404
FXUS63 KARX 221122
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
622 AM CDT TUE OCT 22 2024
KEY MESSAGES
- SPRINKLES/SCATTERED SHOWERS TODAY. GREATER COVERAGE FOR
PRECIPITATION WILL BE ACROSS PARTS OF NORTHEAST IOWA AND
SOUTHERN WISCONSIN, HOWEVER ANY RAINFALL REMAINS LIGHT (60 TO
100% CHANCE THAT THE RAINFALL AMOUNTS WILL BE A TRACE TO LESS
THAN 0.10 OF AN INCH):
- COOLER AND MORE SEASONABLE TEMPERATURES ARE EXPECTED FOR
WEDNESDAY INTO THE WEEKEND.
- THE NEXT CHANCE FOR RAIN WILL BE THURSDAY NIGHT.
ECE/GEFS/CANADIAN ENSEMBLE RUNS FROM THE 21.12Z TO THE 22.00Z
HAVE TRENDED HIGHER WITH PROBABILITIES FOR 0.10" OR MORE OF
RAIN (FROM 40-50% TO 50-60%) FOR MUCH OF THE AREA.
DISCUSSION
ISSUED AT 315 AM CDT TUE OCT 22 2024
OVERVIEW:
EARLY MORNING WATER VAPOR SATELLITE IMAGERY, HEIGHTS, AND LIGHTNING
SHOWED THE CLOSED 500MB LOW PRESSURE CENTER HAD PROGRESSED TO
THE MID-MISSOURI RIVER VALLEY WITH LIGHTNING ON THE SOUTHEAST
SIDE OF THE LOW MOVING INTO PARTS OF IOWA. PATCHY MID AND HIGH
LEVEL CLOUDS WERE NOTED LOCALLY WITH THE MORE EXTENSIVE CLOUDS
ACROSS IOWA. THE LATED SURFACE MAP SHOWED SOUTHERLY FLOW ACROSS
THE REGION AHEAD OF A FRONT THAT WAS BECOMING OCCLUDED OVER
EASTERN NEBRASKA. TEMPERATURES WERE QUITE MILD IN THE MID 50S TO
MID 60S. MEANWHILE, A COLD FRONT WAS NOTED ACROSS NORTH DAKOTA
WITH BRISK NORTHWEST WINDS 30S AND 40S BEHIND THE FRONT. THROUGH
06Z, 6HR RAINFALL AMOUNTS ACROSS IOWA HAVE MOSTLY BEEN A TENTH
OF AN INCH OR LESS. THE LATEST WSR-88D MOSAIC SHOWED BANDS OF
SHOWERS TRYING TO ADVANCE NORTHEASTWARD ACROSS IOWA AND BY 0730Z
WERE TRYING TO REACH PARTS OF THE FORECAST AREA BETWEEN CHARLES
CITY AND OELWEIN.
SPRINKLES/SCATTERED SHOWERS TODAY. GREATER COVERAGE FOR
PRECIPITATION WILL BE ACROSS PARTS OF NORTHEAST IOWA AND SOUTHERN
WISCONSIN, HOWEVER ANY RAINFALL REMAINS LIGHT (60 TO 100% CHANCE
THAT THE RAINFALL AMOUNTS WILL BE A 0.10 OF AN INCH OR LESS):
THE MID-TROPOSPHERIC PATTERN THROUGH TONIGHT CONTINUES TO CALL FOR
THE CLOSED LOW TO TRACK NORTHEAST ACROSS IOWA INTO WISCONSIN,
GRADUALLY WEAKENING AND OPENING UP. MEANWHILE, A 500M TROUGH WILL
SWING THROUGH MANITOBA INTO THE DAKOTAS INTO THE UPPER MISSISSIPPI
VALLEY TONIGHT WITH MUCH COOLER TEMPERATURES FOR WEDNESDAY.
MOISTURE TRANSPORT IS FAVORABLE ACROSS MISSOURI INTO SOUTHERN IOWA
WITH A 55KT LOW LEVEL JET ACROSS MISSOURI. THE MID LEVEL WARM
ADVECTION AND WINDS ALOFT ARE ALSO TRANSPORTING MOISTURE NORTHWARD.
