230
FXUS63 KDVN 171658
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1058 AM CST FRI JAN 17 2025
..UPDATED FOR 18Z AVIATION
KEY MESSAGES
- ONE MORE WARMER THAN AVERAGE DAY TODAY BEFORE TEMPERATURES FALL
TONIGHT INTO EARLY NEXT WEEK
- LOW CHANCES OF PRECIPITATION (20-30%) THIS EVENING FOR PORTIONS OF
THE FORECAST AREA
- DANGEROUSLY COLD WIND CHILLS ARE ANTICIPATED FOR SUNDAY
MORNING THROUGH EARLY NEXT WEEK
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 241 AM CST FRI JAN 17 2025
OUR STRETCH OF WARMER THAN AVERAGE TEMPERATURES CONTINUES FOR ONE
MORE DAY TODAY, THANKS TO PERSISTENT SOUTHERLY RETURN FLOW AROUND A
DEPARTING AREA OF HIGH PRESSURE TO THE EAST. UPPER-LEVEL RIDGING
ALOFT AND DRY AIR IN PLACE WILL ALSO KEEP CONDITIONS DRY FOR A TIME
BEFORE A FEW LARGE-SCALE SYSTEMS APPROACH THE AREA TONIGHT (MORE ON
THAT LATER). A STOUT 40-50 KNOT LLJ ALOFT WILL HELP SUPPORT SOME
GUSTY WINDS FOR A TIME TODAY, WITH GUSTS BETWEEN 20 TO 30 MPH ACROSS
THE AREA. HREF ENSEMBLES SHOW STRONG AGREEMENT FOR LOTS OF SUNSHINE
TODAY, COUPLED WITH THE SOUTHERLY FLOW/WARM AIR ADVECTION, LEADING
TO HIGH TEMPERATURES EXPECTED TO WARM INTO THE MIDDLE 40S NORTH TO
THE LOWER 50S SOUTH. WHILE THIS FORECAST IS CLOSER TO THE 90TH
PERCENTILE OF THE NBM, YESTERDAY'S HIGH TEMPERATURES OVERACHIEVED IN
A SIMILAR MANNER, SO DECIDED TO LEAN TOWARDS THIS PART OF THE NBM
MODEL SPECTRUM.
AS WE GO INTO THE EVENING AND OVERNIGHT HOURS, THERE WILL BE A FEW
LIFTING MECHANISMS APPROACHING THE REGION: 1) A SOUTHERN STREAM
SHORTWAVE/UPPER-LEVEL JET THAT WILL APPROACH THE REGION FROM THE
SOUTHERN GREAT PLAINS, PLACING OUR REGION OVER THE FAR NORTHERN
EXTENT OF THE LEFT-EXIT/UPPER-LEVEL DIVERGENCE REGION OF THE JET,
AND 2) A SURFACE COLD FRONT THAT WILL SWEEP THROUGH THE AREA FROM
THE NORTHWEST. BETWEEN THESE TWO MECHANISMS, THERE WILL BE AT LEAST
A LOW CHANCE (20-30%) OF PRECIPITATION, WITH RAIN BEING THE MAIN
PRECIP TYPE FOR THE SOUTHERN STREAM SHORTWAVE. WE MAINTAINED SLIGHT
CHANCE POPS (15-25%) ATTENDANT WITH THE COLD FRONT, AS WELL,
ALTHOUGH PRECIP TYPE ALONG THE FRONT SHOULD BE SNOW DUE TO
SUFFICIENT SATURATION WITHIN THE DENDRITIC GROWTH ZONE ALOFT.
HOWEVER, HREF ENSEMBLES PAINT VERY LITTLE IN TERMS OF PRECIPITATION
ACCUMULATIONS, OWING TO THE ABUNDANT DRY AIR IN THE LOWER LEVELS
THAT SHOULD HELP TO LIMIT AMOUNTS.
IN THE WAKE OF THE COLD FROPA, WINDS QUICKLY TURN MORE NORTHWESTERLY
AND STRENGTHEN WITHIN THE COLD AIR ADVECTION REGIME. EXPECT GUSTS
TONIGHT OF 25 TO 35 MPH, WITH TUMBLING TEMPERATURES AS LOWS FALL TO
THE TEENS ABOVE ZERO FOR MOST LOCATIONS - COLDEST TO THE
NORTHWEST.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 241 AM CST FRI JAN 17 2025
THE MAIN FOCUS FOR THE LONG TERM PERIOD CONTINUES TO BE ON THE
DANGEROUSLY COLD WIND CHILLS EXPECTED FOR SATURDAY NIGHT THROUGH
TUESDAY MORNING. WE SHOULD REMAIN IN A STAGNANT UPPER-LEVEL PATTERN,
WITH A HUMONGOUS UPPER TROUGH OVER THE MAJORITY OF THE CONTIGUOUS US
AND AN UPPER-LEVEL LOW LOITERING OVER HUDSON BAY IN CANADA.
