Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 230012

Area Forecast Discussion
National Weather Service Hastings NE
712 PM CDT MON AUG 22 2016

.SHORT TERM...(This evening through Tuesday Night)
Issued at 337 PM CDT Mon Aug 22 2016

Quiet conditions reign across the region this afternoon, with
upper air and satellite data showing shortwave ridging sliding
through the region. To the west, satellite imagery shows low
pressure spinning over the Pac NW/western Canada and another
disturbance working its way through the Four Corners area. Been
plenty of sun around today, though upper level cirrus is starting
to stream in from the southwest ahead of that disturbance. At the
surface, we are sitting between a trough of low pressure draped
through the High Plains and high pressure centered over the
Midwest. A tightened pressure gradient and increased mixing has
resulted in a windy day across the region, with southerly winds
between 15-25 MPH and gusts near 30 MPH. Hasn`t been any surprises
with temps/dpts, the southerly winds have helped to bring a bit
more moisture north into the area, dewpoints are still comfortable
but have climbed into the upper 50s/lower 60s. Temperatures
generally in the mid 80s to near 90.

Looking to tonight, the main change to the forecast was to add
chances for thunderstorms. Models are in good agreement showing
that upper level shortwave disturbance currently to our
southwest continuing to shift northeast with time tonight, but
where not all models (though quite a few do) agree with is whether
precipitation develops. Decided to throw in some PoPs for tonight
across our west- southwest, the disturbance is shifting through
western KS/southwestern NE late tonight, and there is the
potential for a 40ish-kt LLJ nosing into the region. Should
thunderstorms move into the CWA, could be strong at times but
currently not anticipating severe weather with shear/instability
being on the lower side.

As we get into tomorrow/tom night, the primary concern remains
with that upper level shortwave disturbance. Models remain in
good agreement showing that upper level disturbance continuing to
push northeast through day, basically crossing right over the CWA.
Because that disturbance is right overhead, hard to say with
complete certainty that there won`t be at least a bit of
precipitation around, and a few models suggest it`s possible, so
decided to insert a slight chance PoP during the first half of the
day. The main focus will be during the afternoon/evening hours,
with better agreement showing more development. Big question is
exactly where and how much of the CWA is affected. The better
chances look to be along/east of an Ord/GI/Hebron line, though the
12Z NAM suggest it`d be a larger area than that initially. Some
keep in mainly along/east of Highway 81. Expecting to see
increasing deeper layer shear and instability across the area,
even the usually-lower GFS is showing 1500-2000+ j/kg of MLCAPE
developing. Severe weather remains a concern, with the entire CWA
in at least a Marginal Risk on the SPC Day 2 outlook. The eastern
third of the CWA is in a Slight Risk. Will keep HWO mention of
hail/wind/+RA as is. As the evening progresses, the brunt of the
action slides east of the CWA, but elevated instability lingers
through the overnight hours even as a surface cold front starts
pushing south through the area, so do the slight chances of

For most of the CWA during the day, winds will be southerly. That
above mentioned cold front will be starting to work into the NW
late in the day, driven by that upper level low currently in the
Pac NW region, but entering central Canada by 00Z Wed. By the time
dawn Wed rolls around, that front looks to have pushed though a
good chunk of the CWA. No notable changes made to
temps/dewpoints,with highs forecast in the mid 80s-lower 90s, and
dewpoints climbing back well into the 60s/lower 70s for many

.LONG TERM...(Wednesday through Monday)
Issued at 337 PM CDT Mon Aug 22 2016

For Wednesday/Wed night, precipitation chances remain in the
forecast, mainly confined to the southern half of the CWA. The
main upper level low pressure system continues to slide east
across southern Canada with time, ending up over western portions
of Ontario by 12Z Thursday. As it slides east the accompanying
surface front loses its southward push, slowing down and lingering
over/near southern portions of the CWA for a good chunk of this
time frame. With upper level lift remaining over the region,
chances for thunderstorms will continue near that frontal
boundary, but the better instability looks to over
central/southern KS. Kept small PoPs pretty far north during the
day (but did trim them post-00Z), mainly due to the GFS solution,
but the majority of other models showing a much sharper gradient
and little/nothing for locations along/north of I-80. If that
trend sticks with the majority, addition trimming of PoPs would be
needed. Northeasterly winds expected for most locations (southern
areas dependent on the frontal location), with highs forecast
right around the 80 degree mark.

Through the rest of the week/weekend, thunderstorm chances remain
in the forecast. In the wake of that northern low,
zonal/southwesterly flow looks to develop, with periodic shortwave
disturbance passing through the Plains. Thursday remains dry,
though if that surface boundary ends up being a touch further
north, some PoPs may be needed across the south. Beyond that, the
better chances look to come during the overnight hours Fri-Mon,
though honestly overall confidence isn`t the highest. As far as
temperatures go, highs for Thur/Fri are forecast to be in the mid
70s-near 80, before climbing back into the mid 80s for the


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday evening)
Issued at 703 PM CDT Mon Aug 22 2016

The wind direction will remain southerly through the TAF valid
period. The wind speed will lighten up some after sunset and then
pick back up by later Tuesday morning. There will be some mid to
high clouds around but expecting VFR ceilings and visibility will
continue. There will be a small chance for thunderstorms on
Tuesday, but currently too low to mention in the TAF. Strong low
level wind shear is likely tonight and will continue to keep this
mentioned in the TAF mainly for the pre-dawn hours Tuesday


.GID Watches/Warnings/Advisories...


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