Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 141726
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1126 AM CST Thu Dec 14 2017

.UPDATE...
Issued at 1125 AM CST Thu Dec 14 2017

Made some minor changes to the forecast for the rest of the day.
Light rain and snow showers will be more prevalent to the west,
but are expected to affect parts of the area this afternoon and
evening. Chances for measurable amounts are highest in the
western parts of the forecast area.

&&

.SHORT TERM...(Today through Saturday)
Issued at 250 AM CST Thu Dec 14 2017

A short-wave trough over the northern High Plains early this
morning will track generally south today with the strongest
large-scale forcing for ascent focused across central NE.
Light precipitation ongoing over western SD as of 0730z will
likewise spread southeast, eventually reaching our northwest
counties by about mid morning. Initial precipitation type will be
snow or a rain-snow mix before transitioning predominantly rain by
afternoon. The best chance of measurable precipitation will
remain across our western counties today with only slight-chance
PoPs from far eastern NE into southwest IA. Any snow accumulation
should be low and less than a half inch. Widespread clouds will
limit daytime heating with highs mainly in the upper 30s to lower
40s.

Tonight, any lingering precipitation should end by mid to late
evening as the short-wave trough passes to our south. By Friday,
mid-level heights will build with westerly low-level winds
supporting the eastward advance of a warmer air mass into the mid-
MO Valley. This warming could be offset by some mid and high-
level clouds, though highs should rebound back into the mid to
upper 40s.

Friday night into Saturday, a polar-branch trough will approach
the region from the west with an associated cold front settling
south into the mid-MO Valley. A mild air mass will remain in place
ahead of the front with highs on Saturday in the mid 40s to mid
50s.

.LONG TERM...(Saturday night through Wednesday)
Issued at 250 AM CST Thu Dec 14 2017

On Sunday, a weakening low-latitude disturbance will eject
northeast across the Ozark Plateau ahead of the aforementioned
polar-branch trough which will shear east across the northern
Plains and upper-MS Valley. The majority of precipitation
associated with the former disturbance will remain to our south,
though a small part of far southeast NE and southwest IA could
get glanced where we will include low PoPs.

During the early to middle part of the upcoming week, medium-range
guidance suggests that a longer-wavelength trough will amplify
over eastern North America. While we could see a brief shot of
cooler air associated with the upper-air pattern change, it
appears that temperatures will remain above normal. By late next
week into next week, the signal for a major western U.S. trough
is becoming more consistent. This trend could translate to a
potentially wetter and whiter forecast as we approach Christmas.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1125 AM CST Thu Dec 14 2017

Expect mainly VFR conditions at KOMA with a possible period of
MVFR ceilings this evening. Mixed rain and snow showers could
affect the KOFK and KLNK locations this afternoon with MVFR
conditions. IFR visibilities possible at KOFK and KLNK but for
now chances seemed low enough to leave out and may adjust if
things change in the next few hours. Any clouds below 4000 feet
AGL are expected to scatter out tonight.

&&

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

$$

UPDATE...Miller
SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Miller



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