Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 211138

Area Forecast Discussion
National Weather Service Omaha/Valley NE
638 AM CDT SAT MAY 21 2016

.SHORT TERM...(today through Monday)
Issued at 315 AM CDT Sat May 21 2016

00z upper-air analysis and early morning water vapor imagery
indicate an upper low over south-central Oregon and an associated
trough centered along the Pacific Coast states. Mid and upper-level
wind maxima currently rounding the base of this trough will
develop northeast through the central Rockies and into the
northern High Plains by tonight, contributing to the reformation
of the low over the northern Rockies, and the bodily movement of
the parent trough through the Interior West.

In the low levels, a loosely organized baroclinic zone presently
arcing from the southern Plains into central High Plains will
develop north today in response to the approach of the western
U.S. trough. Warm advection and isentropic ascent to the north of
this boundary will contribute to an increase in showers and a few
thunderstorms over the central Plains today, with some of this
activity potentially affecting our southwestern counties this
afternoon into tonight.

Elsewhere, a weak short-wave trough translating from the North
Dakota-Minnesota Red River Valley toward the mid Mississippi
Valley will glance the region today, possibly generating some
sprinkles this morning into early afternoon, mainly along and east
of the Missouri River. Clouds again will temper daytime heating
with highs in the upper 60s to lower 70s.

00z ECMWF and GFS deterministic guidance remains consistent in
suggesting that a vorticity lobe and associated mid and upper-
level jet streaks will eject from the lower Colorado Valley into
northern High Plains Sunday into Sunday night, promoting the
eastward advance of a surface cold front across the northern and
central Plains. The progression of this front is slower than
previous model runs with the boundary likely not reaching our
area until early Monday. Ahead of the front, breezy to windy
conditions are expected Sunday afternoon with highs in the mid to
upper 70s.

Thunderstorms developing along the front over western Nebraska Sunday
afternoon and evening should move into our area Sunday night, with
periods of showers and thunderstorms continuing Monday. While a
strong storm or two is possible late Sunday night, the better
potential for a few strong to severe storms will exist Monday
afternoon into evening along the front which will stall over our

.LONG TERM...(Monday night through Friday)
Issued at 315 AM CDT Sat May 21 2016

As we have alluded to in previous nights, and which still appears
to be the case, persistent troughing in the west will result in
prevailing southwest flow across the Great Plains through the
extended range. This upper-air pattern configuration will
maintain a lee cyclone over the central High Plains with a low-
level baroclinic zone oscillating north and south across the
central Plains. Low-amplitude perturbations translating through
this pattern will likely foster multiple thunderstorm episodes
across the forecast area with some severe weather possible, and
flooding appearing more likely. In fact, the most recent 7-day
QPF forecast from the WPC, as well as 00z ECMWF and GFS run-
cumulative QPF indicate a two to four-inch maximum over our area
through the upcoming work week.


.AVIATION...(12Z TAFS for KOMA...KLNK...KOFK through 12Z Sunday)
Issued at 630 AM CDT Sat May 21 2016

A shortwave diving to our east in combination with the approach of
a storm system to the west will lead to a band of sprinkles this
morning and isolated showers and thunderstorms tonight. Will
mention these sprinkles this morning at KOMA and may need to add
shra later tonight. VFR conditions with variable mid and high
clouds. MVFR conditions may approach kofk...thus this will need
to be watched. An increasing low level jet is forecast after 06z
at kofk. If this signal continues...will want to add llws.


.OAX Watches/Warnings/Advisories...


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