284
FXUS63 KDVN 152332
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
632 PM CDT MON SEP 15 2025
KEY MESSAGES
- UNSEASONABLY WARM WEATHER CONTINUES THROUGH MOST OF THIS WEEK
BEFORE FINALLY COOLING DOWN A BIT TOWARD THE END OF THE WEEK.
- BETTER RAIN CHANCES RETURN THURSDAY NIGHT INTO FRIDAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 205 PM CDT MON SEP 15 2025
THE UPPER RIDGE THAT HAS BROUGHT OUR HOT WEATHER HAS NUDGED
INTO THE GREAT LAKES WHILE A TROUGH OVER THE SOUTHEAST UNDERCUTS
IT. MEANWHILE, TO OUR WEST A TROUGH OVER THE NORTHWEST US
CONTINUES TO SPIN, WITH A RELATED SPOKE OF ENERGY PUSHING
NORTHWARD ACROSS THE NORTHERN PLAINS TODAY. THIS HAS BROUGHT
MORE WIDESPREAD SHOWERS AND THUNDERSTORMS JUST TO OUR NORTH OVER
MINNESOTA AND WISCONSIN WHERE SHORTWAVE ENERGY OVERLAPS WITH A
MORE FOCUSED AREA OF LOW LEVEL MOISTURE. THIS MOISTURE IS BEING
PULLED NORTHWARD FROM ARKANSAS AND FOCUSED INTO A MORE NARROW
STRIP ACROSS CENTRAL TO EASTERN IOWA AS THE TROUGH CONTINUES TO
LIFT NORTH. IT'S WITHIN THIS NARROW BELT OF MOISTURE THAT WE
WILL SEE OUR BEST CHANCES FOR SHOWERS AND THUNDERSTORMS TODAY.
INSTABILITY MAXIMIZES IN THIS ZONE AND WEAK BUT APPARENT
CONVERGENCE IN THE LOW LEVELS ASSISTS IN INITIATING CONVECTION
WITH STORMS TRACKING MOSTLY OFF TO THE N OR NNE. PLENTY OF
INSTABILITY TODAY WILL LEAD TO AT LEAST A LOW THREAT FOR DENSER
CORES TO CAUSE GUSTY WINDS AS THEY COME DOWN, BUT WIND SHEAR
REMAINS WEAKER, LIMITING THE OVERALL SEVERE WEATHER THREAT.
CONVECTIVE COVERAGE SHOULD DECREASE SIGNIFICANTLY WITH THE LOSS
OF DAYTIME HEATING, ALTHOUGH WE COULDN'T RULE OUT A FEW STRAY
SHOWERS OR STORMS CONTINUING OVERNIGHT.
LOW LEVEL FLOW TURNS EASTERLY TOMORROW, ADVECTING IN DRIER AIR
FROM THE EAST. THIS PUSHES THE AXIS OF GREATER MOISTURE OFF TO
THE WEST AS WELL, ALMOST ENTIRELY OUT OF OUR FORECAST AREA. THUS
WHILE TOMORROW MAY BE A SIMILAR SHOW AS TODAY AS FAR AS
CONVECTION GOES, THE THREAT AREA SHIFTS A BIT WESTWARD LEADING
TO LOWER COVERAGE IN OUR FORECAST AREA. TEMPERATURES REMAIN WARM
TO HOT, PEAKING IN THE UPPER 80S TO LOW 90S.
LONG TERM /TUESDAY THROUGH MONDAY/
ISSUED AT 205 PM CDT MON SEP 15 2025
THE UPPER RIDGE REALLY TAKES A BEATING OVER THE NEXT SEVERAL
DAYS WITH THE END RESULT BEING AN EVENTUAL END TO THE HEAT. A
TROUGH MOVING THROUGH EASTERN CANADA PUSHES BACK ON THE NORTHERN
EXTENT OF THE RIDGE, WHILE THE PERSISTENT TROUGH TO THE WEST
GRADUALLY NUDGES EASTWARD THROUGH MIDWEEK. THE REMAINS OF THE
RIDGE HOLD STRONGEST ACROSS THE CENTER OF THE COUNTRY, KEEPING
OUR AREA IN THE WARM AIR LONGER. BUT, CHANGE IS COMING. THE
TROUGH TO OUR WEST WILL EVENTUALLY GET HERE AND WHEN IT DOES IT
WILL BRING RAIN CHANCES AND A SHIFT BACK TOWARD COOLER
TEMPERATURES, OR AT LEAST CLOSER TO NORMAL FOR MID SEPTEMBER.
