828 
FXUS63 KOAX 191125
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
625 AM CDT Tue Sep 19 2023

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 252 AM CDT Tue Sep 19 2023

Key Messages:

 - Still warm today, then trending cooler through the remainder
   of the week with highs in the 60s and 70s by the weekend.

 - Sporadic chances for showers and storms through Thursday,
   with showers and storms becoming likely by Friday/Saturday.

Early this morning, scattered showers and storms were continuing 
across much of Iowa and into southeast Nebraska as weak shortwave 
energy continued to push through and moisture transport pointed 
into the area. Latest CAMs suggest some additional activity could 
continue to bubble up throughout the day and into this evening, 
especially in southeast Nebraska and southwest Iowa on the nose of
continued weak moisture transport. However, model soundings 
suggest we'll still be on the dry side, plus the aforementioned 
CAM output is rather spotty with said additional development, so 
overall, shouldn't be too impactful and most will likely stay dry.
Otherwise, we'll see another warm day across the area, with highs
in the mid 80s to lower 90s.

Additional weak bits of shortwave energy will slide through the 
area through Thursday while southerly flow continues to usher 
moisture into the area. As a result, we could see some spotty 
showers and storms, especially during peak diurnal heating and in 
the evening/overnight as low level moisture transport strengthens.
In addition, some weak/subtle surface boundaries (outflow or 
otherwise) may provide additional support for storm development at
times. Still, overall forcing looks rather disjointed and weak, 
so currently thinking most of this timeframe will be dry for most 
areas, so only have spotty 20% chances in the forecast. 
Temperatures will also be slightly cooler, with highs in the upper
70s to lower 80s, though this will likely depend on any precip 
that does develop.

By Thursday evening, precip chances increase as guidance is in 
pretty good agreement of a stronger system approaching with 
moisture transport ramping up and pointing into a surface warm 
front draped across the area. Another stronger shortwave then 
looks to move in Friday into Saturday bringing additional 
widespread showers and storms. There also appears to be at least 
some risk for severe storms on Friday with guidance suggesting 
1000 to 2000+ J/kg of MUCAPE and increasing shear as a mid to 
upper level let begins to nose into the area. Still quite a few 
details to iron out, however, with most guidance suggesting 
ongoing morning convection on Friday morning, which will almost 
certainly play a role in how things pan out. A similar setup looks
possible on Saturday afternoon, albeit farther east (mainly in 
Iowa) as much of the ensemble guidance suggests a dry slot pushes 
into the area. Guidance does show we eventually get some precip to
wrap back in on the back side of surface low over the 
Dakotas/Minnesota, but that may hold off until Saturday night or 
Sunday. All that said, there is a fair amount of spread in the 
evolution of said surface low, so forecast confidence in precip 
beyond Saturday morning is rather low.

Along with the precip, these systems will be bringing in much 
cooler air, as highs look to top out in the 70s on Saturday, and 
may struggle to get out of the 60s on Sunday. The cooler weather 
looks to persist into at least the beginning of next week, along 
with some additional spotty shower and storm chances.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 616 AM CDT Tue Sep 19 2023

Low level wind shear should taper off over the next couple of
hours. Winds will remain out of the south today, with occasional
gusts up to 20 to 25 kts possible from 18-00Z at KOMA and KLNK. A 
few showers and thunderstorms could continue to fester over 
southeast Nebraska and southwest Iowa today, the majority of 
which should remain southeast of the TAF sites. Otherwise, VFR 
conditions should prevail through the period. 

&&

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

$$

DISCUSSION...CA
AVIATION...KG