Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 190518

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1218 AM CDT Wed Apr 19 2017

.SHORT TERM...(Tonight through Friday)
Issued at 235 PM CDT Tue Apr 18 2017

Latest water vapor imagery shows vigorous shortwave trough now
moving east toward Lake Ontario with associated surface low
moving into Wisconsin. Associated trailing cold front extends from
the Wisconsin low southwest into an area of low pressure over far
southwest Kansas. This boundary will continue to slide south over
southern Nebraska/southern Iowa through the evening hours before
becoming nearly stationary along the Kansas/Nebraska border.
Southerly low level flow across the Southern Plains has kept
moisture in place across the region with stratus/fog noted across
much of OK this morning and surface dewpoints in the low 60s to
the south of the boundary. The area of surface low pressure over
eastern Colorado/western Kansas will deepen this evening with
northeastward extending warm front slowly drifting north across
southeastern Nebraska/southwestern Iowa this evening. Latest CAM`s
develop some convection along the boundary later this evening
when southwest nocturnal low-level jet increases. Elevated
convection looks to continue north of the front through the
overnight and into early Wednesday morning which could be capable
of producing some large hail.

A weak mid-upper level impulse will be crossing the Rockies in
southwesterly upper level flow tonight and begin to organize into
a deeper shortwave trough by Wednesday afternoon. By then, the
surface low is forecast to be reside across south-central
Nebraska with the warm front extending east/northeast into west
central Iowa. With daytime heating, MLCAPE values should approach
1500J/kg within the warm sector. This,combined with steepening
mid-level lapse rates and increasing 0-6km bulk shear should allow
convective initiation, provided we erode any remaining capping
inversion. Some of the thunderstorms could quickly become severe
and a few could become supercellular given strength of the
environmental shear. Hail and wind look to be the primary threats
however within backed sfc flow near and just north of the warm
front, we could see some tornadic potential by mid/late afternoon.
Locally heavy rain is also quite possible. Severe potential will
shift eastward and diminish into the evening hours.

Cool high pressure will build into the region into Thursday with
lows around 40 possible across our north.

.LONG TERM...(Friday night through Tuesday)
Issued at 235 PM CDT Tue Apr 18 2017

As we head toward the weekend, an elongated mid/upper-level trough
is forecast to extend across the northwestern CONUS and into
southern Colorado. This is then progged to close off and drift east
across Kansas through Saturday. The medium range models continue to
keep this system to our south with mainly residual high clouds over
our forecast area. Dry conditions will continue into the early part
of next week with warmer southwesterly low level flow.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1214 AM CDT Wed Apr 19 2017

A strong low level jet is taking aim at southeast Nebraska
tonight and Wednesday morning. With deep moisture pooled along the
h85 front...showers and thunderstorms south of KLNK will increase
tonight. As the front lifts too will the
precipitation. Mention showers and tsra at all TAFS sites. Some
hail could accompany the stronger thunderstorms. Surface low
pressure and a cold front pushes across southeast Nebraska and
southwest Iowa during the late afternoon and early evening.
Depending on the wind field and destabilization...strong to severe
thunderstorms could redevelop and affect KLNK/KOMA. VFR cigs to
start...then MVFR with the precipitation and into Wednesday
morning. KOFK on the cool side of the front should remain MVFR/IFR
Wednesday afternoon.




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