Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 280443

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1143 PM CDT SAT AUG 27 2016

.SHORT TERM...(tonight through Monday Night)
Issued at 316 PM CDT SAT AUG 27 2016

Very isolated chance of a thunderstorm over northeast Nebraska this
evening is main concern then focus turns to more widespread
showers/thunderstorms Sunday into Monday.

West/southwest mid/upper level flow extends across the forecast
area with a closed upper low now just west of the Four Corners
region with a large high over the Atlantic coastline. Otherwise, a
sharp shortwave trough axis continues to move across the eastern
Dakotas this afternoon while a couple of subtle shortwaves eject
northeast out of a very subtle wave over eastern Colorado. Not
alot going on at the surface this afternoon with a very
subtle boundary at 18z stretching from southwest Kansas to
extreme southeast Nebraska and northeast into east central Iowa.
Low clouds/drizzle/fog mixed out by mid/late morning but
temperatures have been able to recover into the 80s across much
of the area.

As mentioned above, we have inserted a very small chance for an
isolated thunderstorm over our very far northern counties along
the South Dakota border. Confidence in this occuring is low but
feel a small chance is warranted in the event that the the meager
amount of CIN is unable to hold. Upper level support will move
overhead from a weak impulse coming out of southwesterly flow just
after peak heating when MUCAPE is forecast around 1500 J/kg. In
addition, increasing 0-6km shear will be in place over southeast
South Dakota with 0-3km SRH around 250. The latest versions of
both the Experimental and Operational HRRR generate isolated
activity along the South Dakota border. A majority of the CWA will
remain dry through the night with some potential for patchy fog
development. Otherwise focus then turns to our southern CWA Sunday
morning as showers/thunderstorms spread northeast out of north
Central Kansas and into southeastern Nebraska. Model QPF has
backed off slightly but will continue the trend of spreading pops
north through the day and overnight into Monday as isentropic
upglide increases in warm air advection regime.

.LONG TERM...(Tuesday through Saturday)
Issued at 316 PM CDT SAT AUG 27 2016

Overall confidence in the long term forecast is fairly low,
especially regarding precipitation chances.

Medium range guidance continues maintain fairly good agreement
regarding timing and location of large scale features. At the
beginning of the period, a large upper level trough off will extend
across the Pacific coast with upper ridging moving into the High
Plains. In the lower levels, predominately southerly flow is
anticipated as large area of surface high pressure slowly builds
east/southeast from central Canada into the Central Plains and
eventually east across the Mississippi River Valley. That being
said, it`s tough to rule out any small chance of pcpn in this
pattern as weak shortwaves are forecast to pass overhead and a
weak surface boundary meanders through the region. As a result and
with discussion from surrounding forecast offices, will not adjust
precipitation chances much from previous forecasts.


Issued at 1140 PM CDT SAT AUG 27 2016

Still expect some fog to develop later tonight...with chances
highest across western Iowa. Look for MVFR vsbys mainly 10z-13z.
Recent RAP model runs also hint at some sct-bkn MVFR clouds as
well but did not mention any cigs with those. We could see some
2500-4000 foot cigs by Sunday afternoon.


.OAX Watches/Warnings/Advisories...


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