Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 090956
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
356 AM CST TUE FEB 9 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 355 AM CST TUE FEB 9 2016

AT 3 AM...THE AREA REMAINS IN A MODERATE SURFACE PRESSURE GRADIENT
BETWEEN A 997 MB LOW OVER SOUTHERN LAKE HURON AND A 1028 MB HIGH
CENTERED OVER DEVILS LAKE NORTH DAKOTA. THIS SURFACE PRESSURE
GRADIENT IS PRODUCING SUSTAINED NORTHWEST WINDS OF 10 TO 20 MPH
AND WIND GUSTS OF 20 TO 30 MPH. THESE WIND SPEEDS WILL REMAIN IN
THESE RANGES THROUGH THIS EVENING...AND THEN WEAKEN AS THE SURFACE
PRESSURE GRADIENT STARTS TO WEAKEN. WITH MUCH OF THE SNOW ALREADY
SETTLED AND NO ADDITIONAL SNOW ACCUMULATIONS ANTICIPATED ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...EXPECT ONLY PATCHY TO A
FEW AREAS OF BLOWING SNOW IN THESE AREAS THROUGH THIS EVENING.

FOR MID MORNING INTO THE AFTERNOON...THE MESO MODELS ARE IN GOOD
AGREEMENT THAT A SHORT WAVE TROUGH WILL MOVE SOUTH THROUGH EASTERN
WISCONSIN. IN ADDITION...THE 950 TO 900 MB LAPSE RATES WILL CLIMB
ABOUT 8 C/KM EAST OF AN EAU CLAIRE TO LANCASTER LINE IN WESTERN
WISCONSIN. FINALLY THERE WILL BE SOME WEAK CYCLONIC FLOW ALOFT.
THIS WILL LIKELY RESULT IN THE DEVELOPMENT OF SOME LIGHT SNOW IN
THIS AREA. DUE TO THIS INCREASED THE SNOW CHANCES UP INTO THE
CHANCE RANGE /30 TO 40 PERCENT/. IF THIS SIGNAL CONTINUES...THESE
CHANCES OF SNOW WILL HAVE TO RAISED FURTHER. ADDITIONAL SNOW
TOTALS WILL RANGE FROM A TRACE TO MAYBE A FEW TENTHS OF AN INCH OF
SNOW.

FOR LATE TONIGHT...WIND CHILLS WILL FALL INTO THE 15 TO 25 BELOW
RANGE. THE COLDEST WIND CHILLS ARE LOCATED ACROSS SOUTHEAST
MINNESOTA...NORTHEAST IOWA...AND NORTH OF INTERSTATE 90 IN WESTERN
WISCONSIN. A WIND CHILL ADVISORY MAY BE NEEDED FOR THESE AREAS FOR
LATE TONIGHT AND WEDNESDAY MORNING.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 355 AM CST TUE FEB 9 2016

ON WEDNESDAY AFTERNOON AND EVENING...THE 09.00Z MODELS CONTINUE TO
STRUGGLE ON WHERE THE TIGHT BAROCLINIC ZONE WILL BE LOCATED ON THE
WESTERN PERIPHERY OF THE ARCTIC HIGH. THE GEM AND GFS CONTINUE TO
PRODUCE SOME LIGHT SNOW ACCUMULATIONS ACROSS PARTS OF NORTHEAST
IOWA AND SOUTHEAST MINNESOTA. MEANWHILE THE ECMWF AND NAM KEEP
THIS SNOW BAND WELL WEST AND SOUTH OF THE AREA. CURRENTLY THINKING
THAT THE LATTER MODELS PROBABLY HAVE THE BEST HANDLE ON THIS
SYSTEM...SO LEANED MORE TOWARD THE NAM AND ECMWF SOLUTIONS.

ON THURSDAY NIGHT AND FRIDAY...THE MODELS CONTINUE TO SHOW THAT
WARM AIR ADVECTION WILL DEVELOP AHEAD OF AN APPROACHING ARCTIC
COLD FRONT. WEAK TO MODERATE 275K ISENTOPRIC LIFT DEVELOPS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA. IN ADDITION...THERE IS
WEAK 900 TO 700 MB FRONTOGENESIS. MOISTURE LOOKS VERY LIMITED
WITH SPECIFIC HUMIDITIES OF ONLY 1 TO 2 G/KG. AT MOST THIS SNOW
BAND LOOKS TO PRODUCE AROUND A HALF INCH ACROSS SOUTHEAST
MINNESOTA... NORTHEAST IOWA...AND SOUTHWEST WISCONSIN.

