Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 252019

Area Forecast Discussion
National Weather Service Omaha/Valley NE
319 PM CDT Tue Jul 25 2017

.SHORT TERM...(Tonight through Friday)
Issued at 319 PM CDT Tue Jul 25 2017

A mid to upper-level low over Manitoba will continue east into
eastern Canada while a series of lower-latitude impulses track
from the eastern Great Basin into the mid MO Valley late tonight
into Wednesday. In the low levels, a boundary stretching from the
ND-MN Red River Valley through south-central SD into wrn NE will
serve as the focus for strong to severe storms this afternoon into
evening. The nocturnal strengthening of a LLJ coupled with
increased forcing for ascent attendant to a lead impulse emerging
from the Rockies will sustain thunderstorms overnight, a subset
of which are forecast to move across the area through 12z/Wednesday.
Strong wind gusts and locally heavy rainfall will accompany the
most intense storms, though the nocturnal maximum in stability
will preclude the potential for an organized severe weather

Latest model guidances hints at a relative lull in convective
development from mid morning into early afternoon Wednesday with
an uptick in storm coverage and intensity along the southward-
moving cool front by mid afternoon. The extent and longevity of
the early-day storms will impact the degree of air mass
destabilization, as well as the location of the effective surface
boundary with the greatest risk for a few severe storms being
across southeast NE and southwest IA from mid afternoon into early
evening. Corridors of heavy rainfall (i.e. two to three inch
storm-total amounts) are possible, the locations of which will
likely be modulated by mesoscale features.

A surface high will build into the area Thursday and Friday,
yielding a cooler and drier low-level air mass.

.LONG TERM...(Friday night through Tuesday)
Issued at 319 PM CDT Tue Jul 25 2017

Medium-range guidance continues to advertise the re-
intensification of a long-wave ridge over western North America
during the long-term period with downstream troughing from Hudson
Bay to the Gulf Coast. Weak mid-level perturbations embedded in
northwest flow aloft will foster small chances for showers and
thunderstorms. Otherwise, it appears temperatures will remain
relatively mild with daytime highs near seasonal normals.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 605 AM CDT Tue Jul 25 2017

VFR conditions are expected the bulk of the TAF period. Axis of
low level jet oriented from central Kansas into northeast Nebraska
this morning, thus LLWS remains a concern for KOFK until surface
mixing begins in earnest around 14UTC. Increasing surface pressure
gradient and deep mixing will allow surface winds to increase by
late morning into the 10 to 20 kt range with gusts up to 25kt by
this afternoon. As frontal boundary approaches the area tonight,
thunderstorm activity across South Dakota into central Nebraska
will spread 10-25K ceilings into KOFK by evening. Current
indications are that storms will not affect KOFK until 06Z or
later, with ceilings lowering into 4-6K range. Thunderstorms likely
will not affect KLNK or KOMA until the end or after the TAF


NE...Heat Advisory until 7 PM CDT this evening for NEZ011-016-034-045-

IA...Heat Advisory until 7 PM CDT this evening for IAZ055-069-079-090.



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