Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 252010

Area Forecast Discussion
National Weather Service Sioux Falls SD
310 PM CDT Thu May 25 2017

.SHORT TERM...(This evening through Friday)
Issued at 309 PM CDT Thu May 25 2017

Isolated light rain showers associated with the passage of a cold
front across the area, will gradually taper off this evening. Cloud
cover is considerably increasing, but in terms of precipitation,
light rain or even sprinkles are expected with these showers due to
limited low-level moisture and more stable air as it moves eastward.
In fact, surface observations have been reporting none to a trace of
precipitation with these passing showers. It has been a windy day!
Tight pressure gradients associated with the surface low centered
over north central SD are producing brisk southerly winds gusting
from 30 to 35 mph. Winds are expected to wane down by around sunset.

At upper levels, while the ridge continues to slide east of the FA,
a shortwave will begin to shift northeast, increasing the chance of
precipitation during the nighttime. Low PoP chances are again
expected, but isolated thunderstorms will be possible given a steep
lapse rate and decent CAPE. This will mainly affect our extreme
southern portions of the forecast area through around 13Z.

A mostly dry and warmer Friday is on tap as a surface high pressure
builds in across the region early in the morning. With mostly sunny
skies and breezy northwesterly winds, highs will be in the 70s.
Portions of northwest Iowa could see temperatures in the upper 70s
to near 80.

.LONG TERM...(Friday night through Thursday)
Issued at 309 PM CDT Thu May 25 2017

Relatively quiet medium and extended forecasts continue, with
minimal change needed to the ongoing forecast.  Shortwave energy
pivoting around the base of an central Canadian trough combined with
increased support from brief right entrance region of an upper jet
will bring a risk for scattered showers to the area on Saturday.
Best focus for convection will stay south of the area, but
anticipate a day very similar to Thursday with scattered light
showers moving through by mid-day.

This upper trough brings cooler weather to finish the weekend and
begin next week.  Another favorable setup for afternoon instability
showers presents itself on Sunday and with trough hanging around the
eastern half of the CONUS on Monday, even further instability
showers may develop east of I-29 on Monday.

This upper low isn`t expected to dislodge from the eastern CONUS for
much of the week, which will keep the forecast area under the spell
of cooler and dry high pressure, keeping rain chances minimal and
keeping temperatures cooler than normal to start June.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1202 PM CDT Thu May 25 2017

The main concern is brisk southerly surface winds associated with
the passage of a cold front across the area. Gusts to 40 kts are
expected through early evening, waning down from west to east
through sunset. Isolated light rain showers possible this
afternoon, but ceilings will remain within the VFR category.
Overall, VFR conditions expected through the TAF period.




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