FXUS63 KMKX 081006
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
406 AM CST TUE DEC 8 2009
FORECAST FOCUS ON MAJOR WINTER STORM FOR LATER THIS AFTERNOON
THROUGH WEDNESDAY EVENING.
LATEST WATER VAPOR IMAGERY INDICATED A STRENGTHENING UPPER LEVEL
TROUGH OVER THE SOUTHWESTERN USA...WITH DOWNSTREAM SOUTHWEST FLOW
OVER THE PLAINS BECOMING WEST SOUTHWEST INTO THE WESTERN GREAT
LAKES REGION.
.TODAY THROUGH WEDNESDAY NIGHT...CONFIDENCE: HIGH
PESKY AREA OF LIGHT SNOW OVER IOWA INTO NORTHERN ILLINOIS TRYING
TO MOVE NORTHEAST INTO THE AREA. THIS WAS ASSOCIATED WITH RIGHT
REAR QUADRANT OF JET STREAK...AND MID LEVEL WARM AIR
ADVECTION/FRONTOGENESIS. LOCAL HIGH RESOLUTION MODELS TRY TO KEEP
MOST OF THE LIGHT SNOW WITH THIS FEATURE JUST SOUTH OF THE AREA
THIS MORNING. HOWEVER...GETTING A FEW SITES REPORTING LIGHT SNOW
ACROSS THE SOUTHWEST COUNTIES. WILL ADD LIKELY POPS TO THE FAR
SOUTHWEST COUNTIES EARLY THIS MORNING...WITH LOWER POPS TO THE
NORTHEAST TO ACCOUNT FOR THIS LIGHT SNOW. A DUSTING AT BEST IS
EXPECTED EARLY THIS MORNING.
ANOTHER CONCERN IS THE POTENTIAL FOR ACCUMULATIONS WITH A LAKE
EFFECT SNOW BAND EXPECTED TO MOVE NORTHWEST ACROSS SHEBOYGAN AND
OZAUKEE COUNTIES LATER THIS MORNING AND INTO THE AFTERNOON.
FAVORABLE SOUTHEAST FETCH AND DELTA T VALUES EXIST...WITH LOCAL
HIGH RESOLUTION MODELS SHOWING A MESO LOW TYPE FEATURE MOVING INTO
THESE COUNTIES AFTER 15Z THIS MORNING. NEWEST RUNS TRY TAKING IT
FURTHER TO THE NORTH. FOR NOW...WILL ADD LIKELY POPS FOR LATER
THIS MORNING IN THE NORTHEAST COUNTIES...WITH THE HIGHER POPS THIS
AFTERNOON. THIS AREA COULD SEE 2 TO 3 INCHES OF SNOW WITH THIS
MESO LOW...THOUGH EXACT PATH WILL BE TRICKY TO PINPOINT. THIS WILL
HAVE TO BE WATCHED CLOSELY AS THE MORNING GOES ON.
NOT A WHOLE LOT OF CHANGES WITH RESPECT TO THE MAJOR WINTER STORM
THAT WILL AFFECT SOUTHERN WISCONSIN LATER THIS AFTERNOON THROUGH
WEDNESDAY NIGHT. FOLLOWED THE GFS/ECMWF MODELS WITH THE EVOLUTION
OF THIS SYSTEM. THE LOW DEVELOPS IN THE SOUTHERN PLAINS
TODAY...THEN QUICKLY MOVES NORTHEAST AND DEEPENS TO AROUND 980MB
BY 12Z WEDNESDAY ACROSS FAR SOUTHERN LAKE MICHIGAN PER THE ECMWF.
THE GFS IS A BIT FURTHER EAST OVER FAR SOUTHWEST LOWER MICHIGAN.
LIGHT TO MODERATE SNOW IS EXPECTED TO SHIFT NORTHEAST INTO THE
AREA THIS AFTERNOON...AS MID LEVEL FRONTOGENESIS BEGINS TO MOVE
INTO THE REGION. STRONG UPWARD VERTICAL MOTION FROM A STRONG MID
LEVEL FRONTOGENETIC BAND WITHIN THE DENDRITE SNOW CRYSTAL GROWTH
ZONE WILL THEN SWEEP INTO THE AREA BY EARLY EVENING...LASTING
THROUGH ABOUT 08Z TO 09Z WEDNESDAY. THIS LIFT ALSO CONFIRMED BY
STRONG Q VECTOR CONVERGENCE IN THE MID LEVELS. THE FRONTOGENESIS
WITHIN THE SNOW CRYSTAL GROWTH ZONE WILL BRING THE HEAVY SNOW
ACROSS THE AREA.
