Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 141719

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1119 AM CST Tue Nov 14 2017

Issued at 513 AM CST Tue Nov 14 2017

Monitoring conditions for dense fog development, and currently
having doubts that we`ll get as low as expected. Consensus of all
short term models suggest visibility may not get down to widespread
1/4 mile. Will monitor over the next hour or two, but may be able
to trim a few counties on the north/eastern edge of the existing
advisory, from Norfolk to Fremont to Wahoo to Lincoln.


.SHORT TERM...(Today through Thursday)
Issued at 259 AM CST Tue Nov 14 2017

Most pressing issue is the fog this morning. Satl imagery and
regional obs were showing an extensive shield of stratus/fog
covering most of KS...central/eastern NE...most of IA...and into MN.
Lowest visibilities though are mainly over central NE close to the
back edge of stratus/clear skies. Per latest HRRR-TL ensembles,
conditions should quickly deteriorate over the western periphery of
the CWA the next couple hours within the counties already under a
Fog Advisory this morning.

Moist southerly flow today, ahead of a cold front dropping through
the Dakotas, will provide fuel for possible precip tonight.
Strengthening mid layer ageostrophic forcing is progged to tap into
moisture pooling along the boundary, with precip activity
focused along/south of I-80.

Otherwise, dry conditions will prevail Wednesday through Thursday

.LONG TERM...(Thursday night through Monday)
Issued at 259 AM CST Tue Nov 14 2017

Main issue to contend with in the extended periods is precip chances
Friday/Friday night. Initially, the best chance for rain will be
across the eastern CWA during the morning hours where isentropic
upglide will be most pronounced. Precip chances shift to the
northern CWA during the afternoon hours revolving around Shortwave
trof dragging a cold front through the Dakotas. The surface boundary
is progged to quickly sweep southward through the CWA Friday
evening. Significant timing differences with respect to QPF between
the models. Both the GFS and CMC are quite pretty much similar in
showing precip activity clearing the CWA before 12z Saturday.
Meanwhile, the ECM keeps precip going until 12z Saturday. Dry then
through the rest of the weekend as well as next Monday.

Otherwise, cold air advection associated with the passing front is
progged to be rather weak. As a matter of fact, high temps Saturday
and Sunday will be near normal, topping out in the mid/upper 40s.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1119 AM CST Tue Nov 14 2017

Low-level warm and moisture advections are resulting in
widespread IFR to LIFR stratus across eastern NE today. These
processes are also yielding patchy drizzle which will combine with
areas of fog to reduce visibilities. Expect similar conditions to
persist through the afternoon ahead of a cold front which will
move through the area tonight. With the passage of the front,
expect winds to switch to northwest with ceilings and visibilities
becoming VFR.




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