Area Forecast Discussion
Issued by NWS Hastings, NE

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254
FXUS63 KGID 241037
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
437 AM CST Tue Jan 24 2017

.SHORT TERM...(Today and tonight)
Issued at 435 AM CST Tue Jan 24 2017

Satellite imagery showing the upper level low pressure system of
interest to our area spinning over southern WY early this morning,
overall not too much currently ongoing across the CWA. Seeing a
few more radar returns showing up over the past hour or so, lift
continues to increase as the system shifts closer and do have some
lower level WAA ongoing thanks to S-SWrly 850mb winds, but haven`t
had any reports of anything making it to the ground and nothing
from automated sites yet. The low level stratus that was starting
to move into the CWA about this time yesterday never really went
away, and the majority (esp. across SC NE) still sits with sub-
1000ft ceilings. At the surface, easterly winds continue CWA-wide,
sitting north of a warm frontal boundary across KS and low
pressure system over eastern CO. Visibilities have been all over
the place, and while there has been an occasional 1/4-1/2 mi, most
have been 1+ mile. Temperatures have been very steady all night,
within a few degrees either side of the freezing mark.

Looking to the rest of today/tonight, the general story hasn`t
changed much. Models still showing this upper level low making its
trek mainly east across the Central Plains (mostly through
Nebraska), reaching the Missouri River area roughly by sunrise
Wednesday. The big question through much of this has been where
the frontogenetical/mesoscale band(s) might set up, and the latest
run of models suggest that will have more of an impact on our CWA.
Short term/hi res models showing the potential for the start of a
band to develop over the next few hours through portions of the
CWA and sliding north. By mid morning, the potential is there for
band to be setting up over the northwestern corner of the CWA, and
eventually mainly the northern portions. As far as precip type
goes, with the nose of warmer temps aloft in the area, certainly
can`t rule out a wintry mix initially (thinking mainly sleet) with
the lighter stuff, but models showing as the heavier precip
develops/moves in, should switch over to all snow.

With a slight southern shift in the models with the heavier snow,
did up things across the northern half of the CWA. The forecast
snowfall amounts resulted in totals in the 5-7" range across
Valley/Greeley Counties, so between that and collab with
neighbors, did upgrade them to a Winter Storm Warning (criteria
is 6"). To the south, across Dawson/Buffalo/Hall Counties, totals
of 2-4" not out of the question, especially across the northern
portions of those counties, so they were added to the inherited
Winter Weather Advisory. Am a little concerned about Dawson County
reaching warning criteria, especially the western half, as some
hi-res models have at times shown heavier snow in the band setting
up/pivoting through that area. Amounts reaching near warning
criteria is also a concern across Sherman/Howard/Nance. Day crew
will be having to keep a close eye on how things evolve, the main
banding hasn`t set up yet, so if it happens to shift, changes to
snowfall amounts and headlines certainly aren`t out of the
question.

The current headline is starting plenty early, and debated pushing
back the start time, but with the chance for a wintry mix early
on and collab with neighbors/consistency, kept the timing the
same. That being said, the heavier preciptiation looks to affect
western/northern areas mid-morning and on, with it being closer to
midday and more likely the afternoon for locations roughly HW 281
and east.

For counties south of I-80/NC KS, the chance for more of a RA/SN
mix lingers this afternoon, with totals around 1" in the
northern part of this area, dropping off to a few tenths near the
NE/KS state line.

At the surface, models were just a touch slower pushing the surface
low through the area, meaning the easterly winds will stick around
a little longer. By midday, the western third of the CWA has
more northerly winds building in, but it may be mid/late afternoon
before eastern areas along HW 81 are totally switched over. The
strongest winds look to hold off until this evening/tonight once
the cold front has moved through, and speeds increase into the
20-30 MPH range (gusts near 40 MPH). Though the heaviest precip
looks to be moving out as the stronger winds are moving in, still
could see some blowing snow overnight and into Wed. morning,
causing reductions in visibilities.

.LONG TERM...(Wednesday through Monday)
Issued at 435 AM CST Tue Jan 24 2017

The biggest challenge of this forecast will be the potential for
lingering snowfall with the departing winter system.

The positively tilted and elongated nature of the trough moving
through will help keep some light snow and flurries around for
much of the day. Multiple numerical model solutions suggest that
we could hang on to at least flurries well into the afternoon, at
least in our eastern CWA.

I increased north northwest wind speeds and went with speeds
closer to CONSMOS, as is often the case for cold air advection
scenarios.

Expect a quiet pattern heading into the weekend with an upper
trough in the eastern United States and a positively tilted
ridge over the west coast. This will put us within north/northwest
flow. Although we have a dry forecast, there could be a "sneaker"
wave come through at some points to give us some light
precipitation. For now, the best chance for a sneaky wave looks
like it could be Sunday. Even then, we may not have enough
moisture to support much more than sprinkles/flurries, if that.
Temperatures will remain near normal, with the lack of any arctic
airmass, while cold continental air hangs on in the eastern United
States under the aforementioned trough. Temperatures could nudge a
bit above normal at some point early next week, perhaps Monday, as
a shallow shortwave ridge is forecast to make its way into the
Plains.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Tuesday night)
Issued at 1130 PM CST Mon Jan 23 2017

Low confidence in the forecast for this TAF period. An upper level
low pressure system sliding across the region today will bring
less than ideal ceiling/visibility conditions to the terminal
areas, as well as precipitation chances. Am pretty pessimistic
with cigs/visby through the period, with sub-1000ft cigs
throughout. Visibilities will vary with precipitation moving
in/out of the area. Kept a mention of -fzdz this morning going,
but confidence in it actually occurring is not high. May see a
passing area of precip around 12Z or so, but then may have a bit
of a lull, before better chances return this afternoon and
evening. As far as winds go, current easterly winds look to stick
around well into the daytime hours, then later today/this evening,
switch to the north-northwest and start ramping up in speed.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 9 AM CST Wednesday for NEZ041-
     046>049-060>062.

     Winter Storm Warning until 9 AM CST Wednesday for NEZ039-040.

KS...None.

&&

$$

SHORT TERM...ADP
LONG TERM...Heinlein
AVIATION...ADP



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