FXUS63 KDVN 261745

AFDDVN



Area Forecast Discussion

National Weather Service Quad Cities IA IL

1245 PM CDT Thu Jun 26 2025



.KEY MESSAGES...



- A heat advisory has been issued for much of the area this

  afternoon into early evening. The heat and humidity will

  continue through the weekend. Some relief may occur next week.



- Strong to severe storms will again be possible late this

  afternoon and evening. Damaging winds from wet microbursts is

  the primary risk.



- 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 TONIGHT/...

Issued at 259 AM CDT Thu Jun 26 2025



The LLJ is very weak and mid-level lapse rates are fairly stable. As 

a result, quiet but humid conditions will be seen through sunrise. 

The exception is the Highway 20 corridor where an errant shower or 

thunderstorm might occur.



Hot and humid conditions will be seen across the area today. A heat 

advisory has been issued for a good chunk of the area. Dew points 

will drop somewhat during the day as deeper mixing is promoted 

through wind gusts this afternoon.



Mid-level lapse rates continue to remain fairly stable during the 

day. Some weak diurnal cumulus may develop from thermals this 

afternoon.



Attention then turns to the approaching cold front. The hi-res 

models have been suggesting a pre-frontal trof well in advance of 

the front which is suggested in the current observations in the 

Plains. Several of the hi-res solutions have a line of scattered 

storms developing along the pre-frontal trof with a secondary line 

along the cold front.



Although there are differences between the hi-res models, timing 

suggests late afternoon/evening for the pre-frontal storms in 

eastern Iowa. Most areas east of the Mississippi will remain dry 

into the early evening but a few isolated diurnal storms cannot be 

ruled out.



The storms moving into eastern Iowa late afternoon/early evening 

would have the best chances of being strong/severe. If severe storms 

develop, the primary risk is damaging winds in the form of wet 

microbursts and heavy rainfall.



Tonight the stable mid-level lapse rates east of the Mississippi 

suggests storms will struggle and weaken as they move east. Storm 

dynamics will modify the mid-levels of the atmosphere with time 

allowing storms to move east of the Mississippi later tonight. The 

trailing cold front will also aid in another round of storm 

development in eastern Iowa that moves east of the Mississippi well 

after sunset. However, this second round of storms has the potential 

to be more scattered in nature.



&&



.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

Issued at 259 AM CDT Thu Jun 26 2025



Friday through Monday

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



The cold front moving through the area late Thusday night and Friday 

will push temperatures down to around normal on Friday. The heat 

and humidity builds back in for the weekend with Sunday being the 

hottest day. This far out there is a 50% probability of heat 

headlines for Sunday.



Rain chances are more questionable. The proximity of the front to 

the area on Friday indicates this day has the best chances of seeing 

some rain. The front looks to stall out and dissipate Friday night 

just south of the area. If the front does stall just south of the 

area, the remnants of the front would provide a focus for mainly 

diurnal showers and storms across the far southern areas on Saturday 

but coverage would be in the 20-30% range.



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 40% scattered 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 I cannot fully rule out 

the possibility of a rogue convective 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 655 PM CDT Wed Jun 25 2025



Tributary rivers in east central Iowa are having a minor crest 

into early Thursday from earlier week rainfall, and then should 

see a temporary drop. Bouts of rain through Thursday night over

central to northeast Iowa (i.e. headwater regions of the Cedar,

Iowa, and Wapsi Rivers) will see water gradually come down the 

channel and additional rises by late weekend into early next 

week. Confidence in that general, slow-evolving expectation is 

fairly high. However, in terms of how high of water levels 

reached next week, that is much lower. That is due to 

uncertainty on where exactly the heaviest rain will fall with 

each bout through Thursday night, and timing of the water as it 

is channeled in upstream rivers channeling into the Cedar River.



For now, we continue Flood Watches on the Cedar River, even

though flood stage currently is not probable in the next 48

hours, and more so late in the weekend into next week. A main 

reason we continue the watches are that heavier rainfall could 

fall southeast of where it is predicted through Thursday night,

and there are multiple models (albeit a minority of model 

membership) that do show that. The predicted response on the 

rivers with those 10-15% of higher models show a couple points 

on the Cedar River, including Cedar Rapids, jumping all the way 

to major flood stage late in the weekend into early next week. 

The greater model membership would favor upper end minor stage 

to lower end moderate stage for the city, and coordinating with 

the North Central River Forecast Center (NCRFC), that is where 

we collectively felt most comfortable with the forecast.



&&



.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...08

LONG TERM...08

AVIATION...Schultz

HYDROLOGY...Friedlein

