Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 201725

Area Forecast Discussion
National Weather Service North Platte NE
1225 PM CDT TUE SEP 20 2016

.SHORT TERM...(Today and tonight)
Issued at 350 AM CDT Tue Sep 20 2016

The main challenge in the short term period were temperatures and
sky cover; otherwise, overall sensible weather concerns were low
with no precipitation expected. In the early morning hours,
confidence in fog has lowered some as winds remain elevated,
however, will keep patchy fog in as dew point depression remains low
south of the Sand Hills. Best places for patchy fog will be in river
valleys and in climo prone areas.

Winds aloft over western and north central NE will transition from a
westerly flow to a southwest flow at mid-levels as the 500 hPa high
over the Southern Plains starts to break down gradually in the short
term period. While the high remains over the Southern Plains into
the Middle Mississippi Valley, a mid level trough will be becoming
more amplified over the Pacific Northwest this period. A hot day is
expected over the forecast area as temperatures aloft at low-levels
increase under a southerly flow with 850 hPa temperatures rising to
24-29 C. Soundings and low-levels guidance indicates decent WAA
occurring today. Meanwhile, at the surface, a weak warm front is
expected to lift eastward from western and north central NE by mid
afternoon. However, the temperature forecast will be complicated
some by increasing sky cover, mostly high clouds, that will affect
our insolation. The current thinking is that sky cover will begin to
increase more so mid-late morning as clouds are expected to
overspread SW-NE. However, even with sky cover, highs are expected
to be around 15 degrees above normal most places. Highs are forecast
near 90 to the lower 90s, warmest along and south of US Highway 26-
Interstate 80. Otherwise, dry conditions are expected today though
there will be decent instability. Warm temperatures aloft will make
it difficult for any convective development with decent CIN
anticipated based on model soundings across the forecast area.

.LONG TERM...(Wednesday through Monday)
Issued at 350 AM CDT Tue Sep 20 2016

A very warm day is expected across central and southwest Nebraska
Wednesday, with a thermal ridge oriented southwest to northeast just
ahead of a southeastward moving cold front. Upper level ridging will
transition southeast of the area while a shortwave trough quickly
moves northeast across the central and northern plains. This will
drive a cold front south through the area, with the NAM and ECMWF
models continuing to remain in good agreement with the location of
the front by late Wednesday afternoon. As mentioned a plume of very
warm air, H850mb temperatures of 25C to 30C, will reside just ahead
of the front that will extend roughly from O`Neill to North Platte
to Imperial by late afternoon. At the very least we should see highs
in the upper 80s ahead of the front. Will not push any higher into
the 90s at this point though as mid and upper level moisture, in the
form of clouds, will be streaming across the area as subtropical
moisture is pulled northeast into the region due to a developing
trough of low pressure across the western Conus. Still can`t rule
out an isolated thunderstorm late Wednesday afternoon and evening as
convective temperatures are reached along and ahead of the front.

The cold front will stall across southern Nebraska Thursday and then
lift north as a warm front Friday. Upper level ridging will also
briefly build back over the area ahead of a large upper level low
pressure system that will be developing across the western conus. As
a result Thursday and especially Friday look warm, and have raised
highs a few degrees across southwest Nebraska Thursday and across
all of the area Friday as the warm front lifts north.

The upper level low will become quite deep by the weekend, with a
near meridional southerly upper flow across the central plains ahead
of the system. This will draw deeper subtropical moisture northward,
and showers and thunderstorms are appearing more likely Friday night
through Saturday night.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1224 PM CDT Tue Sep 20 2016

VFR conditions start off at both KLBF and KVTN for Tuesday. Over the
next 24 hours, both sites will experience lowering of ceilings as
the next system moves closer to the region. Ceilings will still stay
in VFR until late Wednesday, however, ceilings will fall below 15
Kft by early afternoon. For KLBF, expect some low level wind shear
once again tonight as the low level jet strengthens over the region.
For KVTN, some patchy fog is possible at the terminal tonight,
however, confidence is low as to whether it will develop or not, and
therefore, have left it out of the forecast for this issuance.


.LBF Watches/Warnings/Advisories...


LONG TERM...Taylor
AVIATION...Kulik is the U.S. government's official web portal to all federal, state and local government web resources and services.