Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 122318

Area Forecast Discussion
National Weather Service Hastings NE
618 PM CDT Thu Oct 12 2017

.SHORT TERM...(This evening through Friday)
Issued at 319 PM CDT Thu Oct 12 2017

It`s been another dry day across the region, with plenty of
sunshine remaining in place. Upper level and satellite data
shows continued southwesterly flow over the Plains, with broad
high pressure extending north-northeast from the Gulf Coast region
and troughing over the western CONUS. At the surface, an area of
low pressure currently resides over the eastern half of CO, with a
trough axis extending north through western NE and central
Dakotas. The resulting winds have been southerly through the day,
weaker in speed across the west (closer to the sfc boundary),
while at times gusting near 20 MPH across the east.

Looking to the short term period today/tonight, models are in good
agreement not showing any notable change in the upper level
southwesterly flow, though that Pac NW system is pushing a bit
further east. Looking toward the north, a piece of energy is shown
by models to push east through central Canada overnight, and it`s
not out of the question that a much more subtle mid level wave
may pass the Central Plains. The surface boundary current to our
west gets pushed south as a cold front by that northern system,
with models not in too bad of agreement showing it through all but
the very southeast corner of the CWA by 12Z tomorrow.

Kept the forecast dry tonight, but there is some concern some
precipitation may affect areas near the front during the first
half of the day tomorrow. Confidence is not high, but there are
a few models that has been persistent showing light qpf "around".
Other models keep the entire short term period dry, and with there
not a lot of deeper moisture in the atmosphere, decided to leave
any mention in as sprinkles, affecting roughly east-southeast
portions of the CWA. The surface front will sag a bit further
south during the day, but its main upper level push has moved off
to the east, so at some point it should start to stall. Expecting
more in the way of cloud cover, especially across the southeastern
half of the CWA, and cooler temps, with highs in the lower/mid

.LONG TERM...(Friday night through Thursday)
Issued at 319 PM CDT Thu Oct 12 2017

Friday night through Saturday evening is the active portion of the
long term period, and there will be the potential for some
strong/marginally severe thunderstorms. Precipitation chances
through this time frame look to come in 2 different waves, the
first being late Friday night. The main surface boundary is shown
by models to start out the night south of the CWA, but pushes back
north with time, as the surface low deepens over the CO/KS border
ahead of the upper level system (the one currently out over the
Pac NW) swinging through the Rockies. Elevated thunderstorms are
expected to develop along the convergence zone of an increasing
LLJ, nosing in from the SSW. Though models vary with the amount
instability available (some closer to 500 j/kg, others closer to
1000 j/kg), all agree on there being high values of deeper layer
shear. Southeastern portions of the CWA are included in the SPC
Day 2 Marginal Risk, hail/winds would be the primary hazards.

As we get into Saturday, through lift from the LLJ will wane
during the morning hours, larger scale lift is on the increase
as the main upper level onto the Plains. Forcing along the sfc
front/upper level trough axis is where the best chances for
precipitation will lie, and are expected to be pushing east out of
the CWA with time. The current forecast has at least low PoPs
hanging around into the evening, there are some models suggesting
that the main precip is out of the CWA by the 21-00Z time frame.
If this trend holds, adjustments will be needed to the PoPs. High
temperatures for Saturday are tricky, and will be dependent on the
timing of the front/exit of precip, so confidence is not high.
Current forecast has upper 50s in the Ord area, to lower 70s in
parts of north central KS. Increased winds from superblend Sat
aftn/evening, with models showing decent pressure rises behind the
front. NW winds with sustained speeds near 20 MPH are possible
CWA-wide by evening.

Once this system pushes east out of the Plains Saturday night, the
forecast for Sunday through midweek remains dry. Flow in the wake
of this system looks to be zonal to low-amplitude northwesterly,
and while there may be an occasional wave moving through, not
expected to be enough moisture to work with. As far as
temperatures go, following highs in the upper 50s/low 60s Sunday,
a rebound back into the lower/mid 70s is forecast for Tue/Wed.


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 616 PM CDT Thu Oct 12 2017

A cold front will move through the terminal areas turning winds to
the north. Winds will be fairly light and increase a little as the
front moves through. Clouds will increase some toward the end of
the period.




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