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959
FXUS63 KOAX 020444
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1144 PM 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 after midnight and 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 will be some severe weather potential at times,
  but confidence on details is rather low.

&&

.DISCUSSION...
Issued at 335 PM CDT Wed May 1 2024

After zipping into the 60s before lunch, increased cloud cover
and spotty shower activity has halted the warming of surface
temps this afternoon. We remain mostly in the low 60s. 20dBz
radar returns pock the entire CWA this afternoon. Still plenty
of dry air below 5000 feet, so mostly only traces have been
reported but as they and the southern moisture transport saturate
the low levels, more measurable rain will be recorded before a
temporary reduction in lift and POPs by sunset.

Surface analysis shows the surface low and front across central
Kansas. The stationary front draped across southeast Kansas this
morning is driving north as a warm front. PWAT values are
climbing as well. Now close to about 0.6", expect PWAT values
to double by about 2AM.

CAPE values are scraping the bottom of the barrel this
afternoon, but will be spiking overnight with a nose of 1000
J/kg MLCAPE poking into far southeast Nebraska as the LLJ ramps
up in the eastern half of the state. Shear values are impressive
with sfc winds perpendicular to those at 700 hPa. Elevated
storms are a threat with hail being the primary concern
overnight. With the broad forcing ahead of the shortwave and
its associated WAA and broad forcing, the HRRR has been latching
on to an elevated MCS that works west to east through the
southern half of the area tonight. Its general shape suggests
it`s a wind machine, but successive HRRR runs produce wind gusts
below the 60mph severe criteria.

Another concern overnight is heavy rain and flooding with PWATs
up to 1.5 inches and deep warm cloud layers (3000 feet of clouds
warmer than 0C). This gives the system more water content and
gives a boost to the coalescence of raindrops. Still, HREF
probabilities for 1" rainfall rates have been nearly halved with
the 12Z run, likely due to the more progressive nature of the
convection forecast overnight. Have opted not to issue a flash
flood watch. The OAX hydrologist is on radar duty overnight to
monitor flooding potential.

Precip should be mostly done by Thursday`s lunch hour as dry
air moves in behind the cold front. The severe weather threat
for Thursday looks a bit overstated for OAX with better odds
south and east of here.

.FRIDAY AND BEYOND...

Another shortwave sweeps through on Friday night. With a LLJ /
cold front interaction, believe an overnight MCS is possible
once again brining a threat of severe hail and wind. Chances are
probably highest south of here.

Surface high pressure builds in over the course of the weekend
leading to clear skies and seasonable temperatures. It`ll be a
beaut! Mid-70s on Monday will represent the week`s zenith.
Monday eve`s severe weather risk may represent the week`s best
chance with a negatively tilted trof sweeping through the
CONUS`s mid-section. Certainly there are lots of timing /
location questions, but with a triple point progged to be
somewhere in the area, it may be another day of damaging
thunderstorms.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
-- Changed Discussion --
Issued at 1144 PM CDT Wed May 1 2024

A large complex of thunderstorms currently from central and
northeast NE into north-central KS will continue east and
affect the terminal locations during the overnight hours. VFR
ceilings will lower to MVFR with a period of IFR conditions most
probable at KOFK and KLNK. Furthermore, visibilities will be
reduced as the strongest storms move through. East or northeast
winds of around 12 kt will switch to northwest on Thursday with
the passage of a front through the area.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Nicolaisen
AVIATION...Mead