483
FXUS63 KARX 171006
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
406 AM CST SUN NOV 17 2024
KEY MESSAGES
- ACTIVE WEATHER FOR THE UPCOMING WEEK WITH POTENTIAL FOR
RAINFALL EXCEEDING 1" (MON-TUE-EC/GEFS/CANADIAN ENSEMBLES
40-80% PROBABILITY).
- TURNING COLDER WEDNESDAY INTO THE WEEKEND
WITH HIGHS IN THE 30S AND 40S. SOME POTENTIAL FOR RAIN/SNOW
MIDWEEK (40-70% PROBABILITY FOR MEASURABLE SNOW OF 0.1" OR
MORE, BUT WILL NEED TO CONTINUE TO ASSESS). STILL BREEZY
SEVERAL DAYS THIS WEEK.
DISCUSSION
ISSUED AT 351 AM CST SUN NOV 17 2024
OVERVIEW:
THE CLOUDS LIMITED HIGHS SATURDAY TO THE MID 40S TO LOWER 50S, BUT
STILL ABOVE NORMAL TEMPERATURES. ISOLATED THUNDERSTORMS DID DEVELOP
OVER NORTHEAST IOWA INTO SOUTHERN WISCONSIN AND ALSO WITH A
SECONDARY LINE LATER IN THE EVENING AS THE SHOWERS INCREASED OVER
PARTS OF JUNEAU AND ADAMS COUNTIES. WIND GUSTS RANGED FROM 25 TO
35 MPH FOR WISCONSIN TO 35 TO 45 MPH FOR PARTS OF IOWA AND
MINNESOTA. THE STRONGER WIND GUSTS WERE AT RST, BYRON, AND
PRESTON. THE LATEST SUBJECTIVE SURFACE ANALYSIS HAD AN OCCLUDED
FRONT OVER EASTERN MINNESOTA WITH A WARM FRONT TOWARD OLZ AND
MLI. SOME PATCHY LIGHT RAIN CONTINUED OVER PARTS OF SOUTHERN
WISCONSIN WITH THE AREA OF FRONTOGENESIS/VORTICITY ADVECTION.
THE 500MB TROUGH WAS STILL TO THE WEST OVER THE DAKOTAS.
RAINFALL AMOUNTS HAVE BEEN LIGHT, GENERALLY 0.05" OR LESS. THE
WSR-88D RADAR ESTIMATES SHOW THERE MAY HAVE BEEN SOME SPOTTY
0.05 TO 0.15" AMOUNTS WITH THE STRONGER SHOWERS/STORMS. THE
LATEST GOES NIGHT MICROPHYSICS SATELLITE IMAGERY SHOWED THE
CLEARING SKIES AT RST WITH CLOUDS TO THE EAST AND WRAP-AROUND
CLOUDS ACROSS NORTHERN MINNESOTA.
ACTIVE WEATHER FOR THE UPCOMING WEEK WITH POTENTIAL FOR
RAINFALL EXCEEDING 1" (MON-TUE-EC/GEFS/CANADIAN ENSEMBLES
40-80% PROBABILITY). TURNING COLDER WEDNESDAY INTO THE WEEKEND
WITH HIGHS IN THE 30S AND 40S. SOME POTENTIAL FOR RAIN/SNOW
MIDWEEK (40-80%) PROBABILITY FOR MEASURABLE SNOW OF 0.1" OR
MORE, BUT WILL NEED TO CONTINUE TO ASSESS):
WATER VAPOR SATELLITE IMAGERY AND HEIGHTS SHOWED THE FULL LATITUDE
TROUGH STRETCHING FROM ONE CLOSED LOW OVER SOUTHERN CANADA/NORTH
DAKOTA AND ANOTHER CLOSED LOW OVER THE SOUTHWEST U.S. AND A RIDGE TO
THE EAST AND THE WEST OF THIS TROUGH. THROUGH TODAY, THE SOUTHERN
PART OF THE FORECAST AREA COULD GET CLIPPED WITH MORE SPRINKLES WITH
MID LEVEL MOISTURE/VORTICITY ADVECTION LINGERING TODAY. THE CLOSED
LOW LIFTS FARTHER NORTH INTO ONTARIO. THE HREF KEEPS THINGS DRY
AND THE RAP DRIES OUT THE 850MB LAYER AFTER 12 OR 13Z, THUS
WILL KEEP THE MEASURABLE POPS SOUTH OF THE AREA. TEMPERATURES
ARE STARTING OUT MILD AND WITH MORE SUNSHINE, ARE LOOKING FOR
HIGHS IN THE UPPER 40S TO LOWER 50S.
TONIGHT INTO TUESDAY, THE CLOSED LOW OVER THE SOUTHWEST U.S.