IN THE WAKE OF THIS COLD FRONT IS THE COLDEST 850 MB AIR THE
WINTER. FORTUNATELY...THE COLDEST 850 MB TEMPERATURES WILL BE
FOUND ACROSS EASTERN ONTARIO...QUEBEC...AND NEW ENGLAND WHERE 925
MB TEMPERATURES WILL FALL AS LOW -36C. ACCORDING TO NAEFS...THESE
TEMPERATURES WILL BE 3 TO 4 STANDARD DEVIATIONS BELOW NORMAL THIS
WEEKEND. MEANWHILE CLOSER TO HOME...WE ARE LOOKING AT 850 MB
TEMPERATURES ANOMALIES OF 1 TO 3 STANDARD DEVIATIONS BELOW NORMAL
ON SATURDAY. IF THIS TREND CONTINUES...THERE MAY BE SOME COLD
HIGH TEMPERATURES THAT COULD BE TIED OR BROKEN. OUR CURRENT
FORECAST MAXIMUM TEMPERATURE GRID CURRENTLY HAS MUCH OF THE AREA
NOT EVEN REACHING 10F. THE RECORD COLD HIGH FOR ROCHESTER ON
SATURDAY IS 5F SET BACK IN 1970 AND IT IS 0F IN 1905 FOR LA CROSSE
WISCONSIN. IN ADDITION TO THIS...IT LOOKS LIKE THE WIND CHILLS ON
SATURDAY MORNING WILL RANGE FROM 15 TO 30 BELOW. IF THIS TREND
CONTINUES...A WIND CHILL ADVISORY MAY BE NEEDED.

FROM SUNDAY INTO MONDAY...THERE CONTINUES TO BE QUESTIONS ON HOW
FAST THE 1040 MB ARCTIC HIGH WILL MOVE EAST OF THE AREA. THE
LATEST ECMWF ENSEMBLE HAS HIGH TEMPERATURES FOR ROCHESTER RANGING
FROM 12 TO 40 FOR SUNDAY. MEANWHILE THE OPERATIONAL ECMWF IS
JUST A DEGREE BELOW ITS ENSEMBLE MEAN. AS A RESULT...THE
CONFIDENCE OF TEMPERATURES FOR THIS TIME PERIOD ARE CURRENTLY
LOWER THAN NORMAL. WHILE THE TEMPERATURE FORECAST IS IN
QUESTION...BOTH THE GFS AND ECMWF CONTINUE TO SHOW THAT A LOW
PRESSURE AREA WILL BE MOVING EAST THROUGH THE REGION. THIS SYSTEM
WILL LIKELY PRODUCE SOME ACCUMULATING SNOW FOR THE AREA...BUT
THE TOTALS ARE HIGHLY QUESTIONABLE AT THIS TIME. THIS IS DUE TO
UNCERTAINTIES ON THE THERMAL STRUCTURE OF THE ATMOSPHERE AND HOW
MUCH MOISTURE THIS SYSTEM WILL BE ABLE TO TAP INTO.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1140 PM CST MON FEB 8 2016

MVFR/LOW VFR CEILINGS EXPECTED AT KRST/KLSE RESPECTIVELY TONIGHT
WITH LINGERING SCATTERED SNOW SHOWERS THAT COULD PERIODICALLY
DROP VISIBILITY TO 2SM AT KRST AND 4SM AT KLSE. SNOW SHOWERS TO
DIMINISH TO FLURRIES BY DAYBREAK ON TUESDAY WITH PERSISTENT LOWER
CEILINGS. FORECAST GUIDANCE SHOWS ANOTHER WEATHER DISTURBANCE
DROPPING SOUTH FROM CANADA TUESDAY AFTERNOON...BRINGING ANOTHER
ROUND OF LOWER CEILINGS FOR THE LATTER HALF OF THE PERIOD. FOR
STARTERS...WILL LOWER CEILINGS ANOTHER 1000 FT TUESDAY AFTERNOON
TO 1500 FT AGL AT KRST AND 2500 FT AGL AT KLSE. NORTHWEST WINDS
WILL PERSIST THROUGH THE PERIOD...SUSTAINED 12 TO 20 KTS WITH
OCCASIONAL GUSTS INTO THE MID 20 KT RANGE.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...ROGERS


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