Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 251125

Area Forecast Discussion
National Weather Service Omaha/Valley NE
625 AM CDT Mon Sep 25 2017

.SHORT TERM...(Today through Wednesday)
Issued at 329 AM CDT Mon Sep 25 2017

Slow-moving front and associated precipitation have arrived.
Subjective 00Z upper-air analysis indicates an upper-level low
centered near the UT-WY border, with upper-level ridging dominating
the eastern half of the CONUS (along with Maria centered well off
the coast of the Carolinas). A 110kt upper-level jet streak was
noted ahead of the trough from western NE into the central Dakotas.
An 850mb high was centered around Lake Erie, with an ill-defined
trough from around western ON toward CO/NM. A front was evident from
the weak low in western ON through eastern SD and northeast to
central NE, then toward western KS and eastern NM. A surface low was
centered in western ON, with a secondary low in northeast NM, and a
front between through MN to western IA to southeast NE through KS
toward the secondary low.

Main forecast concern is persistent rain and isolated thunderstorms
today and tonight, tapering off tonight into Wednesday. Western US
low will eject northeastward through the Dakotas through Tuesday,
leaving troughing in the southwestern US. Front will linger through
today and tonight, with a distinct band of mid-level frontogenesis
and instability above the frontogenetic layer lingering through
Tuesday morning as it slowly slides eastward through the area. In
short, persistent forcing for ascent should continue to drive waves
of rain through Tuesday, tapering from northwest to southeast
through the day. MUCAPE is weak, but there is enough to support at
least an isolated embedded thunderstorm today and perhaps tonight.
By Tuesday, instability is virtually nil, and thunder threat
likewise should be nil. Temperatures today will change little from
morning readings, but did give a slight bump in the afternoon.
Temperatures on Tuesday will remain cool, with highs in the 60s.

In wake of the slow-moving system, high pressure will linger for
several days as an upper-level ridge lingers between the ejecting
low/trough and the western US low, but temperatures will remain on
the cool side as 850mb temperatures linger in the upper single
digits to low teens.

.LONG TERM...(Wednesday night through Sunday)
Issued at 329 AM CDT Mon Sep 25 2017

Cooler temperatures will continue through next weekend, with an
upper-level trough digging into the Great Lakes by late week and
providing a reinforcing push of cooler air into the north central
US. As the surface ridge slowly slides eastward, return flow should
bring moisture back into the central Plains over the weekend, along
with chances for showers and thunderstorms as the western US trough
slowly emerges toward the Plains.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 625 AM CDT Mon Sep 25 2017

11Z mesoanalysis placed the surface cold front along a KSDA to
south of KBIE line with a slow southward advance of the boundary.
A band of post-frontal showers and isolated thunderstorms from
KTQE to west of KLNK will continue east with the potential for
periods of TSRA at both KOMA and KLNK through mid morning. IFR
ceiling will likely prevail at KOFK and KLNK through much of the
forecast period. At KOMA, ceilings could vacillate between VFR
and IFR today before trending toward prevailing IFR by evening.
Otherwise, expect periodic showers to persist through much of the
forecast period.




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