Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 181153

Area Forecast Discussion
National Weather Service Hastings NE
653 AM CDT Tue Oct 18 2016

.SHORT TERM...(Today and tonight)
Issued at 355 AM CDT Tue Oct 18 2016

Compared to the dense fog/stratus/fire weather etc. issues of
yesterday (including a modest high temperature forecast bust of
5+ degrees across much of the CWA due mainly to a combo of slow-
to-clear skies and weaker-than-expected winds), at least "on
paper" these next 24 hours look more straightforward overall. This
yields higher confidence in especially high temps (which will
average roughly 10 degrees cooler than yesterday) and high
confidence that the vast majority of the CWA stays dry through
sunrise Wednesday (except maybe our extreme north late tonight).
Certainly, there are not any weather elements worthy of inclusion
in our Hazardous Weather Outlook product (HWOGID).

Taking a glance at the current scene as of 08z/3AM:
Most importantly, no dense fog concerns for a change! Otherwise,
compared to expectations of 24 hours ago, this ongoing late
night/early morning has thus far averaged a touch breezier than
expected, thanks mainly to a combination of a modest surface
pressure rise max moving through in association with a secondary
cold front (arguably the "true" cold front thermal-wise), along
with limited mixing aloft into a fairly strong corridor of
northwest winds in the lowest few thousand feet. As a result,
while most places have averaged sustained northwest speeds
generally 6-15 MPH, some brief enhanced speeds to 20+ MPH have
occurred here or there, helping keep the boundary layer mixed up
and thus preventing an appreciable temp drop despite what has thus
far been essentially cloud-free skies. There is still plenty of
time for a decent drop closer to sunrise, but it now appears the
majority of the CWA should bottom out no colder than 45-50. In the
big picture of the mid-upper levels, water vapor satellite and
model data reveal reveal a continuation of broad, seasonably-
strong/fast quasi-zonal (nearly west to east) flow over the
Central Plains, as up at 300 millibars a strong, 110+kt jet
stream is centered along an axis from northern CA-southern WY-
Great Lakes. At the surface, the aforementioned west-northwest
breezes are supported by a modest lingering pressure gradient
between a Great Lakes low and a high centered over the Central

Now looking ahead forecast-wise through these next 24 hours...

Early this morning through around sunset:
By most folk`s definition, we are looking at a pretty darn nice
fall day. Confidence remains high in continued dry conditions and
predominantly mostly clear skies for the most part. That being
said, there are a couple of opportunities for enhanced sky cover
today that could nudge things more toward partly or even mostly
cloudy for a time. Right off the bat this morning, some models
(especially RAP) are suggesting that a batch of lower stratus
clouds currently over northeast/far north central NE could
potentially brush into or even expand into parts of our northeast
CWA by sunrise, and possibly linger into the mid-late morning
hours. However, this solution seems a bit aggressive compared to
current satellite trends/other models so will not get too carried
away with sky cover unless this stratus actually shows its hand
locally (again, even if this were to occur it would only affect
northeast zones). Then later in the day, the beginning stages of
enhanced lift out in advance of Wednesday`s incoming disturbance
could promote some increase in mid-high clouds, but again think
"mostly sunny" will define the day as a whole for most. Otherwise,
the current modest surface pressure gradient will gradually relax
as the day goes on in response to the heart of the surface ridge
axis moving in. Wind-wise, this means that while the morning and
early afternoon will feature sustained northwest speeds generally
10-15 MPH (likely a few gusts up to around 20), the mid-late
afternoon will see speeds ease down 10 MPH or less, and downright
light/variable close to sunset. Temp-wise, made very little change
to previous forecast, as am expecting fairly uniform highs in the
68-72 range for most areas.

This evening/overnight:
In short, the vast majority of the CWA has essentially zero risk
of rain through sunrise, with the sole exception of our extreme
north, where a generic "slight chance of sprinkles" has been added
to the post-midnight hours mainly in the Ord area just in case
a brief period of sprinkles/light rain clips that area. However,
confidence in this occurring wasn`t even high enough to go with a
15+ percent measurable rain chance (PoP) and thus the sprinkle
wording. Certainly, various models are in clear agreement that the
vast majority of late-night rain will focus at least slightly
northwest of the CWA over the Sandhills area, where the main swath
of mid-level saturation/frontogenesis will set up as a
progressive, low amplitude shortwave trough steadily tracks out of
the Central Rockies into the Plains. Sky-cover wise, expect a
decent gradient overnight from cloudy/mostly cloudy north to no
worse than partly cloudy south (especially KS zones). At the
surface, breezes look to average around 5 MPH or less from a
generally easterly direction, in weak return flow behind the
departing ridge axis. Although the light winds favor a decent temp
drop, the sky cover gradient complicates the low temp forecast a
bit, and would not be surprised to see parts of the northern CWA
hold up several degrees warmer than southern/eastern zones where
clouds won`t be as thick/prevalent. This thinking actually runs
counter to raw MET/MAV numerical guidance which just looks too
cold, especially northwest. In the end, ended up making very
little change to overnight lows in the south and nudged up
northern areas 1-2 degrees, but could foresee this still being
too cool given clouds. Officially, the forecast currently
advertises lows in the 43-47 range for most of the CWA.

.LONG TERM...(Wednesday daytime through Monday)
Issued at 355 AM CDT Tue Oct 18 2016

The main forecast concern is the chance for precipitation during the
day tomorrow.

A disturbance will move eastward over the Rockies approaching the
region Tuesday night. This will cause the upper level flow to
become slightly southwesterly. This disturbance will move right
over Nebraska causing enough lift to develop some showers. The
best chance for showers will be during the day and evening Wednesday,
but like the previous forecast, have kept and extended the area
for chances into the Wednesday night time period. The rain
doesn`t look to be overly abundant in amounts. Temperatures
Wednesday will be cooler than Today with cloud cover and the
chances for precipitation. There could be some areas where
temperatures fall during the afternoon with the precipitation.
Overall, highs will be in the upper 50s over the northwest with
low to mid 60s over the remainder of the area.

This upper trough will be quick to move out with surface high
pressure following for the day on Thursday. Aloft, ridging will
build in through the remainder of the forecast. Highs will be in
the 60s to mid 70s through Monday with mostly clear skies. A few
wind shift boundaries may move over the region, but they will be
little more than that.


.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Wednesday morning)
Issued at 653 AM CDT Tue Oct 18 2016

General overview:
Confidence remains fairly high in VFR visibility through the
period, and is still reasonably high in VFR ceiling for at least
the vast majority of the period. However, since previous TAF
cycle there have been some new hints in the latest satellite and
model trends that a deck of MVFR stratus could try drifting
southward into mainly the KGRI area at some point this morning.
This is far from a "sure thing", but decided to at least hint at
the possibility by including a "FEW015" cloud group. Should this
sneaky MVFR ceiling actually occur, it would likely not last more
than a couple hours at most. Otherwise, confidence remains high in
rain-free conditions as any precipitation late tonight should
remain to the northwest over the Sandhills region. Any appreciable
low level wind shear (LLWS) issues from the overnight hours should
have ended by now and thus will omit from the new issuance. As
for surface winds, this will be pretty benign with west-northwest
speeds averaging around 10kt or less most of today before becoming
light/variable to light/easterly late this afternoon into tonight.




SHORT TERM...Pfannkuch
LONG TERM...Billings Wright
AVIATION...Pfannkuch is the U.S. government's official web portal to all federal, state and local government web resources and services.