908 
FXUS63 KOAX 232042
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
342 PM CDT Sun May 23 2021

.DISCUSSION...
Issued at 338 PM CDT Sun May 23 2021

Synopsis: 

A large mid/upper level trough continues to move northeast across 
the western US with a lead shortwave axis moving northeast out of 
Colorado and into the High Plains of Neb and SD this afternoon. 
To our east, a large ridge of high pressure remains over much of 
the eastern US. This leaves the nation's mid-section in 
strong/moist southerly flow off the Gulf which can be seen well 
via water vapor imagery. 

Forecast: 

Diurnally driven, widely scattered showers have developed across a 
large portion of the CWA as a few subtle shortwaves were drifting
through the southerly mid-level flow. Expect this activity to 
continue through peak heating before diminishing with sunset as 
low- level lapse rates decrease with the loss of daytime heating. 
Brief heavy downpours could occur with the stronger cells and a 
few rumbles of thunder cannot be ruled out. Severe storms are not 
anticipated this afternoon/evening. 

Much more active weather will be well to our west across western 
Nebraska as a strong lead shortwave trough was ejecting 
northeastward out of Utah/Colorado. This activity is forecast to 
spread east on the nose of a veered nocturnal low-level jet and 
toward northeast Nebraska by 05-06z. Some of the early activity 
could produce severe wind gusts but the complex is forecast to 
weaken as it moves east. 

This decaying activity will likely leave a few outflow boundaries 
across the area by Monday morning where bouts of weak activity could 
linger throughout the morning. By afternoon heating, more organized 
convection could develop across northeast Nebraska along a weak 
frontal boundary with the potential for isolated severe wind/hail 
possible. Otherwise, a persistent low-level jet will focus storms
into the overnight hours into Tuesday morning. 

Again on Tuesday, remnant boundaries will likely be draped across 
the region with additional thunderstorm development across the 
southeastern CWA along a frontal boundary. 

Medium range guidance is still somewhat uncertain as we head into 
mid to late in the work week as weak upper level ridging builds 
overhead before a potent shortwave takes aim at the area. With ample 
moisture still in-place, a heavy rain set up looks possible late 
Wednesday night into Thursday as the nose of the low-level jet 
continue to sustain a convective complex over the area. 

Slightly cooler conditions are possible into the beginning of 
Memorial Day weekend as we briefly return to northwesterly flow 
aloft. This will be short-lived with a return to southerly return 
flow by Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1217 PM CDT Sun May 23 2021

VFR cigs will be the predominant category today however a tempo
MVFR cannot be ruled out into the evening. All three sites are
expected to remain precipitation-free with the exception of KOFK
after midnight tonight as a line of convection moves east across
central Nebraska. These thunderstorms are expected to weaken as
they move into northeast Nebraska so added a Prob30 group for now. Otherwise,
models hint at some lower ceilings (MVFR) spreading over the 
sites by sunrise Monday.


&&

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

$$

DISCUSSION...Kern
AVIATION...Kern