Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 202307

Area Forecast Discussion
National Weather Service Omaha/Valley NE
607 PM CDT Tue Mar 20 2018

.SHORT TERM...(Tonight through Friday)
Issued at 325 PM CDT Tue Mar 20 2018

The primary forecast issues include, clouds decreasing and the
potential for fog tonight into Wednesday morning, then rain
chances Thursday night into Friday.

Water vapor satellite imagery early this afternoon showed two
systems off to our east and southeast, with another weak
disturbance to our west. Main area of precipitation had moved out
of eastern NE but continued in western IA. Will keep some low POPs
going this evening east of the MO river. Temperatures have
remained fairly cool with cloud cover so far today. Clouds should
decrease tonight, but with wet ground from recent precipitation
and light winds, we expect some fog. Highest potential for
visibilities less than 1 mile according to most recent model
guidance is from northeast NE into western IA. Will not issue any
headlines for fog at this point, but locally dense fog is
certainly possible. Low temperatures should be mainly in the mid
20s to around 30, so there will be some frost formation.

After the fog burns off Wednesday morning, we expect a decent
amount of sunshine. Winds initially will be light and variable but
should become south or southwest at 5 to 15 mph. The GFS is more
aggressive than the NAM with warming, and for now gave the warmer
numbers more weight. The period from Wednesday through Wednesday
evening looks dry. A low level jet and isentropic upglide will
bring increasing clouds for Wednesday night. Some showers could
develop mainly in western IA, on the nose of a low level jet after
midnight Wednesday night. Then those should move off to the east
and southeast. Highs Thursday should be warmer than Wednesday, but
there will be a front over the southern parts of the forecast
area. Went with a range of highs from upper 50s north to upper 60s
in the south but some lower 70s could occur near the KS border.
Friday will be cooler, with more clouds and a chance of rain or

.LONG TERM...(Friday night through Tuesday)
Issued at 325 PM CDT Tue Mar 20 2018

This period will be fairly active. It will not be precipitating
the whole time, but there will be episodes. At the start of the
period, the 500 mb pattern should feature a ridge just to our
east from MN into MO, with a trough from western Canada to off the
CA coast. Several weak disturbances will move out of that trough
into our area with the southwest flow. There is some elevated
instability Friday night and again Sunday night, over mainly
southeast NE and the far southern parts of southwest IA so
isolated thunderstorms possible there. Some snow or a rain/snow
mix may occur across mainly northeast NE late Saturday night into
Sunday morning, then again Sunday night.

By Monday, there is decent model agreement that a mid level
trough will extend from Alberta and Saskatchewan down toward the
CA/AZ border. Both the ECMWF and the Canadian models develop a
closed low by Tuesday just of the CA coast, with a split flow
pattern. The GFS is a bit different, showing more of an open wave
over the Rockies. For the early and mid part of next week, we will
most likely be under the influence of the northern part of that
split flow pattern, suggesting that temperatures will be below


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 606 PM CDT Tue Mar 20 2018

MVFR conditions at KOFk will become VFR by 04-06z. MVFR conditions
at KLNK become VFR 00-02z. VFR at KOMA, but IFR conditions could
redevelop 10-15z.




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