HOWEVER, DUE TO THE VERY DRY AIR IN PLACE, MUCH OF THIS IS WEAKENING
AND EVAPORATING. EARLIER, THERE WERE THREE BANDS OF
PRECIPITATION, HOWEVER OVER THE LAST COUPLE OF HOURS, THE
ECHOES HAVE HAD A TOUGH TIME HOLDING TOGETHER AND THE LIGHTNING
FREQUENCY HAS DROPPED OFF. WE'LL CONTINUE TO SEE THE MID-LEVEL
WARM ADVECTION MOVE QUICKLY ACROSS THE FORECAST AREA THIS
MORNING. THE GENERAL TREND OF THE STRONG LOW LEVEL JET ACROSS
MISSOURI IS TO WEAKEN, HOWEVER SOME STRENGTHENING TO 30 OR 35KTS
IS FORECAST LOCALLY. THE HI-RES CONVECTIVE ALLOWING MODELS
CONTINUE THE TREND WITH THE FIRST FEW BANDS OF SHOWERS
WEAKENING, WITH A NORTH TO SOUTH LINE OF SPOTTY SPRINKLES AND
SHOWERS WORKING EASTWARD THROUGH EARLY AFTERNOON. A TRACE OF
PRECIPITATION WILL BE COMMON WITH MEASURABLE PRECIPITATION FOR
PARTS OF NORTHEAST IOWA AND SOUTHERN WISCONSIN, BUT STILL QUITE
LIGHT AT 0.05" OR LESS. CANNOT RULE OUT A RUMBLE OF THUNDER AS
THE AXIS OF 100-200J/KG OF MUCAPE MOVES ACROSS THE FORECAST AREA
THROUGH EARLY AFTERNOON WITH THE UPPER LEVEL TROUGH.
A LOOK BEHIND THE COLD FRONT ACROSS MONTANA INTO NORTH DAKOTA SHOWS
A COUPLE OF NICE BANDS OF RAINFALL WITH AMOUNTS FROM A TRACE TO
A THIRD OF AN INCH. THIS PRECIPITATION IS ASSOCIATED WITH A
COUPLED UPPER LEVEL JET AND MID-LEVEL FRONTOGENESIS WITH A 500MB
TROUGH SWINGING THROUGH. THE STRONGER FORCING PASSES NORTH OF
THE FORECAST AREA BY THE TIME IT REACHES THE LOCAL AREA THIS
EVENING. ALTHOUGH THE RAIN CHANCES ARE GOOD TO OUR NORTHWEST,
THEY TEND TO DECREASE LOCALLY AS THE COLD FRONT MOVES INTO THE
AREA. STILL HAVE THE GREATER RAIN CHANCES NORTH OF I94 WITH
PRECIPITATION GENERALLY LESS THAN 0.05". INCREASED WINDS BEHIND
THE COLD FRONT TONIGHT WITH SOME LOCAL GUSTS 20 TO 30 MPH.
ABOVE NORMAL TEMPERATURES IN THE 70S AGAIN TODAY, BUT FALL TO MORE
SEASONAL LEVELS WEDNESDAY.
THE NEXT CHANCE FOR RAIN WILL BE THURSDAY NIGHT.
ECE/GEFS/CANADIAN ENSEMBLE RUNS FROM THE 21.12Z TO THE 22.00Z
HAVE TRENDED HIGHER WITH PROBABILITIES FOR 0.10" OR MORE OF RAIN
(FROM 40-50% TO 50-60%) FOR MUCH OF THE AREA:
THE 500MB FLOW PATTERN IS MORE ZONAL FOR THURSDAY WITH A COUPLE OF
EMBEDDED SHORTWAVES IN THE FLOW. A TROUGH OFF THE PACIFIC NORTHWEST
COAST IS FORECAST TO WORK EASTWARD ACROSS THE NORTHERN ROCKIES INTO
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY THURSDAY NIGHT. THE
TREND OVER THE LAST COUPLE OF DAYS HAS BEEN TO INCREASE THE
AMPLITUDE OF THE TROUGH AND THE IVT (VERTICALLY INTEGRATED WATER
VAPOR TRANSPORT) AND PWAT (PRECIPITABLE WATER). THIS HAS RESULTED
IN AN INCREASE IN THE PROBABILITY OF A WETTING RAIN (0.10" OR MORE)
FROM THE EC/GEFS/CANADIAN ENSEMBLES FROM THE 21.12Z TO THE 22.00Z
RUNS FROM 40-50% TO 50 TO 60% FOR MUCH OF THE AREA. GOOD NEWS, AS WE
NEED THE RAIN! RIDGING AND WARMER TEMPERATURES BUILD IN FOR THE
START OF NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 621 AM CDT TUE OCT 22 2024
VFR CONDITIONS EXPECTED. SOME SCATTERED SHOWERS WILL BE POSSIBLE
THIS MORNING. ANOTHER ROUND OF SHOWERS LATER THIS EVENING IS
EXPECTED TO MOVE ACROSS CENTRAL WISCONSIN. SOUTHERLY WINDS WILL
CONTINUE THROUGH THE DAY BEFORE A COLD FRONT MOVES THROUGH LATER
THIS EVENING AND SHIFTS THE WINDS TO THE NORTHWEST. WIND GUSTS
OF 20 TO 25KTS WILL BE POSSIBLE AS THE FRONT MOVES THROUGH.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...ZAPOTOCNY
AVIATION...CECAVA
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