WHILE LONG RANGE GUIDANCE DOES GENERALLY AGREE THAT WE WILL
TRANSITION FROM THE WEAKENING RIDGE TO THE EASTWARD NUDGING
TROUGH, WHEN THAT OCCURS AND WHAT THE TROUGH LOOKS LIKE WHEN IT
BEGINS TO IMPACT OUR WEATHER STILL VARIES. THE TROUGH ITSELF
BECOMES CUT OFF FROM THE FLOW TO THE NORTH BY A RIDGE DEVELOPING
IN WESTERN CANADA. THIS TYPE OF CUT OFF LOW SCENARIO IS
NOTORIOUS FOR BEING MORE UNPREDICTABLE WITH WIDER TIMING
UNCERTAINTY THAN NORMAL. BEING AS THE TROUGH ITSELF IS
ENCOMPASSED BY A BROADER RIDGE, THE TEMPERATURES EXPERIENCED IN
THE CORE OF THE TROUGH WON'T BE ALL THAT COOL. NOT LIKE WHAT WE
SAW FROM OUR COOL SPELL EARLIER THIS MONTH. BUT THE TROUGH DOES
COME WITH COOLER TEMPERATURES ALOFT LEADING TO MORE CLOUD COVER
AND ROUNDS OF SHOWERS AND THUNDERSTORMS WHICH REALLY HELP TO
TONE DOWN THE HEAT. THE UNCERTAINTY ON THE ARRIVAL OF THIS
TROUGH IS SHOWN IN PART IN THE NBM INTERQUARTILE RANGE FOR HIGH
TEMPERATURES WHICH FOR MOST OF THIS WEEK IS ONLY 2 TO 3 DEGREES
ACROSS OUR FORECAST AREA. HOWEVER FROM FRIDAY ONWARD IT'S MORE
ON THE ORDER OF 7 TO 10 DEGREES, INDICATING THAT GREATER
UNCERTAINTY ON WHEN THAT COOLER AIR ARRIVES AND HOW COOL EACH
SUBSEQUENT DAY WILL BE (IT DEPENDS ON CLOUD COVER).
AS FAR AS RAIN GOES, WHEN THE TROUGH DOES FINALLY NUDGE CLOSER
TO US WE'LL SEE THE BEST WIDESPREAD RAIN CHANCES WE'VE SEEN IN A
WHILE. AMONG THE 00Z ENSEMBLE GUIDANCE, 70 TO 90 PERCENT OF
MEMBERS PRODUCE MEASURABLE RAIN ACROSS OUR FORECAST AREA IN THE
24 HOURS ENDING FRIDAY EVENING INDICATING HIGHER CONFIDENCE THAT
WE WILL EVENTUALLY GET AT LEAST SOME RAIN. OUR DAILY POP FROM
NBM IS LOWER THAN THAT DUE TO UNCERTAINTY ON WHETHER THAT RAIN
COMES THURSDAY NIGHT OR FRIDAY. IT COULD BE A SUBSTANTIAL
RAINFALL AS WELL, WITH ACCESS TO AT LEAST MODEST MOISTURE AS THE
TROUGH ARRIVES (PRECIPITABLE WATER GETS CLOSE TO 1.5 INCHES)
ALONG WITH ASSOCIATED INSTABILITY. HOWEVER, RAIN BEING AT LEAST
PARTLY OF A CONVECTIVE NATURE INDICATES AMOUNTS WILL BE
VARIABLE BASED ON WHERE DEEPER CONVECTION DEVELOPS.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 630 PM CDT MON SEP 15 2025
VFR CONDITIONS AND LIGHT WINDS ARE EXPECTED THROUGH THE PERIOD.
THERE IS A LOW <15% CHANCE FOR THUNDER AT CID IN THE NEXT 3
HOURS. CURRENTLY RADAR AND SATELLITE TRENDS SUGGESTS CID STAYS
DRY SO HAVE LEFT OUT OF TAF AT THIS TIME.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...NWS
LONG TERM...NWS
AVIATION...GIBBS
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