Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 232045
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
345 PM CDT WED APR 23 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 345 PM CDT WED APR 23 2014

FOR LATE THIS AFTERNOON AND EVENING...THE 23.12Z MODELS ARE IN
VERY GOOD AGREEMENT THAT THE SHORT WAVE TROUGH CURRENTLY OVER
SOUTHEAST MINNESOTA WILL MOVE NORTHEAST INTO NORTHEAST WISCONSIN.
MEANWHILE ANOTHER NORTH WAVE TROUGH OVER NORTH CENTRAL IOWA
CURRENTLY WILL MOVE EAST ACROSS THE SOUTHERN THIRD OF WISCONSIN
AND NORTHERN ILLINOIS. THE HRRR...RAP...AND ARW SHOW THAT THE
RAIN CURRENTLY OVER SOUTHEAST MINNESOTA AND WEST CENTRAL WISCONSIN
WILL MOVE EAST NORTHEAST ACROSS CENTRAL AND NORTH CENTRAL
WISCONSIN. MEANWHILE THE RAIN ALONG AND EAST OF INTERSTATE 35
ASSOCIATED WITH THE SOUTHERN SHORT WAVE TROUGH WILL MARCH EAST
ACROSS THE REMAINDER OF THE FORECAST AREA.

FOR LATE TONIGHT AND THURSDAY...THE MODELS ARE IN GOOD AGREEMENT
THAT STRONG 850 MB MOISTURE TRANSPORT WILL MOVE INTO THE AREA
AHEAD OF AN APPROACHING SHORT WAVE TROUGH FROM THE NORTHERN
PLAINS. AS THIS OCCURS...THE RAIN WILL ONCE AGAIN BECOME
WIDESPREAD ACROSS THE AREA AFTER A BRIEF BREAK IN THE EVENING.
WITH PRECIPITABLE WATER VALUES CLIMBING INTO THE 1 TO 1.25 INCH
RANGE EXPECT ENHANCED THE RAIN RATES ACROSS THE AREA. A TOTAL OF
1 TO 1.5 INCHES OF RAIN LOOKS LIKELY ALONG AND NORTH OF INTERSTATE
90 AND AROUND AN INCH SOUTH OF THIS INTERSTATE. WITH MOST UNSTABLE
CAPES UP TO 250 J/KG ALONG AND SOUTH OF INTERSTATE 94...KEPT A
MENTION OF ISOLATED ELEVATED THUNDERSTORMS /ABOVE 2 KM/ IN THE
FORECAST. WHILE THE 2-6 KM SHEAR IS GREATER THAN 60 KNOTS...THIS
IS JUST TOO GREAT CONSIDERING THE INSTABILITY FOR ANY OF THESE
THUNDERSTORMS TO BECOME SEVERE.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 PM CDT WED APR 23 2014

ON THURSDAY NIGHT...THE 23.12Z MODELS ARE JUST A BIT SLOWER AT
MOVING THE STRONG 700 TO 500 MB FRONTOGENESIS AND THE 500 MB
SHORT WAVE THROUGH WESTERN WISCONSIN. DUE TO THIS...SLOWED DOWN
THE EXIT OF THE PRECIPITATION THROUGH THE AREA. WHILE TEMPERATURES
WILL COOL INTO THE MID 30S NORTH OF INTERSTATE 94...SOUNDINGS SHOW
NO ICE SEEDING FROM ALOFT...THUS KEPT THE PRECIPITATION IN THE
FORM OF RAIN.

FROM FRIDAY NIGHT INTO SATURDAY...THE MODELS CONTINUE TO SHOW THAT
A BACK DOOR CANADIAN COLD FRONT WILL PUSH SOUTH AND SOUTHWEST
THROUGH THE FORECAST AREA. MODERATE TO STRONG 900 TO 600 MB
FRONTOGENESIS DEVELOPS ALONG THIS FRONT OVER SOUTHERN WISCONSIN ON
FRIDAY NIGHT. THIS SATURATES THIS COLUMN IN BUFKIT SOUNDINGS. DUE
TO THIS...ADDED A SMALL CHANCE OF RAIN TO THE FORECAST.

FROM MONDAY NIGHT THROUGH WEDNESDAY...THE MODELS CONTINUE TO
STRUGGLE OF THEIR TRACK OF AN UPPER LEVEL LOW THROUGH THE MID AND
UPPER MISSISSIPPI RIVER VALLEY. AFTER DAYS WHERE THE GFS AND ECMWF
WERE AT ODDS WITH EACH OTHER...THEY CAME TO A CONSENSUS IN THE
23.00Z RUNS THAT THE LOW WOULD TRACK MORE OVER THE UPPER
MISSISSIPPI RIVER VALLEY. THIS WOULD PRODUCE ANOTHER 1 TO 1.5
INCHES OF RAIN ACROSS THE AREA. HOWEVER THE 23.12Z MODELS ARE NOW
SHOWING THAT THE HUDSON BAY HIGH WINDS OUT AND THAT THE UPPER
LEVEL LOW WILL MOVE EAST ACROSS THE MID MISSISSIPPI RIVER VALLEY.
THIS WOULD LEAVE THIS TIME PERIOD DRY. WITH THE MODELS CONTINUING
TO STRUGGLE WITH THE TRACK OF THE UPPER LEVEL LOW...CONFIDENCE IS
NOT THAT HIGH...THUS STAYED WITH THE MODEL CONSENSUS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1230 PM CDT WED APR 23 2014

MAIN AVIATION CONCERNS ARE LIFR AND IFR CONDITIONS AT BOTH RST AND
LSE TAF SITES TONIGHT INTO THURSDAY. LOW PRESSURE WILL PUSH INTO THE
CENTRAL PLAINS THIS AFTERNOON INTO THURSDAY AND SPREAD SHOWERS AND
POSSIBLY A THUNDERSTORM INTO THE AREA. FIRST IMPULSE EJECTING OUT
AHEAD OF THE LOW PRESSURE SYSTEM TO IMPACT THE TAF SITES THIS
AFTERNOON AND PRODUCE MAINLY SHOWERS. CEILINGS SHOULD REMAIN IN THE
VFR RANGE THROUGH THIS EVENING AT BOTH RST/LSE TAF SITES. INCREASING
MOISTURE OCCURS OVER THE REGION AFTER 03Z THURSDAY AND ALLOWS
CEILINGS TO LOWER AT BOTH TAF SITES...AS THE LOW PRESSURE SYSTEM
MOVES INTO THE CENTRAL PLAINS. THE 23.12Z GFS/NAM BUFKIT SOUNDINGS
SHOW CEILINGS LOWERING INTO THE IFR AND POSSIBLY LIFR RANGE BY 12Z
THURSDAY AT RST TAF SITE. FOR NOW LOWERED THE CEILINGS INTO THE
IFR RANGE AT RST BY 09Z THURSDAY...PER PREVIOUS TAF. LSE TAF SITE
APPEARS TO REMAIN IN THE MVFR RANGE WITH CEILING HEIGHTS LOWERING TO
AROUND 1500 FEET BY 12Z THURSDAY. THE 23.12Z GFS/NAM CONTINUE TO
INDICATE VERY LIMITED INSTABILITY ACROSS THE AREA THROUGH TAF
PERIOD. HAVE LEFT OUT MENTION OF ANY THUNDERSTORM POSSIBILITY AT
BOTH TAF SITES...DUE TO LOW CONFIDENCE ON WHERE ANY THUNDERSTORMS
COULD DEVELOP.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ



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