Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 230426 AAB
AFDLBF

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1126 PM CDT Tue Aug 22 2017

.SYNOPSIS...
Issued at 310 PM CDT Tue Aug 22 2017

H5 analysis this morning had a fairly turbulent pattern
across the central CONUS. A broad area of high pressure extended
form Florida west into northern portions of Mexico. On the northern
periphery of the high, numerous shortwaves were noted from northern
Texas into the Tennessee valley. Further north: Low pressure was
located over northern Ontario Canada with a trough of low pressure
extending south into the lower Ohio valley. Shortwaves were noted at
the base of this trough, most notably over nern Kansas, Southern
Indiana and another wave further north over northern Wisconsin.
Further west, a ridge of high pressure was located from Utah north
into southwestern Canada. Southwest of the ridge axis, low pressure
was located off the coast of northern California. At the surface,
high pressure was centered over Burwell Nebraska with southerly
winds noted in the panhandle and western sandhills. Winds across
north central and central Nebraska were light from the east or
nearly calm. Skies were clear and temperatures were in the 70s
across the forecast area.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 310 PM CDT Tue Aug 22 2017

n the near term, temperatures and fog potential are
the main forecast challenges in the near term. For tonight: High
pressure will build southeast into eastern Kansas overnight.
Southerly winds will increase from northeastern Colorado into the
panhandle and western Sandhills overnight. With a frontal boundary
anchored in the panhandle overnight and strong southerly winds
present, this is typically a good setup for fog/stratus formation.
ATTM, the latest NAM12, NAMNest, WARW and SREF visibility/ceilings
model forecasts keep the threat for low clouds/fog west of the
forecast area at 12z Wednesday. In addition, there is no support for
low cigs/visbys in the latest statistical guidance as well. With
this in mind, will not be mentioning fog/stratus in the fcst for
tonight. Southerly winds will continue to increase from west to east
on Wednesday and will eventually become breezy by late afternoon. A
tongue of low level moisture will ride north from eastern Colorado
into far swrn and western Nebraska Wednesday afternoon. Isolated
showers and thunderstorms should develop during the late afternoon
along the moisture axis once temps hit the mid 80s and the cap
begins to erode. Deep layer shear is fairly weak tomorrow
afternoon/evening, so any storms which do develop, will be on the
non severe side. At this time, the area of initiation appears to be
off to the west of the forecast area, so will leave Weds aftn dry
attm.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 310 PM CDT Tue Aug 22 2017

Mid range...Wednesday night through Friday night:
Persistent southerly and southeasterly winds will continue across
western and north central Nebraska from mid week through Friday. The
combination of more favorable low level moisture and a surface
trough to the west will lead to additional clouds and the threat for
morning fog Thursday morning into Friday morning. Not to mention,
favorable zonal flow in the mid levels, will allow weak upper level
disturbances to traverse the central plains, leading to an increased
threat for showers and thunderstorms toward the end of the week. All
three mid range model solutions, including the GFS, NAM12 and ECMWF,
develop episodes of thunderstorms across the forecast area with
isolated coverage Wednesday night, increasing to more scattered
coverage Thursday night into Friday. The superblend initialized with
likely pops for Friday into Friday night, and with some timing
differences noted with the mid range solutions, decided to cap pops
at under 50 percent.

Saturday through Tuesday: Precipitation chances will begin to
decrease into the weekend as ridging aloft begins to build into the
swrn then western CONUS. There continues to be some differences
between the GFS and ECMWF solutions as to where the High sets up
late this weekend. The ECMWF solution is farther east with the high
more in the vicinity of western Utah, while the GFS has this feature
over central California. The latter soln would favor more of a
cooler and increased threat for precipitation, while the ECMWF would
be warmer and drier. For now, generally went with the superblend
forecast with no modifications made to the forecast.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1126 PM CDT Tue Aug 22 2017

VFR is expected overnight through 22z Wednesday.

From 22z Wednesday onward: the model consensus is for no
thunderstorms, but some models, like the GFS and SREF, suggest
isolated thunderstorms may form across Nern Colo and move/develop
northeast into Swrn Neb. The forecast is for isolated
thunderstorms across Swrn Neb which develop northeast into Ncntl
Neb late Wednesday evening.

&&

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

$$

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC



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