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000
FXUS63 KARX 122049
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
349 PM CDT SUN MAY 12 2013

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 345 PM CDT SUN MAY 12 2013

AT 3 PM...A RIDGE OF HIGH PRESSURE OVER WESTERN MINNESOTA KEPT
THE AREA MAINLY SUNNY. DESPITE MIXING UP TO 800 MB THIS AFTERNOON...
TEMPERATURES ONLY CLIMBED TO AROUND 50 IN NORTH CENTRAL WISCONSIN...
AND INTO THE LOWER AND MID 30S ACROSS THE REMAINDER OF THE AREA.

TONIGHT - THE COMBINATION OF LIGHT WINDS...MAINLY CLEAR SKIES...
AND LOW DEW POINTS WILL ALLOW TEMPERATURES TO FALL INTO THE MID
AND UPPER 20S ACROSS CENTRAL AND NORTH-CENTRAL WISCONSIN...AND
AROUND FREEZING FOR THE COUNTIES ALONG THE MISSISSIPPI RIVER AND
IN SOUTHWEST WISCONSIN. DUE TO THIS...WILL KEEP THE CURRENT
FROST AND FREEZE HEADLINES GOING.

MONDAY - A WARM FRONT WILL MOVE EAST ACROSS THE FORECAST AREA. AS
THIS OCCURS...MODERATE TO STRONG 800-600 MB FRONTOGENESIS WILL
DEVELOP ACROSS WESTERN WISCONSIN DURING THE AFTERNOON. IN
ADDITION...THERE WILL BE STRONG 290 TO 300K ISENTROPIC LIFT ALONG
AND NORTH OF INTERSTATE 94. THIS RESULTS IN THE 290-300K
CONDENSATION PRESSURE DEFICITS ONLY NEEDING 10 MB FOR SATURATION
ALONG AND NORTH OF INTERSTATE 94. DUE TO THIS...RAISED THE
PRECIPITATION CHANCES IN THESE AREAS UP INTO THE 50 PERCENT
RANGE...AND KEPT THE 40 PERCENT CHANCES GOING FOR AREAS SOUTH OF
THIS INTERSTATE. THIS IS MORE IN LINE WITH THE GFS. WITH ML CAPES
LESS THAN 40 J/KG...DID NOT MENTION ANY THUNDERSTORMS WITH THIS
FRONTAL PASSAGE.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 345 PM CDT SUN MAY 12 2013

ON MONDAY NIGHT...THE 12.12Z MODELS SHOW THAT THE 900 TO 700 MB
FRONTOGENESIS WILL MOVE QUICKLY EAST OUT OF THE FORECAST AREA
DURING THE EVENING. AS A RESULT...ONLY CARRIED A 20 TO 30 PERCENT
CHANCE OF SHOWER IN CENTRAL AND NORTH CENTRAL WISCONSIN DURING THE
EVENING.

ON TUESDAY...THE MAIN QUESTION IS HOW DEEP WILL THE AREA
ULTIMATELY MIX. THE GFS SUGGESTS THAT THE AREA WILL ONLY MIX TO
AROUND 900 MB. MEANWHILE THE NAM/WRF HAS THE AREA MIXING TO AROUND
850 MB. IF THE GFS IS CORRECT...HIGH TEMPERATURES WILL RANGE FROM
THE UPPER 70S TO MID 80S...WINDS WILL GUST UP INTO THE 20 TO 25
MPH RANGE...AND THE LOWEST RELATIVE HUMIDITIES WILL RANGE FROM
30 TO 40 PERCENT. IF THE NAM/WRF IS CORRECT...HIGH TEMPERATURES
WOULD RANGE FROM THE LOWER 80S TO LOWER 90S...WINDS WOULD GUST TO
AROUND 30 MPH...AND THE LOWEST RELATIVE HUMIDITIES WOULD RANGE
FROM THE TEENS TO MID 20S. THIS WILL GREATLY AFFECT THE FIRE
DANGER ACROSS THE AREA.  WITH NO CLEAR SIGN OF WHICH MODEL IS
CORRECT AND THE ECMWF TAKING MORE OF THE MIDDLE OF THE ROAD...WENT
WITH A BLEND OF ALL 3 MODELS.

