Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 251919

Area Forecast Discussion
National Weather Service Sioux Falls SD
219 PM CDT Fri May 25 2018

.SHORT TERM...(This evening through Saturday)
Issued at 212 PM CDT Fri May 25 2018

The main weather concern this afternoon is scattered thunderstorms
that could create gusty winds and isolated damaging wind gusts.
Atmospheric instability and shear is limited, so long-lasting or
large-hail-producing thunderstorms do not look likely. But the low-
level air mass this afternoon will be dry, leading to evaporation-
accelerated downdraft gusts directly below the any thunderstorms
that do form. This will not be a widespread threat, but worth noting
for those with evening outdoor plans. The takeaway point: If you see
a thunderstorm headed your way today, there is a good chance it has
very gusty winds underneath it.

Skies will clear overnight as an amplified upper-level ridge
develops over the Plains, setting the region up for another sunny
start on Saturday. This strong ridge will also minimize the rain and
shower threat. By early afternoon, temperatures will reach the low
to mid 90s, which is well above the normal mid-70s for this time of
year. The temperatures and humidity looks to stay below Heat
Advisory levels, but even the fact that that we need to be
considering this is enough to say that it will definitely be toasty.

.LONG TERM...(Saturday night through Friday)
Issued at 212 PM CDT Fri May 25 2018

The warm conditions persist through the Memorial Day weekend, before
slightly "cooler" mid 80s return on Tuesday. Again, the heat should
stay below Heat Advisory levels for Sunday & Monday, but be sure to
stay hydrated if enjoying the outdoors, as it will certainly feel
warm. The whole week remains above average for temperatures.

Regarding shower chances, a shortwave trough will move through the
Northern Plains on Sunday, moving through the northern periphery
of the ridge of high pressure. As of now, showers and
thunderstorms aided by this short-wave induced lift look to
remain north of the tri- state area. A better chance for rain
occurs Monday night into Tuesday, as the ridge migrates eastward
and a longwave trough moves over the Plains. By sunrise Tuesday,
areas east of I-29 could already be seeing rain move in. This is
too far out for precipitation details, but might be worth planning
for some rain Tuesday.

This trough keeps rain chances in the forecast through mid
Wednesday. By Thursday into next weekend, another ridge may build,
but does not look as strong as the Memorial Day weekend ridge, so
temperatures are forecast in the upper 80s with a chance for
isolated showers.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1242 PM CDT Fri May 25 2018

Light west winds will be common throughout the area today.
Scattered thunderstorms look likely, especially in southwest MN
after 25/2000z, but these could reach as far southwest as KFSD.
Gusty and isolated damaging winds will be possible under the cores
of thunderstorms, given strong downdrafts due to very dry air in
the low levels of the atmosphere. The thunderstorm threat
decreases quickly after dark, with clear skies and light winds
through Saturday morning.




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