954 
FXUS63 KOAX 201143
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
543 AM CST Wed Nov 20 2019

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 320 AM CST Wed Nov 20 2019

Large scale pattern consisting of a longwave trof situated over the 
west coast with two  distinct embedded circulations. The northern 
branch vort was centered over northern CA while the southern 
branch was lifting from Baja into AZ. Meanwhile, an area of low 
pressure was beginning to organize over the central high plains. 

Today through Thursday

Models showing the southern branch circulation lifting through the 
central Rockies and into the central Plains. Precip development 
progged to occur within area of increasing isentropic upglide in 
the vicinity of the TX/OK border later this morning then expanding
across KS then into the western CWA late this afternoon. 
Environmental moisture will be ample as both the NAM/GFS indicate 
precip water values catapulting to around 1.5" this evening given 
persistent influx of low level moisture. This, coupled with 
increasing ageostrophic forcing through tonight will likely lead 
to generous rainfall accumulations for this time of the year over 
potions of the CWA, particularly over southwest IA with amounts of
an inch or so possible. Across eastern Nebraska amounts ranging 
from a quarter to half an inch will be possible. Convective type 
precip appears possible this afternoon/evening as well in response
to steepening mid layer lapse rates. As for snow, portions of 
northeast NE will be most susceptible for seeing any 
accumulations sometime after midnight. However, any accumulations 
will be on the light side and suspect will be found mainly over 
grassy surfaces. 

Thursday night through Friday morning

GFS and ECM are in rather good agreement with respect to timing and 
placement of a system ejecting out of the central Rockies and 
tracking across KS then into MO. Brunt of precip activity will be 
well south of the CWA. However, there may be enough dynamic forcing 
to at least allow for a small chance of snow over portions of the 
CWA south of I-80.  

A noticeable change in temperatures is on the way over the 
region. A cold front moving through the region will push deep into
the central Plains over the next several days. Thrust of cold air
advection will be relatively weak and result only in slightly 
below normal highs over northeast NE on Thursday followed by most 
of the CWA on Friday. 

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 514 AM CST Wed Nov 20 2019

Deteriorating conditions are expected at all terminals later this
afternoon. Cigs going from VFR to MVFR/IFR with onset of sct SHRA
expanding across ERN NE. ISOLD TSRA will be possible as well
through mid evening. Precip intensity will increase during the
evening hours. After 06Z expect RA to continue through the
remainder of the fcst pd. LLWS be an issue at sites this morning
and through the early afternoon. 

&&

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

$$

DISCUSSION...DEE
AVIATION...DEE