Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 221732
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1232 PM CDT FRI JUL 22 2016

.SHORT TERM...(today through Sunday)
Issued at 342 AM CDT Fri Jul 22 2016

Heat and humidity continue to be the main story for the area into
the weekend. 00Z upper air analysis indicated a 599 dm ridge from
KDDC to KAMA. The analysis did indicate a number of shortwave
troughs topping the ridge. The first was over eastern NEb/western
IA and was responsible for for a good deal of mid-level clouds and
even a few SHRA over western IA early this morning. Upstream
another shortwave associated with some 10 m H5 height falls was
over WY, and finally a stronger system with 30-40 m H5 height
falls was moving into the PAC NW. The lead shortwave will slowly
work east today, but some mid-level moisture, above the EML, will
linger into the morning and possibly the afternoon. This may
continue to lead to weak SHRA activity from the mid-level
moisture field and will hold onto some pops into mid to late
morning. Otherwise another hot and humid day is in store for the
CWA with little change in the airmass from previous days. With
similar mixing another day in the mid and upper 90s with heat
index values well over 100 appears likely.

The WY shortwave trough will move east today, and into the mid and
upper MO River Valley tonight. The GFS/EC are consistent in
focusing lower tropospheric WAA over the CWA tonight and although
mid-level temperatures remain warm, we will likely see at least
scattered convection develop associated with this pattern near
or after midnight, with this activity lifting northeast into IA
by Saturday morning. How much convection and any associated
clouds lingering into Saturday morning creates just enough
uncertainty in conditions for later in the day to extend the
excessive heat warning, but given the current forecast this will
likely be needed for at least part of the area in later forecasts.

As the stronger PAC NW system moves into the northern Rockies, and
eventually the northern Plains this will allow for a surface cold
front to move southeast across the CWA. This front will approach
the CWA by late Saturday afternoon. It appears the NAM over-
amplifies the shortwave allowing for cooling of the EML, but we
prefer the stronger capping from the EC/GFS with any convection
developing to the northwest of the CWA and trying to move in on
Saturday evening. We expect convection will have a hard time
trying to move south through the CWA though on Saturday night with
the warm mid-level temperatures, but will maintain some pops
along the frontal boundary. This front will either stall over the
far southern CWA on Sunday or just across the border into MO/KS.
Highs will be a touch cooler on Sunday, but the south still will
see heat index values over 100 likely.

.LONG TERM...(Sunday night through Thursday)
Issued at 342 AM CDT Fri Jul 22 2016

The extended period of the forecast is looking a bit cooler and
more active as far as rain chances. The southern Plains upper
level ridge will retrograde during this period allowing for lower
heights and cooler temperatures for the CWA, along with periodic
fronts and associated chances for convection. WAA atop the
stalling frontal boundary may lead to the first chance at rain on
Sunday night as models are in fair agreement depicting convection
developing to the west and moving east/southeast along the
boundary with the highest pops in the southern CWA. Additional
shortwave troughs appear possible on Tuesday and Wednesday with a
continued chance of showers and thunderstorms before potentially a
dry period to end the extended as the front drops a bit farther
south.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1226 PM CDT Fri Jul 22 2016

VFR conditions are expected through the TAF period. Have opted to
keep shower/thunderstorm mention out of TAFs as confidence
remains too low in the coverage of any possible showers/storms to
warrant including yet. Winds at KOFK should be variable, with
southerly winds closer 8-10kt at KLNK. At KOMA, winds may briefly
be gusty out of the southeast this afternoon, but otherwise,
speeds will remain around 10kt.

&&

.OAX Watches/Warnings/Advisories...
NE...Excessive Heat Warning until 8 PM CDT this evening for NEZ011-
     012-015>018-030>034-042>045-050>053-065>068-078-088>093.

IA...Excessive Heat Warning until 8 PM CDT this evening for IAZ043-
     055-056-069-079-080-090-091.

&&

$$

SHORT TERM...Boustead
LONG TERM...Boustead
AVIATION...Mayes



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