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508
FXUS63 KOAX 011110
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
610 AM CDT Wed May 1 2024

.KEY MESSAGES...

- Storms redevelop today and linger into Thursday, with
  potential for a few severe storms and flash flooding. The
  highest severe weather threat will be this evening into early
  Thursday near the Nebraska/Kansas border.

- An active weather pattern will continue into the weekend and
  early next week with the highest chances Friday night and
  Monday. There could be some severe weather potential at times,
  but confidence on details is rather low.

&&

.DISCUSSION...
Issued at 359 AM CDT Wed May 1 2024

Early morning radar imagery was showing a band of light returns
associated with some low to mid-level frontogenesis from
central NE to northeast CO. Haven`t seen any ASOS/AWOS obs
reporting ground truth as of 3 AM, with a layer of dry air just
above the surface likely causing most rain to evaporate before
hitting the ground. Still, could eventually see some sprinkles
or light showers into this morning as the band pushes north.
Otherwise, temperatures as of 3 AM were in the upper 40s to 50s.

Attention then turns shower and storm chances from mid morning
today all the way into Thursday. The general setup is that
larger scale troughing will dig into the western CONUS, with
some shortwave energy ejecting eastward and spinning up a
surface low near the CO/NM border by mid-day. As a result,
strengthening southerly flow ahead of the low will begin to push
the surface front responsible for our storms yesterday (that
had stalled from east-central to southwest KS) back north as a
warm front. In addition, low level moisture transport will
strengthen through the day and eventually point into the
forecast area by late morning/early afternoon. As this takes
place, expect shower and storm development near the NE/KS border
this morning to spread northeast across most of, if not the
entire area by this afternoon. While there will be plenty of
shear for storm organization, instability will be limited
despite somewhat steep mid-level lapse rates overspreading the
area this afternoon, with MUCAPE values most likely remaining
under 1000 J/kg. So while there could be just enough for some
elevated strong to severe storms (hail being the main threat)
with the warm front remaining in KS through the day, chances
should remain rather low (5-10%).

Higher severe weather chances will move in this evening and
overnight as the warm front continues to advance toward the
NE/KS border and low level moisture transport continues to
strengthen. The big question will be how far north the front
makes it, as any storms in vicinity or south of the front will
pose a risk for all severe weather hazards, with impressive
shear profiles and plenty of instability to work with. However,
tend to think ongoing precip in our area today will keep the
front farther to the south, a trend that can be seen in most
guidance. Still, would likely see at least an increasing threat
for strong to severe elevated storms, with hail again remaining
the main threat, though some isolated severe gusts could make
the surface per latest CAMs. The threat will then transition to
flooding overnight and into Thursday with continued strong
moisture transport and at least some potential of storms
training over the same area near the warm front and then a cold
front that moves through on Thursday. Guidance also continues to
suggest precipitable water values of 1.25 to 1.50" with warm
cloud depths nearing 3500 m meaning some of the storms will
likely be efficient rain producers. In fact, HREF guidance
suggests a 10-20% chance of a few storms producing 1" per hour
rainfall amounts. There was some consideration given to a flood
watch, especially with several recent rounds of storms leading
to fairly saturated soils in many locations. In collaboration
with neighboring offices, decided to hold off for now in hopes
of narrowing down the highest threat area as additional guidance
comes in. Finally, there is some potential for some stronger to
isolated severe storms along the aforementioned cold front on
Thursday, but latest short term guidance is suggesting the
highest threat will be just to our south and east.

Precip should largely exit by early Thursday afternoon, though
some spotty showers/sprinkles could linger into the evening.
Unfortunately, the pattern stays pretty active into the weekend
and next week. The next shower and storm chances arrive Friday
night into Saturday as another shortwave trough and cold front
dive through the area. Guidance suggests the greatest
instability will be off to our south, but strong shear may yield
a threat for a few stronger storms. Guidance is also in good
agreement of another stronger system sliding through sometime
Monday. Initial thoughts are this could be our next shot of
severe weather, but still quite a few details to work out, with
a decent amount of spread in exact timing/placement, so
confidence is on the lower side. Otherwise, expect continued
high temperatures in the 60s and 70s and lows in the 40s and
50s.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
-- Changed Discussion --
Issued at 933 PM CDT Tue Apr 30 2024

Weak variable winds this morning will increase by 20Z with a few
southeasterly gusts up to 20-25kts. Light returns on radar have
struggled to reach the ground so far. A few sprinkles or light
showers could creep into the area this morning, however the
better chance for thunderstorms arrives this afternoon over
southeast Nebraska, and spreads north. A few storms could become
severe near the KLNK area. Otherwise, expect heavy rain across
the forecast area overnight with ceilings deteriorating to MVFR
and IFR.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...CA
AVIATION...KG