270 
FXUS63 KOAX 231119
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
619 AM CDT Mon Aug 23 2021

...Updated for 12Z Aviation Forecast Discussion...

.DISCUSSION...
Issued at 400 AM CDT Mon Aug 23 2021

At 4 AM, skies were mostly cloudy over the region thanks to a
thunderstorm complex along the NE/KS border that was riding the
nose of the LLJ. These storms could produce some light rain south
of Lincoln through around 9 AM, but in general the environment 
looks less favorable for storm maintenance in southeast Nebraska. 
Aside from that, winds were light and it was a relatively muggy 
morning across the Missouri River Basin (dewpoints in the mid to 
upper 70s).

Muggy with Lingering Storm Chances Today:

The synoptic pattern today will feature an upper level ridge 
centered over Texas and laminar flow from southwest to northeast 
over the Northern Plains (between 700 mb and 200 mb). There are some 
indicators of a weak wave around 700 mb that may lift north
towards our region this afternoon. Otherwise, the main forcing 
mechanism for thunderstorm activity today looks to be a rather 
diffuse frontal boundary draped from north central Nebraska to 
northern Iowa. Surface dewpoints in the lower 70s and 700-500 mb 
lapse rates around 7.5 C/km should contribute to ample MLCAPE 
(~3000 j/kg) along the frontal boundary by this afternoon. Toss in
diurnal mixing, and it looks like we could see increasing 
thunderstorm activity north of Interstate 80 between 1 PM and 4 PM
today. CAMs generally support this conclusion, so forecaster 
confidence in storm development is moderate. Shear profiles may 
allow storms to be briefly supercellular, but with time any 
activity should become outflow dominate. With this in mind, the 
main threats look to be hail large enough to damage cars and winds
capable of downing trees or power lines today.

Another concern today will be the return of the heat, especially 
south of the frontal boundary where storm chances will be nil. Our
going forecast suggests heat indicies of 98 to 104 degrees along 
and south of Interstate 80 between Noon and 6 PM. So it will feel 
pretty muggy out there today in the Lincoln and Omaha Metros. No 
Heat Advisory was issued for today as peak heat indicies look to 
be 1 to 3 degrees below the standard threshold of 105 degrees.

Tonight and Tuesday:

A second weak wave near 700 could bring a couple isolated showers or 
thunderstorms to the region tonight, though confidence in 
precipitation is low. Then we can expect another warm and muggy day 
Tuesday with our region in the warm sector ahead of any advancing 
cold front. By Tuesday afternoon the front may be approaching our
region, and thunderstorm chances will return. Highest storm chances
of around 20-35 percent are expected Thursday evening along the 
Interstate 80 Corridor. 

Temperatures on Tuesday should flirt with Heat Advisory criteria 
again, with peak heat indicies of 100 to 106 along and south of 
Interstate 80. Will reevaluate the need for a Heat Advisory on 
later shifts, but for now the chance of a Heat Advisory is around  
60 percent.

Midweek into the Weekend:

The weather pattern over the U.S. doesn't change much during this 
period. Ensembles suggest the upper level ridge over Texas today 
will move little, just shifting towards the Southeast U.S. Meanwhile 
the parade of weak shortwaves through the northern tier of the U.S. 
looks like it will continue. A pattern like this places us on the 
southern edge of the best rain chances, and on the northern fringe 
of above average temperatures. Therefore the forecast for 
Wednesday through the weekend favors low precipitation chances 
(15-40 percent) and slightly above average temperatures (87-95 
degrees) each day. Confidence in potential rainfall amounts or 
timing remains low. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 619 AM CDT Mon Aug 23 2021

Expect mainly VFR conditions the next 24 hours. There are some MVFR
ceilings in the far northern parts of northeast NE north of KOFK
and some patchy areas of fog, but we don't expect these to have
much of an impact at the TAF sites. Could see some scattered storms
in parts of northeast NE today and mentioned a PROB30 group at
KOFK for 21z-24z. Otherwise chances at KOMA and KLNK are not zero
but too low to include in TAFs. 

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

DISCUSSION...Albright
AVIATION...Miller