ON TUESDAY AFTERNOON AND NIGHT...THE MAIN QUESTION WILL BE WHETHER
THERE WILL BE ANY SHOWER AND THUNDERSTORM DEVELOPMENT ALONG THE
COLD FRONT. BOTH THE GFS AND NAM GENERATE 2500 TO 3000 J/KG ML
CAPES AHEAD OF THIS FRONT. HOWEVER THEIR DEW POINTS ALSO LOOK WAY
TOO HIGH...SO THESE VALUES ARE LIKELY TOO HIGH. IN
ADDITION...THERE IS STRONG CAPPING BETWEEN 850 AND 700 MB AND THE
MODELS. THIS RESULTS IN CINS IN THE EXCESS OF 200 J/KG.
FINALLY...THE STRONGEST 925 MB AND 850 MB MOISTURE TRANSPORT IS
NORTH OF THE INTERSTATE 94 CORRIDOR. AS A RESULT...WENT WITH A
30 PERCENT CHANCE OF PRECIPITATION IN THIS AREA AND KEPT THE MUCH
OF THE REMAINDER OF THE FORECAST AREA DRY.

BEYOND THURSDAY...MUCH UNCERTAINTY EXISTS WITH BOTH TEMPERATURES
AND PRECIPITATION AS THE MODELS STRUGGLE WITH THE TIMING OF A
SHORT WAVE TROUGH MOVING EAST OUT OF THE DAKOTAS. WITH VERY LITTLE
MODEL CONSISTENCY...JUST STAYED WITH THE ALL BLEND DATA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1146 AM CDT SUN MAY 12 2013

GENERALLY QUIET VFR CONDITIONS ACROSS THE TAF SITES THIS AFTERNOON
THROUGH MONDAY MORNING AS COOL CANADIAN HIGH PRESSURE DRIFTS EAST
ACROSS THE UPPER MIDWEST. CLOUDS THIS PERIOD LOOK LIMITED TO A FEW
HIGH-BASED DIURNAL CUMULUS THIS AFTERNOON THEN SCT CIRRUS LATE
TONIGHT/MON MORNING. DIURNAL WARMING/MIXING TO PRODUCE NORTHWEST
WINDS 10-15KTS G20KTS THIS AFTERNOON...BECOMING LGT/VARIABLE AS THE
SFC RIDGE AXIS DRIFTS OVERHEAD TONIGHT...THEN SOUTH TO SOUTHWEST 8-
14KT ON THE BACK SIDE OF THE HIGH ON MONDAY. MON AFTERNOON WILL SEE
AN INCREASE OF MID LEVEL MOISTURE/CLOUDS AND A SMALL SHRA CHANCE AT
THE TAF SITES.

&&

.FIRE WEATHER...TUESDAY
ISSUED AT 345 PM CDT SUN MAY 12 2013

WITH THE DRY AND WINDY CONDITIONS OVER THE WEEKEND...MANY OF FINE
FUELS ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA HAVE DRIED
OUT. AS A RESULT...THERE CONTINUES TO BE CONCERN ABOUT CRITICAL
FIRE CONDITIONS ON TUESDAY. THE MAIN QUESTION IS HOW DEEP WILL THE
AREA ULTIMATELY MIX. THIS GREATLY AFFECTS HOW WARM THE
TEMPERATURES CLIMB...HOW LOW THE RELATIVE HUMIDITIES WILL
FALL...AND HOW HIGH THE WINDS WILL GUST. SINCE IT IS UNCLEAR YET...
WENT WITH A BLEND OF THE MODELS FOR NOW.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FROST ADVISORY FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ032-041-054-
     061.

     FREEZE WARNING FROM 1 AM TO 7 AM CDT MONDAY FOR WIZ017-029-033-
     034-042>044-053-055.

MN...FROST ADVISORY FROM 1 AM TO 7 AM CDT MONDAY FOR MNZ079-088-096.

IA...FROST ADVISORY FROM 1 AM TO 7 AM CDT MONDAY FOR IAZ011-030.

&&

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION.......RRS
FIRE WEATHER...BOYNE