937
FXUS63 KDVN 231620
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1120 AM CDT SAT OCT 23 2021
..HYDROLOGY UPDATE
..AVIATION UPDATE
SYNOPSIS
ISSUED AT 225 AM CDT SAT OCT 23 2021
EARLY MORNING SATELLITE IMAGERY SHOWS MID LEVEL CLOUDS SOUTH OF
I-80 KEEPING TEMPERATURES SLIGHTLY WARMER THERE IN THE UPPER 30S
AND LOWER 40S. ELSEWHERE, TEMPERATURES WERE IN THE LOW TO MID 30S
IN THE COUNTIES WHERE A FROST/FREEZE HEADLINE IS IN EFFECT.
MSAS SURFACE ANALYSIS SHOWS SURFACE RIDGE EXTENDING FROM CENTRAL
MN TOWARDS EASTERN IA, WITH MANY SURFACE OBS REPORTING CALM WINDS
EARLY THIS MORNING. THE WARM FRONT THAT WILL BRING WIDESPREAD
PRECIPITATION ON SUNDAY, IS CURRENTLY DRAPED ACROSS NORTHERN KS
THROUGH SOUTH CENTRAL MO.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 225 AM CDT SAT OCT 23 2021
NO CHANGES TO CURRENT FROST/FREEZE HEADLINES. QUIET AND DRY
CONDITIONS ARE EXPECTED TODAY, WITH SLIGHTLY BELOW NORMAL
HIGH TEMPERATURES.
AFTER A COLD FROSTY START, MUCH OF THE AREA WILL SEE MOSTLY SUNNY
SKIES THROUGH THE DAY WITH WINDS TURNING EASTERLY. WENT WITH THE
NBM FOR HIGHS TODAY, WHICH HAS READINGS MAINLY IN THE MIDDLE TO
UPPER 50S. ATTENTION THEN TURNS TO THE STRONG EASTERN CO LOW AND
ASSOCIATED WARM FRONT THAT WILL LIFT NORTH OVER MO OVERNIGHT. MID
AND HIGH LEVEL CLOUDS WILL INCREASE THIS EVENING KEEPING
TEMPERATURES WARMER OVERNIGHT THAN THIS MORNING. HOWEVER, SOME
PATCHY FROST IS STILL NOT OUT OF THE QUESTION OVER NORTHERN IL
EARLY SUNDAY.
AFTER LOOKING AT MODEL TRENDS, MOISTURE PROFILES, AND WARM FRONT
PLACEMENT, HAVE SLOWED THE ARRIVAL OF RAIN CHANCES SLIGHTLY EARLY
SUNDAY. STRONG LIFT, RICH 850MB THETA-E AIR, AND NEGATIVE
700-500MB THETA-E LAPSE RATES WILL RESULT IN WIDESPREAD STRATIFORM
RAIN, WITH EMBEDDED THUNDER ENTERING OUR NORTHEAST MO, SOUTHEAST
IA, AND WEST CENTRAL IL COUNTIES JUST PRIOR TO 12Z SUNDAY. A QUICK
HALF INCH OF RAIN IS POSSIBLE PRIOR TO SUNRISE.
LONG TERM
(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 AM CDT SAT OCT 23 2021
KEY MESSAGES:
1. WIDESPREAD RAIN AND THUNDERSTORMS SUNDAY INTO MONDAY.
2. MIDWEEK SYSTEM TO BRING MORE RAIN AND EVEN SOME THUNDER TO THE
AREA.
3. MAY SEE SOME STRONG TO SEVERE STORMS AND FLOODING SUNDAY
AFTERNOON.
