541
FXUS63 KDVN 201132
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
532 AM CST FRI DEC 20 2024
KEY MESSAGES
- LIGHT TO MODERATE SNOW WILL AFFECT THE AM COMMUTE AND WILL
LEAD TO SLICK CONDITIONS.
- ACTIVE PATTERN THROUGH THE PERIOD WITH LOW CHANCES FOR
PRECIPITATION UNTIL LATER NEXT WEEK.
- TEMPERATURES WELL ABOVE AVERAGE WITH THE EXCEPTION OF THIS
WEEKEND WILL KEEP ANY PRECIP CHANCES ON CHRISTMAS
EVE/CHRISTMAS AS RAIN.
- PROSPECTS FOR A WHITE CHRISTMAS REMAIN QUITE UNFAVORABLE.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 301 AM CST FRI DEC 20 2024
FINAL SPOKE OF VORTICITY ASSOCIATED WITH THE DOUBLE BARRELED
CLIPPER IS MOVING THROUGH THE AREA THIS MORNING. SNOW IS QUICKLY
OVERSPREADING THE AREA WITH SOME SITES UPSTREAM REPORTING AS LOW
AS 1/2SM VISIBILITY WITH SNOW. MOST OF THE VSBY OBSERVATIONS
ARE BETWEEN 1 AND 2 SM SUGGESTING 0.2 TO 0.5 INCHES AN HOUR
NORTH OF THE CWA.
LOOKING AT THE VORTMAX STRUCTURE AND TRACK, THE WAVE IS
EXPECTED TO MOVE OVER THE FAR WESTERN AND SOUTHERN PORTIONS OF
THE CWA. AS A RESULT OF THIS DECIDED TO EXPAND POP CHANCES
FURTHER WEST. WITH SNOW LINGERING UPSTREAM, THINK THAT LIGHT
SNOW IS POSSIBLE WELL PAST 12Z, ESPECIALLY ALONG AND EAST OF THE
MISSISSIPPI RIVER. DECIDED TO SLOW THIS DOWN BASED ON THE
TIMING OF THE WAVE. CAMS HAVE BEEN SLOW TO LATCH ON THE
WIDESPREAD NATURE OF THIS SNOW, SO NOT USING THEM MUCH FOR THIS
FORECAST. OMEGAS IN THE DGZ ACTUALLY GET STRONGER THAN WHAT IS
CURRENTLY ONGOING NORTH OF US, ALONG AND EAST OF THE MISSISSIPPI
RIVER. WITH THAT IN MIND AND VSBY OBS UPSTREAM, HAVE INCREASED
SNOWFALL TOTALS THROUGH 18Z. ADDITIONAL 1 TO 2 INCHES OF SNOW
ARE POSSIBLE, ESPECIALLY EAST OF THE MISSISSIPPI RIVER. THIS
SNOW WILL LIKELY LEAD TO SLICK ROADS AND SIDEWALKS, ESPECIALLY
WHERE UNTREATED. ONCE THIS WAVE MOVES THROUGH THE AREA, CLOUDS
WILL BE SLOW TO BREAKUP BUT WILL LIKELY BECOME MORE SCATTERED
LATER IN THE DAY.
TONIGHT, ANOTHER WAVE IS EXPECTED TO MOVE INTO OUR AREA. A LACK
OF LOW LEVEL MOISTURE WILL KEEP US DRY WITH THIS WAVE. WE COULD
SEE SOME FLURRIES OVERNIGHT, ESPECIALLY ACROSS IOWA AND MISSOURI.
HOWEVER, THIS WAVE WILL USHER IN MUCH COOLER AIR THAN WE HAVE
HAD THIS WEEK. LOWS TONIGHT WILL BE IN THE TEENS TO SINGLE
DIGITS. IF SKIES CLEAR, ESPECIALLY WHERE SNOW FELL IN THE LAST
24 HOURS, THEN LOWS COULD BE EVEN LOWER.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 301 AM CST FRI DEC 20 2024
OVERALL ACTIVE PATTERN IS EXPECTED TO CONTINUE THROUGH THE
PERIOD, WITH A COLD WEEKEND BEFORE TEMPERATURES WARM WELL ABOVE
FREEZING AND LAST THROUGH THE CHRISTMAS HOLIDAYS. WAVES ARE
FORECAST TO AFFECT THE AREA ALMOST EVERY 24 HOURS THROUGH THE
PERIOD. MOST OF THESE WAVES WILL RESULT IN AN INCREASE IN WIND
AS LOW LEVEL SATURATION WILL BE DIFFICULT TO COME BY. LATER IN
THE PERIOD, PRECIPITATION COULD RETURN TO THE AREA, HOWEVER WITH
TEMPERATURES ABOVE FREEZING, EXPECT THIS TO FALL MOSTLY AS RAIN.
THE WAVES THIS WEEKEND, WHEN WE ARE COLD ALWAYS REQUIRE
ADDITIONAL ATTENTION AS THEY ARE NOT ALWAYS RESOLVED WELL BY THE
GUIDANCE. IN FACT, THE WAVE SUNDAY NIGHT INTO MONDAY LOOKS
RATHER STRONG IN THE VORT FIELDS. THE NBM HAS US DRY AND OUR
TEMPERATURES ARE NEAR FREEZING. SATURATION DOES NOT SEEM TO BE
AN ISSUE WITH THIS WAVE. WHILE WE DON'T HAVE POPS YET, WOULD NOT
BE SURPRISED IF WE NEED TO ADD SOME LATER IF THE TREND
CONTINUES. THIS WOULD LIKELY BE FROZEN AND WILL IMPACT THE AM
COMMUTE ON MONDAY.
LOOKING AHEAD TO CHRISTMAS DAY, CONFIDENCE IS VERY HIGH THAT THE
PROSPECTS FOR A WHITE CHRISTMAS ARE PRETTY BLEAK. THE NBM
DETERMINISTIC HIGH TEMPERATURES HAVE US WARMING INTO THE UPPER
30S NORTH TO THE MIDDLE 40S SOUTH, SO BAD NEWS FOR THOSE THAT
ARE LOOKING FOR SOME SNOWINESS FOR CHRISTMAS.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 532 AM CST FRI DEC 20 2024
SNOW IS MOVING OUT OF THE AREA AND ALL IFR/LIFR SNOW SHOULD BE
OUT OF ALL TAF SITES BY 14Z. SOME FLURRIES AND EVEN 6SM -SN
COULD BE POSSIBLE THROUGH 16Z. OTHERWISE, EXPECT MVFR CIGS TO
HOLD ON MOST OF THE DAY BEFORE TRYING TO SCATTER OUT LATE. WIND
GUSTS IN THE LOW 30KT RANGE WILL DECREASE TO THE 20KT RANGE
LATER THIS AFTERNOON.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...GIBBS
LONG TERM...GIBBS
AVIATION...GIBBS
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