027
FXUS63 KOAX 050410
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1010 PM CST TUE FEB 4 2025
KEY MESSAGES
- FREEZING DRIZZLE COULD LEAD TO SLICK ROADS WEDNESDAY MORNING
INTO EARLY WEDNESDAY EVENING (40-60% CHANCE). SOME QUESTIONS
STILL REMAIN ON EXACT TIMING, BUT BOTH COMMUTES COULD BE
AFFECTED. THE HIGHEST POTENTIAL FOR TRAVEL IMPACTS WILL BE IN
SOUTHEAST NE INTO SOUTHWEST IA WHERE A WINTER WEATHER ADVISORY
HAS BEEN ISSUED.
- THERE IS A 30-40% CHANCE OF MAINLY LIGHT SNOW ACROSS NORTHEAST
NE INTO WEST-CENTRAL IA LATE FRIDAY NIGHT AND SATURDAY WITH A
RAIN-SNOW MIX POSSIBLE ACROSS PORTIONS OF SOUTHEAST NE AND
SOUTHWEST IA.
- LOW SNOW CHANCES (15% POPS) RETURN TO THE FORECAST ON MONDAY.
DISCUSSION
ISSUED AT 345 PM CST TUE FEB 4 2025
TONIGHT AND WEDNESDAY...
A SHORTWAVE TROUGH OVER THE LOWER CO VALLEY AS OF EARLY AFTERNOON IS
FORECAST TO TRAVERSE THE ROCKIES TONIGHT BEFORE MOVING THROUGH THE
CENTRAL PLAINS ON WEDNESDAY. HEIGHT/PRESSURE FALLS PRECEDING THE
MIDLEVEL SYSTEM WILL FOSTER A STRENGTHENING LOW-LEVEL
WARM/MOISTURE ADVECTION REGIME INITIALLY ACROSS THE SOUTHERN
PLAINS TONIGHT, AND EVENTUALLY INTO THE MID AND LOWER MO VALLEYS
ON WEDNESDAY. THOSE PROCESSES WILL CONTRIBUTE TO THE
DEVELOPMENT OF A LIGHT-PRECIPITATION SHIELD, WHICH THE 12Z
MODELS HAVE CONTINUED TO NUDGE EAST COMPARED TO EARLIER RUNS.
NOW, IT APPEARS THE BEST POTENTIAL (PEAK POPS OF 40-60%) FOR
MINOR ICING (< 0.05- 0.07" - DUE TO FREEZING DRIZZLE) EXISTS
FROM THE FALLS CITY AREA INTO SOUTHWEST IOWA, GENERALLY ALONG
AND EAST OF A SIDNEY TO HARLAN LINE. AS SUCH, A WINTER WEATHER
ADVISORY HAS BEEN ISSUED FOR THOSE AREAS FROM 6 AM TO 6 PM
WEDNESDAY.
PRECIPITATION ONSET AND DURATION AT ANY ONE LOCATION IS STILL A
BIT UNCERTAIN DUE TO THE WEAK QPF SIGNAL OFFERED BY THE VARIOUS
MODELS. INSPECTION OF MULTI-MODEL FORECAST SOUNDINGS SUGGESTS
THAT CLOUD HEIGHTS SHOULD LOWER SUFFICIENTLY TO ALLOW FOR LIGHT
FREEZING DRIZZLE TO REACH THE SURFACE BY AS EARLY AS 6 TO 7 AM
OVER FAR SOUTHEAST NE AND EXTREME SOUTHWEST IA. THE LIGHT
PRECIPITATION IS THEN EXPECTED TO SPREAD NORTH ACROSS MAINLY
WESTERN IA THROUGH THE REMAINDER OF THE MORNING AND AFTERNOON.
THESE TYPE OF FORECASTS ARE QUITE CHALLENGING WHEN THE DIFFERENCE
BETWEEN NO IMPACTS AND SIGNIFICANT IMPACTS TO TRAVEL MAY ONLY
BE A COUPLE HUNDREDS OF AN INCH OF FREEZING PRECIPITATION. SO,
WE ARE ERRING ON THE SIDE OF CAUTION WITH THE ADVISORY WITH THE
UNDERSTANDING THAT SOME LOCATIONS IN THE ADVISORY AREA COULD
REMAIN DRY.
WEDNESDAY NIGHT THROUGH FRIDAY...
