Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 231129

Area Forecast Discussion
National Weather Service Omaha/Valley NE
629 AM CDT Wed Jun 23 2021

...Updated Aviation Forecast Discussion...

Issued at 404 AM CDT Wed Jun 23 2021

...Active weather pattern beginning tonight and continuing into

.Today and Tonight:

A mid-level ridge in place over the Rockies early this morning
will build east into the adjacent plains today into tonight.
Embedded within that feature, a subtle shortwave trough presently
over AZ is forecast to crest the ridge axis over the central High
Plains this evening prior to moving through the mid MO Valley late
tonight into Thursday morning. In the low levels, a lee trough
will be maintained over the High Plains with CAM data suggesting
the development of another confluence zone over northern NE later

Abundant sunshine combined with the advection of a warmer low-
level air mass into the region will push afternoon temperatures
into the 90s at most locations.

By late afternoon into evening, weak height falls spreading into
the High Plains coupled with convergence along the above-mentioned
surface boundaries will foster widely scattered thunderstorms
over portions of western NE. The development of a nocturnal low-
level jet will promote upscale growth of the evening storms into
an MCS, which is then expected to move through our area overnight.
While relatively weak mid-level winds will limit the magnitude of
0-3/6-km shear and overall MCS intensity, the presence of a
moderately unstable inflow air mass will sustain the convective
system with an attendant risk for locally strong wind gusts.

.Thursday and Thursday night:

Remnants of the Wednesday night MCS could be ongoing Thursday
morning over portions of the area, leading to considerable
uncertainty in the location of relevant surface boundaries which
might focus additional storms later in the day. And that
uncertainty is evident in the wide array simulated reflectivity
forecasts offered by the various HREF members on Thursday

The most probable scenario depicted by various CAMs and the
majority of parameterized models is for early-day storms to exit
the area during the morning with renewed storm development during
the afternoon and evening hours along an inverted surface trough
and/or residual outflow boundaries. While vertical shear isn`t
forecast to be particularly strong, ample instability will be
supportive organized storm modes with an associated severe-
weather threat.

.Friday and Friday night:

A more prominent mid-level disturbance is forecast to move through
the mid MO Valley in tandem with a surface low and associated
frontal system, supporting the potential for additional,
meaningful rainfall. And given sufficient destabilization within
the system warm sector, there could be some severe-weather threat
from the vicinity of the surface low east along the warm front
during the afternoon and evening hours.

.This weekend into early next week:

The 00z global models are in reasonable agreement in depicting the
development of a high-amplitude blocking pattern, characterized by
a western CONUS ridge and downstream trough situated over the
Great Plains. That pattern will support seasonal afternoon
temperatures with small chances for precipitation.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 630 AM CDT Wed Jun 23 2021

Likely a little bit of wind shear at FL020 out of the SWS at
45kts still ongoing at KOMA and KLNK.

Another round of thunderstorms is anticipated later tonight. Some
could be severe. Expect them to push from west to east after 06Z.
They may be breaking up as they move from west to east. They`ll
lower cigs and produce some rain, but the VFR conditions forecast
through the day will likely prevail.




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