Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 021757
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1157 AM CST Fri Dec 2 2016

.SHORT TERM...(Today and tonight)
Issued at 316 AM CST Fri Dec 2 2016

Generally nice late fall/early winter weather is anticipated
across the local area again today. Other than some passing mid
level clouds...skies will be mostly sunny...winds will be
light...and temperatures will be near...if not a degree or two
above...early December normals.

As evident in satellite imagery this morning...expect some broken
mid level cloud cover to stream across the northern and eastern
portions of Nebraska this morning...before mostly sunny skies
become dominant as a weak ridge of high pressure aloft temporarily
builds across the local area. With a weak surface pressure
gradient under this ridge and very little change in 850 mb temps
from yesterday...expect another nice afternoon with temperatures
near or just above yesterdays readings. In addition...winds will
remain light as an area of surface high pressure slowly
transitions into the Missouri river valley over the next 24 hours.

Also evident in satellite...some high level clouds are
encroaching from the desert southwest...and should eventually get
pulled northeast and towards the local are during the late
afternoon or evening hours today. While it will take a while for
the atmosphere to saturate...could see a few light snow showers
develop before dawn across north central Kansas overnight
tonight...as weak lift ahead of the upper level low across
northern Mexico is realized locally...and introduced some very
small pops to cover this potential. Any precipitation that does
form overnight... however...should be very light and primarily
limited to our north central Kansas counties.


.LONG TERM...(Saturday through Thursday)
Issued at 316 AM CST Fri Dec 2 2016

Chances for precipitation and a blast of very cold air remain the
primary concerns through the long term.

The period starts off Saturday morning with models not in too bad
of agreement looking aloft, with southwesterly flow across the
area. A cutoff low pressure system spins over northwestern Mexico,
while a northern stream shortwave trough is sliding through the
High Plains. Lift increases ahead of the disturbance, and models
also showing the potential for portions of the area to be
influenced by the entrance region of a strong upper level jet.
Precip chances look to spread north-northeast through the daytime
hours Sat, clipping the east- southeastern third or so of the CWA.
PoPs are only in the 20-30% range, as there is some spread between
models with the coverage of any precip and QPF. The NAM is the
most aggressive, actually trying to drop a few inches of snow
across the southern half of the CWA, while a few others have very
little QPF. Overall through the event, precip type may end up
being a mix of both RA/SN, so snow accum may be hard to come by.
At this point do have a few tenths of an inch of snow across SErn
areas, but if things trend closer to the NAM, adjustments will be
needed. Confidence in precip/precip-type for Sat is not the
highest. Current forecast highs are in the upper 30s- lower 40s,
but if it pans out more like the NAM, that may be too warm.

What precip that does affect the CWA on Saturday is expected to
shift off to the east during the evening hours. Upper level zonal
flow looks to build in across the area in the wake of this system
for Sunday, and the forecast remains dry. Though the continued dry
forecast, upper level flow turns more southwesterly as we get into
Monday, as the next round of troughing moves further into the
Rockies. Sun-Mon will bring our last shot of near/slightly above
normal temps, with forecast highs in the mid-upper 40s both days.
Westerly winds during the day on Sunday looks to transition to the
south on Monday, ahead of deepening surface low
pressure/approaching cold front.

That brings us to the Tuesday through Thursday period. At one
point in just the past few days, models had shown the possibility
of a potent closed upper level low pressure system swinging
through the Plains, bringing along the chance for quite a bit of
snow. In the past couple of model runs, and continued in the 00Z
run, models have trended more toward the area being affected by
troughing associated with a closed low over central Canada, with
embedded pieces of shortwave energy...more progressive flow.
Models showing the chance for the first, weaker wave to bring
light precip Monday night into Tuesday. The system bringing the
better chance for precip still looks to push through the area
Tuesday night into Wednesday, not a big change timing-wise from
previous model runs. Still looking to be an all snow event, with
accumulating snow possible for the CWA, but too many
uncertainties/details yet to be ironed out before we can
confidently start throwing out amounts.

One thing that has not changed with several model runs now is the
significant air mass change, ushering in much colder temperatures.
The timing of passage of the cold front hasn`t changed
significantly, with it expected to have pushed through the entire
CWA by 12Z Tuesday. Colder air starts pushing in from the north,
getting an reinforcing shot with the passage of the main system
Tuesday night into Wednesday. Breezy NW winds can be expected both
Tues and Wed. A 15-20 degree drop in highs is currently forecast
from Mon to Tues, into the mid 20s to near 30 degrees. Wind chill
values through the afternoon hours on Tuesday are forecast to fall
into the teens, perhaps some single digits in the northwest.

The ECMWF has the brunt of the precip going on during the daytime
hours on Wednesday, the GFS is a touch quicker (mainly Tue
night/early Wed), GEM in between. Any solution, Wed not looking to
be the nicest of days. Highs are expected to only reach the mid
teens to mid 20s, after starting the morning in the lower-mid
teens. Wind chill values in the single digits either side of zero
are currently in the forecast for Wed morning, and then again
Thurs morning, with only a slight rise during the day.

Though Thursday is forecast to be dry in the wake of this system,
the cold air mass is solidly in place. Current forecast highs
range from the upper teens to mid 20s, starting the day with low
sin the single digits for a good chunk of the CWA. Wouldn`t be too
surprised to see forecast highs for both Wed-Thurs trend down
more, if current model trends hold. We`ll see what the coming
model runs bring.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday)
Issued at 1157 AM CST Fri Dec 2 2016

Significant Wx: MVFR CIGs expected after 15Z/Sat. There is a
chance for IFR -SN after 12Z.

This Afternoon: VFR with invading cirrostratus CIGs from the SW.
Lgt and vrbl winds. Confidence: High

Tonight: VFR. Multi-layered mid-high CIGs gradually descend to
around 10K ft. Lgt and vrbl winds. Confidence: High

Sat thru 18Z: CIGs will gradually lower thru 5K ft down to 2K ft
after 15Z. A couple fcst models are indicating -SN will move
in...but others are not. Lgt and vrbl winds will become SW and
gradually increase close to 10 kts. Confidence: High in MVFR CIGs
but confidence is low on potential for SN.

&&

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

$$

SHORT TERM...Rossi
LONG TERM...ADP
AVIATION...Kelley



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