY WITH HIGHS GENERALLY IN THE UPPER 20S AND LOWER
30S.
SULLIVAN
&&
.LONG TERM.../ISSUED AT 434 AM/...TONIGHT AND BEYOND
THE STORM SYSTEM ACROSS EAST TEXAS THIS MORNING WILL TRACK INTO
THE CENTRAL PLAINS CHRISTMAS DAY...THEN STALL OUT AND SLOWLY
WEAKEN WHILE INCHING ACROSS THE LOWER GREAT LAKES REGION OVER THE
WEEKEND. IMPLICATIONS OF ALL THIS IS STILL EXPECTED TO BE A
POTPOURRI OF PRECIPITATION TYPES ACROSS NORTHERN MICHIGAN BY LATER
TONIGHT INTO CHRISTMAS DAY BEFORE COLDER AIR WRAPS INTO THE SYSTEM
LEADING TO MAINLY LIGHT SNOW FOR THE WEEKEND. THE MAIN FORECAST
CONCERNS CONTINUE TO REVOLVE AROUND THE DETAILS OF THE PLAINS
STORM SYSTEM...PRECIPITATION TYPE AND TIMING AS WELL AS HEADLINE
MANAGEMENT.
SHORT TO MEDIUM RANGE MODELS HAVE COME INTO GOOD AGREEMENT WITH THE
EXCEPTION OF THE GFS WHICH APPEARS TO BE MOISTENING UP THE COLUMN A
BIT TOO QUICKLY.
TONIGHT INTO FRIDAY (CHRISTMAS DAY)...MOISTURE WILL CONTINUE TO BE
TRANSPORTED NORTHEASTWARD INTO NORTHERN MICHIGAN DURING THIS TIME.
INITIAL BONE DRY AIR MASS (PWAT OF 0.13 ON APX 24/00Z SOUNDING) WILL
HAVE TO BE OVERCOME BEFORE PRECIPITATION REACHES THE
SURFACE...ESPECIALLY ACROSS CENTRAL AND NORTHERN ZONES. IN
ADDITION...WARM NOSE IS SHOWN TO BE FIRMLY IN PLACE TONIGHT BEFORE
EVAPORATIVE COOLING TRIES TO WHITTLE AWAY THE WARM AIR LATE
TONIGHT INTO CHRISTMAS DAY. ALL THE WHILE...SURFACE TEMPERATURES
HOVER NEAR THE FREEZING MARK. OVERALL HAVE KEPT THE THEME OF THE
FORECAST IN TACT. DID TWEAK TIMING...SLOWER IN LINE WITH THE
NAM/ECMWF/GEM/UKMET VERSUS THE GFS. SO EXPECT A MIXTURE OF
FREEZING RAIN AND SNOW TO OVERSPREAD AT LEAST THE SOUTHWEST
FORECAST AREA BY DAYBREAK WITH A CHANCE POPS ACROSS CENTRAL
COUNTIES AND REMAINING DRY NORTHEAST. NO HEADLINES FORTHCOMING BUT
DAYSHIFT WILL HAVE TO CONSIDER A WINTER WEATHER ADVISORY FOR
TONIGHT FOR THE MIXED PRECIPITATION. THE PRECIPITATION SHOULD THEN
SPREAD ACROSS THE REMAINDER OF THE FORECAST AREA FRIDAY MORNING
AND CONTINUE THROUGH THE AFTERNOON. THE HIGHER TERRAIN IS
EXPECTED TO REMAIN AT OR SLIGHTLY BELOW FREEZING WHILE LAKESHORE
AREAS LIKELY RISE TO JUST ABOVE FREEZING. STILL TO CLOSE TO CALL
WHETHER EVAPORATIVE COOLING WILL BE ABLE TO OVERCOME WARM
NOSE...SO WILL CONTINUE WITH FREEZING RAIN AND SNOW CHANGING OVER
TO RAIN OR SNOW LAKESHORE AREAS IN THE AFTERNOON. SNOWFALL
ACCUMULATIONS WILL BE EXTREMELY TOUGH TO CALL WITH ANYWHERE FROM
NOTHING TO A FEW INCHES (MAINLY HIGHER TERRAIN) POSSIBLE. ICE
ACCUMULATIONS ARE EXPECTED TO BE LIMITED TO A TENTH OF AN INCH OR
LESS DUE TO TEMPERATURES OF AROUND TO JUST SLIGHTLY BELOW
FREEZING.
