Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 230516 AAB

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1116 PM CST Sun Jan 22 2017

.SHORT TERM...(This evening through Monday)
Issued at 316 PM CST Sun Jan 22 2017

An area of low stratus clouds has persisted just to the east of
the area across eastern Nebraska this afternoon. Models indicate
this area of stratus expanding westward after sunset, and could
possibly move into eastern portions of north central Nebraska
around Ewing...O`Neill and Bartlett this evening. Patchy fog could
also develop along and just west of the leading edge of the
stratus. The time lagged RAP model has been indicating a swath of
1/4 mile visibility across much of Holt and Boyd counties around
midnight onward. Patchy fog has been added to the forecast to
account for this. Will pass the concern along that it is possible
that dense fog could form just west of the stratus field across
this area.

Storm system will be organizing Monday to the west of the area. Mid
level clouds will spread/develop eastward across the region ahead of
the system, so a mostly cloudy day is expected. Nevertheless, warm
temperatures aloft and deep mixing will promote a very mild day,
with highs in the mid 40s and even lower 50s across southwest
Nebraska. South winds will also increase ahead of the system, with
gusts over 20 mph during the afternoon hours.

.LONG TERM...(Monday night through Sunday)
Issued at 316 PM CST Sun Jan 22 2017

The main sensible weather concern in the long term period revolve
around a prospective winter storm affecting the region Tuesday-
early Wednesday. The main challenges with this upcoming system,
outside of reconciling model differences, include: precipitation
type/changeover, location/timing of heaviest snowfall, and snow
amounts. Higher confidence in winds with this system with gusts
forecast up to 35 mph.

Notwithstanding some uncertainty as models continue to show
differences in the large scale pattern, there is increasing
confidence that the system will impact portions of western and
north central NEB. The latest deterministic guidance and ensembles
have started to show less spread than the previous days,
however, the envelope of solutions still encompasses a moderate
area that could be affected by the cyclone. As such, a winter
storm watch was issued across the northernmost counties of the
local forecast area, also Garfield and Wheeler counties, given
the confidence level so far. Beyond Wednesday, minimal sensible
weather impacts are anticipated with temperatures expected to
gradually trend upwards this weekend.

An upper trough will be entering the Northern and Central Plains
Monday Night with a closed low expected to develop across the
Central High Plains early Tuesday. The mid-level low is expected
to move eastward and then lift into southern MN/northern IA by
late Tuesday then into the Upper Great Lakes midday Wednesday.
Consensus shows a 700 hPa track favoring a path east across NEB
into NW IA Tuesday, though there are some differences. Of note,
the Canadian has the most favorable 700 hPa track for snow across
the local forecast area with a track from southwest NE/northwest
KS towards southeast NE, however, it appears to be an outlier
compared to rest of the deterministic guidance. A surface low is
expected to develop on the Central High Plains Late Monday and
will move out eastward across southern NE/northern KS. The surface
low is expected to reach eastern IA Tuesday afternoon. The
surface low is expected to enter the Upper Great Lakes Wednesday
morning. Despite aforementioned uncertainty with phase and
amplitude, current thinking for moderate to heavy snowfall lies
across roughly the northern-third of the forecast area where
favorable deformation will occur. Furthermore, a trowal is
expected to setup with the trowal axis anticipated to lie and
extend westward across the center of the local forecast area from
southeast NEB early on. Given the guidance, and a lean towards the
WPC forecast, there is good potential for warning criteria to be
exceeded (6 inches) thus the watch. Along with the falling snow,
winds will be gusty on the backside of the surface low pressure
system Tuesday and Tuesday night as it departs away from western
NEB. Gusty northwest winds peaking up to 35 mph will promote
blowing and drifting snow in areas. Snow chances then linger on
into Wednesday morning.

Dry and quiet weather is anticipated Wednesday and beyond. A large
amplified pattern will be in place on Wednesday with a broad
trough across the central CONUS and a ridge building and moving
onto the west coast. Fair agreement exists in this time frame
through Sunday despite some large scale differences. The upper
level ridge will continue to build over the western CONUS into
Saturday wherein the ridge will extend from the Pacific offshore
waters near California to the Northern High Plains. The ridge is
expected to dominate the Western CONUS in this time period.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1116 PM CST Sun Jan 22 2017

The RAP and HRRR are verifying. MVFR/IFR cigs should progress
south and west to near KVTN-KBUB overnight and then retreat northeast
late Monday morning...16z-18z. The RAP model lifts the low clouds
east of KONL 18z-20z Monday afternoon.

MVFR/IFR in Rain and snow and low cigs is expected to move into
Nwrn Neb Monday evening. MVFR cigs are expected to redevelop
across Nrn Neb Monday evening.


Winter Storm Watch from late Monday night through Wednesday
morning for NEZ004>010-028-029-094.



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