041
FXUS63 KARX 090455
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1155 PM CDT THU MAY 8 2025
KEY MESSAGES
- AREAS OF FROST IN PORTIONS OF WESTERN WI OVERNIGHT INTO FRIDAY
MORNING. PORTIONS OF WEST-CENTRAL WI MAY FALL BELOW THE
FREEZING MARK.
- TRENDING WARMER THROUGH THE WEEKEND AND INTO NEXT WEEK WITH
WIDESPREAD HIGH TEMPERATURES IN THE UPPER 70S TO MIDDLE 80S.
- SMALL SHOWER CHANCES (15-20%) FRIDAY EVENING AND ON TUESDAY.
MORE SUBSTANTIAL PRECIPITATION CHANCES (20-45%) FOR THE
SECOND HALF OF NEXT WEEK.
DISCUSSION
ISSUED AT 155 PM CDT THU MAY 8 2025
REST OF TODAY - FRIDAY NIGHT: AREAS OF FROST FRIDAY MORNING, SMALL
SHOWER CHANCES LATE FRIDAY EVENING
HARD PRESSED TO FIND A CLOUD ON SATELLITE IMAGERY THIS AFTERNOON AS
SURFACE HIGH PRESSURE CONTINUES TO SLIDE INTO THE LOCAL AREA.
GENERALLY LIGHT EASTERLY SURFACE FLOW HAS KEPT TEMPERATURES MORE
SEASONABLE TODAY WITH AFTERNOON HIGHS GENERALLY IN THE MIDDLE TO
UPPER 60S, PERHAPS AN OCCASIONAL 70 IN SOME SPOTS. AS WE HEAD INTO
THE OVERNIGHT, THE SURFACE HIGH MOVES DIRECTLY OVERHEAD AND WILL
ALLOW FOR EFFICIENT RADIATIONAL COOLING TO TAKE PLACE. AS A RESULT,
EXPECTING TEMPERATURES TO DROP INTO THE LOWER TO MIDDLE 30S ACROSS
MUCH OF WESTERN WI, WITH TYPICAL COLD DRAINAGE LOCATIONS IN WEST-
CENTRAL WI POTENTIALLY FALLING INTO THE UPPER 20S. CONSEQUENTLY,
HAVE ISSUED A FROST ADVISORY FROM 1AM TO 8AM FOR TAYLOR COUNTY SOUTH
THROUGH RICHLAND COUNTY WITH THE LIGHT WINDS AND LACK OF CLOUD COVER
RESULTING IN FAVORABLE CONDITIONS FOR FROST FORMATION. ONE CAVEAT TO
THIS WILL BE THAT DEWPOINTS ARE FAIRLY DRY, PARTICULARLY NORTH OF I-
94 WHERE 17.15Z RAP/HRRR SOUNDING PROFILES AT MEDFORD, WI WOULD
HAVE UNIFORM LOW RHS THROUGHOUT THE COLUMN. AS A RESULT,
DEWPOINTS MAY BE TOO LOW TO FORM FROST IN SOME LOCATIONS EVEN IF
TEMPERATURES FALL TO NEAR FREEZING.
LOOKING TOWARDS FRIDAY, DETERMINISTIC GUIDANCE BEGINS TO DEVELOP A
BROAD UPPER-LEVEL RIDGE INTO THE LOCAL AREA WHICH WILL DOMINATE OUR
WEATHER INTO THE MIDDLE OF NEXT WEEK. CONSEQUENTLY, EXPECTING HIGH
TEMPERATURES TO INCREASE FOR FRIDAY WITH MEDIAN HIGH TEMPERATURES IN
THE NBM RANGING IN THE LOWER TO UPPER 70S ACROSS THE AREA. HEADING
INTO THE LATER EVENING ON FRIDAY, AN UPPER-LEVEL WAVE WILL SKIRT
WELL TO OUR NORTH WITH A TRAILING COLD FRONT PUSHING THROUGH THE
AREA IN NORTHWESTERLY FLOW. OVERALL, THE CAMS ARE NOT
ENTHUSIASTIC ABOUT DEVELOPING MUCH FOR SHOWER ACTIVITY AS ANY
MARGINAL INSTABILITY ALONG THE FRONT QUICKLY DIMINISHES AS IT
ENTERS PORTIONS OF SOUTHEAST MN AND WEST-CENTRAL WI. REGARDLESS,
HAVE OPTED TO KEEP SOME PRECIPITATION MENTION NORTH OF I-90
GIVEN A FEW OF THE CAMS TRY TO HOLD ONTO SOME SHOWERS INTO THE
LOCAL AREA.
SATURDAY - TUESDAY: WELL ABOVE NORMAL TEMPERATURES WITH MINIMAL
PRECIPITATION CHANCES
AS WE HEAD INTO THE WEEKEND, A PRONOUNCED UPPER-LEVEL RIDGE SETS UP
SHOP OVER THE REGION, PROVIDING SUBSIDENCE ALOFT AND KEEPING OUR
SKIES CLEAR THROUGHOUT MUCH OF THE WEEKEND AND INTO THE FIRST HALF
OF NEXT WEEK. CONSEQUENTLY, EXPECTING TEMPERATURES TO WARM
EFFICIENTLY WITH THE DIURNAL MIX OUT DURING THE AFTERNOON MOST DAYS.
