Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 192010
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
310 PM CDT SUN OCT 19 2014

.SHORT TERM...(THIS AFTERNOON THROUGH MONDAY)
ISSUED AT 310 PM CDT SUN OCT 19 2014

SURFACE ANALYSIS SHOWING A WARM FRONT RUNNING NORTH-SOUTH THROUGH
CENTRAL MN INTO A DEEPENING SURFACE LOW NEAR KINL. THE FRONT THEN
EXTENDS NORTHWEST TO LAKE WINNIPEG AS A STATIONARY FRONT WITH COLD
AIR EAST. THE SURFACE CYCLONE IS MOST CLOSELY ASSOCIATED WITH THE
STRONGEST SHORTWAVE TROUGH SOUTH OF LAKE WINNIPEG WHERE
TROPOPAUSE FOLDS DOWN TO NEARLY 750 MB /PER RAP ANALYSIS/...PRETTY
IMPRESSIVE. WATER VAPOR IMAGERY SHOWS WEAKER TROUGH ENERGY MOVING
THROUGH WISCONSIN AT THIS TIME WITH SHORTWAVE TROUGH CURL IN
NORTH-CENTRAL WI 20Z. THE MAIN WATER VAPOR SIGNAL IS VERY DRY AIR
BEHIND THIS FIRST TROUGH...NOT MAKING IT EASY FOR FOR THE STRONGER
LAKE WINNIPEG TROUGH TO CREATE PRECIPITATION ALONE WITHOUT LOW-
LEVEL HELP. MOST OF THE PRECIPITATION WITH THIS SYSTEM IN SRN
CANADA IS EAST OF THE FRONT AND CYCLONE IN VERY LOW CLOUD. THIS
ENTIRE SYSTEM WAS SHIFTING SOUTHEAST TOWARD THE CENTRAL GREAT
LAKES.

WILL BE CLEARING THE SPRINKLES IN THE FORECAST EAST IN THE NEXT
HOURS...AND CLEARING SKIES AS THE WI SHORTWAVE TROUGH PASSES. AIR
MASS IS VERY DRY IN THIS FORCING /PER KMPX AND KGRB 12Z
RAOBS/...BUT SOME STEEPER LAPSE RATES AROUND 7-7.5C/KM IN MID-
LEVELS IS CAUSING 10KFT SHOWERS TO DEVELOP. ONLY HIT AND MISS
SPRINKLES HITTING THE GROUND.

WARM FRONT WILL CONTINUE TO SHIFT IN THIS EVENING AND CYCLONE
WILL PASS THROUGH THRU GREAT LAKES OVERNIGHT. QG FORCING ALOFT
INCREASES OVERNIGHT WITH THE LAKE WINNIPEG SHORTWAVE TROUGH...BUT
THE MORE SUBSTANTIAL DEEPER LIFT REMAINS CLOSER TO THE SURFACE
CYCLONE TRACK - MORE FOR THE NRN GREAT LAKES. AIR MASS IN PLACE
WITH THE FORCING COMING OVER THE FORECAST AREA SUGGESTS NO
WEATHER.

COLD AIR PUSH DIVES INTO WISCONSIN AND GREAT LAKES POST-LOW ON
MONDAY..BRINGING LOWER OVERCAST WITH IT. THE FRONT WILL LIE UP
THROUGH WESTERN WISCONSIN WITH LOWER CLOUDS AND SOME VERY LOW CAPE
EAST OF THE FRONT ACROSS WI. THERE MAY BE SOME SPRINKLES AROUND
NRN-ERN WI MONDAY...HAVE NOT ADD THOSE TO THE FORECAST HOWEVER.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 310 PM CDT SUN OCT 19 2014

MONDAY NIGHT-WEDNESDAY...RIDGE BUILDING WILL DOMINATE THIS PERIOD
WITH CLEARING SKIES MONDAY NIGHT. SOME RIVER VALLEY FOG IS
POSSIBLE WEDNESDAY MORNING...BUT SOME SUGGESTION OF WINDS AT THE
TOP OF THE BOUNDARY LAYER COULD BE LIMITING. WILL ADD PATCHY RIVER
VALLEY FOG TO FORECAST FOR NOW.

WEDNESDAY NIGHT THROUGH SATURDAY...
PREDICTABILITY TAKES A NOTICEABLE DROP AFTER WEDNESDAY AS SEEN IN
THE SPREAD OF DETERMINISTIC MODEL GUIDANCE. IN THE LONG WAVE
PATTERN...COMPLEX READJUSTMENT IS OCCURRING IN THIS PERIOD WITH A
A DEEP CLOSED LOW OVER THE EASTERN U.S. AND CENTRAL RIDGING.

WILL CONTINUE TO USE A BLENDED DETERMINISTIC FORECAST FOR RAIN
CHANCES FOR WEDNESDAY NIGHT AND THURSDAY AS IT APPEARS THE
CONSENSUS CONTINUES FOR A SOUTHERLY RETURN FLOW OF MOISTURE AND
SOME WEAK FORCING. SMALL RAIN CHANCES IN THE 30 PERCENT RANGE FOR
NOW ON WED NIGHT AND THURSDAY ARE CONTINUED UNTIL MORE CONFIDENCE
CAN BE BUILT IN THE SIGNAL.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1229 PM CDT SUN OCT 19 2014

A WARM FRONT WAS PUSHING EAST THROUGH THE REGION EARLY THIS
AFTERNOON. PRETTY GOOD AMOUNT OF MID-LEVEL/ALTOSTRATUS CLOUDINESS
ACROSS THE AREA WITH BASES IN THE 12-15KFT RANGE ASSOCIATED WITH
THE WARM AIR ADVECTION. THIS CLOUD IS EXPECTED TO PUSH EAST OF THE
KRST/KLSE TAF SITES BY 23Z WITH SKIES BECOMING CLEAR. BREEZY
SOUTH/SOUTHWEST WINDS BEHIND THE WARM FRONT EXPECTED TO TAPER WITH
SUNSET/LOSS OF SURFACE HEATING. A COLD FRONT WILL THEN MOVE
THROUGH THE AREA LATE THIS EVENING/OVERNIGHT...SHIFTING THE WINDS
TO THE NORTHWEST. WINDS ARE EXPECTED TO REMAIN AROUND 10 KT
THROUGH THE OVERNIGHT HOURS. MODELS THEN INDICATING MAINLY VFR
STRATOCUMULUS ROTATING SOUTHWARD INTO THE KRST/KLSE TAF SITES BY
12Z...BECOMING BROKEN AT KLSE BY 15Z.

&&

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

$$

SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...BOYNE


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