Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 240456
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1156 PM CDT Sat Mar 23 2024

.KEY MESSAGES...

- Freezing rain and light snow will lead to slick roads in
  northeast Nebraska tonight into Sunday morning. A Winter
  Weather Advisory is in effect.

- Widespread rain expected on Sunday with thunderstorms
  possible. Strong southeasterly winds gusting to 35 to 45 mph
  expected as well.

- A band of heavy snow may clip portions of northeast Nebraska
  (Knox and Antelope counties) Monday (40-70% chance of at least
  4 inches). Combined with wind gusts of 35 to 50 mph,
  significant travel impacts would be possible

- A second, slightly lighter band of snow may bring travel
  impacts to areas farther east of the main band Monday evening
  into Tuesday (40-60% chance). Highest chances would be
  between Norfolk/Columbus and Tekamah.

- Dry weather returns for Wednesday and Thursday with
  temperatures trending back up.

&&

.DISCUSSION...
Issued at 347 PM CDT Sat Mar 23 2024

Today and Tonight:

Water vapor imagery this afternoon continues to feature the
deep trough swirling over the Pacific Coast with largely zonal
flow extending eastward with a weak shortwave squeezing out
light snow into southern Iowa. This deep trough is the sole
focus for the first half of the forecast period with the
expectation that it kicks off a deep lee cyclone that will eject
from Kansas northeastward across Nebraska and Iowa. Ahead of
the surface low will be rainy and windy conditions Sunday, and
on the cool side of the low will come sleet, snow, and more wind
-- especially across far northeast Nebraska.

Before we get to all of those details, it`s important to address
this evening. Temperatures this afternoon have been knee-capped by
the flurries and light snow falling out of some thick cloud cover,
giving us a head start at cooling this evening. With that said, the
cloud cover will keep us somewhat insulated limit cooling once it
builds in again tonight around 9 or 10 PM. Strong warm air advection
in the lower levels will help overspread rainfall for much of the
area around 4 AM, and sub-freezing temperatures in northeast
Nebraska will give us a solid look at freezing rain on the order of
a trace to 0.1" -- making the Sunday AM drive treacherous.

Sunday through Tuesday Morning:

With the rapidly deepening surface system taking shape over the
Colorado High Plains Sunday morning, a very strong surface pressure
gradient is expected to develop, increasing moisture transport, warm
air advection, and wind speeds across the entire area. Wind speeds
are expected to peak Monday late afternoon/early evening with
wind speeds as strong as 35 to 45 mph, and the strongest winds
in far southern Nebraska into Kansas. As of right now, it isn`t
quite getting to Wind Advisory levels but the southerly winds
will certainly increase the travel difficulty for high-profile
vehicles on I-80. Widespread rain is also expected with the
strong forcing and moisture advection, and rumbles of thunder
will join in thanks to steep enough mid-level lapse rates
allowing some elevated CAPE to develop, with an outside chance
for damaging wind or quarter-sized hail to occur after 7 PM
(though it doesn`t look great for it).

Going into the overnight hours Sunday, the ejecting surface low
will begin nudging the cold front eastward, and we`ll begin
seeing surface temperatures falling below freezing in northeast
Nebraska. Despite the cooler surface temperatures, a warm nose
around 825 mb will try to melt frozen hydrometeors while the
layer below re- freezes them with sleet as the result. A very
sharp gradient is expected between rain, sleet, and very heavy
snow closer to north- central Nebraska, with BUFKIT showing an
almost different world at 5 AM between Albion and Ord, Nebraska
(separated by a county and a half. Nevertheless, snow will move
into northeast Nebraska Monday morning into the afternoon and
we`ll see that snow spread east as additional mid-level forcing
and vorticity advection reinforces the main system Monday
evening into early Tuesday. We`ve taken a conservative approach
to Monday evening/night snowfall, but this could increase for
the next forecast. When all is said and done, northwest Knox and
Antelope Counties will see near 4 inches of snow and some sleet
while the Omaha and Lincoln Metros see a trace to half an inch
of snow.

Tuesday and Beyond:

Weak ridging will follow the trough and increase temperatures
quickly after a cool Tuesday and make quick work of any accumulated
snowfall. Behind that low-amplitude will be another weather system
to watch that could cause headaches for early next work week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1149 PM CDT Sat Mar 23 2024

A strong storm system will bring many aviation hazards
this weekend including strong winds, heavy precipitation, ice
accumulations, and IFR/LIFR ceilings and visibilities. Southeasterly
winds of 10 to 15 knots will veer over the next 12 hours to
become more southerly for the rest of the forecast period. Wind
gusts will strengthen steadily late tonight into tomorrow, with
gusts tomorrow evening up to 35 knots possible, especially
across southeast Nebraska (KLNK).

A round of precipitation is expected to move into the region
from the west by 07Z and bring widespread light to moderate
rain to all TAF sites through 16Z. Light ice accumulations from
freezing rain and/or sleet will be possible (60-80% chance)
across portions of northeast Nebraska (KOFK) between 08Z and
12Z. While rain chances diminish after 16Z, scattered rain
showers are expected to linger through the rest of the forecast
period before another round of widespread precipitation build
into the region by 00Z Monday. Isolated to widely scattered
thunderstorms (80% chance for rain, 20-30% chance for
thunderstorms) may move into southeast Nebraska (KLNK) tomorrow
after 21Z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 1 PM CDT Sunday for NEZ011-012-
     015>018-030>034-042>044-050-051.
     Winter Storm Watch from late Sunday night through Tuesday
     morning for NEZ011-016.
IA...None.

&&

$$

DISCUSSION...Petersen
AVIATION...Darrah


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