619
FXUS63 KLOT 101129
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
529 AM CST TUE FEB 10 2026
KEY MESSAGES
- TEMPERATURES WILL REMAIN GENERALLY ABOVE AVERAGE THROUGH THE
UPCOMING 7 DAYS, PARTICULARLY INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 150 AM CST TUE FEB 10 2026
A COLD FRONT WILL MOVE ACROSS THE AREA LATER THIS MORNING,
THOUGH THE AIR MASS BEHIND THE FRONT IS OF PACIFIC ORIGIN, SO
THE COOL DOWN WILL BE PRETTY MODEST. FRONT WILL BE MOISTURE
STARVED, SO ONLY NOTICEABLE IMPACT TO OUR WEATHER WILL BE THE
GUSTY NORTHWEST WINDS THAT DEVELOP LATER THIS MORNING INTO THIS
AFTERNOON IN THE WAKE OF THE FRONT.
ONE TIME PERIOD OF INTEREST WORTH WATCHING FOR SOME PRECIP
CHANCES IS THURSDAY. IN RESPONSE TO A PAIR OF APPROACHING
NORTHERN STREAM SHORTWAVE TROUGHS AND SOUTHERN STREAM RIDGING
ATTEMPTING TO BUILD EASTWARD, LOOK FOR A SUBSTANTIAL TIGHTENING
OF MID-UPPER LEVEL GEOPOTENTIAL HEIGHTS FROM THE CORNBELT
SOUTHEAST INTO THE OHIO VALLEY WEDNESDAY NIGHT INTO THURSDAY
MORNING. THE RESULT WILL BE A QUICKLY DEVELOPING, STRONG MID-
UPPER LEVEL JET STREAK, POTENTIALLY NEARING 170KT AT 250MB
THURSDAY MORNING. SIGNIFICANT AGEOSTROPHIC RESPONSE TO THIS
RAPIDLY DEVELOPING JET STREAK PLUS AN APPROACHING SHORTWAVE
SHOULD LEAD TO THE DEVELOPMENT OF A STRONG/DEEP F-GEN
CIRCULATION WEDNESDAY NIGHT OVER THE CORNBELT. THERE SHOULD BE A
GRADUAL RELAXING OF THE AGEOSTROPHIC FLOW THURSDAY AS THE JET
STREAK BEGINS TO WEAKEN THURSDAY AFTERNOON.
VERTICAL CROSS SECTIONS THROUGH THE F-GEN CIRCULATION SHOW
CONSIDERABLE NEGATIVE SATURATED EPV CO-LOCATED WITH THE WARM
(ASCENDING) SIDE OF F-GEN DRIVEN VERTICAL CIRCULATION,
PARTICULARLY WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. IT IS
QUITE COMMON FOR GUIDANCE TO DEPICT TOO RAPID WEAKENING OF WELL
DEVELOPED F-GEN BANDS AND I AM CONCERNED THAT COULD BE THE CASE
WITH THURSDAY AS WELL. CHANCES OF 0.01" OF QPF FROM THE EPS ARE
NOTABLY HIGHER THAN NBM POPS, UPWARDS OF 70-80% OVER OUR WESTERN
AND SOUTHWESTERN CWA THURSDAY. FRONTOGENETICALLY DRIVEN PRECIP
BANDS CAN BE PARTICULARLY DIFFICULT TO PREDICT THIS FAR IN
ADVANCE, BETWEEN ISSUES WITH PLACEMENT AND DEALING WITH A LIKELY
SHARP CUT OFF TO PRECIP TO THE NORTH OF THE F-GEN, OPTED TO NOT
ADJUST NBM POPS UPWARD YET, BUT THIS WILL BE A PERIOD TO WATCH.
TEMPS GENERALLY LOOK TO BE ABOVE FREEZING, SO BARRING ANY
DYNAMIC COOLING, THE CHANCES FOR ACCUMULATING SNOW DON'T LOOK
TOO HIGH, IN FACT PRECIP COULD BE RAIN/SNOW MIX EVEN.
BY FRIDAY AND INTO THE WEEKEND, A SOUTHERN STREAM SHORTWAVE IS
LIKELY TO TRACK SAFELY SOUTH OF OUR AREA. THE 00Z GEFS AND EPS
SUITE HAVE CONTINUED TO TREND FARTHER SOUTH, BUT THE TIME-LAGGED
NATURE OF THE NBM KEEPS RAIN CHANCES GOING THROUGH THE WEEKEND.
