913
FXUS63 KOAX 122355
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
655 PM CDT Mon Aug 12 2024

.KEY MESSAGES...

- Below average temperatures (highs in the 70s) are expected
  across the region through Tuesday, then back to near normal
  temperatures (widespread 80s) for Wednesday and beyond.

- Periodic shower and storm chances continue through the work
  week, especially during the evening through early morning
  hours. Some severe weather and/or localized flooding appear
  possible on Tuesday night, and again Wednesday afternoon and
  evening.

&&

.DISCUSSION...
Issued at 308 PM CDT Mon Aug 12 2024

--Tonight and Tuesday--

Widespread clouds present across eastern NE and western IA as
of early afternoon will diminish some through the remainder of
the afternoon into evening before becoming widespread again tonight
into Tuesday morning. Areas of fog appear likely as well.
Showers and thunderstorms developing over the the central High
Plains this evening are forecast to consolidate into at least
one longer-lived complex which will track generally east across
KS and perhaps southern NE tonight. The PoP forecast will
indicate that notion with highest values (30-60%) late tonight
into Tuesday morning across southeast NE.

Widespread clouds are likely to linger into Tuesday afternoon,
which will limit highs to the 70s.


--Tuesday night through Wednesday night--

A low-amplitude shortwave trough is forecast to traverse the mid
MO Valley Tuesday night ahead of a stronger mid-level system
moving through the same area on Wednesday night. In the low
levels, there is some model variability in the track of an
associated surface low. The deterministic ECMWF depicts the
northern-most and deepest low over eastern NE by 7 pm Wednesday,
whereas the deterministic GFS and Canadian models indicate
farther south and weaker solutions.

Forcing for ascent attendant to lead disturbance coupled with
warm advection and moisture flux along a nocturnal low-level jet
(LLJ) are expected to foster a band of showers and
thunderstorms across the area Tuesday night into Wednesday
morning. The moisture advection along the LLJ will contribute to
a destabilizing air mass overnight with some potential for
isolated severe storms capable of large hail, damaging winds,
and locally heavy rainfall. Severe weather potential on
Wednesday afternoon and evening will be conditional on: 1) the
eventual surface low track, and 2) the extent to which the
morning precipitation and clouds clear during the afternoon,
allowing the air mass to destabilize. The more northern, deeper
surface low solution (ECMWF) would support the highest ceiling
on severe-weather potential across our area Wednesday afternoon
and evening with the GFS/Canadian model scenarios offering a
lesser severe-weather threat. Regardless, the setup will be
supportive a fairly widespread rainfall event with localized
flooding possible.

Highs on Wednesday will also be contingent on the surface low
track and any lingering precipitation and cloud cover. This
forecast update will indicate readings ranging from the 70s
across portions of northeast NE and west-central IA to around
90 along the KS border.

--Thursday and Thursday night--

Another shortwave trough is forecast progress southeast through
the northern Plains and mid MO Valley, contributing to the
amplification of a broader-scale trough from the Great Lakes to
mid MS Valley by Friday morning. At the surface, a cool front is
expected to move through the area sometime on Thursday with
additional shower and thunderstorm chances along the front.
Severe-weather potential will be conditional on an afternoon/
evening frontal passage. High temperatures will also be dictated
by frontal timing.


--Friday through the weekend--

There`s good model agreement that a mid/upper-level high
centered over the southern High Plains will strengthen with
associated ridging building north through the northern High
Plains. Weak disturbances moving down the backside of the ridge
axis will support minor precipitation chances with highs in the
80s.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 655 PM CDT Mon Aug 12 2024

MVFR ceilings continue at KOMA whereas ceilings of FL030-045
persist at KOFK and KLNK. Satellite denoting gradual clearing
west to east, which should realize in sky conditions becoming
scattered at KOMA between 00-02UTC. Weak isentropic descent will
maintain scattered sky conditions through the evening hours,
then as weak to neutral ascent returns aft 06z, all three TAF
sites will experience deteriorating sky conditions, with MVFR
ceilings FL015-025 developing by 07-09utc and LIFR ceilings
FL003-005 by 10-11utc. In addition, visibilities are expected to
diminish to between 1/2 to 3/4SM by 10z and persist through 13z
before diurnal mixing allows visibilities to improve into MVFR
range. As for ceilings, deterministic and ensembles keep LIFR
ceilings ensconced at all three TAF sites through 15 utc.
Improving ceilings expected by midday as a drier air 850-700mb
may erode depth of cloud layer, and for now have improved
ceilings into low VFR category between 19-20 utc.




&&

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

&&

$$

DISCUSSION...Mead
AVIATION...Fortin