Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 220909
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
409 AM CDT Thu Jun 22 2017

.SHORT TERM...(Today and tonight)
Issued at 408 AM CDT Thu Jun 22 2017

Outside of a few lingering showers/storms across far southeastern
portions of the CWA, quiet conditions are in place early this
morning. Upper air and satellite show continued generally zonal
flow in place across the region, low pressure spins over the
Gulf coast of TX, with another over central Canada. At the
surface, elongated low pressure lies across western and northern
Nebraska, with south to southwesterly winds across the CWA, and
even at this early morning are at times gusting to near 20 MPH in
spots. Still very mild, with 3 am temps ranging from near 70 to
near 80.

The primary concern through the short term period lies with a
passing cold front and accompanying thunderstorm chances later
today. There hasn`t been any significant changes in models with
the general story for today. Models are showing that while the
main upper level low remains well north of our area (ending up in
western Ontario by tomorrow morning), a mid level shortwave
disturbance to its south looks to slide east across portions of
the Plains. At this point, looking like the brunt of it will pass
near the NE/SD border through today, before moving east of the MO
river this evening/tonight. Accompanying this system will be a
surface cold front, which is currently off to the north, near the
SD border. Models aren`t in too bad of agreement, showing a more
noticeable push south through the first half of the day, setting
up roughly over the northwestern third of the CWA by midday. It
continues its southeastward push during the afternoon, but doesn`t
look to totally clear the CWA until early/mid evening. This
frontal boundary will be the main focus for thunderstorm potential
today, with the best chances being across the southeastern half
of the CWA. There is a little better forcing aloft to help with
lift, and again are expecting good heating/mixing along/ahead of
the front, but there are a few things working against having much
coverage. Similar to yesterday, plenty of warm air aloft/capping
is in place, likely keeping anything from developing until later
in the afternoon...and while there is a bit more upper lift in the
area compared to yesterday, it`s still a weaker system in the
grand scheme of things.

One change to the forecast was to dry out the morning hours. The
lingering activity over the far southeast should continue moving
out early this morning, and hires model runs tonight have been
in good agreement keeping things dry until this afternoon. Kept
afternoon PoPs in the 20-40% range, with the highest PoPs right
along the front, though some models would suggest coverage will be
so sparse that 40% might even be too high. What thunderstorms do
develop with have plenty of instability to work with, and deeper
layer shear is roughly 30-40 kts, so severe weather will again be
a concern. Large hail/winds would be the primary hazards.

Better precipitation chances this evening/overnight focus across
our southern counties, closer to the sfc front, but confidence
in just how much is affecting our CWA is on the low side. Models
show the better instability gradually pushing south, but with
elevated instability lingering around well into the overnight
period, kept at least an isolated thunder mention going through
09Z...12Z in the far south.

Another forecast element for today where confidence is not high is
with high temperatures. Having a daytime frontal passage always
makes things tricky. Along/ahead of the front, models are showing
some pretty warm temperatures aloft, and with increased mixing
potential, that could really boost temperatures in a short amount
of time. This would primarily affect the central/southeastern half
of the CWA. To the north, as the front moves in, so does a cooler
air mass with those northwesterly winds. How exactly that timing
works out can really mess up forecast highs. At this point,
decided to go with mid/upper 80s in the north-northwest, to upper
90s across our KS counties. Depending on how the frontal timing
actually evolves, the day crew may be making adjustments.

.LONG TERM...(Friday through Wednesday)
Issued at 408 AM CDT Thu Jun 22 2017

Overview...There will be some chance for rain, but overall the
chances will generally be rather low with most showers and
thunderstorms more isolated in coverage area. There will be a nice
temperature drop for Friday into the weekend behind today`s cold
front with highs only expected to be in the 70s. We do expect a
gradual warmup next week, but not overly hot with temperatures
still in the 80s on Monday and Tuesday and then closer to 90 by
mid week.

Friday...Northerly sfc winds and an upper trough over central
Canada dipping into the northern plains will bring cooler air
into the region. Showers from Thursday night could linger into
Friday morning, but should be rather light and isolated.

Saturday into Sunday...We will remain in a cool northwesterly flow
aloft pattern. Can not rule out a few isolated showers as weak
vort maxes rotate around the base of the canadian trough. There
will be very little if any instability and thus am just calling
for the isolated showers and not thunderstorms at this time.

Monday through Wednesday...An upper level ridge should be located
over the western United States on Monday and then slide east into
the plains on Tuesday. The ridge is expected to flatten out some
by Wednesday and there could even be a subtle trough over the
plains, but forecast models diverge during this late period time
frame and thus confidence is limited. We should eventually tap
back into some southerly flow allowing the low level moisture to
stream back into the region and provide a least small chances for
showers and thunderstorms across portions of our forecast area.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Thursday)
Issued at 1217 AM CDT Thu Jun 22 2017

VFR conditions in the forecast for this TAF period, with the main
concern being with the passage of a frontal boundary this
afternoon. Models still showing some minor timing differences, but
the general story brings the boundary through near/just after
midday. Winds prior to the passage will be south-southwesterly,
with gusts near 20 MPH expected to linger around for a few more
hours early this morning, before switching to the north-northwest
for the remainder of the period. This front will help provide
focus for thunderstorm development later this afternoon, and have
a VCTS mention going for a few hours.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...ADP
LONG TERM...Wesely
AVIATION...ADP


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