568
FXUS63 KILX 191725
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1125 AM CST WED FEB 19 2025
KEY MESSAGES
- THERE IS A CHANCE (20-30%) FOR SCATTERED SNOW SHOWERS THIS
AFTERNOON AND EVENING EAST OF I-55, PERHAPS BRINGING A DUSTING
OF ADDITIONAL SNOWFALL.
- THE STRETCH OF VERY COLD WEATHER WITH SUB-ZERO WIND CHILL VALUES
WILL EXTEND THROUGH FRIDAY MORNING. FROSTBITE AND HYPOTHERMIA
ARE CONCERNS WITH PROLONGED EXPOSURE TO THESE CONDITIONS. A
BONA FIDE WARM-UP WILL THEN OCCUR OVER THE WEEKEND.
- AFTER TODAY, VERY LITTLE PRECIPITATION IS FORECAST THROUGH EARLY
NEXT WEEK. OUR NEXT CHANCE (20 TO 30 PERCENT) COMES NEXT
WEDNESDAY.
UPDATE
ISSUED AT 1026 AM CST WED FEB 19 2025
CLOUD COVER HAS THINNED ACROSS A LARGE PORTION OF CENTRAL IL THIS
MORNING, BUT WILL FILL IN THIS AFTERNOON AS A SHORTWAVE APPROACHES
FROM THE WEST. THIS REMAINS ON TRACK TO PRODUCE SCATTERED SNOW
FLURRIES AND PERHAPS A DUSTING OF SNOW MAINLY EAST OF I-55 FROM
LATE AFTERNOON THROUGH EVENING. TEMPERATURES ARE GENERALLY LOWER
TO MID TEENS AS OF 9 AM, AND WILL ONLY RISE A FEW MORE DEGREES AS
COLD ADVECTION IN NORTHWESTERLY FLOW CONTINUES. UPDATES THIS
MORNING FOR LESS CLOUD COVER THE REMAINDER OF THE MORNING.
37
DISCUSSION
ISSUED AT 138 AM CST WED FEB 19 2025
PERIODS OF SCATTERED SNOW SHOWERS REMAIN A POSSIBILITY THROUGHOUT
TODAY AS A FEW SPOKES OF VORTICITY ROTATING AROUND A CLOSED UPPER
LOW HELP PROVIDE SUFFICIENT SYNOPTIC ASCENT. GLANCING AT THE
THERMAL PROFILE FOR THIS MORNING, WE SEE A FAIRLY SATURATED
PARCEL WITH A DEEP ISOTHERMAL LAYER EXTENDING THROUGH THE
DENDRITIC GROWTH ZONE (DGZ). THUS, THINKING WE MAY SEE A DECENT
BURST OR TWO OF SNOW OUT OF THE GATE TODAY, BUT AS THE BOUNDARY
LAYER DECOUPLES LATER THIS MORNING AND COLD ADVECTION HELPS
STEEPEN LOW- LEVEL LAPSE RATES, DRY AIR IN THE LOWEST 1 KM MAY
PRECLUDE SNOW ACTIVITY THROUGH MUCH OF THE MIDDAY/AFTERNOON
PERIOD. SOME QUESTION AS TO WHETHER OR NOT WE'LL BE ABLE TO ERODE
THE LOW-LEVEL DRY LAYER THIS EVENING ONCE ANOTHER PUSH OF
SYNOPTIC ASCENT AND MID-LEVEL MOISTURE MOVES INTO CENTRAL IL.
THERE COULD BE ENOUGH WET-BULBING AND SEEDER-FEEDER PROCESSES AT
WORK TO HELP SQUEEZE OUT SOME SCATTERED SNOW SHOWERS OR FLURRIES
THIS EVENING IN SOME AREAS EAST OF I-55. WHEREVER THIS MAY PLAY
OUT, AN ADDITIONAL DUSTING OF SNOWFALL WILL BE POSSIBLE.
ASIDE FROM THE LIGHT SNOW CHANCES (20-30%) TODAY, THE BIGGER
IMPACT OF THE FORECAST REMAINS THE CONTINUED VERY COLD
TEMPERATURES. AND, AS THE MSLP GRADIENT TIGHTENS LATER TODAY IN
BETWEEN DEPARTING LOW PRESSURE AND INCOMING HIGH PRESSURE, WE
SHOULD ONCE AGAIN BE STUNG BY WIND CHILL VALUES OF 10 TO 20 BELOW
ZERO BY TONIGHT. HAVE THEREFORE HOISTED ANOTHER COLD WEATHER
ADVISORY FOR THE OVERNIGHT PERIOD, EXCEPT IN SOME AREAS OF EAST
CENTRAL ILLINOIS WHERE LINGERING CLOUD COVER MAY HELP BUOY
CONDITIONS JUST ABOVE ADVISORY CRITERIA.
THE AIR TEMPERATURE THURSDAY AND THURSDAY NIGHT WILL BE EQUALLY
FRIGID AS TODAY, BUT AS THE CENTER OF SURFACE HIGH PRESSURE BUILDS
ACROSS THE CORN BELT THURSDAY NIGHT BEHIND THE DEPARTING UPPER-
LEVEL LOW, WINDS SHOULD GO CALM AND PACIFY THE WIND CHILL EFFECT.
PROGRESSIVELY WARMER CONDITIONS WILL THEN SPAN FRIDAY THROUGH AT
LEAST EARLY NEXT WEEK AS CHOPPY NORTHWEST FLOW HELPS PUMP WARM
DOWNSLOPE WINDS ACROSS THE PLAINS AND INTO THE MISSISSIPPI
VALLEY. WITH THE NORTHWEST FLOW REGIME STYMYING GULF MOISTURE,
THIS SHOULD ALSO BE A FAIRLY DRY PERIOD FOR US. NBM DETERMINISTIC
GUIDANCE IS OFFERING DAILY HIGHS IN THE 40S AND 50S INTO EARLY
NEXT WEEK AND WE SEE NO REASON TO STRAY FROM IT.
BY THE MIDDLE OF NEXT WEEK, THERE IS SOME SEMBLANCE OF LIGHT
PRECIP RETURNING TO THE AREA. SOME GUIDANCE BRINGS A COMPACT LOW
ACROSS THE REGION. OTHER GUIDANCE BRINGS IN A ZONE OF ENHANCED
FGEN THAT TAPS INTO SOME RECYCLED PACIFIC MOISTURE. THEN THERE'S
GUIDANCE THAT SHOWS NOTHING AT ALL. FOR NOW, WILL LEAN ON THE NBM
WHICH SUPPORTS A CHANCE (20-30%) OF LIGHT PRECIP BY WEDNESDAY.
MJA
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1125 AM CST WED FEB 19 2025
VFR CONDITIONS WILL REMAIN IN PLACE INTO THIS AFTERNOON BEFORE
ANOTHER DISTURBANCE BRINGS SCATTERED -SHSN, ESPECIALLY EAST OF
I-55. MVFR CIGS APPEAR LIKELY ACROSS THE AREA, WITH MVFR VSBY
POSSIBLE AT TIMES MAINLY EAST OF I-55. LATEST MODELS FEATURE
CONSIDERABLE DISPARITY IN HOW FAST CLOUD COVER CLEARS OVERNIGHT
INTO THURSDAY MORNING, HOWEVER GUIDANCE CONSENSUS SEEMS TO POINT
TO VFR CONDITIONS BY 12Z. WINDS NW 8-12 KTS THROUGH THE PERIOD.
37
ILX WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST
THURSDAY FOR ILZ027>031-036>038-040>044-047>056-061>063-066>068-
071>073.
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