Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 130454

Area Forecast Discussion
National Weather Service North Platte NE
1154 PM CDT Tue Sep 12 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 334 PM CDT Tue Sep 12 2017

Latest satellite imagery shows convection developing with the most
impressive cloud-top cooling in the far northern Panhandle. The
local radar display shows isolated low-end thunderstorms over
there, another isolated cell is located south of there near
Bayard, NEB. Lightning is predominantly inter- and intra-cloud
with very infrequent CG noted.

Current thinking is the best chances will be across the northeast
Panhandle-northwest NEB-Sandhills. This isolated activity will
occur in response to large scale ascent from a disturbance noted
in water vapor imagery over eastern WY/western SD/northern
Panhandle moving east tonight and modest low-level warm air
advection. Chances will then start shifting more towards central
NEB in the small hours-early tomorrow morning. Dry and fair
conditions are expected tomorrow with well above normal highs by
12-18 degrees -- low to mid 90s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 334 PM CDT Tue Sep 12 2017

Most concerns in the long term generally revolve around the
Thursday night to Saturday time frame where the pattern is
unsettled and there are increased chances for precip. Of which,
potential has grown for some isolated strong to severe
thunderstorms across portions of north central NEB late Friday
afternoon-Friday night. Otherwise, a late cold frontal passage
Friday will lead to a cooling trend with highs slightly below
normal Saturday and Sunday. Forecast highs for the former and
latter span largely the upper 60s to upper 70s, coolest on

Early Wednesday night the large scale pattern will be
characterized by an upper level ridge across Sonora to the Four
Corners extending into the Middle Missouri Valley. Elsewhere,
upper level closed lows will continue to affect parts of the CONUS
 near the central CA coast and over the Ohio Valley. Farther
upstream, an amplifying upper level trough will be moving into the
Pacific Northwest. The upper level trough will dig southeastward
into the Northern Rockies to the western Central Great Basin by
Thursday, in the meantime the aforementioned CA closed low will
move eastward weakening into an open wave and then phase with the
upper level trough. The upper level trough will extend from the
Northern High Plains into the Central Great Basin by Friday with a
lead shortwave trough moving northeastward within the flow from
the Central Rockies into western SD. While increasing chances for
precip begins Thursday night (wherein isolated thunderstorms are
mentioned), best chances for thunderstorms fall late Friday-
Friday night given the current parameter space and model
soundings. Current thinking is the best potential lies over north
central to northeast NEB where forecast are steep mid-level lapse
rates, moderate ML CAPEs, and adequate shear - in the area of an
evolving surface low and associated frontal boundary. Some
uncertainty with respect to timing and coverage so expect further
refinement with later forecast packages.

Cooler air will then infiltrate western NEB Friday night into
Saturday with largely below seasonal normal highs expected on
Saturday. Near to slightly below normal lows and highs are
anticipated Saturday night and Sunday, respectively. Precip
chances continue across western NEB Saturday-Saturday night.
Looking ahead, another unsettled period appears to be Sunday
night-Monday with increased chances of precip. Meanwhile, this
will coincide with a warming trend with above seasonal normal
highs expected again Monday and Tuesday  highs in the lower to
mid 80s.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1154 PM CDT Tue Sep 12 2017

A small area of showers and thunderstorms remains over a portions
of southwest Nebraska. This may move through the KLBF terminal to
begin the TAF period until 07z. Otherwise VFR conditions with
winds prevailing south to southeast up to 10 kts.




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