Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 221155

Area Forecast Discussion
National Weather Service Omaha/Valley NE
655 AM CDT SUN MAY 22 2016

.SHORT TERM...(today through Tuesday)
Issued at 316 AM CDT Sun May 22 2016

00z upper-air analysis showed a substantial trough over the
western U.S. with an amplified downstream ridge from the central
Plains into Canadian Prairie Provinces. Between these features, a
vorticity lobe and associated jet streak where progressing north-
northeast into the northern High Plains. In the wake of this lead
impulse, an upstream short-wave trough and associated jet streak
over the Sierra Nevada early this morning will eject northeast
into the Dakotas by tonight. In response, a weak surface wave will
develop from the lee of the Colorado Rockies into the North
Dakota-Minnesota Red River Valley by 12z Monday, along a cold
front advancing east through the northern and central Plains.

Due in part to the above-mentioned disturbance into the northern
High Plains, a nocturnal 40-50 kt low-level jet (LLJ) has
materialized early this morning from western Kansas into Dakotas.
Warm thermal and moisture fluxes occurring along the LLJ may
contribute to some elevated thunderstorm activity which could
reach our western CWA later this morning before dissipating. The
LLJ, albeit not as strong, will be maintained through the day,
resulting in breezy to windy conditions, especially across
northeast Nebraska. Despite increasing clouds, we should see
slightly warmer temperatures today; in the mid 70s to around 80.

Thunderstorms which are expected to develop along the cold front
over western Nebraska this afternoon and evening should begin to
affect portions of northeast Nebraska late tonight before
spreading east and southeast across the remainder of the area
Monday morning into afternoon. The 00z models continue to indicate
that the front will stall and weaken over or just to the west of
our area Monday owing to cyclogenesis over eastern Colorado.
Severe weather potential Monday afternoon and evening remains
uncertain due to the unknown effect that the early-day storms will
have on diurnal air mass destabilization. Where stronger heating
can occur, a favorable overlap of instability and at least modest
vertical shear shear will be supportive of organized storm modes
and some severe weather as highlighted in the current SPC Day 2

A mid-level disturbance is forecast to emerge from the central
Rockies Tuesday, fostering another round of thunderstorms over
the central Plains. The 00z models differ on the specific location
of the synoptic boundaries, and as a result, the spatial and
temporal details of convective evolution. Regardless, it appears
that ample instability will be in place to support a severe
weather threat Tuesday afternoon into night over eastern Nebraska
and southwest Iowa. See the SPC Day 3 outlook for details.

.LONG TERM...(Tuesday night through Saturday)
Issued at 316 AM CDT Sun May 22 2016

An upper low along the California coast at the onset of the
extended period will translate through the southwestern U.S.
before ejecting into the central Plains on Friday. Weak impulses
preceding this feature will ripple across the central Plains
within the prevailing southwest flow regime, yielding episodic
thunderstorm activity through the middle to latter part of the
upcoming work week. Isolated severe weather will be possible with
Friday appearing to have the greatest potential as the main wave
emerges into the Plains. Flooding will become increasingly
problematic with 00z global models continuing to indicate a
maximum in run-cumulative QPF (of around 4 inches) centered over
eastern Nebraska and southwest Iowa.


.AVIATION...(12Z TAFS for KOMA...KLNK...KOFK through 12Z Monday)
Issued at 642 AM CDT Sun May 22 2016

Showers and thunderstorms are increasing over central Nebraska
with mvfr conditions pushing toward kofk and vfr cigs fl050-100 at
koma and klnk. The storms will try to push east and due to their
isolated nature...will need to monitor and add tsra mention if
needed. Another round of storms will develop over the western High
Plains and move in overnight. Do mention showers and thunderstorms
after 06z with east. Surface winds will be on the gusty side from
the south at 15-25kts.


.OAX Watches/Warnings/Advisories...


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