Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 121726
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1126 AM CST Fri Jan 12 2018

.UPDATE...
Issued at 1019 AM CST Fri Jan 12 2018

Am struggling with how to best depict POPs this afternoon/evening
given the patchy nature of the snow. Most of what`s on UEX/LNX
radars is not reaching the ground...but it could begin at anytime
N and W of the Tri-Cities where CIGs have lowered to around 5K ft.
Will be raising POPs as some areas will see snow...but that means
we may overplay the potential for snow in other areas as we just
don`t know where snow will fall and where it won`t. This will
necessitate svrl updates thru the day as we watch the trends. We
hope to not be caught off guard.

Either way this snow will be light in character with any accum
1" (for the very lucky few) but most likely less than 1" for most.

&&

.SHORT TERM...(Today and tonight)
Issued at 504 AM CST Fri Jan 12 2018

The biggest issue during these next 24 hours will be a pesky round
of light snow/flurries anticipated to affect much of our coverage
area (CWA), perhaps starting later this morning in our far
western/northern counties, but affecting the balance of our CWA
this afternoon into this evening before ending. Confidence is
reasonably high that this will be a low-impact event with
accumulations largely under 1 inch, and with winds no more than
10-15 MPH any blowing impacts should be minimal. The other big
story (probably bigger overall, actually) will be continued frigid
temperatures, and for at least a few hours this morning especially
the northeast half or so of the CWA will continue seeing near-
Advisory wind chill values of -15 to -20 degrees.

As for the here-and-now as of 430 AM, the night has largely panned
out as expected so far, as initially clear skies early in the
night are gradually giving way to increasing mid-high level cloud
cover overspreading the Central Plains in advance of a low-
amplitude disturbance tracking southeastward out of the
Northern/Central Rockies in northwesterly flow aloft. At the
surface, a nearly 1040 millibar high pressure system is located
over ND, and although this ridge axis extends southward into our
area, there is still enough of a pressure gradient to promote
north winds into the 10-15 MPH range, especially within the
eastern half of our CWA with lighter breezes west.

Looking ahead forecast-wise through today/tonight...

Today/this evening:
Have already touched on the highlights of: 1) Light snow mainly
this afternoon/evening and 2) Very cold temps/near-advisory
morning wind chills. While forcing/moisture is fairly unimpressive
with the incoming wave, at least a light dusting of snow and MAYBE
up to around 1 inch in a few spots is likely mainly this afternoon
into this evening. Models vary on the most favored locations, with
some mainly favoring our southwest half while others are more
broad-brushed. As a result, did not get too "cute" with
pinpointing particular areas. Fortunately, with winds averaging no
more than 10-15 MPH from first a mainly easterly/eventually
northeasterly direction this afternoon, any impacts should be very
minor. The vast majority of any possible snow accumulation should
be done by around 9 PM. Temp-wise, knocked down highs 1-3 degrees
from previous, largely due to plentiful cloud cover inhibiting
much of a rise, aiming from a range around 10 north, to around
16-18 far south.

Overnight:
There are some question marks regarding whether mainly low cloud
cover will remain abundant or perhaps break up to some degree.
Nudged down low temps slightly into mainly the 0 to -3 range, but
if it clears much could see further lowering needed. Fortunately,
breezes are expected to be a touch lighter than this morning,
mainly in the 5-10 MPH range at most, helping keep wind chills
across the vast majority of the area slightly "warmer" than -15
but still plenty cold.

.LONG TERM...(Saturday daytime through Thursday)
Issued at 504 AM CST Fri Jan 12 2018

General overview of this 6-day period...Here are the 3 main
stories to focus on:

1) There are 2 more distinct opportunities for a quick-hitting,
mainly light snow event over the weekend, as
additional/reinforcing disturbances drop down from the north-
northwest. The first of these focuses Saturday night into early
morning, and mainly looks to impact the northeast half of the CWA.
Officially, our current forecast calls for less than 1" of
accumulation, but the latest models are hinting that this could
trend upward, especially in our northeast 1/4 or so. The second
round then arrives almost exactly 24 hours later from Sunday night
into early Monday morning, and could be a bit more widespread in
terms of affecting the majority of the CWA with at least a light
dusting, and again perhaps to around 1" in spots if not locally
higher. This second round looks to have a bit more wind with it
(sustained 15-20 MPH/higher gusts), so it will be something to
watch despite the expected low amounts. Beyond Monday morning, the
remainder of the Monday-Thursday time frame remains dry.

2) Remaining cold/below normal through much of this time frame,
with a few exceptions. Temp-wise, Saturday highs are aimed only a
touch "warmer" than today. But then Sunday looks like a BRIEF, one
day warm-up with highs into the mid-30s to mid-40s as a surge of
warm air advection/westerly winds kick in ahead of the next trough
dropping down from the north. Behind this trough and associated
cold front, temps plunge again for Monday-Tuesday with highs
mainly only 10-20 degrees and slightly sub-zero lows especially
Monday night. If trends hold, Monday night could be a Wind Chill
Advisory candidate given widespread -15 to -20 readings most
areas, and slightly colder yet especially far north/northeast.

3) Moderating temps later next week. Although values were nudged
down a few degrees from previous, a modest warming trend is still
anticipated Wednesday-Thursday as high temps rebound roughly 10
degrees each day, reaching the 20s most areas Wed, and mid 30s to
mid 40s Thursday (warmest west). Obviously any reinforcing snow
cover before then could temper this warm-up somewhat.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday)
Issued at 1126 AM CST Fri Jan 12 2018

Significant Wx: Potential for 1-3 hrs of IFR -SN until 02Z.

This Afternoon: VFR CIGs 4-7K ft but there is significant
uncertainty on VSBYs and WX. Confidence is fairly high that both
terminals will see some VFR flurries...but there is potential for
MVFR OR IFR -SN for a brief time. Did bring EAR down to MVFR CIGs
but for now uncertainty is too great to include low VSBYs. Watch
for amendments and follow the METARs. Lgt NE winds under 10 kts.
Confidence: Medium

Tonight: Uncertainty remains on coverage of -SN...but potential
for sub-VFR conds should end by 03Z. One potential complication is
CIGs. Do they remain MVFR behind the SN or even drop to IFR at
EAR? For now indicated improvement to VFR...but that could chg
with later TAFs. Lgt NE winds. Confidence: Medium

Sat thru 18Z: VFR CIGs around 4K ft. Lgt/vrbl winds as winds
gradually shift from N to S. Confidence: Medium

&&

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

$$

UPDATE...Kelley
SHORT TERM...Pfannkuch
LONG TERM...Pfannkuch
AVIATION...Kelley



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