ASSUMING NO UNFORESEEN NORTHWARD SHIFTS IN GUIDANCE, IT LOOKS
LIKE THE WEEKEND SHOULD BE DRY WITH RELATIVELY MILD
TEMPERATURES. GUIDANCE HAS BEEN EXHIBITING A BIT OF A COOL BIAS,
SO TEMPS COULD BE EVEN MILDER THAN THE CURRENT NBM ADVERTISED
MID-UPPER 40S, ESPECIALLY IF CLOUD COVER IS LESS EXTENSIVE.
THOUGH THE SYSTEM PASSING TO OUR SOUTH SHOULD RESULT IN WINDS
OFF THE LAKE, SO TEMPS NEAR THE LAKE WILL BE COLDER THIS WEEKEND
(A SURE SIGN THAT SPRING ISN'T FAR AWAY).
GEFS AND EPS BOTH SUGGEST THERE'LL BE FURTHER AMPLIFICATION OF
UPPER RIDGING OVER THE CENTRAL AND EASTERN U.S. HEADING INTO
EARLY NEXT WEEK. STILL DETAILS TO BE IRONED OUT REGARDING ANY
SHORTWAVE TROUGHS BREAKING OFF THE WESTERN RIDGE AND THROWING A
WRENCH IN TEMPS, BUT POTENTIAL IS LOOKING GOOD FOR TEMPS TO
WARM INTO THE 50S EARLY NEXT WEEK, POSSIBLY WELL INTO THE 50S.
- IZZI
AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 529 AM CST TUE FEB 10 2026
FORECAST CONCERNS FOR THE TERMINALS...
- LLWS EARLY THIS MORNING.
- BREEZY NORTHWEST WINDS THIS AFTERNOON WITH GUSTS AROUND 20-25
KTS.
A STOUT 50-55 LOW-LEVEL JET REMAINS OVERHEAD EARLY THIS MORNING
WHICH IS GENERATING SOME LOW-LEVEL WIND SHEAR AROUND 1500-2000
FT AGL. EXPECT THE WIND SHEAR THREAT TO DIMINISH BY 15Z AS THE
JET WEAKENS AND WINDS BEGIN TO INCREASE AS A COLD FRONT SWEEPS
THROUGH THE AREA. WINDS BEHIND THE COLD FRONT WILL BECOME
NORTHWEST WITH GUSTS AROUND 20-25 KT EXPECTED THIS AFTERNOON.
WHILE GUSTS WILL SUBSIDE THIS EVENING, THERE IS UNCERTAINTY AS
TO HOW QUICK GUSTS WILL EASE AS FORECAST SOUNDINGS SHOW WE COULD
STAY MIXED THROUGH THE NIGHT. SINCE SKIES SHOULD BE MOSTLY
CLEAR HAVE OPTED TO MAINTAIN THE IDEA THAT GUSTS WILL SUBSIDE
AROUND 23-00Z THIS EVENING WITH JUST 10-12 KT WINDS OVERNIGHT,
THOUGH CANNOT FULLY RULE OUT AN OCCASIONAL 18-20 KT GUST
TONIGHT.
OTHERWISE, EXPECT MAINLY VFR CONDITIONS THROUGH THE TAF PERIOD
WITH MID-LEVEL CLOUDS THIS MORNING SCATTERING OUT THIS EVENING.
HOWEVER, AN AREA OF MVFR CEILINGS IS PROGRESSING SOUTHWARD OUT
OF CENTRAL WI AND SOUTHERN MN AND COULD GET INTO THE TAF SITES
BETWEEN 17-19Z THIS AFTERNOON. CONCEPTUALLY, THE INCREASING
WINDS AND DRIER AIR OVERHEAD SHOULD ALLOW THESE CLOUDS TO BECOME
MORE SCATTERED IN NATURE BUT THERE IS A CHANCE (10-15%) THAT
THESE CLOUDS HOLD TOGETHER AND RESULT IN A PERIOD OF MVFR. DUE
TO THE LOWER CONFIDENCE HAVE MAINTAINED THE SCT025 IN THE TAFS
FOR NOW THOUGH WILL BE WATCHING TRENDS CLOSELY.
YACK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 6 PM CST THIS
EVENING FOR WINTHROP HARBOR IL TO GARY IN.
VISIT US AT WEATHER.GOV/CHICAGO
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