Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 191131
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
531 AM CST WED NOV 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST WED NOV 19 2014

AT 3 AM...LIGHT SNOW OR FLURRIES WAS FALLING ALONG AND NORTH OF
AUSTIN MINNESOTA TO WISCONSIN RAPIDS LINE. THIS WAS IN RESPONSE TO
SYNOPTIC LIFT ASSOCIATED WITH A SHORT WAVE TROUGH MOVING EAST
THROUGH WESTERN WISCONSIN. THE 19.00Z MODELS ARE IN GOOD AGREEMENT
THAT THIS SYSTEM WILL MOVE EAST OF THE AREA THIS MORNING. THIS
WILL BRING AN END TO ACCUMULATING SNOW. HOWEVER WITH CYCLONIC FLOW
ALOFT AND 950 TO 900 MB LAPSE RATES RUNNING AROUND 9C/KM...WE WILL
LIKELY SEE FLURRIES OR SCATTERED SNOW SHOWERS THROUGHOUT THE
REMAINDER OF TODAY. IN ADDITION TO THIS...THE NORTHWEST WINDS WILL
GUST INTO THE 25 TO 35 MPH RANGE THIS AFTERNOON. THIS MAY RESULT
IN SOME PATCHY AREAS OF BLOWING SNOW. THIS WILL BE MORE LIKELY IN
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND ON THE RIDGE TOPS AND
OPEN AREAS OF WESTERN WISCONSIN.

FOR TONIGHT...IT CONTINUES TO LOOK LIKE WE WILL SEE CYCLONIC FLOW
ALOFT AND YET ANOTHER SHORT WAVE TROUGH MOVING THROUGH NORTHERN
MINNESOTA AND WISCONSIN. HOWEVER THE MODELS CONTINUE TO SHOW THAT
CLEARING WILL TAKE PLACE THIS EVENING. AM A BIT CONCERNED THAT THE
CLOUDS MAY STICK AROUND A LOT LONGER THAN WE CURRENTLY HAVE IN OUR
FORECAST GRIDS. IN ADDITION...SOME OF THE SOUNDINGS SUGGEST THAT
THERE WILL BE SOME WEAK OMEGA IN THE DENDRITIC ZONE AND STILL SOME
STEEP LAPSE RATES IN THE 950 TO 900 MB LATER. THIS WOULD SUGGEST
THE POTENTIAL FOR AT LEAST SOME FLURRIES. LOOKING UPSTREAM...THERE
IS SOME LIGHT SNOW ASSOCIATED WITH ACROSS NORTHERN MANITOBA.  IF
THIS TREND CONTINUES...THE DAY SHIFT MAY HAVE TO ADD THESE TO THE
FORECAST.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 352 AM CST WED NOV 19 2014

ON THURSDAY...THE MODELS CONTINUE TO SHOW THAT ANOTHER OF VERY
COLD AIR WILL MOVE SOUTHEAST INTO THE UPPER MISSISSIPPI VALLEY AND
GREAT LAKES. 850 MB TEMPERATURES WILL RANGE FROM -14 TO -18C.
NAEFS SHOWS THAT THIS IS 2 TO 3 STANDARD DEVIATIONS BELOW NORMAL.
THIS WILL LIKELY RESULT IN ANOTHER DAY WITH TEMPERATURES IN THE
TEENS.

LATE FRIDAY NIGHT INTO SATURDAY...A NEGATIVELY TITLED SHORT WAVE
TROUGH IN THE SOUTHERN STREAM WILL MOVE FROM THE MID MISSISSIPPI
RIVER VALLEY NORTHEAST INTO THE GREAT LAKES. STRONG WARM AIR
ADVECTION WILL MOVE INTO THE AREA ON FRIDAY NIGHT AND THEN
CONTINUE INTO SATURDAY MORNING. 850 MB TEMPERATURES CLIMB FROM
BETWEEN 0C TO -4C AT 00Z SATURDAY TO BETWEEN 2 AND 6C BY 18Z
SATURDAY. WITH DRY AIR ABOVE 850 MB...SOUNDINGS CONTINUE TO SHOW
THAT THERE WILL BE NO ICE CRYSTAL SEEDING FROM ALOFT. AS A
RESULT...THE PRECIPITATION WILL BE PRIMARILY IN THE FORM OF
LIQUID. THERE WILL BE THE POTENTIAL FOR FREEZING RAIN WHERE
TEMPERATURES HAVE NOT SUFFICIENTLY WARMED. IN ADDITION...MAY HAVE
TO CONTEND WITH COLD ROADS TOO INITIALLY. IN ADDITION TO THE
FREEZING RAIN THREAT...SOUNDINGS SUGGEST THAT THERE MAY BE SLEET
DUE TO THE VERY COLD NEAR THE GROUND ALONG AND NORTH OF INTERSTATE
90. FORTUNATELY...IT LOOKS LIKE THE PRECIPITATION WILL BE ARRIVING
MUCH LATER /BETWEEN 3 AM AND 6 AM/ THAN ORIGINALLY
ANTICIPATED...SO THIS WILL ALLOW FOR A CHANCE TO WARM UP BEFORE
ITS ARRIVAL. WITH VERY WARM ALOFT LATER ON SATURDAY MORNING AND
DURING THE AFTERNOON...EXPECT THE WINTRY MIX TO TRANSITION QUICKLY
OVER TO RAIN.

