Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 271900
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
200 PM CDT WED MAY 27 2015

.SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 200 PM CDT WED MAY 27 2015

WATER VAPOR IMAGERY THIS AFTERNOON SHOWS A DEPARTING MID-LEVEL
TROUGH OVER THE GREAT LAKES REGION WHILE A RIDGE OF HIGH PRESSURE
WAS BUILDING IN FROM THE PLAINS. NICE LOOP OF THE EXPERIMENTAL 1-MIN
GOES-14 RAPID SCAN SHOWS BACK EDGE OF DEFORMATION CLOUD FROM
DEPARTING WAVE EXITING EAST OF CENTRAL WI WHILE SCATTERED-BROKEN
CUMULUS FIELD WAS EXPANDING WITH DAYTIME HEATING ACROSS NORTHEAST IA
INTO SOUTHWEST/CENTRAL WI. OTHERWISE...A VERY NICE DAY IN PLACE WITH
TEMPERATURES RANGING FROM THE UPPER 60S ACROSS NORTH CENTRAL WI...TO
THE LOWER/MIDDLE 70S ELSEWHERE ACROSS THE FORECAST AREA.

WILL HAVE TO WATCH A WEAK FRONTAL BOUNDARY COMING THROUGH NORTHERN
WI EARLY ON THIS EVENING WHICH MAY SPARK A FEW SHOWER/ISOLATED
THUNDERSTORMS...MAINLY NORTH OF I-94. OTHERWISE...HIGH PRESSURE WILL
DOMINATE THE WEATHER SCENE LATER TONIGHT THROUGH MUCH OF THURSDAY
FOR A BRIEF RESPITE FROM THE WET WEATHER PATTERN. LOOK FOR LOWS
TONIGHT RANGING FROM THE MID 50S ACROSS THE SAND COUNTRY OF CENTRAL
WI...TO THE UPPER 50S/NEAR 60 ELSEWHERE. THERE WILL BE A NOTICEABLE
INCREASE IN MID/HIGH CLOUD CLOVER FROM WEST TO EAST BY THURSDAY
AFTERNOON IN RESPONSE TO WARM AIR ADVECTION/ISENTROPIC LIFT ACROSS
THE PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. HOWEVER...LOOKS
LIKE ANY SHOWER ACTIVITY SHOULD HOLD OFF TO THE WEST AND NORTH OF
THE AREA AS HIGH PRESSURE HOLDS. LOOK FOR HIGHS THURSDAY TOPPING OFF
IN THE UPPER 70S TO THE MIDDLE 80S.

LIKELIHOOD OF SHOWERS AND THUNDERSTORMS OVERSPREAD THE AREA FROM WEST
TO EAST BY LATE THURSDAY NIGHT IN RESPONSE TO INCREASING 850MB
MOISTURE TRANSPORT/LIFT AHEAD OF A COLD FRONT PUSHING OUT OF THE
NORTHERN PLAINS INTO MN. OVERNIGHT LOWS IN THE WARM AIR ADVECTION
ARE EXPECTED TO ONLY FALL INTO THE 60-65 DEGREE RANGE.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 200 PM CDT WED MAY 27 2015

FOR FRIDAY THROUGH FRIDAY NIGHT...WILL SEE A COLD FRONT DROP SLOWLY
SOUTHEAST ACROSS THE REGION WITH AMBIENT MOISTURE TO WORK WITH FOR
WIDESPREAD SHOWER/THUNDERSTORMS. CAPE WILL BE RATHER LIMITED FOR ANY
SEVERE THREAT DUE TO ONGOING CONVECTION/CLOUD COVER...BUT RAINFALL
MAY GET A BIT HEAVY AT TIMES GIVEN PRECIPITABLE WATER VALUES
CREEPING INTO THE 1.6-1.8 INCH RANGE. GIVEN THE RECENT RAINFALL AND
FAIRLY WE GROUND...WILL SEE AN INCREASED HYDROLOGY CONCERN. SEE
HYDROLOGY DISCUSSION BELOW FOR DETAILS. OTHERWISE...APPEARS
TEMPERATURES AHEAD OF THE FRONTAL PASSAGE FRIDAY WILL BE HELD DOWN
SOME BY CLOUDS/ONGOING CONVECTION. RIGHT NOW...APPEARS HIGHS WILL
TOP OFF IN THE 70S.

