Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 251143

Area Forecast Discussion
National Weather Service Hastings NE
643 AM CDT Sun Jun 25 2017

.SHORT TERM...(Today and tonight)
Issued at 328 AM CDT Sun Jun 25 2017

Today...The cool weather will continue as the 1027 mb sfc high of
Canadian origin tracks directly across our forecast area. Despite
the area of high pressure at the sfc and relatively dry near sfc
layer, there will be some mid level clouds and moisture tracking
across our forecast area today that may result in some isolated
and very light precipitation primarily over our southwestern
zones. MUCAPE values will generally be around or less than 100
J/kg through this evening and thus severe weather is not expected
as it may be hard enough given such limited instability to even
get a few claps of thunder. Given at least non-zero instability
will continue to keep the possibility of thunder in the forecast
this afternoon and evening for those southwestern zones.

The wind will be noteworthy in that it will be very light and
variable with the sfc high right overhead.

Tonight...We do expect a little more in the way of elevated
instability to work into the forecast area but MUCAPE values
should still hold below 500 J/kg. Several forecast models indicate
that the small thunderstorm chances should expand further north to
encompass the remainder of our forecast area, but the highest
chances of seeing some light measurable rainfall will continue to
be across southern zones. Given the continued meager instability,
severe weather is not expected.

.LONG TERM...(Monday through Saturday)
Issued at 328 AM CDT Sun Jun 25 2017

The long term period starts out with upper level northwesterly flow
in place across the Plains, with continued ridging over the Rockies
and broad troughing over the eastern half of the CONUS. An embedded
shortwave low pressure system is expected to slide through the Great
Lakes region during the day, pushing a backdoor cool front south
through the area. Thunderstorm chances remain in the forecast during
the daytime and early evening hours, with models showing the
potential for lift with a more subtle wave moving through, as well
as with the entrance region of an upper level jet streak in the
region. Expecting little capping with cool temps in place aloft.
Exact placement of precip will be dependent on exactly where the sfc
boundary sets up. Severe weather is currently not anticipated with
any thunderstorms that develop, plenty of shear is shown by models,
but the main instability axis looks to be to our south and west. Not
expecting a notable chance in highs for Monday compared to today,
forecast to range from the mid 70s to lower 80s.

Once any precip that develops slides south of the CWA, the rest of
Monday night is forecast to be dry, as is the daytime hours on
Tuesday. Aloft, the ridge axis, though becoming less amplified with
time, is expected to push east into the region, thanks to an upper
level low moving through western Canada. At the surface, the
easterly winds building in on Monday gradually turn southerly as we
get closer to Tuesday morning, thanks to high pressure sliding east-
southeast into the Midwest and deepening low pressure over the
northern High Plains ahead of the approaching system. Expecting
Tuesday to be breezy as the pressure gradient tightens across the
region, with speeds of 15-25 g 30 MPH in the forecast. Temps are
expected to continue climbing up, with highs in the mid 80s for most
locations. Tuesday evening/night brings the next best chance for
thunderstorms to the area. The main upper low remains well to our
north, but the southward extending trough axis looks to swing
through the region, sparking off thunderstorm development. First
developing over the High Plains along the sfc boundary in the
afternoon, activity is expected to push east-southeast with time,
aided by an increasing low level jet (~50kts). The highest PoPs are
currently across the northern half of the CWA, with some question
with southward coverage due to models showing more capping being a
potential issue. This also looks to be our next chance for severe
weather, with instability values are expected to increase, with
models showing MLCAPE of 1500-2000j/kg not out of the question.
Roughly the northwestern half of the CWA has been included in the
SPC Day 3 Slight Risk area, with the majority of the rest of the CWA
in the Marginal Risk area.

In the wake of this system`s passage, mainly zonal flow is expected
to set up aloft across the region through the rest of the forecast
period. This pattern allows for the potential of more shortwave
disturbances passing through, bringing periodic thunderstorm
chances. Hard to have a lot of confidence with timing/location, but
at this point a couple more disturbance look to pass through Wed and
Thurs, most likely affecting the late day-overnight time frames.
Strong/severe weather may again be a concern. May be a break in
action in the Fri/Sat time frame, before PoPs return Sat night-Sun,
but that`s getting pretty far out in the forecast period, so take
that timing with a grain of salt.

As far as temps go Wed-Sat, Wed is still forecast to be the overall
warmest day, with highs either side of 90 degrees. Maybe a touch
cooler Thursday, with forecast highs in the mid 80s for Fri-Sat.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Monday)
Issued at 626 AM CDT Sun Jun 25 2017

VFR conditions will continue throughout the TAF valid period. The
wind will be light and variable right through the period with a
sfc high located over region. Overall the wind will be a touch
more out of the north or east this morning and then more out of
the south by afternoon and perhaps more southwest by tonight, but
again very light and at times variable.




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