Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 130350

Area Forecast Discussion
National Weather Service Omaha/Valley NE
950 PM CST Sun Nov 12 2017

Issued at 944 PM CST Sun Nov 12 2017

With surface high pressure over the area, temperatures dropped
like a rock and several locations were at or below the forecast
lows. Per GOES 16 satellite imagery...fog is forming in river
valleys and dense fog is beginning to form over parts of
Iowa/Missouri/Kansas. Have updated to expand fog and include dense
fog for parts of southeast Nebraska and southwest Iowa later
tonight and Monday morning. A dense fog advisory may be needed
later tonight.


.SHORT TERM...(Tonight through Wednesday)
Issued at 244 PM CST Sun Nov 12 2017

The forecast area sits in between a mid-level shortwave trough to
our east and weak mid-level ridging to our west. At the surface,
a high pressure ridge continues to slide southeast over the area
which has led to sunny skies and fairly light winds. Southerly
low-level return flow will quickly increase tonight and
especially into early Monday. Point forecast soundings show
saturated low levels with potential for fog development by 09-12Z
Mon across much of our southern CWA. Will be monitoring fog
development closely through the overnight as some of the fog could
potentially be dense in areas, especially south of I-80. Clouds
will increase by Monday afternoon in continued warm/moist low-
level warm air advection pattern. Despite cloud cover, highs by
Tuesday should reach into the upper 50s. A mid- level shortwave
will approach the area by late Tuesday night when we have a small
chance for showers in our far southeastern counties which will
mostly be driven by low-level warm air advection.

.LONG TERM...(Wednesday night through Sunday)
Issued at 244 PM CST Sun Nov 12 2017

Temperatures will remain slightly above normal for much of the week
ahead of our next upper-level trough which should begin to affect
the area Friday. Warm-air advection regime could induce light pcpn
ahead of the system before a strong cold front behind the system
brings additional pcpn chances into early Saturday.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 535 PM CST Sun Nov 12 2017

A departing storm system has the low clouds still pushing away
with surface high pressure over the TAF sites along with light and
variable winds. Low level rh progs show just a couple of a degree
spread Monday morning. The winds aloft pick up from the southwest,
at KOFK then KLNK and KOMA, so the question will be how widespread
the fog and stratus will be with the return flow. There is some
consensus in the hi-res models that visibilities will drop at KLNK
and KOMA improving by 17z. Cigs drop to MVFR and patchy IFR 13-16Z
so have these deteriorating conditions in the TAFs Monday morning
with improvement in the afternoon.




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