THE LOW WILL THEN PULL NORTHEAST ON WEDNESDAY...GRADUALLY BRINGING
MODERATE...THEN LIGHT SNOW TO THE AREA. STRONG NORTHWEST WINDS IN
THE WAKE OF THE STRONG LOW WILL SWEEP ACROSS THE AREA...CAUSING
BLOWING AND DRIFTING SNOW. WINDS OF 20 TO 30 MPH...WITH GUSTS TO
40 MPH...ARE EXPECTED WITHIN THE STRONG COLD AIR ADVECTION
REGIME. THESE WINDS SHOULD BRING THE BLOWING SNOW THROUGH
WEDNESDAY EVENING...THE DURATION OF THE WINTER STORM WARNING.
KEPT SNOW ACCUMULATIONS FAIRLY SIMILAR TO THE PREVIOUS FORECAST.
GENERALLY EXPECT LIQUID EQUIVALENT VALUES OF AROUND 1.00 INCH IN
THE WEST TO AROUND 1.25 INCHES IN THE NORTHEAST. GIVEN THE
STRONGER WINDS EXPECTED AND THE 1000/500MB THICKNESS FIELD SETUP
ACROSS THE AREA...WENT WITH A GENERAL 10 TO 1 SNOW TO LIQUID
RATIO. THICKNESSES NEAR 540DKM IN THE FAR SOUTHEAST COUNTIES COULD
YIELD LOWER RATIOS...THOUGH AM EXPECTING ALL SNOW GIVEN THE COLD
LOOK OF THE FORECAST SOUNDINGS. EXPECT A 5 TO 8 INCH AREA IN THE
FAR SOUTHEAST...TO AROUND 10 INCHES IN THE WESTERN COUNTIES...TO A
10 TO 14 INCH AREA IN THE NORTHEAST COUNTIES...DUE TO THE LAKE
EFFECT SNOW POTENTIAL TODAY. THE WINTER STORM WARNING WILL REMAIN
AS IS FOR NOW.
.THURSDAY THROUGH MONDAY...CONFIDENCE: MEDIUM
HIGH PRESSURE MOVING SOUTH OF THE REGION PER THE ECWMF WILL BRING
QUIET WEATHER TO THE AREA THURSDAY AND FRIDAY. MUCH COLDER
TEMPERATURES WILL REMAIN IN THE AREA DURING THIS TIME...WITH
1000/500MB THICKNESSES HOVERING AROUND 505 TO 510 DKM. A COLD
FRONT PASSING THROUGH THE REGION ON SATURDAY DOES NOT HAVE MUCH
MOISTURE OR UPWARD MOTION TO WORK WITH DESPITE THE ECMWF QPF
DEPICTION...SO LEFT THIS PERIOD DRY. THE VERY COLD AND DRY
CONDITIONS SHOULD PERSIST ACROSS THE REGION THROUGH THE WEEKEND.
&&
.AVIATION....AVIATION...STRONG WINTER STORM AND HEAVY SNOW TO
AFFECT SRN WI TNT AND WED. LGT SNOW ASSOCIATED WITH AN INITIAL
BURST OF WARM ADVECTION WILL MOVE FROM NRN IL INTO SRN WI THIS AM.
MVFR CIGS WILL DEVELOP WITH MVFR TO IFR VSBYS.
STEADIER SNOW WILL DEVELOP LATE THIS AFTERNOON AND EVENING AS
STRONG LOW PRESSURE OVER THE SOUTHERN PLAINS MOVES TO SRN LAKE MI
BY 12Z WED. MVFR CIGS AND IFR VSBYS WITH THE LGT SNOW LATE THIS
AFTERNOON WILL TRANSITION TO A HEAVY SNOW MUCH OF TNT WITH VLIFR
VSBYS AND IFR TO LIFR CIGS.
IN ADDITION TO THE HEAVY SNOW GUSTY ELY WINDS WILL PREVAIL TNT AND
BACK TO A NORTHERLY AND EVENTUALLY A WLY DIRECTION ON WED. THE
SNOW WILL BECOME LIGHTER ON WED AS THE LOW MOVES AWAY.
&&
.MARINE...GALE WARNING IN EFFECT TONIGHT THROUGH WEDNESDAY NIGHT.
INTENSIFYING LOW PRESSURE OVER THE SOUTHERN PLAINS WILL REACH
SOUTHERN LAKE MI BY 12Z WED AND CONTINUE NEWD TO QUEBEC CANADA BY
12Z THU. THE LOW WILL BE UNSEASONABLY STRONG WITH ELY GALES TNT
FOLLOWED BY WNWLY GALES WED AND WED NT. VERY HIGH WAVES ARE FCST.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WARNING FROM NOON TODAY TO MIDNIGHT CST WEDNESDAY
NIGHT FOR WIZ046-047-051-052-056>060-062>072.
LM...GALE WARNING FROM 6 PM THIS EVENING TO 6 AM CST THURSDAY FOR
LMZ643>646.
&&
$$
SHORT/LONG TERM...08/WOOD
AVIATION/MARINE...20/GEHRING
