Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 180939 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Hastings NE
439 AM CDT Fri Aug 18 2017

.SHORT TERM...(Today and tonight)
Issued at 353 AM CDT Fri Aug 18 2017

Main forecast issue for the short term will be early morning

Upper level shortwave trough is in the process of departing the
area, with some lingering showers along outflow/surface front
today. Decent subsidence behind the wave/surface front, so we
stand a nearly certain chance of being dry by this afternoon into
the night time. Temperatures will be rather seasonable as we will
be under the influence of ridging from an approaching shortwave
ridge within west northwest flow. Highs will be in the mid 80s to
near 90 with lows tonight near 60. There will not be much in the
way of support for strong to severe storms early this morning, and
expect any leftover rain to be in the process of shoving east of
the outlook area during the morning.

.LONG TERM...(Saturday through Thursday)
Issued at 353 AM CDT Fri Aug 18 2017

The daytime of Saturday should be dry and relatively warm thanks
to quiet northwesterly flow aloft and fairly strong southerly flow
at 850 mb and below. High temperatures are expected to reach the
upper 80s to low 90s across the region.

Scattered thunderstorms are expected to develop in the area
Saturday evening as a subtle upper-level wave moves into the area.
A few storms will likely persist through the overnight as the
low-level jet continues to strengthen. Right now, SPC has the
majority of central Nebraska and northwestern Kansas in a
"marginal" risk for severe weather. This seems reasonable with the
GFS and NAM showing a strip of 2500 J/kg of MUCAPE and 30 to 40
kts of deep-layer shear across the Sandhills, gradually decreasing
from west to east.

The upper level pattern will gradually shift to more zonal and
eventually southwesterly flow during the day on Sunday. Despite
this, in may ways Sunday will be almost a carbon copy of Saturday.
It should be dry and warm during the day, before chances for
thunderstorms return during the evening and overnight. There is a
little more uncertainty on thunderstorm coverage, though, with
both the latest GFS and Euro keeping the best coverage farther
north along the NE/SD border. Once again, a few strong to severe
storms are possible, although the highest threat will be farther

Heading into Monday, thunderstorms should mostly clear the area
by around daybreak. The GFS shows some lingering showers or
storms, but this threat isn`t high enough to warrant including in
the forecast. Chances for thunderstorms return during the
afternoon and evening as a wave moves into the area out of the
southwest. There is some uncertainty of timing of this wave, but
it appears that the best chances for rain/storms will hold off
until evening. See the "Eclipse" discussion below for more
forecast details and their impacts on the Eclipse.

Thunderstorm chances continue into Tuesday morning as a cold
front pushes southward through the area. As high pressure builds
in behind this front, expect generally cooler temperatures
compared to the preceding weekend, especially Wednesday and
Thursday. Precipitation chances during this period will also
primarily confined to the High Plains of Nebraska and Kansas,
although I will maintain slight chances across the western two-
thirds of the CWA due to uncertainty.


A total solar eclipse will occur Monday, Aug. 21st around 1 PM

Rain & Thunderstorms:
The overall consensus is that whatever thunderstorms develop
Sunday night will mostly clear out of central Nebraska around
daybreak and almost certainly by late morning. As mentioned
above, another shortwave will bring precipitation chances back
into the area during the afternoon and especially during the
evening. The GFS moves this wave in more quickly than the Euro,
but even then I think that most development would hold off until
after 3 or 4pm. The bottom line is that I think that the threat
for rain/thunderstorms impacting eclipse viewing is low.

As noted by previous forecasters, the cloud cover forecast
remains a bit more uncertain. The latest model consensus shows
"partly cloudy" across the area, ranging from 40 to 50 percent
cloud cover. With relatively high available moisture, this seems
like a fair assessment, and there will likely be areas of clouds
that some will have to contend with. The good news is that breezy
winds should mix out thick low-level clouds and afternoon cumulus
development should be delayed due to reduced solar heating. The
best I can say right now is that there will likely be at least
some opportunity to view the eclipse, but this could be
interrupted by some mid and high level clouds at some locations.

Temperatures & Winds:
Southwesterly winds of gusting up to 20 MPH will be favorable for
seasonably warm conditions. Accounting for the decreased solar
radiation due to the eclipse, I expect temperatures to be in the
upper 70s to low 80s at 1pm, and I expect high temperatures to
eventually reach the upper 80s and low 90s by late afternoon.


.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Friday)
Issued at 100 AM CDT Fri Aug 18 2017

LLWS looks like it might be an issue overnight, as there will be a
shot at some scattered thunderstorms, then clearing on Friday.




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