FRIDAY NIGHT...PRECIPITATION IS LIKELY TO CONTINUE IN THE
EVENING...AND WITH COLDER AIR MOVING UP FROM THE SOUTH AS THE
UPPER LOW GETS A LITTLE CLOSER...THE FORM IS LIKELY TO TRANSITION
TO MAINLY LIGHT SNOW. THERE COULD ALSO BE DRIZZLE OR FREEZING
DRIZZLE AS WELL OVERNIGHT AS MID LEVEL MOISTURE BEGINS TO STRIP
OUT DUE TO A DRY SLOT MOVING IN OVERHEAD (MOISTURE LIKELY
SHALLOWING OUT TO AROUND TO JUST BELOW THE -10C ISOTHERM).
SNOWFALL ACCUMULATIONS OF AROUND AN INCH OR SO LOOK POSSIBLE.
SATURDAY...SYSTEM STALLS OUT ACROSS NEAR THE IOWA/ILLINOIS/WISCONSIN
BORDERS AND ACTUALLY MAY RETROGRADE WEST SOUTHWESTWARD AS NORTHERN
STREAM ENERGY DROPS DOWN FROM THE NORTHWEST. THIS WILL LIKELY
PLACE NORTHERN MICHIGAN SQUARELY IN THE DRY SLOT THEREBY
RESULTING IN LITTLE TO NO ACTIVITY (LOW CHANCE POPS).
SATURDAY NIGHT INTO SUNDAY...SYSTEM MOVES SLOWLY EASTWARD LIKELY
REMOISTENING MID/UPPER LEVELS WHICH SHOULD LEAD TO PERIODS OF
MAINLY LIGHT SNOW. THE LAKES COULD ALSO GET INTO THE ACT AS WELL
AS WINDS VEER MORE NORTHWEST.
SULLIVAN
&&
.MARINE.../ISSUED AT 434 AM/
EAST/SOUTHEAST GRADIENT WIND PICKS UP TODAY. WINDS SHOULD THEN
INCREASE TO GALE FORCE WITHIN LAKE MICHIGAN/HURON NEARSHORE ZONES BY
LATER TONIGHT INTO THE DAY ON CHRISTMAS SO WILL UPGRADE GALE WATCH TO
A WARNING.
AJS
&&
.AVIATION.../ISSUED AT 620 AM/...VALID FOR 12Z TAFS
CIGS WILL BE BORDERLINE MVRF AND IFR THIS MORNING BEFORE LIFTING
TO MAINLY MVRF THIS AFTERNOON. DOWNSLOPING EASTERLY FLOW WILL
LIKELY SCATTER OUT LOW CIGS AT TVC THIS AFTERNOON. CHANCES FOR A
MIXTURE OF FREEZING RAIN AND SNOW WILL INCREASE FROM SOUTHWEST TO
NORTHEAST LATER TONIGHT AS A STORM SYSTEM IN THE PLAINS
APPROACHES. WINDS WILL ALSO BE ON THE INCREASE TODAY INTO TONIGHT.
AJS
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING FROM 5 PM THIS AFTERNOON TO 5 PM EST FRIDAY FOR
LMZ323-341-342-344>346.
LH...GALE WARNING FROM 5 PM THIS AFTERNOON TO 5 PM EST FRIDAY FOR
LHZ345>349.
LS...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 PM EST FRIDAY
FOR LSZ321-322.
&&
$$