AS A RESULT, PROBABILITIES FOR HIGH TEMPERATURES IN THE NBM TO REACH
INTO THE MIDDLE 70S OR WARMER ARE VERY HIGH (OVER 80%) FROM SATURDAY
THROUGH TUESDAY, WITH MANY LOCATIONS REACHING INTO THE 80S. GIVEN
THAT AVERAGE HIGH TEMPERATURES ACROSS THE AREA RANGE FROM THE MIDDLE
60S TO LOWER 70S THIS TIME OF YEAR, THIS WILL BE AROUND 10-15
DEGREES ABOVE NORMAL. SO CERTAINLY QUITE WARM, BUT WITH DAILY RECORD
HIGHS AT LA CROSSE AND ROCHESTER GENERALLY IN THE UPPER 80S TO 90S
THIS TIME OF YEAR AND NO SHIFT OF TAILS PRESENT IN THE 08.00Z EFI,
THINKING THAT DAILY RECORD HIGHS ARE UNLIKELY DURING THIS PERIOD.
LOOKING TOWARDS THE START OF NEXT WORK WEEK, THE OVERALL UPPER-LEVEL
PATTERN ACROSS THE CONUS CONTINUES TO FEATURE THE BROAD RIDGE
OVERHEAD WITH PIECE OF UPPER-LEVEL ENERGY ATTEMPTING TO MOVE INTO
THE REGION FROM THE SOUTH WITH A AMPLIFYING UPPER-LEVEL TROUGH OVER
THE WESTERN CONUS. AS THIS PIECE OF UPPER-LEVEL ENERGY MOVES THROUGH
THE AREA ON TUESDAY, CANNOT RULE OUT SOME SHOWER POTENTIAL WITH THE
GRAND ENSEMBLE (GEFS/EC/CANADIAN ENSEMBLE) HAVING SOME PROBABILITIES
(20-40%) FOR MEASURABLE PRECIPITATION.
WEDNESDAY - THURSDAY: STAYING WARM, SHOWER & STORM CHANCES
SIGNALS IN LONG-RANGE DETERMINISTIC AND ENSEMBLE GUIDANCE SUGGEST
THAT THE AFOREMENTIONED TROUGH OVER THE WESTERN CONUS BEGINS TO
PIVOT EAST INTO THE NORTHERN PLAINS FOR THE MIDDLE OF NEXT WEEK.
OVERALL, PROBABILITIES IN THE GRAND ENSEMBLE (GEFS/EC/CANADIAN) HAVE
FAIRLY HIGH PROBABILITIES (50-70% CHANCE) FOR MEASURABLE RAINFALL ON
WEDNESDAY AND THURSDAY. THIS APPEARS TO BE SUPPORTED BY CLUSTER
ANALYSIS AS WELL OF THE GRAND ENSEMBLE WHICH ALL CLUSTERS DEPICT THE
TROUGH EJECTING EAST WITH SOME TIMING AND POSITION DIFFERENCES.
ADDITIONALLY, EACH CLUSTER HAS MEDIUM TO HIGH PROBABILITIES FOR
MEASURABLE PRECIPITATION WEDNESDAY AND THURSDAY ACROSS THE LOCAL
AREA. AS FAR AS TEMPERATURES ARE CONCERNED, SEEMS VERY LIKELY WE
WILL REMAIN ABOVE NORMAL THROUGH THURSDAY FOR HIGH TEMPERATURES WITH
SOUTH TO SOUTHEASTERLY SURFACE FLOW AND A 50 TO 70 PERCENT CHANCE IN
THE 08.00Z EFI THAT HIGH TEMPERATURES TREND ABOVE MODEL CLIMATOLOGY
FOR MUCH OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1153 PM CDT THU MAY 8 2025
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. HOWEVER, FRIDAY
EVENING A COLD FRONT WILL BE MOVING IN WITH SOME INSTABILITY FOR
HIGH-BASED SHOWERS OR STORMS. THE COVERAGE OF TSRA/SHRA ALONG
THE FRONT IN CENTRAL MN SHOULD BEGIN TO DIMINISH AS IT MOVES
INTO SOUTHEAST MN AROUND 1-2Z. WAS CLOSE TO ADDING A PROB30 AT
KRST WITH A GUST TO 30KTS IN TSRA. DUE TO THE DEEP, DRY
SUBCLOUD LAYER, GUSTY WINDS COULD BE AROUND ANY MORE VIGOROUS
SHOWER OR WEAK STORM. INSTABILITY WILL BE WANING AS SHOULD THE
WEATHER AS IT CONTINUES SOUTHEAST. PROB30 MAY NEED TO BE ADDED
IN FUTURE TAFS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...FROST ADVISORY UNTIL 8 AM CDT FRIDAY FOR WIZ017-029-034-
042>044-053-055.
MN...NONE.
IA...NONE.
DISCUSSION...NAYLOR
AVIATION...BAUMGARDT
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