DISCUSSION:
PROGRESSION OF THE LARGESCALE PATTERN HAS NOT CHANGED WITH THIS
FORECAST ITERATION. A WARM FRONT WILL STALL EITHER JUST SOUTH OR
JUST INTO THE CWA SUNDAY AS SEASONABLY HIGH PWATS MOVE INTO THE
AREA. LIFTING OVER THESE BOUNDARIES WILL LEAD TO HEAVY RAIN ACROSS
THE AREA. THE CLOSED UPPER LEVEL LOW WILL MOVE EAST INTO THE AREA
ON SUNDAY AND CONTINUE TO PRODUCE ASCENT FOR PRECIP. ONCE THE LOW
MOVES EAST, THE WRAPAROUND WILL CONTINUE PRECIP INTO MONDAY. WEAK
RIDGING BUILDS BACK INTO THE AREA BEFORE ANOTHER STRONG WAVE
MIDWEEK. THIS WAVE HAS SLOWED A LITTLE AND IN SOME GUIDANCE BEGINS
TO CLOSE OFF AND TRY TO SWING NEGATIVE OVER THE AREA. ADDITIONAL
HEAVY RAINFALL IS POSSIBLE WITH THIS SYSTEM AS WELL. ANOTHER
FROST/FREEZE IS POSSIBLE MONDAY NIGHT MAINLY NORTH OF HIGHWAY 34.
AFTER THIS RIDGING BUILDS IN FOR NEXT WEEKEND ALONG WITH QUIETER
WEATHER.
MOST ATTENTION IN THIS SHIFT WAS FOCUSED ON THE HEAVY RAIN EVENT
SUNDAY INTO MONDAY. THERE REMAINS A CONDITIONAL THREAT FOR SEVERE
WEATHER AS WELL IN THE AFTERNOON. LET'S FIRST DIVE INTO THE
SYNOPTIC PATTERN. LATEST GUIDANCE WOULD SUGGESTED A NORTHERN SHIFT
TO THE HEAVIEST RAIN AS THE H92 AND H85 LOWS ARE FURTHER NORTH. THIS
IS REPRESENTED IN THE 00Z GUIDANCE, EXCEPT FOR THE GEM WHERE THE
NAM/GFS PULL THE FRONT FURTHER NORTH AND THE ECM IS WHERE THE US
MODELS WERE 24 HOURS AGO. SO THE QUESTION OF WHERE IS NOT MORE
CLEAR WITH THIS RUN. TO THROW A LARGER WRENCH INTO THIS, THE CAMS
ARE SOUTH WITH THE HEAVIER RAINFALL. CAMS ARE GREAT WITH MODE, BUT
NOT THAT GOOD WITH LOCATION. STILL, THIS DOESN'T ADD MORE
CONFIDENCE TO WHERE THE HEAVIEST RAINFALL WILL OCCUR. WITH THE
LATEST GUIDANCE, ANYWHERE SOUTH OF HWY 30 COULD SEE THE BAND WITH
THE MOST CONSISTENT SIGNAL BEING NEAR THE IA/MO BORDER.
AS FAR AS QPF GOES, STILL THINK 2 TO 4 IN THE BAND IS REASONABLE
WITH HIGHER AMOUNTS POSSIBLE. PWATS ALONG THE FRONT PUSH 1.5 INCHES
WHICH IS NEAR RECORD FOR THIS TIME OF YEAR. WITH THE STRONG
SYNOPTIC LIFT, AIDED BY CONVECTIVE ELEMENTS, WE WILL SEE SOME HEAVY
RAIN THAT MAY LEAD TO LOCALIZED FLASH FLOODING. A FLASH FLOOD WATCH
WILL LIKELY BE NEEDED LATER TODAY IF WE CAN NAIL DOWN A BETTER
THREAT AREA. I DO THINK THE RAIN WILL BE THE MAIN THREAT WITH THIS
SYSTEM.
