FXUS63 KOAX 041902

AFDOAX



Area Forecast Discussion

National Weather Service Omaha/Valley NE

202 PM CDT Tue Aug 4 2026



.KEY MESSAGES...



- Rain chances shift to southeast Nebraska and southwest Iowa

  Tuesday evening into Wednesday (60-90% chance).



- Milder temperatures through Thursday, warming back up going

  into the weekend. Dry, seasonably warm weather expected over

  the weekend.



- Wildfire smoke continues to drift in from the north. A small

  amount may be found at the surface. Most will be elevated and

  may produce some hazy skies. 



&&



.DISCUSSION...

Issued at 200 PM CDT Tue Aug 4 2026



Surface analysis shows the cooler Canadian air has pushed

through all but the last southeastern counties of the CWA.

Behind the front, temps are mostly in the 60s and 70s with brisk

northerly winds. Ahead of it, Falls City, Nebraska City, and

southwest Iowa have managed 80 before the cooler air has arrived.

KOAX has been interpreting returns from rain since before 

sunrise. Radar estimates suggest some locations between Norfolk 

and Sioux City (including Wayne) have received 1.5". Ground 

truth shows gauges mostly reporting closer to half of that. 



These showers and associated lightning/thunder are slowly

sliding east/southeast and are expected to dissipate and push 

out of the southeastern corner CWA by about 7pm tonight as the

shortwave responsible for their forcing continues east.



The dry spell won't last long as another vort max - currently

over the high country of Colorado - pushes through overnight.

That combined with the extra lift provided by the summer

nocturnal jet, and likely PoPs (80-90%) are expected in the 

areas within 50 miles of I-80. With PWAT values near the 90th

percentile for August, some localized heavy rain is possible in

the urban areas of Omaha and Lincoln. CAM QPF suggests rainfall

of 3.5" is possible at Omaha, which would overwhelm the city's

drainage system. Considered a flood watch, but will hold off for

now due to low confidence as to where the QPF bullseye is most

likely to set up, but western Iowa/Omaha metro has best odds. 



The SPC added an area of "marginal threat" for severe weather

this evening. Most of the lift is displaced north of the front,

but just ahead of it, there is 1500 J/kg of CAPE and 40-50 knots

of bulk shear. Should a storm tap into that instability, it

could produce some borderline severe weather. 



Overnight's instability will be elevated... leaving lots of

thunder and lightning, but little severe threat. 



.WEDNESDAY...



Rainfall will continue over the southern half of the area

through Wednesday's first half before continuing southeast. 



Skies will be clearing from north to south, but they'll remain

marred by the wildfire smoke drifting in from Canada. Expect a 

20-30% reduction in sunlight. There may be some smoke found at 

the surface, too, but models seem to be overdoing it so far 

based on observations from up north and I have opted not to 

include it in the forecast for now.



Temperatures will be cooler for Wednesday behind the front with

highs relegated mostly to the 70s as high pressure works in from

the north. 



.THURSDAY AND BEYOND...



Southerly return flow develops as the sfc high slides east.

Those winds help push temps past the 80F mark. More showers and

storms are possible late on Thursday night as another shortwave

sweeps through Kansas. 



Temps will continue to warm into the weekend, but as the H5 

pattern becomes quasi-zonal, temps should moderate to near 

seasonal averages or a few degrees warmer into the lower 90s. 



&&



.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...

Issued at 1220 PM CDT Tue Aug 4 2026



Line of showers and storms in the northern half of the area are

expected to push southeast and out of the area by 6pm tonight.

These showers and storms will be impactingLNK and KOMA from

about 00Z to 02Z this evening. 



More convection is expected to develop by 9pm tonight, and

expand and slide east through the overnight hours. These storms

should remain sub-severe, but will produce some wind gusts of

40 mph or so and leave MVFR cigs at KOMA and perhaps KOFK and

KLNK, too. 



Wildfire smoke drifting in from the north is mostly elevated at

5-8,000 feet, but there will be some at the sfc, too...

especially on the northern and western edges of the area as the

TAF period continues.



&&



.OAX WATCHES/WARNINGS/ADVISORIES...

NE...None.

IA...None.



&&



$$



DISCUSSION...McCoy

AVIATION...Nicolaisen