799
FXUS63 KARX 051136
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
536 AM CST MON JAN 5 2026
KEY MESSAGES
- ANOTHER ROUND OF FREEZING RAIN IS POSSIBLE (40-60%) TONIGHT
INTO TUESDAY MORNING, PRIMARILY ALONG AND NORTH OF I-90.
- POTENTIAL EXISTS FOR A STRONGER WINTER SYSTEM LATE THIS WEEK
BRINGING RAIN AND SNOW TO THE UPPER MISSISSIPPI RIVER VALLEY
(30-50%).
DISCUSSION
ISSUED AT 352 AM CST MON JAN 5 2026
ANOTHER ROUND OF FREEZING RAIN TONIGHT INTO TUESDAY
AN ACTIVE UPPER LEVEL PATTERN CONTINUES TODAY AS A 500HPA
SHORTWAVE TROUGH EJECTS INTO THE GREAT PLAINS ALONG A FLATTENING
RIDGE THIS AFTERNOON, RESULTING IN A DEEPENING LOW OVER THE
CENTRAL UNITED STATES. THESE FEATURES TRANSLATE EASTWARD INTO
THE UPPER MIDWEST OVERNIGHT INTO TUESDAY MORNING, BRINGING
ANOTHER BOUT OF WINTRY PRECIPITATION TO THE UPPER MISSISSIPPI
RIVER VALLEY.
THROUGHOUT THE DAY, 850HPA WARM AIR ADVECTION WILL CONTINUE,
SUSTAINING THE STOUT WARM NOSE IN THE 900-800HPA, NEARING 4C PER
05.00Z HREF SOUNDINGS WITH LITTLE VARIATION AMONGST THE
ENSEMBLE MEMBERS. THIS WARM LAYER RESULTS IN THERMAL PROFILES
VERY FAVORABLE FOR THE FULL MELTING OF HYDROMETEORS AS THEY FALL
INTO/THROUGH IT. HEADING INTO THE OVERNIGHT HOURS, A WEST TO
EAST BAND OF OF 700-600HPA FRONTOGENESIS AND ISENTROPIC ASCENT
ON THE 290K SURFACE WILL DEVELOP, GENERALLY ALONG AND NORTH OF
I-90, LEADING TO A MAXIMUM OF UPWARD VERTICAL MOTION AND THUS
PRECIPITATION (40-60%). WITH THE WARM LAYER ALOFT AND
PRECIPITATION EXPECTED TO DEVELOP, CONCERN TURNS TO
PRECIPITATION TYPE.
NORTH OF I-94, CONFIDENCE IS HIGHEST THAT FREEZING RAIN WILL BE
THE PREDOMINANT TYPE AS RAP/HRRR SOUNDINGS SUGGEST A SHALLOW
NEAR SURFACE LAYER OF BELOW FREEZING TEMPERATURES IS FAVORED
BELOW THIS WARM NOSE, ALLOWING FOR SUPERCOOLING OF THE MELTED
HYDROMETEORS. SOUTH OF I-94 TOWARDS I-90, CONFIDENCE IN
PRECIPITATION TYPE DECREASES AS NEAR SURFACE TEMPERATURES HOVER
RIGHT AROUND FREEZING. DEPENDENT ON SMALL TEMPERATURE
VARIATIONS, EITHER RAIN OR FREEZING RAIN COULD ULTIMATELY END UP
BEING THE PREDOMINANT TYPE. SOUTH OF I-90, ABOVE FREEZING TEMPERATURE
PROFILES ARE CURRENTLY FAVORED RESULTING IN AN ALL LIQUID,
ALBEIT COLD, RAIN. GIVEN THE PRIMARY FORCING OF THIS
PRECIPITATION IS THE FRONTOGENESIS BAND, THERE IS PLENTY OF TIME
FOR LATITUDINAL VARIATION WITH REGARDS TO THE AXIS OF HIGHEST
QPF AND ULTIMATE ICE ACCUMULATION.
