733
FXUS63 KOAX 170853
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
353 AM CDT Tue Jun 17 2025

.KEY MESSAGES...

- Severe storms (5-15% chance) and heavy rain/flooding potential
  (5-20% chance) return late this afternoon and evening. Overall
  severe and flooding chances are lower than previous forecast,
  but with the best timing for strong to severe storms being
  6-10 PM.

- Lingering showers and storms will continue into a cool
  Wednesday, with Thursday starting a warming trend going into
  the weekend.

- 70-80% chance for oppressive heat overspreading the central
  plains Friday and persisting through the weekend, with heat
  indices expected to reach at least 100 degrees.

&&

.DISCUSSION...
Issued at 349 AM CDT Tue Jun 17 2025

Today:

Water vapor imagery this morning features messy zonal flow across
the northern half of the CONUS while shortwaves from current
and previous convection littering the Central Plains and Ohio
Valley region. A recent surface analysis has a primary surface
low over southeast Colorado with a theta-e axis extending
southeast along a warm front that is being caught up to by the
earlier MCS from yesterday as it pushes into southeast Kansas.
Looking locally, strong winds have been induced in wake of the
MCS, powered by a meso- high directly behind the convection
dramatically increasing the pressure gradient at the surface,
combined with downshear anvil cooling. A few gusts of 30-50 mph
have been observed overnight, directly along the gradient, which
has since moved south with the main convection. Otherwise rain
continues to fall across the area, with residual cloud cover
expected to put a damper on our convective airmass this
afternoon, with much of the severe risk continuing to slide
south and west, closer to the deepening surface low and deeper
well of moisture.

Model guidance continues to be very messy for today, with the main
thing to watch for being how well our airmass can recover from
yesterday`s convection. Overall severe potential is lower than with
previous forecasts, owing to a shift south of better moisture
access that will be shunted southward by the nocturnal MCS.
Highs this afternoon are set to reach the low 80s, with some
peaks at sunshine spreading by 5 PM that could give us a quick
boost in temperatures and evaporation of residual moisture. By
that time, the main guts if a more potent shortwave trough will
make the most of the instability across the High Plains, and
begin moving eastward -- spreading storms into northeast, then
eastern Nebraska after 00z. Our best chances at seeing a severe
storm should come early this evening, with the elevated storms
having less than 1500 J/kg of CAPE and lackluster shear to work
with. Marginally severe hail and wind will be the primary
threats, though some localized flooding cannot be ruled out,
especially if storms are able to linger and train where healthy
rainfall fell yesterday. Weak convection is expected to continue
into the overnight hours as the shortwave slowly meanders
eastward, finally leaving the forecast area Wednesday afternoon.
Highs Wednesday afternoon will be similarly cool, and make for
a great evening outdoors as things clear out and a northwest
breeze blows.

Thursday and Beyond:

The main story for Thursday through the weekend continues to be the
warming trend that will quickly trade out "warm" for "dangerously
hot" as highs in the upper 80s Thursday give way to near 100-degree
highs this weekend. Heat indices will be taking a shot at 105
degrees from Friday through Sunday, and we`ll be taking aim at our
first chance at a Heat Advisory. A squat mid/upper ridge is still
forecast to build eastward and bring with it a potent low-level
thermal ridge that should max out locally Saturday and Sunday. Our
forecast continues to conservatively nudge upward the initial
output from the NBM as bias correction continues keep highs near
the bottom of the distribution of the inputs to the forecast.
Models are in good agreement that a front will try to begin
chipping away at the northern edge of the heat by Monday, but we
have some ways to go before being able call for cooling
temperatures quite yet.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1218 AM CDT Tue Jun 17 2025

A line of convection has continued to fester across eastern
Nebraska with rain, and intermittent lightning expected to
continue through a good chunk of the first 6 hours of the
period. Rain rates so far have not been high enough to reduce
visibilities or ceilings to MVFR territory, with that expected
to continue through the period. We`ve back off of storm chances
in the latter TAF period for now, as the ongoing storms pushing
through earlier than expected throwing timing off. Generally
storms are expected to return, but may not until after 00z --
staying weak through that time. Otherwise, expected a cloud VFR
day tomorrow with east-southeasterly winds for much of the day.

&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...Petersen