Area Forecast Discussion
Issued by NWS La Crosse, WI

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000
FXUS63 KARX 100455
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1155 PM CDT WED APR 9 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM CDT WED APR 9 2014

SHORT TERM FORECAST FOCUSED ON PRECIPITATION CHANCES ASSOCIATED
WITH FRONTAL PASSAGE OVERNIGHT.

LATEST WATER VAPOR IMAGERY OVERLAID WITH 500MB RAP HEIGHTS SHOWS
DEEP TROUGH MARCHING OFF THE SOUTHEAST US COAST WITH UPSTREAM
RIDGING EXTENDING WEST OF THE MISSISSIPPI RIVER TO THE WEST
COAST. IN THE PAST 24 HOURS THIS RIDGE HAS BROKEN
DOWN...INDICATING A CHANGE IN OUR WEATHER PATTERN IN THE DAYS TO
COME. TWO SHORTWAVE TROUGHS OF INTEREST ARE SKIRTING ACROSS THE
US/CANADIAN BORDER FROM NORTH DAKOTA WESTWARD TO NORTHWEST
MONTANA. AT THE SURFACE...A COLD FRONT IS PUSHING ACROSS THE
NORTHWEST HALF OF NORTH DAKOTA. ITS A WARM...BREEZY AFTERNOON AS
READINGS HAVE PUSHED INTO THE 60S...BRUSHING 70 DEGREES ACROSS
SOUTHERN MN / NORTHERN IA.

MILD SOUTHWESTERLY FLOW ON TAP THIS EVENING AHEAD OF THE
AFOREMENTIONED COLD FRONT. WITH INCREASED CLOUD COVER AND THE MILD
AIRMASS...LOWS TONIGHT LOOK TO RANGE FROM MIDDLE 40S TO NEAR 50.

EXCELLENT MODEL AGREEMENT IN THE COLD FRONTAL PASSAGE...BETWEEN
06Z AND 12Z ACROSS THE AREA. COMBINATION OF UPPER LEVEL PV
ADVECTION AND MID LEVEL FRONTOGENESIS WILL SUPPORT THE CHANCE OF
SHOWERS. THE GREATEST FORCING EXISTS FROM CENTRAL MINNESOTA INTO
CENTRAL AND NORTH CENTRAL WISCONSIN. A LOOK AT THE HI-RES MODELS
SUGGESTS LIGHT ACTIVITY ALONG THE MN/IA BORDER AS WELL. THE MAIN
LIMITING FACTOR IS THE DRIER AIRMASS IN PLACE...AND FEEL THAT A
LOT OF THE FORCING/LIFT WILL GO INTO SATURATION
INITIALLY...LIMITING QPF. AT THE SAME TIME...ITS PASSAGE DURING
THE NIGHT WILL LIMIT ANY TSTORM POTENTIAL LOCALLY...WITH
INSTABILITY WANING AND MAINLY LIMITED NORTHWEST OF THE AREA FOR
THIS EVENING. WILL MAINTAIN HIGHER POPS ALONG AND NORTHEAST OF
I-94.

BY THURSDAY MORNING...THE NORTHWEST HALF OF THE FORECAST AREA
LOOKS TO BE DRY WITH ANY REMAINING SHOWERS CONFINED TO SOUTHWEST
INTO CENTRAL WISCONSIN. COOL CANADIAN HIGH PRESSURE QUICKLY BUILDS
IN...THOUGH ITS AIRMASS WILL BE MODIFIED A BIT. NOT EXPECTING TOO
MUCH OF A TEMPERATURE DROP TOMORROW...AND SHOULD BE A PLEASANT
AFTERNOON FOR MOST. HIGHS MIDDLE 50S TO LOWER 60S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 328 PM CDT WED APR 9 2014

MANY FEATURES TO FOCUS ON IN THE LONG TERM...BUT THE BIG PICTURE
IS THAT PRECIPITATION CHANCES WILL BE ON THE INCREASE STARTING
SATURDAY FOLLOWED BY A RETURN TO MUCH BELOW NORMAL TEMPERATURES
INTO EARLY NEXT WEEK. LOOKS LIKE AN ACTIVE WEATHER
PATTERN...ESPECIALLY FOR THE SOUTHERN HALF OF THE FORECAST AREA.

ANOTHER SHORTWAVE TROUGH MOVES THROUGH DURING THE DAY
FRIDAY...YET MODEL DIFFERENCES ARE MORE PRONOUNCED WITH THIS
FEATURE. MAINLY STRENGTH AND TIMING DIFFERENCES...WITH THE
GFS/NAM/GEM CAMP A FASTER AND DRIER SOLUTION. THIS WOULD RESULT IN
PRECIPITATION CHANCES CONFINED ALONG AND NORTH OF I-90 WHILE THE
09.12Z ECMWF HAS BETTER SATURATION WHICH PAINTS LIGHT QPF ACROSS
MUCH OF THE AREA. LOOKS TO BE ENOUGH WEAK INSTABILITY TO WARRANT
AN ISOLATED THUNDER MENTION. PUSHED HIGHER CHANCES IN THE
NORTHWEST HALF...MAINLY IN THE 12-18Z TIME FRAME.

