Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 210920 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Hastings NE
420 AM CDT Mon Aug 21 2017

.SHORT TERM...(Today and tonight)
Issued at 335 AM CDT Mon Aug 21 2017

Eclipse...Sky cover forecasts will be dicey and confidence is
shaky for this forecast. It`s looking more apparent that western
totality areas should fair better overall than to the east, at
least regarding the thickness of mid to high level sky cover. Both
the HRRR and nested NAM indicate that there could be a glimmer of
hope by 18Z, especially for areas near and to the north and west
of Hastings, but less hope of unobstructed eclipse farther to the
east and south of Hastings. So far, the cirrus advancing to the
north/northeast from an approaching wave to our southwest is
rather thin and having a hard time holding together for now.
Between the tri-cities, Kearney has the best chance at an
unobstructed eclipse, with Hastings more likely to fare a bit
worse. Essentially it boils down to this...can we get the thicker
clouds to hold off just long enough until the eclipse is over?
This is a situation where we really will not have a much better
handle on sky cover until a few hours before the eclipse itself,
so look for any last minute updates as small holes in the clouds
could appear in relatively short notice.

Today/Tonight...We start out with some patchy fog in our
west/north, with low-lying areas along the Platte, and possibly
near Ord seeing some locally dense fog. This should lift in a few
hours before the eclipse begins.

I knocked down high temperatures a couple of degrees from
Superblend and also decreased wind speeds around 18Z as well
nearest to the eclipse totality. Also adjusted hourly temperatures
from the expected added darkness of the eclipse. Once the eclipse
is over, increasing cirrus should help keep temperatures a bit
cooler than what would have normally occurred if temperatures
were allowed to rise quicker earlier in the day.

As for chances of precipitation, with a surface boundary nearby, I
expect at least isolated showers/thunderstorms to POP up by late
afternoon. We are under marginal risk of severe weather, with
better chances of severe weather to the east of our CWA. Any
developing convection will help push the surface cold front south
of the CWA by the end of the night, and end our chances of
precipitation. With relatively high moisture and dewpoints near
70 or in the lower 70s for several areas in the central and
eastern CWA, our instability should climb to near 2000 j/kg or
more, but bulk shear is limited, so not expecting a huge outbreak
of severe weather in this case, with better support to the east as
the timing of a shortwave trough moving in from the southwest
will likely help get storms going by late afternoon. Again, there
will be better chances of severe weather east of here, but chances
for us are not non-zero. Low-end severe possible with potential
hazards of 60 mph wind gusts and quarter size hail.

.LONG TERM...(Tuesday through Sunday)
Issued at 335 AM CDT Mon Aug 21 2017

After any lingering showers/storms exit the area Tuesday morning,
dry and a bit cooler weather is expected for the rest of the day as
high pressure settles in overhead. This trend will continue
Wednesday and Thursday as well, as we remain in quiet northwesterly
flow aloft. High temperatures are expected to reach the low to mid
80s on Tuesday, with a slow warming trend through Thursday.

A more active pattern begins to set up once again Thursday night as
models bring a slew of upper level waves through the area. As such
we have slight chances for thunderstorms Friday through Sunday,
although it appears that the best chances will occur Friday and
Saturday nights. Beyond Sunday, it appears that we will go back into
a drier and a cooler pattern for the beginning of the following


.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Monday)
Issued at 1256 AM CDT Mon Aug 21 2017

Low-level wind shear will be the biggest concern. Technically an
isolated thunderstorm is possible overnight, but chances are so
low that this has been left out of the forecast.




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.