Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 172003

Area Forecast Discussion
National Weather Service Omaha/Valley NE
303 PM CDT Sat Mar 17 2018

.SHORT TERM...(Tonight through Tuesday)
Issued at 236 PM CDT Sat Mar 17 2018

Surface high pressure was building into eastern Nebraska on
Saturday afternoon, and will eventually overtake all of eastern
Nebraska and western Iowa this evening. There is quite a bit of
low level moisture and cloud cover trapped under this high in a
stable low level airmass, and looks to remain firmly in place
through tonight and into Sunday. Given that dewpoint depressions
are currently small, with some reduced visibility across the
region this afternoon, this seems to be a decent scenario for fog
to build back down this evening with winds becoming calm. Unsure
at this time just how thick the fog will get, and see some
potential for dense fog but have not issued any advisory products
at this time mainly because the density of the low level clouds
may work to limit overall density. Regardless, this will be
something to watch through the evening hours. If/when fog
develops, will also need to watch temperatures. Clouds will limit
the diurnal fluctuation but still expect a good portion of the
area to drop below freezing which could result in roads getting a
bit slick especially if fog becomes dense.

Big question on Sunday is how long the clouds will hold on across
the area, and currently it seems likely that most of the area will
have cloud cover through much of the day. There are indications
that some mixing will take place on the southwest edge of the
clouds, perhaps bringing some sunshine into the area, and
increasing southeast winds could help mechanically mix a bit of
that stubborn moisture out as well. If sunshine breaks through,
could see temperatures end up a few degrees warmer, but by late
afternoon expect mid/upper clouds to build into the region so any
sunny period could be short lived.

An organized storm system will move out into the Plains late
Sunday, with the surface low expected to track across southern KS.
While this system will pull some moisture and lift into the local
area, the strongest forcing is likely to remain to the south while
the low/mid level flow pulls in dry advection from the northeast.
Thus expect precip to be limited Sunday night into Monday. Any
precip that does fall in this period could be a mix of rain and
snow (have removed any mention of freezing rain from the fcst) with
the best chance for snow in the local area being in northeast
Nebraska...although little to no accumulation is expected.

Monday evening into Tuesday morning, a slow moving disturbance
will move from northwest to southeast across the region. This
system will work with remnant moisture from the previous system
along with persistent weak to moderate vertical motion to
overcome any remaining dry layers and produce an area of light to
moderate precipitation. Have increased precip chances quite a bit
with this system but amounts will again be quite light owing to
the relatively weak forcing. That said, much of the area has a
good chance for periods of snow (perhaps with some rain mixed in)
Monday night into early Tuesday morning, with the best chance
again in northeast Nebraska and west central Iowa. Any
accumulation at this time looks to range from a dusting to less
than 2 inches.

.LONG TERM...(Tuesday night through Saturday)
Issued at 236 PM CDT Sat Mar 17 2018

A warming trend is expected Tuesday through Friday as upper level
ridging is likely to build over the Plains with strong agreement
from all guidance. Also have strong agreement in a predominant
long wave trough setting up over the western CONUS and far eastern
Pacific, which will favor southwesterly flow over the local
region. Expect to see an eventual increase in low level moisture
from the Gulf with some potential for thunderstorms as short wave
trough energy moves out into the local area by Friday or Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1241 PM CDT Sat Mar 17 2018

Low MVFR to IFR cigs are forecast to remain in place across
eastern Nebraska TAF sites through Sunday morning. Cigs may lower
to LIFR category for a time at all sites between 06Z and 15Z, with
MVFR vsbys in fog. A gradual improvement is expected late in the
TAF period, generally after 16Z Sunday, with VFR conditions
expected after 18Z.




SHORT TERM...Barjenbruch
LONG TERM...Barjenbruch
AVIATION...Dergan is the U.S. government's official web portal to all federal, state and local government web resources and services.