Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 281100
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
500 AM MDT Wed Jun 28 2017

.DISCUSSION...(Today Through Tuesday)
Issued at 208 AM MDT Wed Jun 28 2017

Upper wave is moving through the northern plains, and storms have
shifted east into MN and IA. Water vapor shows a weak wave across
northwestern WY, a stronger wave moving into ID, and a low
spinning over WA. Surface winds are northwesterly around 10 kts,
and temps range from the lower 50s across northeastern WY to the
lower 70s across south central SD.

Initial wave will push into northeastern WY by 18Z, indicated in the
models by a line of frontogenesis and Q-vector convergence. Expect
storms to develop across northeastern WY and the Black Hills early
afternoon, then expand across western SD during the evening as
the stronger, secondary wave moves in. While ML CAPE of 600-1000
J/kg is significantly weaker than yesterday`s instability, 0-6 km
shear around 50 kts will be sufficient for isolated strong to
severe storms. Showers and thunderstorms will continue overnight
and into Thursday, moving out of the CWA Thursday night.

Highs today will be in the mid 70s to upper 80s, warmest across
south central SD. Cooler air will pour into the northern plains
Thursday as the trough moves through, dropping highs about 10
degrees.

One more piece of energy from the upper trough may bring a few
showers/storms to central SD Friday, but otherwise dry weather is
expected Friday and Saturday as an upper ridge builds over the
western CONUS. A wave will briefly flatten the ridge Sunday and
bring another round of showers/storms, but then dry weather will
return for early next week. A warming trend will also begin this
weekend, with highs returning to near 90 by the 4th of July.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 458 AM MDT Wed Jun 28 2017

VFR conditions will prevail outside of -TSRA through the period.
Relatively clear skies this morning will be replaced by VFR BKN
CU/SC deck by afternoon. Scattered -TSRA will develop over
northeast WY early this afternoon and spread east through tonight
with local MVFR conditions.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION...Pojorlie
AVIATION...Helgeson


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