FXUS63 KARX 300923
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
320 AM CST MON NOV 30 2009
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
FORECAST CONCERNS INCLUDE PRECIPITATION TYPE/CHANCES ACROSS THE
NORTH TODAY...THEN COLDER WITH LIGHT SNOW CHANCES WED/WED NIGHT.
SURFACE MAP EARLY THIS MORNING HAD A RIDGE OF HIGH PRESSURE
EXTENDING FROM OK NORTHEASTWARD THROUGH WI WHILE LOW PRESSURE WAS
LOCATED JUST WEST OF LAKE WINNIPEG CANADA. CLOSER TO THE LOCAL
AREA...IR SATELLITE SHOWING BACK EDGE OF STUBBORN
STRATUS/STRATOCUMULUS SHIELD HAS NOW PUSHED INTO NORTHWEST WI
THROUGH CENTRAL IA. AREA TEMPERATURES AT 2 AM UNDER THE CLOUD COVER
WERE RELATIVELY MILD IN THE MID 30S.
30.00Z MODELS SHOWING OVERALL DECENT AGREEMENT THROUGH THE PERIOD.
FOR TODAY...WILL BE WATCHING THE LOW WEST OF LAKE WINNIPEG EARLY
THIS MORNING MOVE INTO CENTRAL LAKE SUPERIOR BY EARLY THIS EVENING.
RESPECTABLE WING OF WARM AIR ADVECTION AND FAIRLY STRONG ISENTROPIC
LIFT //NOTED ON GFS/NAM 285K SURFACE// ASSOCIATED WITH THE LOW
SWINGS ACROSS AREAS NORTH OF THE I-94 CORRIDOR THIS AFTERNOON FOR
RAPID COLUMN SATURATION. NAM MODEL SOUNDING SHOWS A SATURATED COLUMN
OVER MEDFORD WI BY 21Z THIS AFTERNOON WITH ALL SNOW INDICATED. MAY
SEE THE POTENTIAL OF A SLUSHY HALF INCH ACROSS PORTIONS OF TAYLOR
COUNTY. SLIGHTLY FURTHER SOUTH ACROSS CLARK COUNTY...MODEL SOUNDINGS
INDICATE A RAIN/SNOW MIX LIKELY. BASED ON THE STRENGTH OF THE
SIGNAL...HAVE INCREASED POPS INTO LIKELY CATEGORY ACROSS TAYLOR
COUNTY...TRAILING OFF IN A FAIRLY RAPID FASHION TO NIL PRECIPITATION
CHANCE SOUTH OF I-94.
THE LOW AND ASSOCIATED FORCING DEPART EAST OF THE AREA BY EARLY THIS
EVENING AS A RIDGE OF HIGH PRESSURE BUILDS IN FROM THE WEST. THIS
WILL ALLOW FOR MOSTLY CLEAR SKIES TONIGHT SOUTHWEST OF I-94 AND
SLOWLY CLEARING SKIES NORTHEAST OF I-94.
FAIRLY STRONG PUSH OF MILD AIR INTO THE AREA OCCURS ON TUESDAY AS A
VIGOROUS LOW MOVES ACROSS THE NORTHERN PLAINS. NAM 850-925MB MEAN
LAYER TEMPERATURES PUSH INTO THE +2 TO +8C RANGE BY AFTERNOON.
INCREASED CLOUDS ACROSS THE NORTH IN ISENTROPIC LIFT WILL LIKELY
TEMPER THE WAA ACROSS THAT AREA. OTHERWISE...MAX TEMPERATURES WILL
LIKELY CRACK LOWER 50S ACROSS PORTIONS OF NORTHEAST IA INTO FAR
SOUTHWEST WI.
MODELS IN GOOD AGREEMENT MOVING THE LOW INTO LAKE SUPERIOR REGION
TUESDAY NIGHT...SWINGING A STRONG COLD FRONT THROUGH THE AREA. WILL
LIKELY SEE FALLING TEMPERATURES THROUGH THE DAY WEDNESDAY AS NAM
SHOWS 925-850MB TEMPERATURES PLUMMETING FROM 0 TO MINUS 4C IN THE
MORNING...TO MINUS 6-MINUS 8C BY LATE IN THE AFTERNOON. ALSO WILL
SEE ISOLATED-SCATTERED SNOW SHOWERS DURING THE DAY WEDNESDAY WITH
STEEP LOW LEVEL LAPSE RATES/COLD CYCLONIC FLOW OVERHEAD. COLD AIR
ADVECTION/ISOLATED-SCATTERED SNOW SHOWER ACTIVITY CONTINUES THROUGH
WEDNESDAY NIGHT WITH LOWS DIPPING INTO THE MID TEENS TO LOWER 20S.
.LONG TERM...THURSDAY THROUGH SUNDAY
30.00Z GFS/ECMWF SHOW A CHILLY PERIOD THURSDAY THROUGH FRIDAY AS A
COLD MID-LEVEL TROUGH LINGERS OVERHEAD. COLD CYCLONIC FLOW AND
STRONG LOW LEVEL LAPSE RATES WILL ALSO LIKELY CONTINUE TO PRODUCE
ISOLATED-SCATTERED SNOW SHOWERS. HIGHS THU/FRI ARE ONLY EXPECTED TO
TOP OFF IN THE 20S WITH OVERNIGHT LOWS IN THE TEENS. CURRENT
EXTENDED GRIDS HAVE THIS HANDLED WELL.
GFS AND ECMWF THEN BEGIN TO DIVERGE IN THEIR SOLUTIONS FOR SATURDAY
AND SUNDAY. THE ECMWF WANT TO BUILD A RIDGE INTO THE AREA FOR SOME
MODERATION IN TEMPERATURES WHILE THE GFS SHOWS ANOTHER REINFORCING
SHOT OF COLD AIR MOVING INTO THE AREA AS A SECONDARY MID-LEVEL
TROUGH ROTATES THROUGH THE UPPER MIDWEST. WITH THIS UNCERTAINTY...
OPTED TO LEAVE CURRENT DRY GRIDDED DATABASE FOR THIS TIME PERIOD
ALONE FOR NOW.
&&
.AVIATION...
LOOK FOR VFR CONDITIONS THROUGH TONIGHT AS DRIER AIR FROM THE
DAKOTAS CONTINUES TO FLOW IN ON WESTERLY WINDS. ONLY REAL ITEM OF
CONCERN IS THE LINGERING EARLY MORNING STRATUS DECK OVER KRST AND
KLSE...WHICH SHOULD CLEAR OUT THIS MORNING. ALTOSTRATUS WILL LIKELY
FILL BACK IN OVER THE TAF SITES BY NOON...ASSOCIATED WITH A SYSTEM
MOVING SOUTHEAST THROUGH NORTHERN WISCONSIN...WITH CLOUD BASES
GRADUALLY LOWERING IN HEIGHT INTO THE EVENING. AGAIN...ALL BASES ARE
EXPECTED TO STAY VFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT/LONG TERM...DAS
AVIATION..........AJ
