Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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124
FXUS63 KOAX 201742
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1242 PM CDT Fri Oct 20 2017

.SHORT TERM...(Today through Sunday)
Issued at 327 AM CDT Fri Oct 20 2017

Greatest concern in the near term is the potential for wind gusts
approaching advisory criteria.  Forecast soundings depicting deep
mixing during the afternoon hours, with effective momentum
transfer from H8 to the surface. HRRR, RAP and NAM all indicating
potential for gusts 38-42kts. Mitigating factor for maximum
momentum transfer to be realized will be due to increase in mid-
to high level cloudiness during the afternoon. Increased wind
gusts from previous forecasts, but kept speeds just below wind
advisory criteria for now. Fire danger will be elevated in areas
of cured agricultural vegetation due to increased winds. Another
result of deep mixing will be much warmer than normal
temperatures for today, with maximum temperatures 15-20 degrees
above seasonal normals.

Progressive long wave trough will move into the intermountain west
by late tonight. Large scale ascent and warm air advection may
lead to isolated to scattered thunderstorm develop late this
evening into the overnight hours. As trough moves into plains
early Saturday, frontal boundary will push into forecast area,
thus expect coverage of showers and storm to increase. Bulk shear
values in the 35-45kt range and SBCAPE 1000-1500 sufficent to
support strong to isolated severe storms, especially south of
I-80. Focus of stronger convection appears to be south of the
forecast area. Trough moves quickly across plains and front will
be through most of the forecast area by late afternoon, thus
total rainfall amounts likely will be less than one inch in
most locations, with precipitation threat ending by early
evening. Low level cold advection in the wake of the front will
make for a more typical fall day across the area on Sunday.

.LONG TERM...(Sunday night through Thursday)
Issued at 327 AM CDT Fri Oct 20 2017

Broad, large scale trough will dominate weather regime through
Monday. There`s a slim chance of showers Sunday night into Monday,
as jet streak moves around base of trough; however, left forecast
dry. More significant short wave will drive trough southward into
eastern U.S. Monday, presenting area with another surge of cooler
air. Temperatures will rebound somewhat by mid- week as upper
level ridging builds into the area from the southwest. Warm- up
will be brief, as another progressive short wave sweeps across
plains. Right now, there appears little moisture avaiable for
precipitation to occur, so expect dry frontal boundary passage,
but reinforcement of cooler than normal temperatures for the end
of the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1236 PM CDT Fri Oct 20 2017

Gusty south winds are expected at all sites today, continuing into
tonight. MVFR ceilings are likely after midnight as showers move
into the area. There may be embedded thunder tonight, but
confidence on coverage is too low to mention until closer to
morning at KOMA, then in the late morning at KOMA/KLNK. A wind
shift to northwesterly will move into the sites late in the TAF
period, with winds remaining gusty.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Fortin
LONG TERM...Fortin
AVIATION...Mayes



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