Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KARX 232340
AFDARX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
640 PM CDT SUN AUG 23 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 312 PM CDT SUN AUG 23 2015

CHALLENGES THROUGH MONDAY INCLUDE CLOUD COVER...TEMPERATURES AND
WIND STRENGTH. SOME DIFFERENCES EMERGE BETWEEN 23.12Z GFS/NAM
CONCERNING DEPTH OF MIXED LAYER MONDAY AFTERNOON. OTHERWISE...
GLOBAL MODEL SUITE IN GOOD OVERALL AGREEMENT AND WILL FOLLOW A
BLENDED APPROACH FOR THE FORECAST.

FOR TONIGHT...A STRONG SURFACE LOW CURRENTLY OVER SOUTHWEST
ONTARIO WILL SLIDE EASTWARD...ALLOWING LARGE STRATOCU FIELD ACROSS
MUCH OF WI AND NORTHERN MN TO SLOWLY PUSH EAST. SHOULD SEE FAIR
AMOUNT OF CLEARING SOUTH AND WEST OF THE I-94 CORRIDOR OVERNIGHT
WITH LOSS OF SOLAR. TO THE NORTH AND EAST ACROSS NORTHERN WI...
CLOUDS LIKELY TO HOLD FOR MUCH OF THE NIGHT. TEMPERATURES TONIGHT
WILL FALL INTO THE 40S MOST LOCATIONS...EXCEPT THE VALLEY FLOORS
WHERE LOWER 50S WILL BE COMMONPLACE. DESPITE LIGHT NORTHWEST
WINDS...DRY AIR MASS AND STRONGER WINDS IMMEDIATELY OFF THE
SURFACE WILL PROHIBIT ANY FOG FORMATION.

FOR MONDAY...EXPECT TO SEE FAIR AMOUNT OF CUMULUS REDEVELOPMENT
WITHIN CYCLONIC FLOW ALOFT ALONG AND EAST OF THE MS RIVER LATE
MORNING AND AFTERNOON AS CONVECTIVE TEMPERATURES ARE REACHED.
23.12Z GFS SHOWS THE AFTERNOON BOUNDARY LAYER MIXING TO BETWEEN
5000 AND 6000 FT AGL...WHEREAS THE NAM IS NOT AS BULLISH UP TO
4000 FT AGL. THIS DIFFERENCE RESULTS IN A MIXED LAYER MAXIMUM WIND
SPEED DIFFERENCE OF ABOUT 10 KTS...25 TO 30 KTS FROM THE NAM AND
35 TO 40 KTS FROM THE GFS. THINK THE GFS IS TOO DEEP WITH ITS
MIXED LAYER...SO WILL LEAN TOWARD THE UPPER END OF THE NAM
GUIDANCE. THIS RESULTS IN NORTHWEST SURFACE WIND FROM 15 TO 25 MPH
WITH FREQUENT GUSTS UP TO 35 MPH...A BREEZY DAY FOR SURE BUT SUB-
ADVISORY. A REINFORCING SHOT OF COOLER AIR ROTATES AROUND
DEPARTING LOW TONIGHT THROUGH MONDAY...KEEPING TEMPERATURES
SIMILAR TO TODAY DESPITE A BIT MORE SUNSHINE. EXPECT HIGHS TO
RANGE FROM THE MID-UPPER 50S ACROSS NORTHERN WI TO NEAR 70
DEGREES ACROSS NORTHEAST IA INTO SOUTHWEST WI.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 312 PM CDT SUN AUG 23 2015

MONDAY NIGHT THROUGH THURSDAY WILL BE PARTLY TO MOSTLY SUNNY AND
DRY AS A STRONG 500 HPA RIDGE BUILDS ACROSS THE ROCKIES AND
SPILLS INTO THE UPPER MIDWEST. AFTER ONE MORE BREEZY DAY ON
TUESDAY WITH NORTHWEST WINDS FROM 10 TO 15 MPH...EXPECT A RETURN
TO A LIGHTER WIND REGIME AS SURFACE PRESSURE GRADIENT RELAXES
WITH HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS INTO THE
GREAT LAKES REGION. TEMPERATURES TUESDAY THROUGH THURSDAY WILL
RISE SLIGHTLY EACH DAY AS THERMAL RIDGE PUSHES EAST...BUT WILL
REMAIN BELOW LATE AUGUST NORMALS WITH DAILY HIGHS BY THURSDAY INTO
THE MID TO UPPER 70S. CONCURRENT OVERNIGHT LOWS WILL ALSO RISE A
BIT EACH DAY...REACHING THE UPPER 40S TO LOWER 50S BY THURSDAY
MORNING.

THE NEXT BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE LATE
THURSDAY NIGHT AND CONTINUE THROUGH FRIDAY INTO PARTS OF SATURDAY
AS MEDIUM RANGE GUIDANCE HINTS AT A BAGGY EASTERN PACIFIC TROUGH
UNDERCUTTING THE WESTERN CONUS RIDGE AND MOVING INTO THE UPPER
MIDWEST. OVERALL LOW CONFIDENCE OF TIMING AND SPATIAL DISTRIBUTION
OF CONVECTION GIVEN MUCH WETTER ECMWF/GEM COMPARED TO THE DRIER
GFS. FOR NOW...SUPERBLEND 20 TO 40 POPS SEEM REASONABLE. DRY
CONDITIONS TO RETURN LATE NEXT WEEKEND WITH HIGHS BY SUNDAY
POSSIBLY BREAKING THE 80 DEGREE MARK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 640 PM CDT SUN AUG 23 2015

GENERALLY VFR WEATHER EXPECTED AS UPPER LOW SLOWLY RETREATS IN
ONTARIO. AREA TO BE IMPACTED BY WRAP AROUND HIGH BASED STRATUS AND
GRADIENT THAT WILL KEEP WINDS RATHER STRONG AGAIN MONDAY.

VFR CEILINGS HAVE LIFTED NORTH AND EAST OF KLSE AS OF 23.23Z...AND
THIS TREND EXPECTED TO CONTINUE MUCH OF TONIGHT. STILL TAF SITES
WILL BE NEAR EDGE OF CLOUDS AND MAY BE BATTLING SOME OCCASIONAL
CEILINGS MOVING BACK IN. BASED ON MPX SOUNDING AND SHORT TERM
GUIDANCE...BULK OF MOISTURE IS IN 700-850 MB LAYER AND THIS IS
EXPECTED TO SHIFT BACK SOUTH ON MONDAY...ESPECIALLY ON WISCONSIN
SIDE OF AREA. WILL KEEP SCATTERED IDEA FOR CLOUDS UNTIL AFTERNOON
HOURS MONDAY WHERE CEILINGS SHOULD MOVE BACK IN.

&&

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

$$

SHORT TERM...ROGERS
LONG TERM...ROGERS
AVIATION...SHEA



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.