Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 272139
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
339 PM CST THU NOV 27 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 339 PM CST THU NOV 27 2014

AT 3 PM...A 1033 MB SURFACE HIGH...CENTERED OVER SOUTHEAST
MINNESOTA AND NORTHEAST IOWA...WAS PRODUCING PARTLY TO MOSTLY
SUNNY SKIES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY. DESPITE...
THE SUNSHINE...TEMPERATURES WERE VERY COLD RANGING FROM 3 IN
AUSTIN MINNESOTA TO 21 IN LONE ROCK WISCONSIN.

FOR TONIGHT AND FRIDAY...27.12Z MODELS ARE IN GOOD AGREEMENT THAT
A SHORT WAVE OVER WESTERN NORTH DAKOTA WILL MOVE QUICKLY SOUTHEAST
ACROSS NORTHERN MINNESOTA TONIGHT...AND NORTHERN WISCONSIN ON
FRIDAY. AS THIS SYSTEM APPROACHES...A BAND OF MODERATE TO STRONG
900 TO 600 MB FRONTOGENESIS WILL MOVE EAST ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY. THIS BAND WILL MOVE EAST THROUGH
SOUTHEAST MINNESOTA AND NORTHEAST IOWA BETWEEN 28.06Z TO
28.10Z...AND THROUGH WESTERN WISCONSIN BETWEEN 28.09Z AND 28.18Z.
THERE IS PLENTY OF DRY AIR AHEAD OF THIS WAVE...SO THE INITIAL
LIFT WILL GO TO SATURATING THE AIR MASS BELOW 700 MB. ONCE
SATURATED THE SOUNDINGS INITIALLY SHOW THAT THE 850 MB TO 550 MB
LAYER WILL BE LOCATED IN THE DENDRITIC GROWTH ZONE NORTH OF
INTERSTATE 94...AND ONLY ABOUT 50 TO 100 MB SOUTH OF THIS
INTERSTATE. HOWEVER AS STRONG WARM AIR ADVECTION CONTINUES THROUGH
THE NIGHT...THE AMOUNT OF AREA IN THE DENDRITIC GROWTH ZONE BECOME
LESS AND LESS...WENT WITH THE HIGHEST SNOW TO LIQUID RATIOS THIS
INITIALLY...AND THEN DECREASE THEM ON FRIDAY. SNOW TOTALS WILL THE
GREATEST NORTH OF WISCONSIN 29 /FAR NORTHERN CLARK AND TAYLOR
COUNTIES IN NORTH CENTRAL WISCONSIN/ WHERE SNOW TOTALS ARE AROUND
3 INCHES. DUE TO THIS SNOW...ISSUED A WINTER WEATHER ADVISORY FROM
MIDNIGHT TONIGHT THROUGH 3 PM FRIDAY. FURTHER SOUTH...EXPECT SNOW
TOTALS OF 1 TO 3 INCHES BETWEEN INTERSTATE 94 AND WISCONSIN
29...AND FROM A TRACE TO AN INCH /NEAR INTERSTATE 90/ FOR THE
REMINDER OF THE AREA.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 339 PM CST THU NOV 27 2014

ON SATURDAY...VERY WARM AIR WILL BE BROUGHT ISENTROPICALLY OFF OF
THE CNETRAL PLAINS. UNFORTUNATELY THIS AIR WILL NOT MIX DOWN TO
THE SURFACE. AS A RESULT...ONLY HAVE HIGH TEMPERATURES RANGING
FROM THE MID 30S TO MID 40S. ONLY THING WE WILL HAVE TO WATCH IS
THAT THE MODELS MAY BE UNDOING SOME OF WARMING AS THEY TRY TO MELT
THE SNOW ON THE GROUND. LIKE YESTERDAY...THE NAM IS INITIALLY RUNNING
ABOUT 1 TO 2 INCHES TOO HIGH ON THEIR SNOW DEPTH. WE WILL HAVE TO
WATCH THIS PERIOD CLOSELY.

ARCTIC COLD FRONTS WILL MOVE QUICKLY SOUTHEAST ACROSS THE AREA ON
SUNDAY MORNING AND LATE SUNDAY NIGHT. THE 850 MB TEMPERATURES
BEHIND THE FIRST FRONT WILL FALL FROM A BALMY 8-14C AT 12Z SUNDAY
TO 0 TO -12C BY 00Z MONDAY...AND EVEN COLDER AIR MASS /-16 TO
-22C/ WILL MOVE INTO THE AREA BY 12Z MONDAY. HIGH TEMPERATURES
CURRENTLY RANGE FROM 8 TO 20F ON MONDAY. HOWEVER THE ECMWF SUGGEST
THAT THE TEMPERATURES WILL BE VERY SIMILAR TO WHAT THEY WERE THIS
AFTERNOON.

FROM WEDNESDAY NIGHT THROUGH THURSDAY...THE GFS AND ECMWF CONTINUE
TO DISAGREE ON WHETHER A LOW PRESSURE SYSTEM WILL AFFECT THE AREA
OR NOT. THE GFS KEEPS PERIODICALLY MOVING A LOW INTO THE AREA.
SOMETIMES IT IS LOCATED OF THE MID MISSISSIPPI RIVER VALLEY AND
OTHER TIMES TO THE NORTHWEST AND WEST OF THE AREA. MEANWHILE THE
ECMWF HAS KEPT HIGH PRESSURE ACROSS THE AREA. DUE TO THIS...MADE A
CHANGE TO THE MODEL CONSENSUS AND REMOVED THE 20 TO 30 PERCENT
PRECIPITATION CHANCES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY EVENING)
ISSUED AT 1130 AM CST THU NOV 27 2014

WEAK UPPER LEVEL SHORTWAVE TROUGH IS SLATED TO SLIDE ACROSS THE
UPPER MISSISSIPPI RIVER VALLEY ON TUE. RELATIVELY STRONG LOW LEVEL
WARM AIR ADVECTION LEADS IT IN...HELPING WITH AN INCREASING/LOWERING
CLOUD DECK...ALONG WITH HELPING POWER SOME AREAS OF -SN. CURRENT
MODEL TRENDS FAVOR KEEPING THE BULK OF THE ACCUMULATING SNOWS TO THE
NORTH. HOWEVER...BUFKIT SOUNDINGS AND RH FIELDS SUGGEST THERE COULD
BE A PERIOD OF MVFR CIGS LATE TONIGHT/FRI MORNING FOR
KRST/KLSE...AND PERHAPS SIMILAR VSBYS IN -SN. FOR NOW...WILL DROP
KRST INTO MVFR...BUT KEEP -SN IN THE FLURRY/P6SM CATEGORY. WILL HOLD
VFR FOR KLSE. CONDITIONS WILL BE MONITORED AND UPDATES MADE AS
NEEDED.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY
 FOR WIZ017.
MN...NONE.
IA...NONE.
&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION....RIECK



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