359
FXUS63 KDVN 170543
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1243 AM CDT WED SEP 17 2025
..06Z AVIATION UPDATE
KEY MESSAGES
- WARM AND DRY CONDITIONS CONTINUE FOR THE NEXT COUPLE OF DAYS.
- PERIODS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED AS EARLY AS
LATE THURSDAY AND LASTING THROUGH THE WEEKEND.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 211 PM CDT TUE SEP 16 2025
OUR HOT, DRY RIDGE REMAINS PARKED OVER THE GREAT LAKES WHILE A
SLOW MOVING TROUGH SPINS OVER THE NORTHERN ROCKIES. WE CONTINUE
TO SEE A PLUME OF MOISTURE STREAMING SOUTH TO NORTH AROUND THE
RIDGE WHICH WILL AGAIN LEAD TO SHOWERS AND THUNDERSTORMS
DEVELOPING THIS AFTERNOON. BUT THIS MOISTURE PLUME HAS SHIFTED A
BIT WESTWARD COMPARED TO YESTERDAY, SO THESE SHOWERS AND STORMS
ARE LIKELY TO REMAIN WEST OF OUR FORECAST AREA THIS EVENING.
EASTERLY SURFACE WINDS HAVE BEEN PUSHING IN SOME LOW LEVEL DRY
AIR WHICH HAS HELPED PUSH THE AXIS OF BETTER MOISTURE AND
INSTABILITY WESTWARD. HOWEVER, WE REMAIN FAIRLY HOT, WITH
TEMPERATURES IN THE UPPER 80S TO NEAR 90.
A MOSTLY CLEAR SKY AND LIGHT OR CALM WINDS WILL LEAD TO A COOL
NIGHT TONIGHT, WITH TEMPERATURES FALLING TOWARD THE DEWPOINT
(IN THE UPPER 50S TO LOW 60S). THERE'S AT LEAST SOME CONCERN FOR
FOG AS THERE WAS SOME NOTED THIS MORNING JUST TO OUR EAST IN A
SIMILAR FLOW REGIME. WE'VE INCLUDED THE MENTION OF PATCHY FOG IN
THE FORECAST, MAINLY ACROSS ILLINOIS. WEDNESDAY WILL BE ANOTHER
HOT AND DRY DAY SIMILAR TO TODAY. THE AXIS OF MOISTURE AND
INSTABILITY WILL AGAIN BE LARGELY TO OUR WEST, LIMITING THE
POTENTIAL FOR STORMS IN OUR AREA.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 211 PM CDT TUE SEP 16 2025
WE'LL SEE SOME CHANGES IN THE LONG TERM, EVENTUALLY. A TROUGH
MOVING EAST THROUGH CANADA ON WEDNESDAY BEGINS TO PUSH BACK THE
NORTHERN EXTENT OF THE RIDGE. A PORTION OF THIS TROUGH ACTUALLY
HEADS SOUTHWARD AND GETS ABSORBED BY THE LARGER TROUGH TO OUR
WEST, SPINNING OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS.
THIS HAS THE EFFECT OF SLOWING ITS EASTWARD PROGRESSION FOR A
BIT, BUT ALSO LEADING TO ITS EVENTUAL BREAK UP. SO OUR FORECAST
FOR THURSDAY CONTINUES TO PUSH TOWARD THE DRY AND WARM SIDE AS
THE TROUGH TAKES LONGER TO REACH US.
THE TROUGH TO OUR WEST GETS BROKEN INTO SEVERAL SMALLER WAVES,
AND THE FIRST TO IMPACT OUR AREA HEADS OUR WAY LATE THURSDAY
INTO FRIDAY. IT'S THIS PERIOD WHERE WE'LL HAVE THE BEST DYNAMIC
SUPPORT FOR SYNOPTIC SCALE LIFT IN OUR AREA, AND THUS OUR BEST
RAIN CHANCES. AT THE SURFACE WE CONTINUE TO HAVE A WARM AND
MODERATELY MOIST AIR MASS IN PLACE, SO THE ARRIVAL OF THE COOL
TROUGH ALOFT WILL GENERATE INSTABILITY FOR THE PRODUCTION OF
SHOWERS AND THUNDERSTORMS, POSSIBLY IN MULTIPLE ROUNDS. WHILE
THE OVERALL SEVERE WEATHER THREAT LOOKS LOW AT THIS POINT, IT IS
WORTH NOTING THAT THE TROUGH'S PRESENCE ALOFT WILL GIVE US
ACCESS TO GREATER WIND SHEAR THAN WE'VE SEEN IN A WHILE, AND
THERE SHOULD BE AT LEAST SOME INSTABILITY AROUND AS WELL. SO I
CAN'T RULE OUT A PERIOD OF MORE ORGANIZED THUNDERSTORMS AT SOME
POINT, BUT THE LACK OF A CAP WILL LIKELY PREVENT MORE EXTREME
INSTABILITY FROM DEVELOPING. WE'LL ALSO SEE COOLER DAYTIME
TEMPERATURES, MAINLY IN THE 70S AND 80S, AS CLOUDS AND COOLER
AIR ALOFT KEEP US FROM GETTING AS HOT. BUT WE DON'T GET A
THOROUGH CHANGE IN AIR MASS, THOUGH, AS THE LOW LEVEL MOISTURE
LINGERS. DEWPOINTS PERSISTING IN THE 60S WILL BUOY NIGHTTIME
TEMPERATURES ENSURING WE STAY ABOVE NORMAL EVEN ON OUR COOLER
DAYS.