NOW TO THE SEVERE THREAT. SPC HAS A MARGINAL RISK FOR MOST OF THE
AREA, A SLIGHT FOR SOME OF THE SOUTH AND AN ENHANCED FOR THE FAR
SOUTHERN COUNTIES. THE SLIGHT AND ENHANCED ARE FOR A HAIL THREAT. I
AM NOT CONFIDENT WE WILL SEE MUCH FROM A SEVERE THREAT. THERE IS NO
DOUBT SUFFICIENT SHEAR FOR LLVL ROTATION. NOT SURE THE REPEATED
BOUTS OF CONVECTION WILL ALLOW FOR ENOUGH LLVL CAPE TO BUILD FOR A
TORNADO THREAT. NONETHELESS WITH THE SHEAR, THE 2% MAKES SENSE. AS
FAR AS THE HAIL AND ENHANCED GOES, THINK THAT THE HAIL THREAT IS
ACTUALLY NOT THAT HIGH. WHILE WE HAVE SHEAR AND COULD SEE ELEVATED
HAILERS, THE OVERALL ENVIRONMENT FOR LARGE HAIL IS NOT THAT GOOD FOR
US. THINK THERE WILL BE AN OVER ABUNDANCE OF HAIL EMBRYOS AND THUS
WILL COMPETE WITH EACH OTHER TO GET LARGE. WE WILL LIKELY SEE A
LOT OF PEA SIZED HAIL STORMS AND MAYBE A QUARTER HERE OR THERE.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1107 AM CDT SAT OCT 23 2021
STARTING THE TAF PERIOD OUT CALM, WITH LIGHT EASTERLY WINDS AND
RELATIVELY CLEAR SKIES. THROUGH THE DAY, CLOUDS WILL BE ON THE
RISE. THIS EVENING AND TONIGHT, LOW CLOUDS AND RAIN WILL BEGIN TO
PUSH IN FROM THE SOUTH, QUICKLY DROPPING CIGS TO 500-1000 FT, AND
VISIBILITIES WILL ALSO BE REDUCED TO 2-4 SM. THESE CONDITIONS WILL
LAST THROUGH THE DAY TOMORROW, AS THE SYSTEM WILL BE SLOW TO MOVE
OUT. RAINFALL CAN BE HEAVY AT TIMES AND EMBEDDED THUNDERSTORMS
WILL ALSO BE POSSIBLE, ESPECIALLY AT BRL. RIGHT NOW, WILL STICK
WITH FORECAST FOR IFR CONDITIONS MOVING IN FROM THE SOUTH AROUND
06Z AND FILLING MUCH OF THE AREA BY 15Z. SOME LIFR CONDITIONS
CANNOT BE RULED OUT TOMORROW MORNING AT BRL AND MLI, BUT WILL
FURTHER EVALUATE THIS POTENTIAL IN THE NEXT FORECAST RUN.
HYDROLOGY
ISSUED AT 1107 AM CDT SAT OCT 23 2021
GIVEN THE CHANCE FOR HEAVY RAIN, WITH SOME SEEING 2 TO 4 INCHES
OR MORE, THERE IS POTENTIAL FOR RIVER RISES SUNDAY. HEAVIEST
RAINFALL IS CURRENTLY FORECAST TO FALL ALONG AND SOUTH OF
INTERSTATE 80, LEADING TO POTENTIAL IMPACTS ALONG THE ROCK, SKUNK,
LA MOINE AND FOX RIVERS. BASED ON MOST OF THE ENSEMBLE GUIDANCE,
A HIGH END EVENT WOULD PUT THESE RIVERS INTO FLOOD WITH THE LA
MOINE HAVING THE BEST CHANCE. RIVER FORECASTS ARE NOT REFLECTING
THIS HEAVY RAINFALL YET, BUT THESE RIVERS WILL LIKELY SEE RISES IF
THIS HEAVY RAIN DOES FALL FOR AN EXTENDED PERIOD. STAY TUNED FOR
FUTURE UPDATES, AS HEADLINES MAY BE NECESSARY.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...GROSS
SHORT TERM...GROSS
LONG TERM...GIBBS
AVIATION...GUNKEL
HYDROLOGY...GUNKEL
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