Winter Storm Warning 1, NWS Hastings, NE

AREA FORECAST DISCUSSION
National Weather Service Hastings NE
1243 PM CDT Fri Mar 13 2020

.SHORT TERM...(Today through Saturday night)
Issued at 448 AM CDT Fri Mar 13 2020

Quiet conditions reign across the region early this morning, with
upper air and satellite data showing generally zonal flow in
place...set up between areas of low pressure spinning over far
southern CA and over southern Ontario. Satellite data showing
increasing mid-upper level cloud cover streaming in from the WSW,
with northeastern areas still under mostly clear skies. At the
surface, high pressure continues to be the main driver across the
area, centered over central NE/SD. As a result, winds early this
morning remain light/variable.

The primary concern through the short term period, mainly after
noon  today through Saturday afternoon, remains with
precipitation chances and the potential for accumulating snowfall.
Overall, no significant changes were made to the forecast, and
there continues to be some uncertainties. In the grand scheme of
things, models are in good agreement showing that upper low
currently over srn CA sliding up into the Four Corners region
today, filling/weakening into an open wave as it does so. It's not
until late in the day Saturday that it finally pushes through the
area. While broader scale lift will increase tonight/tomorrow as
it moves in, today's weather will be driven by a mid-level
shortwave/increased frontogenetical forcing out ahead of that
western system. PoPs will be on the increase today, but one big
question lies with the timing of the onset of precipitation.

At the surface, that area of high pressure currently over the area
will gradually slide east with time today...bringing in easterly
winds CWA-wide by this evening. This easterly/drier lower level
flow may result in areas struggling to see much in the way precip
through a good chunk of the day...something recent runs of the
HRRR/RAP continue to show. Main change to the forecast was to
reflect that slower onset the further east you go...there is
decent support that it'd be late afternoon before some
north/northeastern areas see anything. These same models suggest
the Tri-Cities could be dry through midday. The best, most
widespread chances look to come this evening through roughly
midday Saturday.

Another question is how quickly precipitation types transition.
Have rain as the primary type through the majority of
today...think the biggest uncertainty will be across far SWrn
portions of the CWA, where some models have at least a few inches
already in the 18-00Z period. Think that with the marginal
temperatures and it occurring during the afternoon hours, it'd
struggle to accumulate that much. Currently only have around
0.5-1.0" of snow in the SW through 00Z. Most accumulation is
forecast to occur from 00Z this evening through 18Z Saturday. Did
lower highs some for Saturday into the mid 30s, so think that
chances of any lingering precip changing back over to liquid is
not high.

By the time it's all said and done, storm total snowfall amounts
did not change notably. Still forecasting generally 3-4" of snow
from roughly HWY 281 west and NE/KS state line north (locally
higher amounts certainly aren't out of the question)...falling to
around 3" in the Hebron area, and 1-2" across the far southern 3
counties. Fortunately, wind doesn't look to be a significant
factor. Winds remain easterly through the event...increasing this
evening-Sat into the 15-20 MPH range (gusts closer to 25 MPH
possible). This along with the expected wetter nature of the snow
should limit blowing/drifting.

After collab with neighboring offices, changes to the Winter
Weather Advisory include 1) Adding Fillmore, Nuckolls and Smith
counties...and 2) Segmenting the start time. Kept the 4 PM start
time for most of the advisory area...but for counties roughly
along and northeast of an Ord-Aurora-Geneva line, felt that was
too early (due to both the onset of precip and switch over to
snow), and pushed the start time back to 7 PM. Obviously the day
crew will be keeping a close eye on how things evolve. There is
some concern that some of those locally higher amounts mentioned
above could be closer to warning criteria (6+ inches)...with the
main threat of that looks to be across western portions of the
CWA.

While this round of precipitation looks to come to an end during
the daytime hours on Saturday...a few models hint at the
potential for some light QPF to linger around into the Sat
evening/overnight hours. There is a lack of forcing, the CWA will
be sitting on the backside of the departing system...so kept any
precip mention as FZDZ, and have in confined to western areas.
Confidence in this is not high at all.

.LONG TERM...(Sunday through Thursday)
Issued at 448 AM CDT Fri Mar 13 2020

Unfortunately, plenty of uncertainties remain as we get into the
long term section of the forecast, mainly with precip chances...so
overall confidence isn't high.

The forecast for the daytime hours on Sunday into Sunday evening
is  dry, with models in pretty good agreement showing zonal flow
aloft in place across the region. We are sitting on the northern
side of weak ridging, driving by high pressure over the Gulf,
while a stronger area of low pressure spins over the OR/CA coast.
Next chance for precip arrives late Sunday night into Monday, and
while model blend kept PoPs in the 20-30% range, think the areal
extent is too much. Have PoPs across the entire CWA, but most
recent model runs suggest the better chances would be across the
southern half of the CWA. Have a mention of both RA and
SN...forecast highs for Monday are in the mid-upper 40s.

The forecast for Wednesday through Friday continues to have PoPs
every day...driven by shortwave disturbances out ahead of the main
upper level low pressure system...which digs south along the CA
coast with time, and by Thursday evening has moved into CO. Plenty
of details to iron out in the coming days...but a mention of both
RA and SN remains, depending on the sfc temp...and the chance of
some thunder returns Wed and Thurs. As far as highs go, Tuesday is
in the mid 40s to near 50, with more 50s for Wed/Thur.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Saturday)
Issued at 1243 PM CDT Fri Mar 13 2020

Significant Wx: IFR CIGs/VSBYs in wet snow.

Plowing and de-icing will be required.

This afternoon: VFR CIGs 4-6K ft with -RA moving in. Light rain
should begin to mix with snow at EAR. SE winds 6-12 kt.
Confidence: High

Tonight: CIGs/VSBYs decay to IFR as rain/snow mix will change to
all snow 00Z-03Z...first at EAR. VSBY could fall as low as 3/4 mi.
E winds 15-25 kt. Confidence: High

Sat thru 18Z: IFR CIGs/VSBYs. -SN will end around 15Z but models
suggest IFR fog could linger thereafter. E winds 15-25 kt.
Confidence: Medium

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory from 4 PM this afternoon to 4 PM CDT
     Saturday for NEZ046-060>062-072>076-082>086.

     Winter Weather Advisory from 7 PM this evening to 4 PM CDT
     Saturday for NEZ039>041-047>049-063-064-077.

KS...Winter Weather Advisory from 4 PM this afternoon to 4 PM CDT
     Saturday for KSZ005-006.

&&

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

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>