Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 291726

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1226 PM CDT FRI JUL 29 2016

.SHORT TERM...(today through Sunday)
Issued at 322 AM CDT Fri Jul 29 2016

Early-morning water vapor imagery and 00z upper-air analysis
indicate a low-amplitude short-wave trough and associated mid and
upper-level wind maxima translating southeast through the mid
Missouri Valley. Forcing for ascent attendant to these features
has contributed to a broken band of light showers and a few
thunderstorms from south-central South Dakota into southwest Iowa
as of 07z. Latest short-term convection-allowing model guidance
and 00z parameterized data suggest that light convective
precipitation may persist this morning mainly over our western
counties before diminishing by afternoon with the passage of the
short-wave trough to the southeast.

Tonight, another weak impulse is forecast to track across the
Dakotas into the upper Mississippi Valley, enhancing low-level
warm advection over the Nebraska sandhills into south-central
South Dakota. Isolated showers and thunderstorms may materialize
within this regime, potentially affecting western portions of
northeast Nebraska late tonight into Saturday morning.

Saturday into Sunday, mid-level heights will build over the
north-central U.S. in advance of a strong short-wave trough
translating from the British Columbia coast to the lee of the
Canadian Rockies. At the surface, a lee trough will deepen over
the High Plains, yielding warming daytime highs and strengthening
southeast winds (namely Sunday afternoon). The best precipitation
chances appear to be Saturday night into early Sunday across
southeast Nebraska and southwest Iowa where warm advection and
isentropic ascent are focused along a nocturnally strengthening

.LONG TERM...(Sunday night through Thursday)
Issued at 322 AM CDT Fri Jul 29 2016

The above-mentioned Canadian short-wave trough will lift northeast
through central Canada in advance of the next upstream trough
tracking from the northeast Pacific into the northern High Plains
and south-central Canada by the middle of next week. This will
promote building mid-level heights during the early part of this
upcoming week, a notion supported by 00z deterministic and GEFS
mean guidance. Of interest, the ECMWF and Canadian models suggest
that a weak front will settle south through the mid Missouri
Valley during that time frame, which would temper daytime highs.
In contrast, the deterministic GFS and GEFS mean indicate that
the front will remain to our north with daytime highs returning
back to the 90s. Based on the mid-level pattern, this latter
scenario appears more probable.

Mid-level heights will temporarily lower over the north-central
CONUS with the passage of the short-wave trough through south-
central Canada Wednesday into Thursday, with an associated cold
front settling south into the mid Missouri Valley. The arrival of
this front will bring increasing precipitation chances and cooler
daytime highs.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1223 PM CDT Fri Jul 29 2016

VFR conditions are expected through much of the forecast period
with scattered to broken mid clouds during the daylight hours.
Surface high pressure will build overhead tonight with guidance
bringing in some patchy fog so did add a tempo group to all sites
during the morning hours.


.OAX Watches/Warnings/Advisories...


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