SPEAKING OF ACCUMULATION, THE 05.00Z HREF HIGHLIGHTS 30-60%
PROBABILITIES FOR GREATER THAN 0.1" OF ICE ACCUMULATION AND
10-30% 0.2" ALONG AND NORTH OF I-94. THESE VALUES ARE SLIGHTLY
HIGH OUTLIERS, LIKELY OWING TO THE INFLATED HRRR WHICH SUGGESTS
NEARLY 1/2 AN INCH OF ICE ACCUMULATION DURING THE EVENT! THE
OTHER MEMBERS OF THE ENSEMBLE ARE FAR MORE TAME AND MUCH MORE
CONSISTENT AROUND THE 0.1-0.2 INCH MARK, WHICH IS FAR MORE
REASONABLE AT THIS POINT AND MORE IN LINE WITH THE 05.00Z LREF
WHICH SUGGESTS 10-30% PROBABILITIES FOR GREATER THAN 0.1 INCHES.
HOWEVER, THERE SHOULD BE SOME RESPECT GIVEN TO THE HRRR, AS
THERE IS THE POTENTIAL THIS FRONTOGENESIS DRIVEN PRECIPITATION
OVERPERFORMS. REGARDLESS, TRAVEL CONDITIONS WILL QUICKLY BECOME
HAZARDOUS OVERNIGHT WHEREVER FREEZING RAIN FALLS AND GIVEN THE
CURRENT TIMING, EXPECT SOME IMPACT TO THE TUESDAY MORNING
COMMUTE.
LATE WEEK WINTER SYSTEM POTENTIAL
A MORE POTENT WINTER SYSTEM LOOMS ON THE HORIZON AS THE 05.00Z
LREF DEPICTS A LONGWAVE TROUGH SHIFTING EASTWARD THROUGH THE
UNITED STATES THURSDAY, SUPPORTING A LOW PRESSURE SYSTEM AT THE
SURFACE. THIS SYSTEM IS CURRENTLY EXPECTED TO SLIDE SOUTHEAST OF
THE UPPER MIDWEST THROUGH THE WEEKEND, POTENTIALLY PUTTING OUR
AREA WITHIN THE DEFORMATION BAND WHICH WOULD RESULT IN
PRECIPITATION ACROSS PORTIONS OF OUR AREA. THERE IS STILL
VARIATION REGARDING STRENGTH AND POSITION OF THE LOW AMONGST
THE 05.00Z LREF MEMBERS, SO PLENTY OF UNCERTAINTY SURROUNDS THE
SYSTEM. HOWEVER, CURRENT PROBABILITIES OF PRECIPITATION SIT
AROUND 30-50% IN THE NBM WITH RAIN TRANSITIONING TO SNOW THE
FAVORED PRECIPITATION TYPES.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 535 AM CST MON JAN 5 2026
A FAIRLY LOW CONFIDENCE AVIATION FORECAST THROUGH MUCH OF TODAY
AS MODEL GUIDANCE STRUGGLES TO RESOLVE THE ONGOING MVFR/IFR
STRATUS, FOG, AND POCKETS OF CLEARING. BASED UPON CURRENT
TRENDS, A PERIOD OF VFR CONDITIONS IS POSSIBLE AT BOTH KRST AND
KLSE IN THE NEXT FEW HOURS AS THE LOW STRATUS OVERHEAD SHIFTS
SOUTHEASTWARD, BUT THERE HAS BEEN SOME EXPANSION OF THIS LOW
STRATUS INTO A POCKET OF AFOREMENTIONED CLEARING. THIS EXPANSION
MAY ULTIMATELY RESULT IN LITTLE TO NO RESPITE FROM THE MVFR/IFR
CONDITIONS AT AND AROUND THE TAF SITES AND AS SUCH AMENDMENTS
WILL LIKELY BE NEEDED THROUGH THE MORNING HOURS. MORE SOLIDLY
MVFR/IFR CONDITIONS ARE EXPECTED TONIGHT AS RAIN DEVELOPS OVER
THE AREA GENERALLY AFTER 03Z. AREAS ALONG AND NORTH OF I-94 ARE
MOST FAVORED TO SEE THIS RAIN TRANSITION TO FREEZING RAIN.
ARX WATCHES/WARNINGS/ADVISORIES
WI...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO NOON CST
TUESDAY FOR WIZ017-029.
MN...NONE.
IA...NONE.
DISCUSSION...FALKINHAM
AVIATION...FALKINHAM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page