Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 222304

Area Forecast Discussion
National Weather Service Omaha/Valley NE
604 PM CDT FRI JUL 22 2016

.SHORT TERM...(tonight through Monday)
Issued at 335 PM CDT Fri Jul 22 2016

12z Upper-air analysis revealed a mid-level high centered over northern
Oklahoma/southern Kansas with a ridge axis extending northwest
through the northern High Plains to the lee of the Canadian
Rockies. Immediately upstream from this ridge was a polar-branch
short-wave trough over the Pacific Northwest. In the low levels,
early afternoon mesoanalysis indicates a weak front/trough stretching
from northwest Iowa through northeast and south-central Nebraska
into northwest Kansas.

Similar to yesterday afternoon (albeit farther south), radar and satellite
data indicate a mesoscale convective vortex (MCV) over northwest Kansas
with a downstream corridor of elevated convection observed from
south-central into southeast Nebraska. While the bulk of this convection
may settle south into Kansas, at least isolated storms will remain
possible into this evening across portions of southeast Nebraska.

Elsewhere tonight, both parameterized and convection-permitting model
guidance remains quite dispersive in the areal coverage and
location of convective precipitation. A weak perturbation over
Wyoming this afternoon will crest the mid-level ridge axis over
the mid Missouri Valley tonight before shifting east of the area
Saturday. Conceptually, forcing for ascent (DCVA) associated with
this feature in conjunction with strengthening warm advection along
the nocturnal LLJ should increase the odds of MCS formation tonight
somewhere to the west and north of the aforementioned surface
boundary, warranting highest POPs across our northern CWA.

On Saturday, areas of clouds and isolated storms may linger
through part of the morning before giving way to another day of
hot and humid conditions ahead of a cold front approaching our
area from the northwest. As a result, we will be extending the
excessive heat warning until 7 PM Saturday.

The cold front will advance southeast through eastern Nebraska and western
Iowa Saturday night into early Sunday with a slight chance of
thunderstorms along and ahead of it. High temperatures on Sunday
will be cooler (most noticeably so across northeast Nebraska),ranging
from mid 80s north to lower 90s south.

Sunday night into Monday, we begin to see larger model spread in
the location of the low-level baroclinic zone which will stall to
our south. Given the uncertainty, we will only include slight
chance POPs over southern parts of the area.

.LONG TERM...(Monday night through Friday)
Issued at 335 PM CDT Fri Jul 22 2016

12z Medium-range guidance remains consistent in suggesting that
the upper high currently to our south will retrograde into
the southwestern U.S. during the middle to latter part of this
upcoming week. A resultant transition to northwest flow aloft
will occur over the north-central states with several embedded
perturbations traversing the mid Missouri Valley, along with
multiple frontal passages. Consequently, there will be a chance
of thunderstorms through much of the extended period with near or
slightly below normal high temperatures.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 605 PM CDT Fri Jul 22 2016

Low confidence forecast in regards to chances for TSRA. Will
include a PROB30 group for KOFK later tonight but chances for
KOMA and KLNK look too low to mention at this time. Will amend as
needed. LLWS should develop again tonight at KLNK and KOMA with
nocturnal low level jet. Some patchy fog or haze is possible
around sunrise...otherwise generally look for VFR conditions
through the period outside of any convection.


.OAX Watches/Warnings/Advisories...
NE...Excessive Heat Warning until 7 PM CDT Saturday for NEZ011-012-

IA...Excessive Heat Warning until 7 PM CDT Saturday for IAZ043-055-



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