Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 211147
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
647 AM CDT Mon May 21 2018

.SHORT TERM...(Today through Wednesday)
Issued at 300 AM CDT Mon May 21 2018

Main forecast concerns for today are the potential for fog and how
fast clouds will clear out. Have gone with highs 72 to 77 for
this afternoon.

Large scale pattern had the following main features. A closed low
was over southern SD and that should continue to lift northeast.
Another closed low was digging southward from central CA. Mid
level flow in our area will remain mainly zonal today and tonight,
then turn to the southwest and remain that way through mid week.
Closed low over CA should move to near the ID/NV/UT border area by
Wednesday morning, then to eastern MT by Thursday morning.

At the surface, ridge of high pressure will build eastward today,
with return flow developing tonight. Expect some showers and
thunderstorms to move in from the west tonight with low level warm
air advection and isentropic upglide. The 00Z NAM remained fairly
dry tonight, but other models have at least a weak to moderate
precipitation signal on the nose of a 30 to 40 knot low level jet.
Kept precipitation chances going then for Tuesday through
Wednesday. Will need to monitor for heavy rain potential Tuesday
night, but chances look highest in southeast SD, northwest IA and
southwest MN.

Temperatures by Tuesday will rise above normal. Highs should be
in the 80s both Tuesday and Wednesday.

.LONG TERM...(Wednesday night through Sunday)
Issued at 300 AM CDT Mon May 21 2018

Pattern will remain somewhat active into late week, but at this
time the chance for organized severe storms does not look high
into mid week. However, it is late May. By Thursday afternoon,
there is a decent amount of instability but 0-6 km shear is still
fairly low.

Low level flow should be from the south into Friday, then a weak
cold front is expected to push through Friday night. Right now it
appears that a mid level ridge will build in from the west for the
weekend, with warm and mainly dry conditions.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 630 AM CDT Mon May 21 2018

Variable clouds and fog this morning with MVFR/IFR/VLIFR and
patchy VFR conditions being reported. The trend will be for the
dry air to work into the area during the day with improving
conditions to VFR/MVFR 15-18Z. The low level jet increases tonight
with thunderstorms possible after 06z.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Zapotocny



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