AFTER SOME LINGERING SHOWER/ISOLATED THUNDER CHANCES SATURDAY
MORNING...LOOK FOR COOLER/DRY WEATHER THROUGH THE WEEKEND AS
CANADIAN HIGH PRESSURE DRIFTS ACROSS THE REGION. PLAN ON HIGHS
SATURDAY AND SUNDAY IN THE LOWER/MIDDLE 60S.

LATEST ECMWF AND GFS HOLD RIDGE ACROSS THE AREA THROUGH TUESDAY
NIGHT FOR DRY AND WARMING CONDITIONS. LOOK FOR HIGHS MONDAY IN THE
UPPER 60S/LOWER 70S...WARMING INTO MIDDLE 70S ON TUESDAY.

NEXT CHANCE OF SHOWERS/THUNDERSTORMS APPEARS TO BE WEDNESDAY AS THE
RIDGE BEGINS TO BREAK DOWN...ALLOWING SHORTWAVE TROUGH ENERGY TO
APPROACH FROM THE PLAINS. PLAN ON HIGHS IN THE 75-80 DEGREE RANGE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1205 PM CDT WED MAY 27 2015

GOOD VFR CONDITIONS EXPECTED THIS TAF PERIOD AS A WEAK RIDGE OF HIGH
PRESSURE AT THE SFC AND ALOFT...AND A DRIER LOW/MID LEVEL AIRMASS...
MOVE EAST ACROSS THE UPPER MIDWEST. A WEAK FRONT SLIDING THRU THE
AREA LATE THIS AFTERNOON MAY TRIGGER AN ISOLATED SHRA OR TSRA...BUT
COVERAGE/CHANCE TOO SMALL TO INCLUDE IN TAFS FOR NOW.

GIVEN ALL THE RECENT RAINS AND NOW RATHER MOIST LANDSCAPE...
CONSIDERED A BR MENTION IN BOTH KRST/KLSE TAFS IN THE 09Z-13Z TIME
FRAME. HOWEVER ALSO LEFT THAT OUT FOR NOW...AS TEMP-DEW POINT
SPREADS LATE TONIGHT LOOK TO REMAIN IN THE 5F OR MORE RANGE...ALONG
WITH SOME HIGH CLOUDS SPILLING ACROSS THE REGION. GRADIENT TIGHTENS
A BIT LATE TONIGHT AS WELL...FOR SFC WINDS IN THE 5-8KT RANGE AROUND
SUNRISE TO KEEP THE BOUNDARY LAYER MIXED.

&&

.HYDROLOGY...(THURSDAY NIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 200 PM CDT WED MAY 27 2015

SLOW COLD FRONTAL PASSAGE WILL PROVIDE THE MECHANISM FOR MORE
RAINFALL THURSDAY NIGHT THROUGH FRIDAY NIGHT. WITH PRECIPITABLE
WATER VALUES AHEAD OF THE FRONT INCREASING INTO THE 1.7-1.8 INCH
RANGE...EXPECTING SOME OF THIS RAINFALL TO BE ON THE HEAVIER SIDE.
RIGHT NOW...HAVE TOTAL FORECAST RAINFALL FROM MAINLY THURSDAY NIGHT
THROUGH FRIDAY NIGHT IN THE 1-1.5 INCH RANGE. RIVERS HAVE BEEN
FEELING THE RECENT HEAVIER RAINFALL WITH SOME MODERATE RESPONSES.
WITH THIS ADDITIONAL FORECASTED RAINFALL AMOUNT...WILL HAVE TO WATCH
FOR ADDITIONAL RISES. NOT THINKING FLOODING AT THIS POINT...BUT
DEFINITELY WITHIN BANK RISES. WILL CONTINUE TO MONITOR.

&&

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

$$

SHORT TERM...DAS
LONG TERM....DAS
AVIATION.....RRS
HYDROLOGY....DAS


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