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Area forecast discussion 
National Weather Service Hastings NE
610 PM CST Sat Feb 13 2016

Short term...(this evening through sunday)
issued at 404 PM CST Sat Feb 13 2016

Other than a lingering outside shot of some light freezing drizzle
in far west-central/northwest zones yet late this afternoon/early
this evening...and a modest chance for a quick hit of light snow
overnight mainly in the far north/northeast...the big story for
the majority of the County Warning Area over these next 24 hours is the beginning
stages of the much-anticipated warm-up that will almost assuredly
allow the last half of February to average solidly above-normal
(see long term section below for more on the warmth through next
week). Not to get too carried away...as a few more cold days are
surely ahead...but now that we are in/nearing the final 1/3 of the
winter season the odds of seeing more days such as this are
steadily dwindling.

Taking a look at the here-and-now as of 21z/3pm...for the most
part today has Shook out pretty much as expected...with one last
day of well-below normal cold (especially in Nebraska zones). As
mentioned in the "update" discussion earlier this
morning...fortunately the possible threat of freezing drizzle in
the western County Warning Area that has dogged the forecast for the past few days
has apparently not materialized...except for maybe a few spits of
it in the western Dawson County area. However...it has been a
very close call for our County Warning Area getting more of it...with at least
light/nuisance freezing drizzle reported as close as the North
Platte area/Highway 83 corridor in western Nebraska. Locally...we
can think drier low-level air that pushed in from the east over
the past 24 hours...thus keeping cloud ceiling heights from
solidly dropping to the roughly 1000 feet or less often needed for
legit drizzle production.

In the big picture of the middle-upper levels...water vapor
satellite and short term model data indicate that flow aloft over
the Central Plains has turned considerably more zonal (west-to-
east) over the past 24 hours...as a fairly compact-but-rather-
potent shortwave trough is currently approaching the region from
the southern Montana/northern Wyoming area. This wave has even promoted a
few lightning strikes in that area this afternoon. Cloud-
wise...the majority of the County Warning Area remains shrouded under lower
stratus...but an increasing amount of at-least filtered sunshine
is breaking into far southern zones as the low stratus deck
retreats northward leaving only high cirrus as the main cloud
type. At the surface...the "last gasp" of the stubborn Arctic
airmass remains in place over the local area...although it is
already in the beginning stages of retreating eastward as the
center of the strong roughly 1036 millibar ridge axis has now
moved east into Illinois. In between this departing high and low
pressure approaching from the northwest...south-southeast breezes
have become a touch breezy today in most areas...generally 10-20
miles per hour. With weak-but-steady low-level warm air advection already
underway...suspect most places will actually rise a few more
degrees and observe high temperatures closer to sunset. For
now...still expect highs to range from low 20s northeast...middle 20s
central and as warm as middle-upper 30s in the far southern County Warning Area where
some sun has broken through.

Now finally looking ahead forecast-wise through today/tomorrow:

This evening/tonight: the main question is...will the far
northern/northeast County Warning Area get clipped with up to a few tenths of an
inch of light snow (maybe even a few sleet pellets?)...or will
this system essentially miss our County Warning Area completely to the north and
east? In the middle-upper levels...the aforementioned approaching
shortwave trough will quickly race east-southeast across The Heart
of Nebraska overnight...reaching the Iowa/NE/MO border area by sunrise
Sunday. For sure...the strongest large-scale forcing/isentropic
lift will focus at least slightly to the north/northeast of the
County Warning Area...where a swath of 2+" of snow is expected tonight mainly
along a path from eastern South Dakota into Iowa. However...between midnight
and sunrise...a quick shot of forcing and low-middle level saturation
will swing across our northern/northeast County Warning Area...right under The
Heart of the middle level wave. Although models differ on the
details...at least felt it was justified to raise snow chances
into "high chance" category over far northern counties such as
valley/Greeley/Nance...and even bring a "slight chance of
flurries" mention as far south as a Ravenna-Grand Island-Fairmont
line. Even so...would be surprised to see snow accumulate to more
than a few tenths of an inch at most. Actually...with steady
warm-air advection evident especially around 850 millibars...it's
not out of the question that this precipitation could actually take the
form of a few brief sleet showers...but decided to not introduce
a formal sleet mention to the forecast due to lower confidence in
this precipitation type. Speaking of low-level warm air advection...at
least slightly-rising temperatures are likely across the County Warning Area especially
between midnight and sunrise...as surface winds steadily turn
westerly behind the passing surface trough/warm front. If
anything...might have underdone these westerly wind speeds a
bit...but generally expect them to average 10-15 miles per hour with some
higher gusts possible. Getting back to temperatures...actual lows were
changed little...aimed from near-20 northeast to middle-upper 20s
southwest. However...by daybreak have most of the County Warning Area aimed into
the 25-31 range and actually expect a fair amount of clearing
skies especially in central/western zones by that time.

