Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 300504
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1104 PM MDT MON AUG 29 2016

.UPDATE...
Issued at 852 PM MDT Mon Aug 29 2016

Diurnally driven showers and thunderstorms have ended across
northeast WY and south central SD. Skies will be mostly clear
overnight across northeast WY and far western SD, with high clouds
remaining over eastern portions of the cwa through at least late
tonight. With light winds and forecast RH near 100 percent, have
added some patchy fog for late tonight/early Tuesday across
portions of the southwest SD plains and the Black Hills. Lows will
mostly be in the 50s, with lower 60s over south central SD and
some 40s over the higher Black Hills.

&&

.SHORT TERM...This Evening Through Tuesday Night
Issued at 329 PM MDT Mon Aug 29 2016

Surface cold front almost stationary across south central SD,
still draped between PIR-9V9 and PHP-VTN. Upper low over srn CO-
nrn NM is drawing moisture northward ahead of it into central
Plains, with some thunderstorms developing over Cherry Co NE along
the cold front that may clip south central SD late afternoon and
early evening. Surface high pressure is pushing southward through
the Dakotas, with northeast winds bringing cooler temperatures to
the forecast area.

Upper ridge builds over the northern Plains through midweek...giving
the forecast area mostly dry conditions. CAPE values ov 1000-
2000j/kg over the Black Hills Tuesday and upslope flow may produce
some thunderstorms in the afternoon, but higher CIN will inhibit
convection for the plains. With lee trof developing over MT Tuesday,
south winds will warm temperatures in the western zones, but highs
will be cooler over central SD where east-southeast winds will
prevail.

.LONG TERM...Wednesday Through Monday
Issued at 329 PM MDT Mon Aug 29 2016

The upper level ridge will increase in amplitude over
the Rockies and the high plains over Wednesday as an upper trough
deepens over the west coast. The will lead to warm temperatures and
dry weather through Thursday. The surface pressure gradient
indicates that breezy to windy southeasterly winds will develop,
which should keep minimum relative humidities in the 20 to 30
percent range over western South Dakota. The RH will be lower over
northeastern Wyoming, ranging from 15 to 25 percent on Wednesday and
Thursday. Southwesterly flow aloft will develop on Friday as the
ridge and the upper trough both shift slightly eastward. This will
result in cooler temperatures for the weekend as well as better
chances for showers and thunderstorms.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1104 PM MDT Mon Aug 29 2016

VFR conditions are expected across much of the area overnight
into Tuesday. However, patchy fog is possible late tonight/early
Tuesday across portions of the southwest SD plains and the Black
Hills. There will be a chance for showers and thunderstorms
Tuesday afternoon over the Black Hills.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

Update...26
SHORT TERM...55
LONG TERM...10
AVIATION...26



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