599
FXUS63 KARX 090843
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
240 AM CST TUE FEB 9 2010
SHORT TERM
TUESDAY THROUGH THURSDAY NIGHT
FORECAST CONCERNS REMAIN CENTERED ON THE SNOWFALL TODAY/TONIGHT.
CURRENT WATERVAPOR IMAGERY HAS THE UPPER LEVEL SHORTWAVE TROUGH
CHURNING OVER IOWA...WITH TRENDS POINTING TO ITS TURNING THE CORNER
AND HEADING EAST...PER MODEL SOLUTIONS OF THE PAST FEW DAYS. AT THE
SFC...THE ASSOCIATED LOW CENTER WAS WELL SOUTH...BUT AN INVERTED
TROUGH EXTENDED NORTHWARD INTO THE REGION...STRETCHING ACROSS
EASTERN IA INTO SOUTHERN MN. 88-D RADAR IMAGERY HAD A BROAD AREA OF
SNOW ACROSS EASTERN IA/WESTERN ILL INTO SOUTHEAST MN AND SOUTHERN
WI. THIS PCPN WAS ROTATING COUNTERCLOCKWISE ACROSS THE REGION.
THE SHORTWAVE TROUGH WILL CONTINUE TO KICK EAST TODAY //WITH AN
ASSIST FROM A 150+ KT BRANCH OF THE SOUTHERN PORTION OF THE UPPER
LEVEL JET //...MOVING ACROSS THE OH RIVER VALLEY TONIGHT...AND
CONTINUING TOWARD THE MID ATL COAST ON WED. THE SFC TROUGH WILL
CONTINUE TO SAG SOUTH AS IT TOO MOVES EAST. QG CONVERGENCE REMAINS
AMPLE THROUGH THE LAYERS...MAXIMIZED OVER THE FORECAST AREA FROM NOW
THROUGH 00Z TONIGHT. ISENTROPIC UPGLIDE ON THE 280-295 K SFCS ALSO
REMAIN HEFTY...BUT THIS LIFT ALSO EXITS EAST BY 00Z. THIS WRAPPING
OF THE RELATIVELY WARM/MOIST AIR NORTH OF THE HEART OF THIS STORM
SYSTEM SHOWS UP WELL VIA THETA-E ADVECTIONS/CONVERGENCE...AND THIS
TROWEL SIGNATURE WAS HELPING POWER/FUEL THE AREAS OF SNOW...AND WILL
CONTINUE THROUGH TODAY. SOME CURVATURE IN THE UPPER LEVEL FLOW WILL
ALSO ACT TO ENHANCE ALL THIS AVAILABLE LIFT. SO...WITH PLENTY OF
SATURATION TO WORK WITH...THE SNOW WILL CONTINUE TODAY...DIMINISHING
THIS EVENING AS THE SYSTEM PULLS EAST.
AS FOR ADDITIONAL SNOW TOTALS...THE HIGHER AMOUNTS SHOULD BE FROM
THE MISSISSIPPI RIVER EASTWARD. AMOUNTS HERE SHOULD RANGE FROM 3 TO
5 INCHES TODAY/TONIGHT. WEST OF THE RIVER AMOUNTS OF 1 TO 3 INCHES
ARE EXPECTED.
WINDS WILL ALSO BE A FACTOR TODAY...AS THE PRESSURE GRADIENT
CONTINUES TO STRENGTHEN ON THE BACKSIDE OF THE SYSTEM. SOME
DRIFTING/BLOWING OF THE FALLING/FALLEN SNOW WILL LIKELY
RESULT...ESPECIALLY IN THE OPEN AND UNSHELTERED AREAS OF SOUTHEAST
MN AND NORTHEAST IA...ALONG WITH AREA RIDGE-TOPS. THIS WILL PROBABLY
BE MORE OF A CONCERN LATER THIS AFTERNOON AND EVENING...WHEN THE
WINDS ARE EXPECTED TO BE THE MOST BLUSTERY.
