275
FXUS63 KOAX 162023
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
323 PM CDT Mon Sep 16 2024

.KEY MESSAGES...

- Periodic shower and storm chances through the weekend,
  typically peaking at night. Highest chances are currently
  Tuesday night into Wednesday and Friday night into Saturday
  night (peak probabilities of 40-70%).

- Temperatures are expected to remain above-normal through the
  work week with highs in the 80s.

- Cooler weather favored this weekend into next week with highs
  in the 70s.

&&

.DISCUSSION...
Issued at 322 PM CDT Mon Sep 16 2024

Tonight and Tuesday:

Early afternoon water vapor imagery shows a prominent
mid/upper-level low centered over CA/NV with a minor short-wave
trough situated over CO. The CO disturbance will track northeast
into SD and NE tonight, while a nocturnal low-level jet (LLJ)
develops from western KS into northeast NE, eastern SD, and
western MN. Similar to last night, those two features will
contribute to the development of widely scattered showers and
thunderstorms across portions of eastern NE, perhaps into
western IA late tonight through much of Tuesday morning. The
models differ on the timing and specific location of the showers
and storms, so the maximum PoP values will be limited to 30-40%.
The strongest storms will be capable of brief periods of heavy
rain with localized amounts of 0.25-0.5" possible.

Considerable morning cloudiness will diminish by afternoon with
highs in the mid to upper 80s. Readings may end up cooler in
areas where precipitation and/or clouds linger a bit longer.
We`ll see stronger south winds tomorrow with sustained speeds of
15 to 25 mph with gusts up to 30 to 35 mph, especially in
northeast NE.


Tuesday night into Wednesday night:

The above-mentioned CA/NV low is forecast to progress northeast,
deepening over the northern Rockies into northern High Plains.
Meanwhile, an associated short-wave trough is expected to pivot
through the eastern semi-circle of the parent low with height
falls/forcing for ascent overspreading the northern and central
Plains into upper MS Valley. That forcing for ascent will
combine with a zone of enhanced moisture transport along a
40-50 kt LLJ to foster a complex of showers and thunderstorms
which will move into eastern NE late Tuesday night into
Wednesday morning (30-60% PoPs). It still looks like the showers
and thunderstorms will diminish/dissipate prior to reaching
western IA Wednesday afternoon. Similar to previous days,
morning convective cloud debris will diminish by afternoon with
highs in the mid to upper 80s.

Another round of showers and thunderstorms are possible (20-50%
PoPs) across much of the area Wednesday night into Thursday
morning, again aided by the LLJ.


Thursday:

The northern High Plains upper low will continue northeast into
south-central Canada with an embedded vorticity maximum moving
through the base of that system across the northern Plains and
upper MS Valley. At the surface, a weak front attending the mid-
level system will advance southeast into the area during the
afternoon and evening. The potential for early-day showers and
storms (see previous section) leads to some uncertainty on how
unstable the air mass will become ahead of the front by
afternoon. However, some of the models suggest the development
of moderate amounts of instability and vertical shear during the
afternoon/early evening. Should that scenario unfold, some
severe-weather threat would exist if storms are able to
redevelop along the front at that time.

The forecast will call for hot temperatures ahead of the front
with highs in the low 90s.


Friday through the weekend:

Another mid-level trough/low will slowly track from the Desert
Southwest into the central and southern Rockies by Saturday, and
eventually into the Great Plains Sunday. In the low levels, a
surface front initially stalled to the south of the area Friday
morning is projected to lift north into the mid MO Valley before
eventually moving back south as a cold front. The overall
synoptic setup will be supportive of a potentially more widespread,
heavier rainfall event, especially from Friday night into
Saturday night. Any severe-weather threat will largely be
dictated by the location of the primary synoptic boundary; along
and south of which the most unstable air will reside.

The forecast will indicate highs in the 80s to low 90s on Friday
with 70s on Saturday and Sunday. Similar to the severe-weather
potential, those numbers will ultimately be dependent on the
surface front location.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1213 PM CDT Mon Sep 16 2024

VFR conditions will prevail into early Tuesday. From about 09z
Tuesday through the end of the forecast period, latest CAM data
indicate the potential for widely scattered showers and storms,
which could briefly drop visibilities into the MVFR category.
However, confidence in specific timing and location of that
convection is currently too low to include a SHRA/TSRA mention
in the forecast. Otherwise, a brief light shower is possible
(20% chance) at KOFK prior to 20z today, and at KLNK in the
19-20z time frame (20% chance). South winds with sustained
speeds of 13-15 kt with gusts of 20-25 kt are expected this
afternoon at the terminal locations. The gusty winds are likely
to continue tonight at KOFK, while diminishing at KOMA and KLNK.

&&

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

&&

$$

DISCUSSION...Mead
AVIATION...Mead