Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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951
FXUS63 KOAX 222007
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
307 PM CDT Thu Aug 22 2019

.SHORT TERM...(Tonight through Sunday)
Issued at 305 PM CDT Thu Aug 22 2019

The main forecast concerns are in regards to precipitation chances
over the next few days.

Upper air charts from 12Z this morning showed a thermal ridge at
850 mb and 700 mb extending from southern CA and AZ up into MT.
There was a fairly strong trough at 500 mb extending from western
Canada down into NV, with 12 hour height falls of up to 90 meters.
A compact vort max was noted in central NE, and this feature will
be monitored as it moves east for development of showers and
storms into our area. The short range convection allowing models
(CAMs) generally keep measurable precipitation chances west of a
line from Wayne to Beatrice overnight. Will make some last minute
adjustments to the forecast over the next hour or two, based on
most recent observations and trends.

The previously mentioned trough will be pushing eastward toward
the Plains over the next few days. Most of the model guidance
keeps rain chances fairly low in western IA through Saturday, with
chances increasing from east to west in eastern NE. Heaviest rain
amounts should stay to our west, where large scale forcing will
be stronger and instability will be greater. Rain chances should
be a bit higher (30 to 60 percent) for most of the forecast area
Saturday night into Sunday, as forcing and deeper moisture move
into eastern NE and western IA.

.LONG TERM...(Sunday night through Thursday)
Issued at 305 PM CDT Thu Aug 22 2019

The chance for showers and thunderstorms will linger at least for
Sunday night into Monday, then chances are a bit more random.

This period looks to be cooler than normal. Highs should be in the
70s to lower 80s. Expect lows to be in the 60s Sunday night, then
mainly 50s to lower 60s Monday night through Thursday.

The 12Z runs of the GFS and ECMWF are in good agreement with the
large scale pattern into mid week, then start to diverge a bit.
The ECMWF shows fairly zonal flow over the northern half of the
US by Friday, while the GFS as a ridge from the Four Corners
Region into the Gulf of AK and a trough to our east.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1218 PM CDT Thu Aug 22 2019

MVFR ceilings at KLNK should scatter out to VFR by 20z. Otherwise,
VFR conditions through most of the period, but additional MVFR
ceilings could develop at KOFK/KLNK 09-14z.

&&

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

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...DeWald



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