Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 240535
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1135 PM CST Mon Jan 23 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 354 PM CST Mon Jan 23 2017

Due to the shortness of the hour and that much of the afternoon
was dedicated to extensive fcst collaboration...this AFD will be
brief. Please refer to the fcst HWO and WSW for details as
currently envisioned.

First thing to say right out of the gate is confidence in the
precip fcst Tue-Tue night is below average. Just not sure how this
evolves. There are too many models depicting too many different
scenario`s...especially the mesoscale models. Release of
convective instability and the associated release of latent heat
is resulting in bands of narrow but significant QPF and resulting
in the formation of a new low and/or altering the path of the
primary low.

This fcst is a broad-brush approach looking primarily at synoptic
features (track of 700 mb and 500 mb lows). However...the
mesoscale will play a role and that will necessitate changes to
the fcst that will have short lead-time.

We`ve hoisted a Winter Wx Advisory for all the counties along Neb
Hwy 92 north to include Valley/Greeley/Nance as well.

However...it is important to understand that this is just our
first swing at highlighting the potential with this system. I
would venture to say it is likely this advisory will be expanded.
There is even a chance part of the fcst area may need to be
upgraded to a warning with little advance notice.

Fcst issues...

1) Fog. Low stratus has lingered from GRI-AUH and conds are
favorable for it to rapidly expand across the fcst area this eve.
Would not be surprised to see dense fog (vsby 1/4 mi or less).

2) Frzg drzl. Confidence is low on this. The soundings have the
look...but do temps even radiate to frzg? Temps made it into the
40s and 50s over much of the fcst area. Does this warmth radiate
away before clouds move in? Nudge low temps up. Gut feeling is
that we may have over-played this threat. Watch temperatures.

3) Thunder? It`s possible. There is enough elevated instability
that we could see some lightning late tonight. Mesoscale models
are indicating some mid-lvl convection after midnight tonight that
lifts across the fcst area in the morning.

4) A break? Much of the day could be dry tomorrow. Am concerned
the fcst sounds too wet.

5) We are unsure of how the snow evolves. We probably see a
significant band of snow develop over Nrn Neb during the day and
current expectation is that it will curl around the backside of
the 700mb low as it moves across the area in the late afternoon
hrs. Believe most of the snow will fall from 4 pm-4 am.

6) Snowfall amts: this advisory is a first shot...but it may not
fully encompass the area or the amounts correctly just yet. There
have been multiple runs of the NAM and RGEM that indicate a narrow
band of 4-8" of snow somewhere in cntrl Neb. Please allow us room
for fcst adjustments.

.LONG TERM...(Tuesday night through Monday)
Issued at 354 PM CST Mon Jan 23 2017

Much of the above will cross over into this section. Please see
above.

After this system departs...temps much closer to normal will
settle over the region thru Sat...but more warm appears to be on
the horizon next week. Dry.

&&

.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 from 3 AM Tuesday to 9 AM CST Wednesday
     for NEZ039>041-046>049.

KS...None.
&&

$$

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



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