FXUS63 KDVN 261926

AFDDVN



Area Forecast Discussion

National Weather Service Quad Cities IA IL

226 PM CDT Thu Jun 26 2025



.KEY MESSAGES...



- Heat Advisory remains in effect for a portion of the area this afternoon

  into the early evening. Additional heat headlines may be 

  needed this weekend, particularly on Sunday.



- Strong to severe storms remain possible this afternoon and

  evening, with damaging winds being the main threat.



- With a wet pattern across the area and a daily risk of showers

  and thunderstorms capable of producing heavy rainfall, area

  rivers are expected to see rises. Refer to the hydrology

  section for more information.



&&



.SHORT TERM /THROUGH FRIDAY/...

Issued at 211 PM CDT Thu Jun 26 2025



Hot and humid conditions were observed across the area, with 

heat indices around 2 PM this afternoon around the 95 to 102

degree range, and temperatures hovering around 90 degrees for

most locations. We are keeping an eye on a line of showers and 

storms that have developed over central Iowa ahead of a cold 

front that will eventually cross our area by this evening into 

the overnight hours, albeit in a decaying fashion after midnight

tonight. Before then, some air mass convection is progged by 

some of the CAMs late this afternoon as instability builds to 

the tune of 1500-2500 J/kg MLCAPE. Although deep-layer shear 

appears to be quite meager (<25 knots), steep low-level lapse 

rates and high Pwats to around 2 inches should support the 

threat for locally strong winds due to wet microbursts. SPC has 

maintained a Slight Risk (level 2 of 5) for severe weather for 

areas along and northwest of a Sigourney Iowa to Galena Illinois

line, with a Marginal Risk (level 1 of 5) for severe storms 

elsewhere in our CWA. Along the Highway 20 corridor, low-level 

shear appears to be stronger due to a more veering wind profile 

instead of a uni-directional profile farther south, so a brief 

tornado can't be ruled out across our far north.



Friday looks to be largely dry, with the line of showers and storms 

diminishing to only a few showers by sunrise. CAM guidance suggests 

very little in the way of additional activity along the front as it 

sweeps through the CWA. Also, the front should help usher in some 

cooler conditions, with high temperatures warming to the upper

70s north to the middle 80s south.



&&



.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

Issued at 226 PM CDT Thu Jun 26 2025



Friday night through Monday

Assessment...Very high (>90%) of heat and humidity continuing.



Heat and humidity builds back in for the weekend with Sunday 

being the hottest day. It is possible for heat indices to once

again warm to above 100 degrees F as temperatures warm to near

90 degrees with lower to middle 70s dew points. LREF exceedance

probabilities of heat indices of 100 degrees or more are around

10 to 30% - something to keep an eye on.



With the heat dome back into the area for Sunday, the question 

becomes will a weak upper level disturbance approaching the area 

generate diurnal convection. The model consensus suggests this with 

a 30 to 50% coverage Sunday afternoon/evening.



An approaching front on Monday (associated with the pattern change 

aloft) raises questions regarding the rain potential. Several 

deterministic model runs suggest very little in the way of rain. 

However, there are several members from the respective ensemble runs 

that generate rain. Thus, the model consensus is biased toward 

the ensembles but the areal coverage for any rain is only 

20-40%.



Monday night through Wednesday

Assessment...medium (40-60%) confidence on near normal temperatures.

Low (<25%) confidence on rain chances.



The pattern change to west-northwest flow aloft will help keep 

temperatures around or slightly above normal. With the heat dome

suppressed southward, the more tropical moisture that would 

fuel storms is not present. Thus, the deterministic model runs 

and nearly all of their respective ensemble members have dry 

conditions Monday night through Wednesday.



However, there are weak disturbances in the flow aloft moving 

through the area Tuesday and Wednesday. Thus, we cannot fully 

rule out the possibility of a rogue storm developing during the

diurnal heating cycle on Tuesday and Wednesday. If this were to

occur, areal coverage would be under 10 percent.



&&



.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...

Issued at 1245 PM CDT Thu Jun 26 2025



VFR conditions will continue with widespread FEW to BKN daytime

cumulus clouds in place. We are watching a broken line of

showers and storms approaching eastern Iowa from the west ahead

of a cold front, which will eventually move through this evening

into the overnight hours tonight. Some of these storms could be

strong to severe, with locally strong wind gusts to around 40 

knots possible along with MVFR/IFR visibility reductions under

heavy downpours. This afternoon, we can't rule out an isolated 

storm, so used PROB30 groups to highlight this threat. By Friday

morning after sunrise, MVFR ceilings are possible, along with a

wind shift behind the front.



&&



.HYDROLOGY...

Issued at 212 PM CDT Thu Jun 26 2025



Forecast crests along portions of the Cedar River have trended lower 

into next week due to less rainfall anticipated over the next 24 

hours, particularly across the upstream section of the basin 

(northwest of Vinton). Additional rounds of heavy rainfall over the 

weekend into early next week could result in changes to the timing 

and magnitude of the forecast crests. However, the latest river 

level forecasts are only accounting for forecast rainfall (QPF) over 

the next 24 hours. Confidence has increased enough at Marengo along 

the Iowa River to potentially reach Minor flood stage by this 

weekend, so have issued a River Flood Watch for this site.



&&



.DVN WATCHES/WARNINGS/ADVISORIES...

IA...Heat Advisory until 7 PM CDT this evening for IAZ052-053-

     064>068-077-078-087>089-098-099.

IL...Heat Advisory until 7 PM CDT this evening for ILZ007-009-

     015>018-024>026-034-035.

MO...Heat Advisory until 7 PM CDT this evening for MOZ010.



&&



$$



SHORT TERM...Schultz

LONG TERM...08/Schultz

AVIATION...Schultz

HYDROLOGY...Uttech

