Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 150931
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
331 AM CST Fri Dec 15 2017

.SHORT TERM...(Today through Sunday)
Issued at 328 AM CST Fri Dec 15 2017

Relatively mild to start the weekend, then cooler with a small
chance for precip on Sunday.

Mid level trough was exiting the Plains this morning, tracking
southeast through southern Missouri. Heights are forecast to rise
the next couple of days behind this wave and ahead of next shortwave
ejecting into the region from mean trough position in the
southwestern U.S. Much warmer airmass under the building height
regime should put temperatures well into the 50s by Saturday over
much of our area. 850 temps rise from sub-zero this morning to near
5C this afternoon then 10C on Saturday. Favorable west to
southwest surface winds this afternoon and decreasing cloud cover
suggest highs should reach the 45 to 50 degree range.

Saturday will likely be warmer, especially in our south, given
warming temperatures aloft. However weak surface front is forecast to
settle across eastern Nebraska and southwest Iowa, turning winds to
northeast to the north of the front and shaving several degrees off
potential warming. So despite plenty of sunshine, expect highs in
northeast Nebraska to hold in the middle 40s while southeast
Nebraska should reach the upper 50s.

Shortwave ejecting from the southwest Saturday night and Sunday
morning is expected to track across Missouri, with bulk of deeper
moisture drawn north on the east side of path from eastern Texas
into the Ohio Valley. However weak lift and mid level moisture
associated with minor potential vorticity anomaly will skirt our
southeast CWA Sunday morning. Models have been advertising light
precipitation there, and continue the trend this morning. Forecast
soundings suggest nose of warm air over top of cooler near-freezing
surface temperatures could provide a mix of precipitation types for
a few hours Sunday morning. However given light QPF and short
duration of any precipitation, expect impacts will be minimal in
southeast Nebraska and southwest Iowa.

Cooler temperatures will follow this system Sunday afternoon as
northeast surface flow and more cloud cover hold temperatures closer
to normal.

.LONG TERM...(Sunday night through Thursday)
Issued at 328 AM CST Fri Dec 15 2017

Another major pattern shift still looks likely by the end of the
week, bringing much colder air to the region. Leading up to it,
mainly northwest to west mid level flow will dominate the weather
across the Plains through mid week as upper trough/low in the
southwest U.S. gradually fills and tracks across the South.
Meanwhile a deep low drifting through the Gulf of Alaska will
creep southeast and eventually settle into the Rockies and
Northern Plains by Thursday.

Ahead of this system we should continue to see above-normal
temperatures with only minor perturbations nudging temps one way or
the other Monday and Tuesday. Wednesday looks to be the warmest day
as stronger southerly flow develops ahead of approaching strong
trough, then much colder air and a chance for precipitation will
arrive Thursday. GFS and ECMWF have shown decent consistency in
timing and precipitation placement the last few runs, so forecast
confidence is increasing. Expect generally falling temperatures
much of the day Thursday, with precipitation expanding across all
of eastern Nebraska and southwest Iowa. Current indications point
to mainly snow in our north and rain changing to snow in the south
through the day.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1115 PM CST Thu Dec 14 2017

VFR conditions are expected through the TAF cycle. Lower-end VFR
ceilings will continue to exit the area, leaving just scattered
cirrus later tonight through Thursday. Northwest winds will
decrease to around 5-8kt overnight, becoming southwesterly at
around 5-10kt during the day on Thursday.


&&

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

$$

SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...Mayes



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