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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KOAX 212327
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
627 PM CDT Sun Apr 21 2024

.KEY MESSAGES...

- Southwest winds gusting 30 to 40 mph Monday could bring some
  fire weather concerns to portions of the area where fuels
  remain dry.

- Showers and storms are expected (50-70% chance) late Monday
  afternoon into Monday evening, primarily near and south of
  Interstate 80. A few could be strong and produce gusty winds.

- Several rounds of showers and thunderstorms are expected
  Thursday through the weekend, though confidence is somewhat
  low on exact timing of any given round. Severe weather will be
  possible at times.

&&

.DISCUSSION...
Issued at 319 PM CDT Sun Apr 21 2024

Fairly quiet across the region early this afternoon as a
surface ridge was passing through. Really the only thing of note
was RH values had fallen into the upper teens and lower 20s as
of 2 PM*, leading to some fire weather concerns, though winds
remained fairly light, with only a few spots gusting to near 20
mph. The biggest thing to note from a fire standpoint this
afternoon/early evening is that wind direction will turn
counterclockwise from northwest to southwest as the surface
ridge passes off to the east.

Monday looks to be warmer (highs in the 70s), but breezy, with
southwest winds gusting 30 to 40 mph. Speeds are expected to be
highest in the mid to late morning as we mix into the low level
jet, but we`ll still remain fairly breezy in the afternoon along
with RH values dipping into the upper 20s to lower 30s. This
will bring increased fire weather concerns, especially where
fuels remain dry in portions of west-central IA. While at this
time we don`t quite meet red flag criteria, it will certainly be
a day to exercise caution.

Also of note Monday afternoon will be a cold front moving
southeast across the area, bringing a switch to (lighter)
northwest winds along with shower and storm chances. Latest
guidance suggests there could be some light rain developing near
the front by 5-6 PM, but greater chances will likely hold off
until a few hours later when some shortwave energy pushes in
from the west. Instability/moisture looks to be quite limited,
with a few hundred J/kg of MUCAPE at 7 PM and falling
thereafter. However, vertical shear will be quite strong and
support some degree of storm organization, so wouldn`t
completely discount a strong storm or 2 potentially bringing
some gusty winds down from aloft. This precip will exit early
Tuesday morning and give way to a couple slightly cooler days
with highs in the 60s through Wednesday. There are also some
small precip chances Wednesday (20%) as guidance suggests some
weak shortwave pushes in.

The pattern then becomes much more active Thursday as an upper
level trough sets up over the western CONUS and several stronger
shortwaves eject through the area bringing us continuous shower
and storm chances at least through the weekend. There will
definitely be some breaks in the precip in that timeframe,
though there remains quite a bit of spread on exact timing of
individual waves. As it stands, the most favored periods for
storms are Thursday night through Friday and Saturday night
through Sunday (i.e. daytime hours Saturday appear the most
likely to be dry). However, every 6 hour period from Thursday
through Sunday has at least a handful of various ensemble
members suggesting ongoing precipitation somewhere in the area.
In addition, there will be chances for severe weather at times,
though again, confidence remains low in exact timing. For what
it`s worth the GEFS-based Colorado State machine learning severe
weather probabilities indicate at least 5 percent chance for
severe weather in the area Thursday through Sunday, with the
highest chances being Friday and Sunday. So overall, fairly
confident we`ll see showers and storms in this period, but
confidence is on the lower side regarding exact timing. Severe
weather of all types, including flooding given the repeated
rounds, would be possible, but still lots of details to be
worked out from that standpoint (shear, instability, moisture
availability, etc.).

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
-- Changed Discussion --
Issued at 609 PM CDT Sun Apr 21 2024

VFR conditions are expected through the period with a few
increasing high clouds overnight. Southerly winds are expected
overnight under 12 kts. With an increasing southwesterly low-
level jet overnight, wind shear is possible from 11z-14z at
mainly KOFK and KLNK but cannot rule it out at KOMA so did
include it at all three sites. Winds will begin to mix down
after 14z with gusts on Monday up to 30-35 kts.
-- End Changed Discussion --


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.

&&

$$

DISCUSSION...CA
AVIATION...Kern