Sunday daytime: any chance of possible light snow/sleet should be
over with by daybreak...as the aforementioned potent shortwave
trough and its associated forcing will quickly depart into the
eastern Midwest/lower Great Lakes region as the day wears on.
Although a weaker upstream wave will start approaching western
portions of the local area by late in the day...any possible light
precipitation from this wave should hold off until Sunday night...thus
providing high confidence in a dry daytime period cwa-wide. Skies
in most areas should average somewhere between mostly sunny and
partly cloudy for most of the day...although high clouds will
likely be on the increase middle-late afternoon. Certainly the big
story will be at the surface/low-levels...where steady 10-15 miles per hour
west-northwest breezes/downslope flow will combine with sunshine
to result in a notable/roughly 20-25 degree warm-up versus today!
Although lingering snow cover could be a "wild card" factor that
holds a few areas slightly below expectations...ended up making
very little change to previous forecast...aiming most of the County Warning Area
well into the middle-upper 40s...and warmer low-middle 50s mainly in Kansas
zones.

Long term...(sunday night through saturday)
issued at 404 PM CST Sat Feb 13 2016

The main forecast issue will determining be temperatures and perhaps
small chances of precipitation with a series of waves to come through.

The ridge in the west and trough in the east will continue to give
US northwest flow to begin the long term forecast beginning Sunday
night. A weak trough will give US a small shot at some precipitation
Sunday night...but it looks like this should remain mainly rain if
we get anything at all. We will be near the left front quadrant of
the upper jet by late Sunday night. Lower-levels looks awfully dry
and I decided to go with chance flurries/sprinkles Sunday night.
Another wave comes along Monday night...and this perhaps has a bit
more of a kick...so I went with a 20 percent chance of rain showers
for much of the County Warning Area.

The upper ridge will nudge east over the course of the work week and
a noticeable warm-up will ensue. We should be easily 10 to 20
degrees above normal for several days. Generally went toward bias
corrected models for highs in the long term and negated some of the
snow cover effects as this should be largely gone by then. Went
toward consraw for lows.This significantly boosted temperatures for
both highs and lows. A more significant shortwave trough will arrive
sometime Friday behind the exiting ridge...which might give US some
precipitation Thursday night/Friday...but keeping it dry for now as
ambient conditions look rather dry. One area of concern will be fire
weather Friday behind the cold front coming through Thursday night.
Downsloping may keep the temperature up and dewpoints down...and
wind speeds from the northwest could be strong with gusts possibly
over 30 miles per hour. This will bear watching. This string of mild weather
may continue for several days.

&&

Aviation...(for the 00z kgri/kear tafs through 00z Sunday evening)
issued at 540 PM CST Sat Feb 13 2016

Ceilings are expected to rise through the night and a strong low
level jet will develop as we near dawn. The main concern will
center around strong low level wind shear that will come into play
due to the strengthening low level jet. The wind shear will be a
factor from just before dawn through around mid-morning. The wind
will veer with time from southeasterly this evening to
southwest after midnight and then even westerly by later Sunday
morning.

&&

Gid watches/warnings/advisories...
NE...none.
Kansas...none.
&&

$$

Short term...pfannkuch
long term...heinlein
aviation...wesely

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