Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
000
FXUS63 KOAX 250453
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1153 PM CDT Sun Mar 24 2024

.KEY MESSAGES...

- Widespread rain expected through this evening with
  thunderstorms possible. A few could be strong this evening and
  overnight near the Nebraska/Kansas border. Additional strong
  to isolated severe storms will be possible in far eastern
  Nebraska and southwest Iowa Monday afternoon.

- We`ve converted the Winter Storm Watch into a Winter Storm
  Warning and added a Winter Weather Advisory for line of
  counties to the east for Monday.

- A band of mixed precipitation followed by heavy snow will
  clip portions of northeast Nebraska Monday (40-70% chance of
  at least 4 inches in Knox/Antelope Counties). Combined with
  wind gusts of 35 to 45 mph, whiteout conditions and
  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 in
  vicinity of Norfolk (within a county or 2).

- Dry weather returns for Wednesday and Thursday with
  temperatures trending back up into the 60s by Thursday into
  the weekend. &&

.DISCUSSION...
Issued at 358 PM CDT Sun Mar 24 2024

Today through Tuesday Morning:

Water vapor imagery this afternoon continues to feature the deep,
positively-tilted trough over the western half of the CONUS serving
as the catalyst for the busy short-term forecast. A recent surface
map places a deepening surface low over the midpoint of the
Colorado/Kansas state line, with a lifting warm front extending east-
northeast across south-central Nebraska into eastern Nebraska and
southwest Iowa. A sharp gradient in surface temperatures has set up
locally, with temperatures in eastern Nebraska climbing into the 50s
while central and parts of northeast Nebraska continue to hover
around freezing. Widespread forcing for ascent aided by strong warm
air advection and PVA are resulting in scattered rain, which is
expected to continue in waves in eastern Nebraska and Iowa, while
Northeast Nebraska sees it continue somewhat continuously through
tomorrow morning. Somewhat steep lapse rates in the mid-levels will
likely result in thunderstorms, with a 5 to 10% chance that we see
quarter-sized hail or a damaging wind gust near the KS/NE border
this evening.

During the overnight hours, continued frontogenesis and surface cold
air advection will push the freezing line into northeast Nebraska
around 2 to 4 AM. Along this line, liquid rainfall will transition
to a heavy wintry mix of rain, snow, sleet, and freezing rain due to
a warm isothermal layer in the low-levels and then eventually into
heavy snow to the west. There`s still wiggle room for temperatures
based on the latest model guidance, but the general trend has been
for colder temperatures to push in earlier based on p-type and
temperature trends in the HRRR as an example. This line will
continue pushing east through the morning while east of it will see
a lull in rainfall, before the line pushes farther eastward and
precipitation increases once again Monday afternoon and evening. As
Monday night goes on, the arm of snowfall will become more ragged
and lower dramatically in coverage. Despite this, much of
Nebraska and Iowa will see some snowfall (even through many
will struggle to see a dusting) by daybreak Tuesday. Strong
winds will follow behind that freezing line, with gusts of 35 to
45 mph continuing into through around noon Tuesday.

As far as snow totals go, the eastward trend in cooler temperatures
and the mixed precipitation line in model guidance nudges us to
increase snowfall totals in northeast Nebraska, with Knox and
Antelope Counties seeing at least the some western portions see 6
inches of snow in addition to some ice. Confidence in the blowing
snow further limiting visibility during the peak snowfall has
decreased due to the character of it being generally heavy and wet,
but we are still very close to blizzard conditions. In the meantime,
we`ve converted the Winter Storm Watch to a Warning, and added a row
of counties to the east of it into a Winter weather Advisory with
the combination of up to 2 inches of snow and some ice. Those
outside of the advisories or warnings will likely see less than an
inch, but could still see slickness for the Tuesday morning
commute.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1138 PM CDT Sun Mar 24 2024

Thunderstorm chances tonight have decreased from the last
forecast issuance, so have removed TS from TAFs. There is still
ongoing convection in northeast Kansas that will work its way
into southeast Nebraska over the next couple hours, reaching
KLNK between 06Z and 07Z, and KOMA around 08Z. A few lightning
strikes may be possible with this round of precip before 12Z at
KLNK and KOMA. A second round of spotty showers and
thunderstorms (40%-50% chance) may impact portions of east-
central Nebraska and southwest Iowa (KOMA) tomorrow after 21Z.
Have opted to exclude from TAFs at this time due to timing and
coverage concerns.

Widespread precip has brought LIFR ceilings and reduced
visibilities across northeast Nebraska (KOFK) and western Iowa.
Current guidance suggests that snow will remain west of KOFK
until 14Z, but more recent short range model runs have trended a
little cooler and quicker. As such, there is a chance (30-40%)
that the rain to snow transition will happen sooner than
previously thought (as early as 10Z - 12Z).


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Storm Warning from 4 AM Monday to 7 AM CDT Tuesday for
     NEZ011-016.
     Winter Weather Advisory from 7 AM Monday to 7 AM CDT Tuesday
     for NEZ012-017-030-031-042.
     Wind Advisory until 10 AM CDT Monday for NEZ088>093.
IA...None.

&&

$$

DISCUSSION...Petersen
AVIATION...Darrah


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.