ANOTHER COLD FRONT IS EXPECTED TO MOVE THROUGH THE AREA
WEDNESDAY NIGHT WITH NORTHWEST WINDS GUSTING TO 30-35 MPH ON
THURSDAY MORNING. ANY COLD ADVECTION WILL END EARLY IN THE DAY
WITH DOWNSLOPE-ENHANCED WARMING CONTRIBUTING TO TEMPERATURES
WARMING IN THE UPPER 30S TO MID 40S BY THURSDAY AFTERNOON.
SIMILAR HIGH TEMPERATURES ARE FORECAST FOR FRIDAY.
FRIDAY NIGHT AND SATURDAY...
THE 12Z GLOBAL MODELS REMAIN IN FAIRLY GOOD AGREEMENT IN THEIR
DEPICTION OF ANOTHER LOW-AMPLITUDE SHORTWAVE TROUGH MOVING
THROUGH THE CENTRAL PLAINS FRIDAY NIGHT AND SATURDAY MORNING.
THAT SYSTEM WILL BE ATTENDED BY A WARM-ADVECTION PRECIPITATION
SHIELD SPREADING NORTH THROUGH THE LOWER MO VALLEY INTO
PORTIONS OF SOUTHEAST NE AND SOUTHWEST IA, AND SECONDARY, LIGHT
SNOW AREA ACROSS THE DAKOTAS AND MN INTO NORTHEAST NE, DRIVEN
LARGELY BY FRONTOGENTICAL FORCING IN THE MIDLEVELS. THE FORECAST
WILL CONTINUE TO ADVERTISE THE HIGHEST POPS OF 30-40% WITHIN THE
SOUTHERN FRINGES OF THE LIGHT-SNOW BAND FROM NORTHEAST NE INTO
WEST-CENTRAL IA WITH DECREASING PRECIPITATION CHANCES WITH
SOUTHWESTWARD EXTENT ACROSS THE AREA. THE PREDOMINANT
PRECIPITATION TYPE IS EXPECTED TO BE SNOW, THOUGH A RAIN-SNOW
MIX APPEARS POSSIBLE WITHIN THE NORTHERN EXTENT OF THE WARM-
ADVECTION REGIME ACROSS FAR SOUTHEAST NE AND SOUTHWEST IA.
SNOWFALL AMOUNTS REMAIN UNCERTAIN, BUT UP TO AN INCH
ACCUMULATION APPEARS POSSIBLE NEAR THE SD BORDER.
SUNDAY AND MONDAY...
HIGH PRESSURE IS EXPECTED TO QUICKLY BUILD THROUGH THE REGION ON
SUNDAY WITH ANOTHER LOW CHANCE (15-20% POPS) OF LIGHT SNOW ON
MONDAY.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1010 PM CST TUE FEB 4 2025
MVFR CIGS AROUND 2500 FT ARE STARTING TO PUSH NORTH INTO
SOUTHEAST NEBRASKA AND WILL CONTINUE TO EXPAND NORTHWARD, NOW
LOOKING MORE LIKELY TO REACH KOFK AS WELL AS KLNK AND KOMA.
WINDS WILL BE SHIFTING TO SOUTHEASTERLY OVERNIGHT TONIGHT AS THE
SURFACE LOW APPROACHES SOUTH OF OUR AREA. WE COULD SEE SOME
POCKETS OF LIGHT SNOW OR FREEZING DRIZZLE DEVELOP STARTING AFTER
12Z AT KLNK AND KOMA. WITH THAT EXPECT CIGS AT THESE TWO
TERMINALS TO CONTINUE TO GRADUALLY LOWER THROUGH THE DAY ON
WEDNESDAY, POSSIBLY GETTING DOWN TO IFR BY WEDNESDAY AFTERNOON.
RIGHT NOW POTENTIAL IS ONLY AROUND 25% FOR IFR CONDITIONS AT
KOMA AND 15% AT KLNK, BUT THAT IS UP FROM NEAR ZERO WITH THE 00Z
PACKAGE SO TRENDING UPWARD. CIGS WILL START TO CLEAR NEAR THE
END OF THE TAF PERIOD, WITH IT BEING DIFFICULT TO PIN DOWN THE
EXACT TIMING, SO HAVE LEFT IT OUT OF THE TAFS FOR NOW. WE ALSO
COULD SEE SOME LLWS DEVELOP STARTING AROUND 04-06Z, SO WILL
LIKELY SEE THAT INCLUDED IN THE NEXT TAF PACKAGE.
OAX WATCHES/WARNINGS/ADVISORIES
NE...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST WEDNESDAY FOR
NEZ091-093.
IA...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST WEDNESDAY FOR
IAZ056-069-079-080-090-091.
DISCUSSION...MEAD
AVIATION...MCCOY
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