WILL LIFT NORTHEAST THROUGH THE PLAINS, DEEPENING , BECOMING
NEGATIVELY TILTED, AND MERGING WITH THE TROUGH OVER THE PACIFIC
NORTHWEST. 850 MB MOISTURE TRANSPORT VECTORS SHOW A MARKED
INCREASE FROM MONDAY 12Z TO 18Z ACROSS IOWA AND THE MOISTURE
TRANSPORT STRENGTHEN ACROSS THE MISSISSIPPI VALLEY THROUGH
MONDAY NIGHT. IN RESPONSE TO THIS, PRECIPITABLE WATER VALUES OF
LESS THAN 0.50" CLIMB TO 1 TO 1.25". THE 17.00Z NAEFS SHOWS
THIS IS 3 TO 4 STANDARD DEVIATIONS ABOVE NORMAL. THE
PRECIPITATION SHIELD IS FORECAST TO OVERSPREAD THE FORECAST AREA
FROM SOUTH TO NORTH DURING THE DAY MONDAY, DECREASING FROM SOUTH
TO NORTH DURING THE DAY TUESDAY. THE EFI CONTINUE TO SHOW
ANOMALOUS PRECIPITATION WHEN COMPARED TO CLIMATOLOGY WITH THE
SHIFT OF TAILS 1 TO 2 OVER CENTRAL MINNESOTA AND EASTERN
DAKOTAS. THE ECMWF, CANADIAN, AND GEFS ENSEMBLES CONTINUE TO
SHOW HIGH PROBABILITIES (40-80%) FOR 1" OF RAINFALL FOR THE
FORECAST AREA. CANNOT RULE OUT ISOLATED THUNDERSTORMS WITH THE
STRONGER MOISTURE TRANSPORT. MUCAPE VALUES SHOWS LIMITED
INSTABILITY WITH POCKETS OF 100 OR 150 J/KG. BOTH SPC/CSU
SEVERE WEATHER PROBABILITIES REMAIN SOUTH OF THE FORECAST AREA
MONDAY. DID NOTICE SPC ADDED A GENERAL THUNDER AREA FOR TUESDAY
AS THE UPPER LEVEL TROUGH BECOMES NEGATIVELY TILTED. WITH THE
CAPE WEAKENING OVER THE AREA, HAVE LEFT OUT THUNDER MENTION ON
TUESDAY FOR NOW. COLDER AIR EVENTUALLY WRAPS INTO THE SYSTEM
THROUGH THE DAY TUESDAY. IF THERE IS STILL ANY PRECIPITATION, IT
COULD TRY TO MIX WITH SNOW. WE CURRENTLY HAVE HIGHS IN THE
UPPER 40S AND 50S THROUGH TUESDAY. WILL NEED TO MONITOR THIS
THOUGH AS THIS TIME OF YEAR, CLOUDS AND PRECIPITATION CAN LIMIT
THE HIGHS.
WPC HAS MUCH OF AREA IN THE 5% RISK FOR EXCESSIVE RAINFALL. THE 6-
HR RAINFALL FLASH FLOOD GUIDANCE IS GENERALLY 2.25" TO 3", SO WITH
NO FROST IN THE GROUND, WE SHOULD BE ABLE TO HANDLE THE RAIN THAT IS
BEING FORECAST.
AS THE LARGE CLOSED LOW LINGERS OVER THE UPPER MISSISSIPPI VALLEY
WEDNESDAY AND FINALLY MOVES EAST THURSDAY, A RAIN/SNOW MIX IS
FORECAST WEDNESDAY INTO THURSDAY. THE TRACK COULD STILL CHANGE
THROUGH WEDNESDAY AND THURSDAY, BUT THE 17.00Z ECE/GEFS/CANADIAN
ENSEMBLES HAVE A 40 TO 70% CHANCE OF MEASURABLE SNOW (0.1" OR MORE)
OF SNOW AND 20-40% PROBABILITY OF 1" OR MORE.
MUCH COOLER TEMPERATURES FOR WEDNESDAY INTO THE WEEKEND WITH
HIGHS IN THE 30S AND 40S. BRISK WIND GUSTS ARE STILL FORECAST
FOR MUCH OF THE WEEK.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 941 PM CST SAT NOV 16 2024
ATTENTION REMAINS ON STATUS OF MVFR STRATUS OVERNIGHT AS THE
LIGHT RAIN AND SMALL CHANCE FOR THUNDER HAS SHIFTED EAST OF THE
AREA. BASED ON LATEST SATELLITE AND GROUND OBSERVATION TRENDS,
STILL EXPECT THIS STRATUS TO CLEAR OUT WEST TO EAST FROM 06Z TO
15Z WITH VFR CONDITIONS EXPECTED FOR THE REST OF THE PERIOD
THEREAFTER.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...ZAPOTOCNY
AVIATION...FERGUSON
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