THE TROUGH SLOWLY WOBBLES EAST OVER THE COURSE OF SEVERAL DAYS,
WITH MULTIPLE EMBEDDED WAVES MOVING THROUGH OUR AREA OVER THE
WEEKEND. MODEL GUIDANCE IS CONSIDERABLY MORE VARIABLE ON EACH
SUBSEQUENT WAVE AFTER THE FIRST ONE, SO THERE'S LESS CONFIDENCE
IN TIMING AND LOCATIONS IMPACTED WITH RAIN FROM EACH OF THEM.
HOWEVER, THERE IS HIGH CONFIDENCE OVERALL THAT PERIODS OF
SHOWERS AND THUNDERSTORMS WILL AFFECT JUST ABOUT EVERYONE. AMONG
THE 00Z GUIDANCE, NEARLY 100 PERCENT OF MEMBERS PRODUCE
MEASURABLE RAIN ACROSS THE ENTIRE FORECAST AREA IN THE 48 HOURS
ENDING SUNDAY NIGHT. SO CONFIDENCE IS HIGH THAT IT WILL RAIN
THIS WEEKEND, EVEN IF THE POP EACH PERIOD IS CONSIDERABLY LOWER
DUE TO THE UNCERTAINTY ON TIMING OF EACH OF THOSE EMBEDDED
WAVES. THIS IS WHY WE FEEL THE MESSAGE THROUGH THE WEEKEND IS
ABOUT PERIODS OF SHOWERS AND THUNDERSTORMS, SOMETHING WE HAVEN'T
SEEN THAT MUCH OF IN RECENT WEEKS.
WHILE GUIDANCE BEGINS TO DIVERGE ON THE HANDLING OF THIS
WEEKEND'S TROUGH, EVEN MORE VARIANCE IS NOTED FOR NEXT WEEK.
WHILE ALL GUIDANCE DOES MOVE THE TROUGH OUT OF OUR AREA BY
MONDAY, THE ECMWF NOTABLY DROPS ANOTHER TROUGH SOUTHWARD THROUGH
THE PLAINS, CUTTING OFF AND SETTLING NEAR THE OZARKS FOR
MIDWEEK. THIS KEEPS COOLER TEMPERATURES AND SOME RAIN CHANCES
AROUND EVEN IN OUR AREA. OTHER GUIDANCE, NOTABLY THE GFS AND
CMC, TRACK THIS WAVE MORE CLEARLY TO THE EAST, LEAVING SOME
DEGREE OF RIDGING IN ITS WAKE WITH THE POTENTIAL FOR A RETURN TO
HOT TEMPERATURES. THE SPREAD IN THE PROBABILISTIC NBM ALSO
REFLECTS THIS GREATER UNCERTAINTY, WITH THE IQR FOR HIGH
TEMPERATURES RISING TO 7 TO 10 DEGREES OR MORE THIS WEEKEND AND
THROUGH NEXT WEEK. SO WHILE THE DETERMINISTIC FORECAST DOES SHOW
A RATHER CONSISTENT FORECAST OF HIGHS IN THE LOW 80S, THERE'S
MORE TO THAT STORY. IF RIDGING TAKES HOLD WE'LL START TO WARM UP
AGAIN, TO THE UPPER 80S OR EVEN 90 AGAIN. IF THE ECMWF STYLE
TROUGH COMES MORE INTO PLAY THEN WE'LL BE COOLER, IN THE 70S,
WITH BETTER RAIN CHANCES.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1238 AM CDT WED SEP 17 2025
WILL KEEP THE SIMPLE ONGOING VFR TAF CYCLE GOING ON MORE DAY.
LIGHT EAST TO SOUTHEAST SFC WINDS AND PASSING HIGHER LEVEL
CLOUDS THROUGH WED EVENING. AGAIN JUST A LOW CHANCE FOR SOME
MVFR FOG AT A FEW OF THE TAF SITES BEFORE DAWN, AND WILL BANK ON
THE SCTRD AFTERNOON THUNDERSTORMS POPPING UP STAYING WEST OF ALL
THE TAF SITES. CID WILL HAVE THE BEST CHANCE FOR A ROGUE SHOWER
OR STORM GETTING INTO THE VCNTY BY LATE AFTERNOON, BUT WILL NOT
MENTION IT AT THIS TIME.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...KIMBLE
LONG TERM...KIMBLE
AVIATION...12
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