Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 230529
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1129 PM CST Thu Feb 22 2018

.SHORT TERM...(This evening through Friday)
Issued at 326 PM CST Thu Feb 22 2018

FGEN enhanced band of snow has materialized from near Broken Bow
to Amelia to near Spencer. This should quickly move northeast
out of the area late this afternoon. Locally, up to 5 inches of
snow accumulation is possible within this band. Otherwise snow
accumulations have been on the order of 1 to 3 inches. Low level
moisture will remain in the boundary layer through the night, and
with light winds some areas of fog area likely across southwest
Nebraska. A dry day is expected Friday ahead of the next weather
system set to arrive Friday night. It is uncertain if the lower
cloud deck will dissipate Friday morning as winds remain light and
moisture abundant, but if it does lift at least partly cloudy
skies are expected for a time before increasing middle and high
clouds during the afternoon.

.LONG TERM...(Friday night through Thursday)
Issued at 326 PM CST Thu Feb 22 2018

The primary sensible weather impact is the winter storm affecting
the region Friday night-Saturday. Otherwise, weather highlights
in the long term include unsettled weather with low-end chances
for precipitation mid-late week and generally below-normal highs.

Regarding the winter storm, moderate to heavy snow is anticipated
with banded snow expected to develop. Expected snow amounts Friday
night-Saturday were 4 to 8 inches generally in a swath from
southwest NEB to north central NEB thus a Winter Storm Watch was
issued. Further, there remains potential for freezing drizzle at
the onset and early on. However, confidence in this occurring is
low. Elsewhere, light measurable snow is expected during this time
period.

The large scale pattern will feature an upper level trough over
the western CONUS with a shortwave trough at the base near the
Mojave Desert late Friday afternoon. This shortwave trough is
expected to eject eastward into the Central High Plains by early
Saturday morning with the upper level trough becoming neutrally
tilted. Thereafter the shortwave trough will track into the
Middle Mississippi Valley by early Saturday evening while
becoming negatively tilted. A Colorado low is expected to develop
at the surface late Friday night and evolve eastward to southern
IA/northern MO Saturday. Guidance are in fair agreement through
Saturday with respect to phase but there are some differences in
amplitude and timing.

Deterministic guidance in decent agreement with a enhanced zone of
mid tropospheric deformation and frontogenesis developing
Saturday morning and shifting east during the day. Further, this
combined with the location and orientation of trowal/WCB as the
system evolves and the overall track of negative PV anomaly
support banded snowfall with convective enhancement possible
attributable to potential instability. Of which, near and aloft
of the main forcing there is some near-zero to negative EPV.
Further, BUFKIT soundings do show decent lift with respect to
omega in the DGZ with some evidence of a cross-hair signature.
Current thinking for the time period of heaviest snowfall is mid-
morning to early afternoon. Current forecast in the area of the
winter storm watch is 4-8 inches. Regarding the aforementioned
low-end chance for freezing drizzle, this is primarily confined
to the tomorrow night-early Saturday morning time frame wherein
thermodynamic profiles initial are not that saturated/absence of
ice in the cloud. Otherwise, with convective enhancement think
likelihood for ice accum impacts are low.

Fair weather is expected Saturday night through Tuesday with a
fairly progressive large scale pattern in place. By Monday-Tuesday
another upper-level trough sets up over the western CONUS and
this will bring low-end chances for precipitation to the area late
Tuesday night to Thursday. Otherwise, forecast highs remain below
seasonable normal values.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1129 PM CST Thu Feb 22 2018

VFR conditions currently across most of western Nebraska. Some
patchy fog has set in at the KLBF terminal with 1/4SM FZFG. Areas
of fog should develop mainly across southwest Nebraska. At KLBF,
fog is forecast with prevailing visibility 1/4sm from 06z- 08z,
then 2sm BR until 13z. Uncertainty exists on the duration of 1/4SM
FZFG, but an improving trend is forecast overnight. VFR conditions
by 15z with only scattered mid or high clouds into the afternoon.
At KVTN, MVFR ceilings possible until 08z or 09z, then VFR
expected. By Friday evening, an approach winter system will bring
lowering ceilings to near 1500 feet by the end of the TAF period.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Friday evening through Saturday evening
for NEZ008>010-025>029-036>038-057>059-069>071.

&&

$$

SHORT TERM...Taylor
LONG TERM...ET
AVIATION...Roberg



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