WILL CONTINUE THE WARNINGS/ADVISORIES AS IS...RUNNING THROUGH 00Z
TONIGHT. WHILE SNOWFALL WILL BE DIMINISHING THIS AFTERNOON ACROSS
SOUTHEAST MN/NORTHEAST IA...BLOWING/DRIFTING SNOW COULD BECOME A
PROBLEM. THERE COULD BE A NEED TO EXTEND ADVISORIES INTO THE EVENING
TO ACCOUNT FOR BLOWING/DRIFTING ISSUES...BUT WILL WAIT AND SEE HOW
THIS DEVELOPS THROUGH TODAY.
LONG TERM
FRIDAY THROUGH MONDAY
A GOOD AMOUNT OF VARIANCE BETWEEN THE GFS AND ECMWF SOLUTIONS LOWERS
FORECAST CONFIDENCE FOR THE LONG TERM PERIOD. BOTH MODELS DO AGREE
ON A SOMEWHAT DIRTY NORTH/NORTHWEST UPPER LEVEL FLOW THROUGH THE
WEEKEND...BUT ON TIMING/STRENGTH/PLACEMENT OF THE VARIOUS
PERTURBATIONS THEY DO NOT. STILL SOME SUGGESTION OF LIGHT PCPN FOR
FRIDAY VIA BOTH MODELS...WITH THE GFS THEN SLIDING A MORE ROBUST
UPPER LEVEL SHORTWAVE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON
SAT/SAT NIGHT. THIS SOLUTION WOULD BRING A PRETTY GOOD SHOT OF LIGHT
SNOW TO THE REGION. THE EC IS WEAKER AND FARTHER WEST WITH THIS
FEATURE. QUITE A BIT OF VARIANCE WITHIN THE MODELS
THEMSELVES...ESPECIALLY THE GFS...AND ENSEMBLE MEMBERS ALSO SHOW A
VARIETY OF POTENTIAL SOLUTIONS. CURRENT FORECAST IS DRY FOR THE
UPCOMING WEEKEND...AND THINK THIS IS BETTER WAY TO GO FOR NOW. WILL
LET LATER MODEL RUNS TRY TO ADD SOME CLARITY.
AVIATION
TODAY AND TONIGHT
A TROUGH OF LOW PRESSURE FROM SOUTHWEST MINNESOTA ACROSS CENTRAL
ILLINOIS WILL PULL AWAY FROM THE UPPER MIDWEST DURING THE NEXT 24
HOURS AS IT DROPS SOUTH AND EAST. AS THE TROUGH PULLS AWAY...EXPECT
WINDS TO BACK TO THE NORTH AND INCREASE...AIDED BY ARCTIC HIGH
PRESSURE TRYING TO BUILD IN FROM SOUTH CENTRAL CANADA. THESE
NORTHERLY WINDS WILL BRING DRIER AIR INTO THE TAF SITES IN THE LOW
LEVELS...MAINTAINING AT LEAST MVFR CEILINGS...IF NOT VFR. IT IS
POSSIBLE AFTER MIDNIGHT TONIGHT FOR THE CLOUDS TO SCATTER OUT...
ESPECIALLY AT KRST. REGARDING VISIBILITIES...IFR CONDITIONS IN LIGHT
SNOW SHOULD BE THE RULE THROUGH EARLY THIS AFTERNOON. SNOW IS THEN
EXPECTED TO GRADUALLY TAPER OFF...ALLOWING KLSE TO CLIMB TO MVFR.
HAVE KEPT KRST AT IFR THROUGH THE REST OF THE AFTERNOON...THOUGH...
DUE TO POTENTIAL FOR BLOWING SNOW FROM THE INCREASING WINDS. ONCE
THE SNOW COMPLETELY ENDS THIS EVENING...AND WINDS DIMINISH SOME FROM
NIGHTTIME COOLING...EXPECT VISIBILITIES TO JUMP TO VFR AT BOTH TAF
SITES.
ARX WATCHES/WARNINGS/ADVISORIES
WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ032-
WIZ033-WIZ034-WIZ041-WIZ042-WIZ043-WIZ044-WIZ053-WIZ054-
WIZ055-WIZ061.
MN...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR MNZ086-
MNZ087-MNZ094-MNZ095.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR MNZ079-
MNZ088-MNZ096.
IA...WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR IAZ008-
IAZ009-IAZ010-IAZ018-IAZ019-IAZ029.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ011-
IAZ030.
SHORT/LONG TERM... RIECK
AVIATION.......... AJ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page