ON SATURDAY NIGHT...ANOTHER NEGATIVELY TILTED SHORT WAVE TROUGH
IN THE SOUTHERN STREAM WILL MOVE TO OUR SOUTHEAST. SOUNDINGS
CONTINUE TO SUGGEST THAT THIS PRECIPITATION WILL BE LIQUID. LIKE
YESTERDAY...THE CONSOLIDATED MINIMUM TEMPERATURE GRID LOOKS TOO
COLD...SO RAISE THEM A COUPLE OF DEGREES ABOVE FREEZING. THIS IS
LIKELY NOT ENOUGH YET...BECAUSE 6 OF THE LAST 7 COBB RUNS SHOW
THAT THE TEMPERATURES WILL BE IN THE LOWER TO MID 40S ACROSS
NORTHEAST IOWA AND SOUTHWEST WISCONSIN...AROUND 40 ALONG
INTERSTATE 90...AND IN THE MID AND UPPER 30S ACROSS THE REMAINDER
OF THE AREA. WITH TEMPERATURES ABOVE FREEZING...REMOVED THE WINTRY
MIX FROM THE FORECAST.

FROM SUNDAY NIGHT INTO MONDAY...TWO WAVES /ONE IN THE SOUTHERN
STREAM AND YET ANOTHER ONE IN THE NORTHERN STREAM/ WILL BRING YET
ANOTHER ROUND OF PRECIPITATION. THIS PRECIPITATION WILL LIKELY
START OUT AS RAIN AND THEN TRANSITION OVER TO SNOW AS COLDER AIR
MOVES INTO THE REGION.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 531 AM CST WED NOV 19 2014

RADAR AND SURFACE OBSERVATION INDICATE THE BACK EDGE OF THE SNOW
IS IN THE INTERSTATE 35 CORRIDOR AND IS MAKING DECENT EASTWARD
PROGRESS. EXPECT THAT MOST OF THE SNOW SHOULD MOVE BY BOTH TAF
SITES BY THE MIDDLE OF THE MORNING. ONCE THE WARM FRONT MOVES
THROUGH...THE WINDS WILL COME AROUND TO THE WEST/NORTHWEST AND
WITH GOOD LOW LEVEL LAPSE RATES BEHIND THE FRONT...EXPECT TO SEE
GUSTS DEVELOP BY MID MORNING. WITH SUSTAINED WINDS AROUND 20 KNOTS
AND GUSTS TO BETWEEN 25 AND 30 KNOTS AT KRST...SOME VISIBILITY
REDUCTIONS IN BLOWING SNOW WILL BE POSSIBLE. UNCERTAIN ON HOW
LONG THIS WILL LAST...BUT WOULD NOT EXPECT IT TO LAST TOO LONG
GIVEN THE LIGHT SNOW ACCUMULATIONS THAT OCCURRED AND WILL ONLY
CARRY THIS THROUGH 18Z. WITH THE LOW LEVEL LAPSE RATES AND
CYCLONIC FLOW...THIS SHOULD BE ENOUGH TO PRODUCE SOME FLURRIES
BEHIND THE MAIN BAND OF SNOW WITH THE 19.06Z NAM INDICATING THIS
MAY LAST THROUGH MUCH OF THE AFTERNOON AT KLSE. AS HIGH PRESSURE
BEGINS TO BUILD IN LATE TONIGHT...THE CONCERN BECOMES WHETHER THE
CLOUDS WILL SCATTER OUT OR NOT. MODELS TRENDS ARE USUALLY TOO FAST
WITH THIS AND WITH THE NAM SHOWING GOOD LOW LEVEL RH REMAINING IN
PLACE UNDER THE CYCLONIC FLOW...STAYED ON THE PESSIMISTIC SIDE AND
MAINTAIN THE MVFR CEILINGS THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04



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