FXUS63 KDLH 241828
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
1228 PM CST THU DEC 24 2009
.AVIATION...18Z TAF ISSUANCE
ANOTHER WAVE OF SNOW WILL MOVE ACROSS NORTHWESTERN WI/NERN MN THIS
AFT AND CONTINUE AT LEAST THROUGH 12Z FRIDAY. VSBYS WILL BE BLO
3SM AND CIGS BLO OVC010. THERE WILL BE NO IMPROVEMENT THROUGH THE
DAY FRIDAY. WINDS WILL INCREASE TO G30KT...BUT NR KDLH GUSTS TO
40KT ARE EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 1052 AM CST THU DEC 24 2009/
MESOSCALE UPDATE...CONCERNING THE BREAK IN THE SNOW AND ADDITIONAL
HEAVY SNOW THIS AFTERNOON/TONIGHT...
3 TO 5 HOUR BREAK IN MODERATE TO HEAVY SNOW EXPECTED THROUGH EARLY
TO MID AFTERNOON.
LEAD SHORT WAVE TROF HAS LIFTED RAPIDLY NWD TO NEAR THE CANADIAN
BORDER LATE THIS MORNING..TAKING LEADING WAVE OF MDT/HEAVY SNOWS
WITH IT. IN ITS WAKE..5 TO 8 INCHES OF NEW SNOW HAS BEEN PRODUCED..
AND WEAK SUBSIDENCE HAS SPREAD ACROSS THE DLH CWA FOR A FEW HOURS.
WE WANT TO EMPHASIZE THAT THE STORM IS **NOT OVER** AND THAT
ADDITIONAL VERY HEAVY SNOW AND A RAMP UP TO BLIZZARD CONDITIONS IS
STILL EXPECTED BEGINNING THIS AFTERNOON.
WV SATELLITE IMAGERY SHOWS THE INTENSE UPPER LEVEL IMPULSE OVER NE
TEXAS IS NOW BEGINNING TO LIFT NNEWD..WITH STRONG SFC LOW
DEVELOPMENT WELL UNDERWAY ACROSS THE ARKLATEX REGION. TO THE NORTH
OF THE SFC LOW FROM ARKANSAS AND MISSOURI NWD ALL THE WAY TO
MINNESOTA..LOW LEVEL FLOW IS BACKED TO SERLY AND IS RESULTING IN
BROAD PERSISTENT ISENTROPIC LIFT WITHIN AN ENVIRONMENT THAT IS
ALREADY SATURATED THRU A DEEP LAYER. IN ADDTION..SOURCE REGION OF
THE LOW LEVEL FLOW CONTAINS VERY HIGH ABSOLUTE MOISTURE CONTENT
/MIXING RATIOS 4-7 G/KG/ WITH MOISTURE TRANSPORT MAGNITUDE PROGGED
TO INCREASE FROM 50 TO ALMOST 200 G/KG/S THRU THE AFTENROON AND
EVENING ON THE 290K ISENTROPIC SURFACE.
ONCE WEAK SUBSIDENCE ABATES AS LEAD WAVE LIFTS INTO CANADA BY 1-2
PM..ADDITIONAL DEVELOPMENT OF MDT/HEAVY SNOW IS EXPECTED EARLY/MID
AFTERNOON. CURRENT RADAR DATA FROM KMPX/KARX/KDMX TO OUR SOUTH
SUPPORTS THIS IDEA WITH ADDITONAL NEW ECHOES RAPIDLY EXPANDING IN
COVERAGE/INTENSITY AND MOVING NORTH AT AROUND 30 MPH. AT THIS
RATE..ACCUMULATING SNOW WILL SPREAD BACK INTO THE BRAINERD/HINCKLEY/
SIREN AREAS BY NOON AND NORTHWARD TO THE WALKER/GRAND RAPIDS/DULUTH/
ASHLAND AREAS BY 1-2 PM.
SNOW WILL THEN CONTINUE TO INCREASE IN COVERAGE/INTENSITY INTO THIS
EVENING..WHEN PEAK OF THE STORM IS EXPECTED TONIGHT AND CHRISTMAS
MORNING WITH 1-2 INCH/HOUR SNOWFALL RATES AND 30-40 MPH
EAST/NORTHEAST WINDS IN AREAS ADJACENT TO LAKE SUPERIOR.
MILLER/CHRISTENSON
&&
.POINT TEMPS/POPS...
DLH 30 28 30 17 / 100 100 100 90
INL 26 24 25 14 / 100 100 100 90
BRD 28 26 29 17 / 100 100 100 90
HYR 31 30 33 20 / 100 100 100 70
ASX 32 30 32 19 / 100 100 100 70
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR MNZ010>012-018-
019-021-025-026-033>036-038.
BLIZZARD WARNING UNTIL 6 AM CST SATURDAY FOR MNZ020-037.
WI...WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR WIZ002>004-
006>009.
BLIZZARD WARNING UNTIL 6 AM CST SATURDAY FOR WIZ001.
LS...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LSZ121-
140>148.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY FOR
LSZ121-140>148.
&&
$$
DJM/CLC