NEXT SHORTWAVE TROUGH SLATED TO ARRIVE SATURDAY MORNING AS AN
AREA OF LOW PRESSURE DEVELOPS ACROSS THE NORTHERN PLAINS. THIS
FEATURE IS MUCH STRONGER WITH ITS UPPER LEVEL SUPPORT AND LOW
LEVEL MOISTURE RETURN FROM THE GULF OF MEXICO. 09.12Z GUIDANCE IN
REASONABLE AGREEMENT WITH HIGHER CHANCES SATURDAY MORNING WEST OF
THE AREA...BUT MOVE IN DURING THE DAY. THE GFS IS A FAST OUTLIER
WHILE THE GEM/ECMWF AND THE NAM TO SOME DEGREE HOLD THE COLD FRONT
BACK THROUGH 00Z SUNDAY WITH CONVECTION REDEVELOPING ON THE
BOUNDARY. AS THIS NORTHERN / INITIAL WAVE MOVES OFF SATURDAY
NIGHT...A SECONDARY SOUTHERN LOW PRESSURE DEVELOPS ACROSS
OKLAHOMA AND KANSAS SUNDAY INTO SUNDAY NIGHT...THEN LIFTING
THROUGH MID MISSISSIPPI RIVER VALLEY. PREVIOUS RUNS HAD
DIFFERENCES IN WHERE THE WAVE EJECTS...PUTTING THE LOCAL AREA ON
THE COLDER...NORTHWEST FRINGE. THIS TREND SEEMS TO HAVE CONTINUED
IN THE 09.12Z GUIDANCE. THE HIGHER CHANCES FOR THE LATTER HALF OF
THE WEEKEND INTO MONDAY MORNING WILL BE CONFINED SOUTHEAST OF A
CHARLES CITY IOWA TO LA CROSSE TO NEILLSVILLE WISCONSIN LINE.
SOME REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS COULD PRODUCE
HEALTHY QPF AMOUNTS /0.75 TO 1.5 IN/ ACROSS NORTHEAST IOWA INTO
SOUTHWEST WISCONSIN...RESULTING IN SOME MINOR RISES ON AREA
RIVERS...CREEKS...AND TRIBUTARIES.

TEMPERATURE WISE...DESPITE THE CLOUD COVER AND THREAT OF
PRECIPITATION FRIDAY AND SATURDAY READINGS ARE EXPECTED TO CLIMB
INTO THE 60S. FRIDAY WILL LIKELY BE A TAD WARMER...MIDDLE TO
UPPER 60S AND THEN A FEW DEGREES LESS ON SATURDAY.

THE CORE OF THE COLD AIR ARRIVES MONDAY MORNING AS 850 MB
TEMPERATURES CRASH TO THE -5 TO -7C RANGE...FALLING TO AROUND -10C
TUESDAY THROUGH WEDNESDAY. THIS SUPPORTS HIGHS IN THE MIDDLE 40S
AND LOWS IN THE 20S TO LOWER 30S. NORMAL HIGHS/LOWS ARE MID TO
UPPER 50S/MID 30S...SO GET EXCITED FOR ANOTHER STRETCH OF
UNSEASONABLY COOL DAYS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1151 PM CDT WED APR 9 2014

FRONT MOVING RAPIDLY ACROSS MN AND WILL CROSS THE TAF LOCATIONS
OVERNIGHT. WIND WILL SWITCH TO THE NORTHWEST BEHIND IT. WILL BE A
LITTLE BIT BREEZY AGAIN TOMORROW...BUT NOT AS MUCH AS IT WAS
WEDNESDAY. OTHER CONCERN IS SHOWER CHANCES ALONG THE PASSING
FRONT. RADAR SHOWS SOME RETURNS...BUT NOT MUCH MAKING IT TO THE
GROUND. MAINTAINED THE VCSH IN THE TAFS...BUT NO MVFR RESTRICTION
ANTICIPATED.

&&

.FIRE WEATHER...
ISSUED AT 715 PM CDT WED APR 9 2014

SEVERAL GRASS FIRES HAVE OCCURRED OVER A PART OF WESTERN WI IN THE
PAST 3-5 HOURS. ONE LARGE FIRE OVER NORTH END OF FORT MCCOY CAN BE
EASILY SEEN IN RADAR AND SATELLITE IMAGERY. FIRE ALSO APPARENT
NEAR FOUR CORNERS WITH SUBTLE CLUES ON BOTH RADAR AND SATELLITE.
ANOTHER FIRE REPORTED BY LAW ENFORCEMENT NEAR NORWALK. WITH
SUNSET...WINDS WILL DIMINISH A LITTLE...AND HUMIDITY WILL
INCREASE. THIS SHOULD ALLOW CREWS TO GET AHEAD OF THE FIRES.
MEANWHILE...RED FLAG WARNING WEST OF THE MISSISSIPPI RIVER ALLOWED
TO EXPIRE ON SCHEDULE AT 7 PM WITH THE DIMINISHING WIND AND
INCREASING HUMIDITY.

WILL HAVE TO MONITOR FIRE CONDITIONS FOR THURSDAY AS WELL. ANY
RAIN TONIGHT WILL BE SPOTTY AND LIGHT...AND WINDS WILL BE GUSTY
AGAIN BUT FROM THE NORTHWEST. TEMPERATURES WILL BE A LITTLE LOWER
SO FIRE RISK PERHAPS NOT QUITE AS HIGH...BUT STILL WILL NEED TO BE
WATCHED.

&&

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

$$

SHORT TERM.....ZT
LONG TERM......ZT
AVIATION...MW
FIRE WEATHER...MW



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