CONFIDENCE IN THIS OVERALL SYNOPTIC PATTERN IS VERY HIGH GIVEN
NEARLY UNANIMOUS CONSENSUS AMONG THE GEFS, EPS, AND GEPS ENSEMBLE
CLUSTER ANALYSIS. AN ARCTIC AIR MASS WILL OVERTAKE THE CENTRAL
UNITED STATES, WITH 850 MB LEVEL TEMPERATURES EXPECTED IN THE -20 TO
-30 DEGREE C RANGE PER BOTH THE GEFS AND EPS ENSEMBLE MEANS. THE
COLDEST OF THIS AIR MASS LOOKS TO MOVE THROUGH MONDAY NIGHT AND
TUESDAY MORNING, WITH 850 MB TEMPERATURES PROGGED BETWEEN -25 TO -30
DEGREES C. AS WE'VE BEEN MENTIONING IN PREVIOUS SHIFTS, WE CAN SAY
WITH CERTAINTY THAT THIS WILL BE THE COLDEST AIR MASS OF THE SEASON
SO FAR. NOT ONLY ARE THESE 850 MB TEMPERATURES PROGGED IN THE LOWEST
1% OF CLIMATOLOGY PER THE ECMWF ENSEMBLES, BUT WITH 850 MB TEMPS
AROUND -27 TO -28 DEGREES C POSSIBLE OVER THE QUAD CITIES AT 12Z/6
AM TUESDAY MORNING, IF THESE VALUES COME TO FRUITION, THEY WILL FALL
IN THE TOP 10 COLDEST 850 MB TEMPS IN THE ENTIRE SPC SOUNDING
CLIMATOLOGY (PERIOD OF RECORD GOES BACK TO 1995, ENCOMPASSING NEARLY
19,923 SOUNDINGS)! FOR THOSE THAT DON'T LIKE THE EXTREME COLD, ONE
SAVING GRACE IN TERMS OF TEMPERATURES IS THAT WE WON'T HAVE AN
EXTENSIVE SNOW PACK THAT WOULD OTHERWISE REALLY HELP TEMPERATURES
PLUMMET. STILL, IT'S GOING TO GET FRIGID, WITH FORECAST OVERNIGHT
LOWS IN THE SINGLE DIGITS AND TEENS BELOW ZERO FOR SATURDAY NIGHT
THROUGH MONDAY NIGHT AND DAYTIME HIGHS ONLY IN THE SINGLE DIGITS AND
LOWER TEENS ABOVE ZERO FOR SUNDAY THROUGH TUESDAY. MINIMUM WIND
CHILLS SHOULD FALL TO THE -15 TO -30 DEGREE F RANGE EACH NIGHT,
WHICH WOULD NECESSITATE COLD WEATHER HEADLINES.
BY WEDNESDAY, THE LARGE-SCALE PATTERN CHANGES, WITH SOUTHERLY FLOW
RETURNING TO HELP TEMPERATURES WARM UP CLOSER TO SEASONAL VALUES AND
THE UPPER TROUGH BREAKING DOWN. HIGHS BY WEDNESDAY ARE PROGGED TO
WARM BACK UP TO THE MIDDLE TO UPPER 20S PER THE LATEST NBM.
THE FORECAST REMAINS DRY THROUGH MID NEXT WEEK, BUT CAN'T RULE OUT
SOME WAVES EMBEDDED IN THE N/NW FLOW. GIVEN THE LOW AMPLITUDE NATURE
OF THESE, THEY ARE HARD TO RESOLVE IN THE MODELS AT THIS JUNCTURE,
AND AS SUCH THE NBM HAS A DRY FORECAST. JUST MENTIONING THIS AS THE
ARCTIC AIR WILL BE VERY EFFICIENT AT PRODUCING AT LEAST FLURRIES AND
POSSIBLY SOME LIGHT SNOW, THUS SOMETHING TO WATCH FOR.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1055 AM CST FRI JAN 17 2025
WINDS ARE THE MAIN CONCERN FOR AVIATION DURING THE PERIOD.
INITIALLY INTO THIS AFTERNOON WILL SEE GUSTY SW WINDS 15-30 KT,
WITH SOME PERIODIC LOCALLY HIGHER GUSTS 35-40 KT POSSIBLE AT
THE RIVER SITES. A COLD FRONT WILL MOVE ACROSS THE TERMINALS
21Z-03Z WITH WINDS DIMINISHING AND VEERING TO WESTERLY AS THE
FRONT APPROACHES, THEN TURNING NORTHWEST AND RAMPING UP POST-
FRONTAL, ESPECIALLY AFTER A FEW HOURS OF THE FRONTAL PASSAGE
WHEN THE COLD ADVECTION STRENGTHENS. THIS WILL FOSTER NORTHWEST
WINDS BECOMING SUSTAINED AT 15-25+ KT WITH GUSTS 25-35+ KT,
DIMINISHING SOME LATE TONIGHT INTO SAT AM BUT STAYING GUSTY.
THERE IS A CHANCE FOR MVFR CEILINGS POST-FRONTAL, BUT CONFIDENCE
ON DURATION AND TIMING IS LOW (POTENTIALLY CLOUD STREETS /
NARROW BANDS OF HORIZONTAL CONVECTIVE ROLLS) TO PRECLUDE MENTION
AT THIS TIME.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...SCHULTZ
LONG TERM...MCCLURE/SCHULTZ
AVIATION...MCCLURE
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