Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 120912

Area Forecast Discussion
National Weather Service Omaha/Valley NE
312 AM CST Sun Nov 12 2017

.SHORT TERM...(Today through Tuesday)
Issued at 311 AM CST Sun Nov 12 2017

Ending light precipitation this morning, then warming temperatures
and an increase in low level moisture potentially leading to another
round of drizzle by Tuesday, are the primary forecast concerns.

Mid level shortwave was moving through eastern Nebraska this morning
as seen on water vapor imagery and RAP analysis. Associated lift was
triggering areas of light rain from northeast Nebraska to southwest
Iowa. Also, cold front was drifting southeast of our area at early
morning with north to northwest winds behind it, helping to
gradually dry out low levels. Still areas of drizzle and fog were
noted generally near and south of I-80 as of 2 AM. As shortwave
makes steady progress east this morning, trailing subsidence is
expected to scour out low clouds, drizzle and fog early in the day,
with the spotty light rain moving east early. Plenty of sunshine is
expected by late morning most areas, helping temperatures rebound
well into the 40s this afternoon.

Surface high pressure will be overhead this afternoon and should
slide east later tonight and Monday, allowing southerly return flow
to set up once again. Low level theta-e advection will lead to
increasing cloud cover by Monday afternoon, but increasing mid level
heights suggest warming atmosphere, and temperatures a bit higher
than this afternoon.

Forecast soundings from GFS indicate rapid increase in low level
moisture profile across all of eastern Nebraska and southwest Iowa
Monday night and Tuesday as theta-e advection strengthens ahead of
approaching shortwave entering the Northern Plains. Weak lift above
saturated surface-850mb layer points to another round of drizzle by
Tuesday afternoon. The increase in moisture and subsequent
thickening cloud cover should keep lows in the 40s Tuesday morning,
but temper highs a bit in the afternoon. Still, highs well into the
50s if not lower 60s are likely.

.LONG TERM...(Tuesday night through Saturday)
Issued at 311 AM CST Sun Nov 12 2017

Near-normal temperatures are forecast through the rest of the week
as mid level flow remains west to southwest before next
trough/shortwave enters the Plains on Friday.

However the beginning of the longer-term period will feature a cold
front slipping across our area, attendant to Tuesday shortwave, and
triggering scattered showers across our southeast CWA Tuesday night.
Surface high building in behind the front should clear skies for
Wednesday, but increasing low level moisture on back side of high
will lead to more cloud cover again Thursday and Friday, much like
what we`ll see over the next couple of days.

Models differ on timing with Friday trough, as GFS is faster again
this morning as compared to ECMWF and Canadian. Rain/showers could
begin as early as Thursday afternoon, but more likely later Thursday
night and Friday when a majority of longer-term models advertise mid
level trough over our area. A mix with or change to snow is possible
in northeast Nebraska as precipitation is ending Friday night and
colder air filters south.

Degree of that cooling for the weekend is in question as well, with
ECMWF some 10C colder at 850mb compared to the GFS for Saturday
afternoon. For now, will maintain our current compromise forecast of
near 50 for Saturday afternoon highs.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1135 PM CST Sat Nov 11 2017

LIFR cigs and vsbys were in place across parts of southeast
Nebraska at the start of the period including KLNK and KOMA. Short
range models suggest improving conditions will spread south across
the area through 12Z as upper trough swings across and east of the
area. VFR conditions will then prevail by 15Z and continue through
the remainder of the forecast period.




LONG TERM...Dergan
AVIATION...Fobert is the U.S. government's official web portal to all federal, state and local government web resources and services.