Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 200828

Area Forecast Discussion
National Weather Service Omaha/Valley NE
328 AM CDT FRI MAY 20 2016

.SHORT TERM...(today through Sunday)
Issued at 328 AM CDT Fri May 20 2016

00z upper-air analysis revealed the continued presence of a
split-flow pattern with an amplifying trough over the western
U.S. and a weaker downstream system over the central and southern
Plains. This latter upper-air system will translate east through
the mid and lower Mississippi Valley tonight with the primary zone
of large-scale forcing for ascent overspreading those areas.
However, forcing attendant to a mid-level deformation axis (most
clearly seen at 700 mb) may be sufficient to support the
continuation of isolated showers this morning into afternoon.
Lingering clouds will temper the degree of daytime heating with
highs generally in the mid to upper 60s.

Another weak vorticity lobe will progress through portions of the
northern Plains and upper Mississippi Valley tonight, before
eventually glancing the mid Missouri Valley early Saturday.
Forecast soundings indicate a considerable amount of dry air
present below 700 mb and a generally stable thermodynamic
stratification. As such, we will maintain a dry forecast though a
few sprinkles or light showers from elevated convection are within
the realm of possibility. Again, some lingering cloudiness could temper
the potential for maximum diurnal heating with highs in the lower
to mid 70s.

The major trough evolving over the western U.S. will gradually
develop east toward the Rockies this weekend with several
perturbations pivoting north-northeast through the eastern semi-
circle of the parent system. The associated surface cold front
will concurrently advance east through the northern and central
High Plains with the greatest thunderstorm chances remaining to
our west. Nonetheless, strengthening low-level warm advection
occurring along a nocturnal low-level jet may contribute to
isolated thunderstorm development Saturday night. Strong southerly
winds will continue on Sunday with breezy to windy conditions and
warmer temperatures of around 80. We will maintain the slight
chance POPs across the western counties, though it appears that
the surface cold front will remain to the west of the area through
the afternoon.

.LONG TERM...(Sunday night through Thursday)
Issued at 328 AM CDT Fri May 20 2016

A substantial lead impulse will eject northeast through the
Dakotas Sunday night, encouraging the continued eastward advance
of the surface cold front into the mid Missouri Valley. As
highlighted by the Day 3 Convective Outlook from the SPC, the
greater probability of severe weather will remain to our west.
However, a few strong to marginally severe storms will be possible
within a broader-scale MCS which will move into our area Sunday
night. The cold front will decelerate and eventually stall over
the region Monday in response to a deepening lee cyclone over the
central High Plains.

Troughing will persist over the western U.S. through the extended
period with prevailing southwesterly flow over the Great Plains.
A number of weak perturbations translating through this pattern
will interact with a low-level baroclinic zone oscillating over
the central Plains to support a continued chance of thunderstorms
through the early to middle part of the upcoming work week. Due
to uncertainties in the specific location of the surface front and
timing of the upper-air disturbances, severe weather and flooding
potential remains uncertain. Temperatures will remain at or
slightly above seasonal normals.


.AVIATION...(06Z TAFS for KOMA...KLNK...KOFK through 06Z Saturday)
Issued at 1129 PM CDT Thu May 19 2016

VFR conditions initially will give way to MVFR cigs
overnight...generally after all 3 TAF sites. These MVFR
cigs will likely hold on into mid day on Friday before lifting to
VFR. Isolated showers may flirt with KOMA/KLNK overnight and into
Friday morning, but coverage and timing uncertainties preclude any
mention in the TAFs currently. Clouds will tend to decrease toward
the end of the period with the KS/MO system shifting east.


.OAX Watches/Warnings/Advisories...


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