Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 190444
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1144 PM CDT Sun Jun 18 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 337 PM CDT Sun Jun 18 2017

A relatively tranquil weather period is forecast the next couple of
days before the next chance for precipitation slated for Tuesday
night and Wednesday.

Upper storm system that brought the active weather to the Plains the
last couple of days had helped deepen trough over the Great Lakes
region today. Northwest upper level flow on back side of trough from
the Pacific Northwest into the Mississippi Valley region was drawing
cooler and drier air into our area as surface high pressure settled
into the region. Cyclonically curved flow just to our northeast was
helping induce cumulus formation in the Dakotas to eastern
Nebraska, with more congested clouds noted farther northeast.
Expect clouds in our CWA will dissipate with loss of daytime
heating.

Meanwhile 100-110kt upper level jet nosing into the High Plains of
the Dakotas is forecast to progress east while diving into Nebraska
and western Iowa overnight. Induced weak warm advection regime under
jet will thicken mid level clouds tonight and may squeeze out a few
sprinkles or light showers in parts of our area overnight.

Then the main focus of the forecast will be cooler temperatures
Monday and Tuesday. An impulse riding through the northwest mid
level flow will push a backdoor cool front into central Nebraska on
Tuesday. 850 temperatures in the lower and middle teens and plenty
of sunshine should make for pleasant days, with highs generally in
the lower 80s.

A stronger shortwave will move across the southern Canadian Plains
beginning Tuesday night through Wednesday. Strong return flow is
expected through much of the Plains then. Potent mid level warm
advection may trigger some elevated convection as low level jet
rides over cooler surface air Tuesday night.

By Wednesday, most of our area will be in warm sector ahead of
approaching cold front attendant to Canadian system. GFS suggests
abundant moisture will have returned ahead of this boundary, with
lower 70s dew points yielding 3000+ J/kg of MLCAPE, and bulk shear
vectors of 35kt normal to low level convergence. Canadian model is
not quite as robust in regards to instability, but still respectable
2500 J/kg MLCAPE. If either scenario is close to reality, will have
decent shot of severe storms if inhibition can be overcome
Wednesday afternoon and evening.

.LONG TERM...(Wednesday night through Sunday)
Issued at 337 PM CDT Sun Jun 18 2017

Mid level flow will buckle behind Canadian system, carving out
shallow mean trough position for the end of the week. Longer term
model solutions have varying degrees of amplification of this
feature, with ECMWF dropping a strong shortwave into the region on
Saturday. Canadian and GFS are less amplified at this time, and
paint a much more scattered precipitation pattern than the
widespread precip shown by ECMWF. With this wide variation on
potential outcomes, will not sell out toward one over the others,
and maintain a chance for precip Friday through Sunday. What is
common among the solutions is a cold front dropping south of our
area, bringing cooler temperatures to the region, with highs
somewhere between 75 and 85 each day.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1138 PM CDT Sun Jun 18 2017

VFR conditions through the period. There will be some mid clouds
around 10000` early in the TAF period, and there may be a few
sprinkles moving through the area, but not significant enough to
mention. Northwest winds less than 7 knots initially, but winds do
increase to 12 to 22 knots by 16-17z, diminishing by 23-24z.

&&

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

$$

SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...DeWald



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