Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 152154
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
354 PM CST Sun Jan 15 2017

.SHORT TERM...(tonight through Wednesday)
Issued at 345 PM CST Sun Jan 15 2017

...Prolonged Periods of Freezing Rain with Significant Icing
for Parts of the Area into Monday ...

Early afternoon water vapor imagery indicated the closed mid-
tropospheric low pressure system over northern Mexico. The 12Z
upper air analysis indicated 80-100+kt H30 jet segments off the
West Coast...across northern Mexico...across the Rockies into the
Great Lakes and Ohio Valley. Broad diffluent flow continued for a
large area from the NM/TX/CO/wrn OK/KS. Large-scale ascent over
the Plains was resulting in a large shield of precipitation across
KS, with the northern extent into central Nebraska and southern
IA. The 12Z OAX sounding showed drier air from 3-7Kft. Forecast
soundings indicate this dry air being overcome this afternoon
with periods of light freezing rain/rain depending on the surface
temperatures.

Latest observations, although initially in the mid
30s...have now dropped to freezing or slightly below freezing
with the onset and progressive expansion of precipitation south of
a line from Columbus to Fort Calhoun. WSR-88D trends show moderate
freezing rain moving across the KS/NE border associated with an
embedded vorticity maximum in the southwest to northeast flow
aloft across Kansas. Precipitation amounts in this band have been
around 0.05 to .1 per hour. Local impacts/conditions should
deteriorate with temperatures/surfaces cooling and freezing
tonight.

The short range models remain in good agreement through the
short range forecast period with broad isentropic ascent
continuing through the overnight period as the closed h5 low
pressure system track toward the Texas panhandle toward eastern
Kansas by midday Monday and into northwest Kansas by 00Z Monday
evening. Ongoing freezing rain will continue tonight with
temperatures in the 20s to lower 30s with additional rounds of
precipitation later tonight and Monday morning. There may be a mix
of freezing and sleet/snow on the northern fringes...and
temperatures warm to above freezing toward falls city Monday
morning. With the surface low track remaining to our south from
eastern Kansas into northwest Missouri. This warming will be
limited to the southeast parts of the forecast area where
temperatures warm into the mid and possible upper 30s at KFNB.
Elevated instability does approach FNB by midday Monday, so this
will need to be watched. As the colder air works into the system,
there may be some light snow with the deformation band in
northeast Nebraska. Amounts continue to be in the light range at
this time in the 1 to 2 inch range.

Left the headlines in place with good confidence on the icing of
0.25 to .50 with higher amounts locally, however far northeast
Nebraska toward the South Dakota border should see more limited
impact.

Northwest winds increase as little more into the 10 to 15kt range
Monday night. The warming trend for Wednesday still looks on
track.

.LONG TERM...(Wednesday night through Sunday)
Issued at 345 PM CST Sun Jan 15 2017

A mid latitude trough is progged over the central U.S. ahead of a
full-latitude trough over the wet coast. The EC is a little
stronger earlier with moisture being drawn northward Thursday
before swinging the closed h5 low eastward. The GFS has the
track/moisture more northwestward Thursday night and Friday and a
leading wave in the flow from the West Coast rapidly catches up to
it Friday night and Saturday then lifts north. The
complex...unsettled weather pattern persists Saturday night
through Sunday night, with the full latitude trough over the
central U.S., however the details vary over where the
precipitation will focus. h85 Temperatures are mild for the time
of year +6 to +12 deg C cooling to +4 to +6 Friday and below 0 deg
C by Sunday. With highs in the 40s...rain would be the predominant
precip type...change to snow later in the extended with the colder
air.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1124 AM CST Sun Jan 15 2017

Mosaic radar data as of 17z indicated the northern edge of light
freezing rain along the I-80 corridor with a continued slow
northward shift of the precipitation shield this afternoon into
tonight. Expect the resultant deterioration of weather conditions
at the eastern NE TAF sites with the predominant precipitation
type being freezing rain through the duration of the forecast
period. IFR ceilings/visibilities will likely materialize at KLNK
and KOMA this evening and after midnight at KOFK.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Ice Storm Warning until 3 AM CST Tuesday for NEZ015-032>034-
     042>045.

     Ice Storm Warning until 3 AM CST Tuesday for NEZ050>053-065>068-
     078-088>093.

     Winter Storm Warning until 3 AM CST Tuesday for NEZ011-012-
     016>018-030-031.

IA...Ice Storm Warning until 3 AM CST Tuesday for IAZ043-055-056.

     Ice Storm Warning until 3 AM CST Tuesday for IAZ069-079-080-090-
     091.

&&

$$

SHORT TERM...Zapotocny
LONG TERM...Zapotocny
AVIATION...Mead


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