672
FXUS63 KOAX 170443
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1143 PM CDT Tue Jul 16 2024

.KEY MESSAGES...

- A few strong to isolated severe storms could clip portions of
  northeast Nebraska from 5 to 11 PM this evening (20-40%
  chance of storms, 10-20% chance of severe storms). Hail and
  damaging winds are the primary threats.

- An extended stretch of cooler-than-average temperatures
  will persist into next week.

- Next widespread rain chances will be Friday afternoon into
  Saturday. There are additional spotty chances Sunday into next
  week.

&&

.DISCUSSION...
Issued at 245 PM CDT Tue Jul 16 2024

Main feature of note early this afternoon was a cold front sitting
near the NE/SD border. This front will continue to sag south through
the evening, helping to spark some showers and storms across central
and possibly northeast NE (generally near and west of Highway 81).
Farther to the south and east, clouds and spotty showers lingered
through much of the morning, greatly limiting any destabilization
and likely almost eliminating any severe weather threat in those
areas. Even in northeast NE, instability does look somewhat
limited per latest SPC mesoanalysis (1000 J/kg MUCAPE contour
barely touches Boone county), with guidance trending slightly
farther west with the primary CAPE gradient compared to the
forecast yesterday at this time. As a result, the highest
chances for severe weather should mostly remain to our west, but
any storms that do get going in northeast NE would have 35-45
kts of 0-6 km shear to work with, suggesting some supercellular
structures capable of large hail would be possible initially.
Eventually expect a transition to more of a cluster/linear
feature with the primary threat shifting to damaging winds.
Can`t completely rule out a tornado with a boundary in the area,
but low level shear looks quite weak. Storms should quickly
weaken and mostly dissipate as they push southeast farther into
our area.

Some guidance does hint at fog development across northeast NE early
Wednesday morning, favoring areas that receive rain and are able
to clear out fast enough. However, model soundings suggest winds
aloft could be a touch too strong for widespread development.
For the remainder of Wednesday we`ll remain under the influence
of cyclonic flow aloft with CAM reflectivity fields suggesting
potential for a few spotty sprinkles/light showers. Model
soundings do reveal a little instability in the cloud layer, but
it`s pretty shallow, low levels are somewhat dry, and surface
high pressure will be building in, so overall potential will be
limited. All in all, probably less than a 10% chance we see
something, but not 0%. Continued "cool" and mostly dry weather
is favored into Thursday with surface high pressure remaining in
control. In fact, the entire area is expected to bottom out in
the 50s Wednesday night/Thursday morning, which by my quick,
very unofficial look is the first time that`s happened since
June 10th.

Our next widespread shower and storm chances come Friday afternoon
into Saturday with guidance in good agreement that a fairly potent
shortwave trough dives southeastward into the area. Guidance does
suggest there could be a little instability and shear to work with
as it moves through, perhaps yielding a severe weather threat, but
plenty of details to still be worked out, including exact timing
which will certainly play a role. For what it`s worth the GEFS-based
Colorado State Machine-Learning Probabilities suggest the highest
chances for severe weather will stay across western NE. Guidance has
trended toward precip lingering at least on and off through the
weekend with suggestions that a cutoff low forms just to our south
and spins somewhere over eastern KS/western MO, keeping at least
southern portions of the forecast area within the associated
precipitation shield. At this point, it doesn`t look like heavy rain
by any means, but maybe enough to be annoying for weekend outdoor
activities. Something to keep an eye on...

Heading into next week, on and off precip chances (around 20%)
continue with an amplified trough/cutoff low remaining somewhere in
the region. Temperatures also stay below average for this time of
year, with highs in the mid 70s to lower 80s and lows in the upper
50s to lower 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1142 PM CDT Tue Jul 16 2024

VFR conditions through the period with northerly winds less than
9 knots.

&&

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

&&

$$

DISCUSSION...CA
AVIATION...DeWald