Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 052339
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
639 PM CDT TUE MAY 5 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM CDT TUE MAY 5 2015

AT 3 PM...LIGHT RAIN CONTINUES TO FALL ALONG AND SOUTH OF THE
INTERSTATE 90 CORRIDOR. HOURLY RAINFALL AMOUNTS ARE RANGING FROM
JUST A TRACE TO 0.05 INCHES PER HOUR. THIS RAIN IS BEING PRODUCED
BY 900 TO 800 MB FRONTOGENESIS AND A SURFACE WARM FRONT IN
NORTHERN IOWA. 05.12Z MODELS CONTINUE TO SHOW THAT THE WARM FRONT
WILL MOVE SLOWLY NORTH TO THE INTERSTATE 90 CORRIDOR TONIGHT AND
INTO CENTRAL MINNESOTA AND NORTHERN WISCONSIN ON WEDNESDAY. THIS
FRONTOGENESIS AND WARM FRONT WILL CONTINUE TO BE FOCUS OF RAIN.
WITH SOME DRIER AIR IN THE MID LEVELS MOVING INTO THE REGION
DURING IN THE WARM SECTOR OF THIS FRONT...THINKING THAT THIS AREA
COULD BE DRY MUCH OF WEDNESDAY. BOTH THE ARW AND NMM SUGGEST THIS
POSSIBILITY FOR MUCH OF THE DAY.

INSTABILITY LOOKS REALLY WEAK FROM TONIGHT INTO WEDNESDAY...BUT
WITH THE FRONT IN THE AREA AND 850 TO 700 MB LAPSE RATES IN THE 8
TO 10 C/KM RANGE...CANNOT COMPLETELY RULE OUT A THUNDERSTORM...SO
JUST KEPT AN ISOLATED STORM IN THE FORECAST.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 343 PM CDT TUE MAY 5 2015

FROM WEDNESDAY NIGHT INTO THURSDAY...THE 05.12Z MODELS CONTINUE TO
SHOW THAT THE AREA WILL BE LOCATED IN THE WARM SECTOR OF THE
SYSTEM. THERE CONTINUES TO BE MODERATE MOISTURE TRANSPORT INTO THE
AREA...BUT THE BEST CONVERGENCE REMAINS NORTH AND WEST OF THE
AREA SO THERE IS A POSSIBILITY THAT THIS PERIOD COULD BE DRY. THIS
IS ESPECIALLY THE CASE IN WESTERN WISCONSIN. AS A RESULT...KEPT
THE PRECIPITATION CHANCES THE LOWEST IN THESE AREAS.

ON THURSDAY NIGHT...THE COLD FRONT WILL MOVE EAST THROUGH THE
AREA. 0-1 KM MIXED LAYER CAPES CLIMB INTO THE 1 TO 2K RANGE AHEAD
OF THIS FRONT. LIKE THE PAST COUPLE OF DAYS...THE 0-6 KM SHEAR
REMAINS LESS THAN 30 KNOTS...SO NOT EXPECTING ANY SUPERCELLS.
HOWEVER WITH THE COLD FRONT PRODUCING LINEAR CONVECTION AND 0-3 KM
UP TO 40 KNOTS COULD NOT RULE SOME ISOLATED DAMAGING WIND.

FROM FRIDAY INTO SATURDAY...THE MODELS DIVERGE SOME. THE GFS
BUILDS A HIGH PRESSURE AREA INTO THE AREA. MEANWHILE THE GEM AND
ECMWF STALL THE FRONT TO OUR SOUTHEAST AND SEVERAL WAVES OF LOW
PRESSURE CONTINUE TO BRING ROUNDS PRECIPITATION INTO THE SOUTHEAST
PORTION OF THE FORECAST AREA. WITH QUITE A BIT OF UNCERTAINTY IN
THIS TIME FRAME...JUST STAYED WITH THE MODEL CONSENSUS.

FOR EARLY NEXT WEEK...THE GFS CONTINUES TO TRACK THE SURFACE LOW
TO OUR SOUTHEAST. MEANWHILE THE ECMWF HAS TRENDED A BIT FURTHER
NORTHEAST AND IT HAS PARTS OF SOUTHWEST WISCONSIN AND NORTHEAST
IOWA ENTERING THE WARM SECTOR OF THIS SYSTEM. DUE TO INCONSISTENT
SIGNALS IN THE TRACK AND EVEN TIMING...OPTED TO STAY WITH THE
MODELS CONSENSUS FOR NOW.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 639 PM CDT TUE MAY 5 2015

IFR/MVFR CONDITIONS ARE EXPECTED AT THE TAF SITES INTO MID
MORNING WEDNESDAY. A WARM FRONT WILL GRADUALLY LIFT NORTH ACROSS
THE TAF SITES TONIGHT INTO WEDNESDAY PRODUCING PERIODS OF LIGHT
RAIN SHOWERS TONIGHT AND CEILINGS OF 400-700 FT AT KRST AND 900
TO 1200 FT AT KLSE. VISIBILITIES WILL ALSO BE REDUCED TO AROUND 2
SM AT TIMES IN BR. LOOK FOR CONDITIONS TO IMPROVE MID MORNING ON
WEDNESDAY AS THE WARM FRONT SHIFTS TO THE NORTH OF THE TAF SITES.
SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE AT THE TAF SITES
WEDNESDAY AFTERNOON BUT CONFIDENCE WASN/T HIGH ENOUGH TO INCLUDE
THEM IN THE TAF YET...WILL BE KEEPING A CLOSE EYE ON THIS
POTENTIAL. WINDS WILL INCREASE TO 12 TO 16 KTS LATE WEDNESDAY
MORNING INTO WEDNESDAY AFTERNOON WITH GUSTS OF 20 TO 27 KTS
POSSIBLE. THE STRONGEST WINDS ARE EXPECTED AT KRST.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...WETENKAMP



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