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495
FXUS63 KOAX 041716
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1216 PM CDT Sat May 4 2024

.KEY MESSAGES...

- Cooler today and tomorrow, with highs in the 60s and dry
  weather expected.

- There is a chance of severe thunderstorms (15 to 30 percent
  chance) Monday afternoon and evening.

- Additional chances for showers and storms possible through the
  end of the week, but no organized threat for severe storms.

&&

.DISCUSSION...
Issued at 409 AM CDT Sat May 4 2024

Today and Tomorrow:

Water vapor imagery this morning shows a modest troughing over the
far north-central CONUS, with a shortwave extending southward,
pivoting eastward through the largely zonal mid/upper flow that the
base of the trough sits on. A recent surface analysis shows high
pressure moving into northwestern Nebraska behind a cold front that
has helped spark early morning convection moving to the southeast of
the forecast area. KOAX radar imagery this morning features the
continued departure of the MCS/bow that has brought widespread gusts
of 35 to 45 mph, and has struggled to keep up with its own outflow.

A cooler and drier airmass is set to move in behind this convection
and make for a rather comfortable weekend, with highs in the low-to-
mid 60s expected today before only slightly warmer highs settle in
for Sunday in the upper 60s. Winds this afternoon will slowly
diminish from the gusty northwesterly flow this morning and begin
turning southeasterly in anticipation of a stronger storm system to
kick off the work week.

Monday and Beyond:

The main focus of the forecast period comes Monday, when a high-
amplitude and negatively-tilting trough pivots eastward from the
Rockies, shooting a cutoff low northeastward just to the north of
the forecast area. Robust forcing for ascent will be in full effect
by the afternoon hours along a dryline, with convective initiation
expected to occur in central Nebraska. By the time it reaches
eastern Nebraska and western Iowa, a narrow corridor of surface-
based CAPE ranging from 1000-2000 J/kg will provide ample
instability to accompany 0-6 km bulk shear values of 40 to 50
kts or more to allow for an increased probability of severe
storms (up to 30 percent for parts of southeast Nebraska. All
hazards will be possible thanks to the favorable curvature in
the low-level hodograph and combo of strong forcing/sufficient
instability/strong shear, though will take the form of a
line/cluster of storms. This activity is expected to quickly
pivot through the forecast area Monday afternoon and evening,
leaving the area dry by midnight as storms lift north and east.

For Tuesday through the rest of the work week, we`ll continue to be
under the influence of the Monday system, which at this point will
be occluded and cut off over the far northern High Plains. The main
mid/upper level jet will be laid over the southeastern edge of the
forecast area, keeping highs from rising much above the mid-to-low
70s with increasing chances for showers and storms returning for
Thursday continuing into the weekend as the occluded system to the
north finally gets slowly pulled away in the mid/upper flow.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
-- Changed Discussion --
Issued at 1211 PM CDT Sat May 4 2024

Low clouds are scattering out this afternoon with skies expected
to become mostly clear. Winds out of the north-northwest gusting
to 25 kt should weaken over the next few hours and continue that
trend through the evening. With light winds overnight and clear
skies, we`re a little concerned for fog development overnight
tonight, though none of the forecast guidance is suggesting it
at this time. Will do some more in-depth analysis before the
next TAF package to see if the potential needs to be included.
We`ll see winds shift to southeasterly overnight, starting to
increase around 15-16Z which would clear out any fog that might
develop.
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&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...McCoy