Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 132056

Area Forecast Discussion
National Weather Service North Platte NE
356 PM CDT Wed Sep 13 2017

.SHORT TERM...(This evening through Thursday)
Issued at 310 PM CDT Wed Sep 13 2017

Local radar display shows elevated convection upstream with
isolated to scattered showers and thunderstorms over portions of
northeast CO, the northern Panhandle, and western WY. Current
thinking is the best chances for initiation or activity to move
off the higher terrain will occur late this afternoon-early
evening. Chances for precip then spread east into the western
Sandhills and north central NEB mid-evening through the rest of
tonight. Similar low temperatures are expected tonight compared
to yesterday with light winds prevailing and partly cloudy skies
-- upper 50s to lower 60s.

Upper level flow overhead becomes southwest late tomorrow as an
upper level trough digs over the Pacific Northwest and Northern
Intermountain West while weak ridging moves east into the Middle
Mississippi Valley and the Upper Great Lakes. Generally fair
conditions and above normal temperatures are anticipated during
the day.

.LONG TERM...(Thursday night through Wednesday)
Issued at 310 PM CDT Wed Sep 13 2017

A relatively active period is anticipated through the weekend
with increased precip chances, also some strong to severe
thunderstorms will be possible Friday afternoon-Friday evening.
Otherwise, a cooling trend is expected through the weekend with
Saturday forecast to be the coolest (highs largely 2-8 degrees
below seasonal normal values). Temperatures are then expected to
rebound and start reading above normal again Monday through mid-

Large scale pattern will feature an amplifying upper level trough
across the Northern Rockies into CA early Thursday night with an
open wave becoming absorbed within the flow near UT. The upper
level trough is expected to evolve and become positioned across
the Northern High Plains into the Southwest US Friday, meanwhile a
lead shortwave trough will move northeast into western SD from
the Central Rockies. Increased chances for precip with a few
rumbles of thunder possible Thursday night, however, the best
chances for thunderstorms occur Friday afternoon-Friday night.
Some isolated strong to severe thunderstorms will be possible over
portions of north central NEB as well as steep mid-level lapse
rates (7-8.5 C/km) combine with moderate ML CAPEs (approaching
and exceeding 1000 J/kg) and deep layer vertical wind shear of
2540 kts. Organized multicells appear most likely with respect
to storm mode and given the synoptic set-up. A deepening surface
low is expected to be located near southwest NEB-northwest KS
Friday with its associated frontal boundary extending northeast
into southwest SD. Of note, there remains some uncertainty with
the position of the low and the front at this time. Isolated to
scattered showers and weak convection are then anticipated to
continue in portions of western NEB Friday night. With the front
pushing south and east late Friday-Friday night, cooler air will
enter. Saturday is anticipated to be the coolest day with highs
forecast in the mid 60s to mid 70s, coolest in northwest NEB. A
few isolated showers cannot be ruled out Saturday, mainly across
northwest NEB and northern NEB.

Looking ahead to Saturday night and beyond, mid- and upper-level
troughing will dominate the large scale pattern over the western
CONUS. Western NEB will stay largely underneath west to southwest
flow during this time period. Outside of a disturbance embedded
in the flow bringing increased chances Sunday night into Monday,
drier conditions are expected to prevail for the most part Monday
night-Wednesday. Highs are expected to return to the 80s Monday
through Wednesday.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1211 AM CDT Wed Sep 13 2017

Latest satellite imagery shows increasing mid- and upper-level
clouds across the eastern NEB Panhandle, elsewhere mid-level
clouds are present across southwest into central NEB. Current
thinking is isolated showers and a few rumbles of thunder will be
possible late this afternoon-tonight across western NEB. Out of
KVTN and KLBF terminals, think the latter is more likely to be
affected at this time thus mention in the TAF. Clouds will
continue to increase across the eastern Panhandle into western NEB
this afternoon then spread across the remainder of the area this
evening. Clouds decreasing early tomorrow morning.




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