Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 122317
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
517 PM CST Tue Dec 12 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 418 PM CST Tue Dec 12 2017

Main sensible weather concerns revolve around winds from late
tonight through tomorrow. Winds will increase late tonight with
windy conditions expected to be in place by late morning tomorrow
continuing into the afternoon. Peak gusts up to 40 mph are expected,
strongest outside the northeast Panhandle and far northwest NEB.
Otherwise, highs will see a modest drop tomorrow compared to today`s
highs, albeit still above seasonable normal values. Latest visible
and IR satellite imagery shows clear skies overhead though some
smoke is apparent drifting from an active fire in the Black Hills
into the extreme northeast Panhandle and extreme northwest NEB.

Latest water vapor imagery shows an amplified upper level ridge over
the western CONUS extending across British Columbia into the Yukon
with a shortwave trough noted over central Alberta. This disturbance
will dive southeast into southeast SD-northeast NEB by end of
tonight. Meanwhile, a developing surface low will move from southern
Manitoba into the Upper Mississippi Valley. An associated cold front
will track across the forecast area early tomorrow. Prior to the
front, mild lows are expected given elevated winds with lows
forecast in the upper 20s to 30s. Northwest winds will increase
tomorrow with gusts up to 40 MPH expected primarily across north
central and southwest NEB - peaking late morning-afternoon. A strong
belt of 850 hPa winds combined with sufficient mixing will promote
decent momentum transfer given BUFKIT soundings. Highs are expected
to read in the mid 40s to mid 50s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 418 PM CST Tue Dec 12 2017

The amplified upper ridge over the Intermountain West gives way to a
substantial wave this weekend, then transitions to more of a zonal
pattern toward the middle of next week. At the surface, a strong
cold front clears the forecast area Thursday, another passes through
the Plains in association with the mid level wave Saturday, and a
weaker fropa is progged for Monday.

Precipitation... Maintained chc PoP Thursday as forecast soundings
indicate decent forcing and lift with the front, along with extra
support aloft from a shortwave. Moisture will be the limiting factor
as dry air remains near the surface and saturation in the mid levels
will be short-lived. Temperature profiles support snow for most of
the event, except for rain at peak heating of the day. Any precip
will be light, alleviating the overall accumulation threat. The
model suite has trended slightly wetter with Saturday`s system,
although differences remain between the GFS and ECM in the placement
of the possible deformation band (ECM hints at the Sandhills, GFS
eastern Neb). H5-7 fgen is maximized over the area with a fairly
broad ribbon of saturation and the tail of an 100kt H3 jet lies
overhead, but lift and moisture are lacking in the low levels.
Again, this appears to be a rather light precip event, but will have
to be watched if moisture availability increases at the sfc.

Temperatures... Nudged cooler Thu highs and Thu night lows in the
wake of the cold front. Cloud cover combined with northerly flow and
temps around -5C at H85 (noticeable CAA) will push highs back to
around normal (near 40F). Thu night may still be too warm with this
forecast package as clouds begin to clear in the evening and the
winds lighten. Trended Fri max temps toward the warmer guidance as
downslope winds take over and an H85 thermal ridge sets up across
the High Plains. With highs in the lower/mid 50s and dry downsloping
winds, fire weather conditions are elevated, primarily SW Neb. The
roller coaster continues with the fropa on Saturday dropping highs
back into the 40s.

Wind... Thursday will be quite gusty along and behind the cold
front. A fairly substantial 1.5 PV anomaly aids in the mixing of 40+
kt flow at H85, while a 10+ mb sfc pressure gradient exists across
the state. Peak gusts could approach 40 mph west and 30 mph north
central.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 517 PM CST Tue Dec 12 2017

A cold front will move across western Nebraska between 06z and
12z, with northwest winds increasing to 32015g25kt behindf the
front, Winds will peak near 33023g32kt between 12z and 20z, then
gradually diminish toward the end of the Taf period.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...ET
LONG TERM...Snively
AVIATION...Roberg


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