Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 171802

Area Forecast Discussion
National Weather Service Hastings NE
102 PM CDT Thu Aug 17 2017

.SHORT TERM...(Today and tonight)
Issued at 337 AM CDT Thu Aug 17 2017

Surface analysis shows a high pressure system across the forecast
area this morning with clouds and precipitation around during the
day. This is keeping the skies clear across the area.

The surface high is expected to move through the forecast area
during the day today. Expect skies to remain mainly clear through
the daytime hours. Winds will be from the west around 5 to 10 mph.

By tonight, there is an upper level wave approaching the area. The
models have some slightly difference in timing of precipitation
moving into the area. The NAM is a little later than the GFS. Have
kept some low pops into the west during the evening, but overnight
will be the better chance for there being some showers and
thunderstorms around the area.

.LONG TERM...(Friday through Wednesday)
Issued at 359 AM CDT Thu Aug 17 2017

Overall...near normal temperatures with multiple...generally
small...chances for thunderstorms exist through the extended

Expect a weak upper level ridge to nudge across the plains on Friday
...likely resulting in a break in precipitation chances from Friday
afternoon through Saturday...when the upper level pattern flattens
out and becomes more zonal. This will result in an increasing chance
for thunderstorms Saturday afternoon and evening and again Sunday
afternoon and multiple upper level disturbances track
across the local area.

By models begin to diverge across the local area
with a more pessimistic GFS indicating we could see a few clouds and
showers around with the EC indicating an upper level ridge will
likely develop across the region. This would likely have an impact
on Eclipse viewing conditions...and kept pretty close to a blended
solution of model data until things become a bit more clear. Beyond
Monday...while the axis of the upper level ridge will eventually
transition eastward...multiple disturbances rotating around high
pressure in the southwest will bring additional chances for showers
and thunderstorms to the local area. That said...while there are
numerous chances for precipitation through the extended
periods...most chances look fairly spotty/scattered for the time
being with near seasonal temperatures accompanying this occasionally
unsettled time period.


A total Solar Eclipse will occur Monday August 21st around 1pm CDT.

Still quite a bit of uncertainty with the forecast for next fact...the global models are in more disagreement this
morning than 24 hours ago. This forecaster...however...remains
fairly optimistic that we should have a decent shot for good eclipse
viewing weather during the late morning through afternoon hours as
the convection expected Sunday night should be clearing the area by
early morning...and then any activity Monday afternoon or evening
should be much more spotty. As a result...did trend cloud cover down
just a bit for the afternoon hours with no precipitation mentioned
in the official forecast for the eclipse path during the daytime
hours Monday.


.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Friday)
Issued at 102 PM CDT Thu Aug 17 2017

General overview:
VFR ceiling/visibility expected to prevail, with a low probability
of a passing shower/thunderstorm late tonight/early Friday
morning. Low level wind shear (LLWS) looks to also become an issue
late tonight/early Friday. Read on for more specifics...

Ceiling/visibility/rain potential:
Confidence is high in VFR conditions with about the only possible
caveat being a brief visibility reduction if a passing
shower/thunderstorm happens to move over. Confidence is not
overly-high regarding shower/thunderstorm potential tonight but
felt it was at least worth a generic "vicinity" (VCTS) mention
from mainly 07-12Z. Not anticipating severe storms, but small
hail/gusty winds probably not out of the question.

Surface winds should not be a big issue, with prevailing speeds
largely under 12kt, although directional changes will occur from
westerly this afternoon, to southerly overnight, to northwesterly
behind a passing cold front late in the period. At least marginal
LLWS is a concern mainly 07-12Z as the low level jet increases,
setting up 30+ kt of shear between the surface and mainly 1,000
ft AGL as winds at that level accelerate to 40-45kt.




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