668
FXUS63 KUNR 131116
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
516 AM MDT Sat Jul 13 2024

.KEY MESSAGES...

-Hot this weekend with isolated/scattered storms at times, some
 strong to severe

-Elevated fire weather conditions continue through the weekend

-Cooler early to mid next week with isolated to scattered storms
 at times

&&

.DISCUSSION...(Today Through Friday)
Issued at 104 AM MDT Sat Jul 13 2024

Water vapor shows upper ridge across the western/central CONUS,
with disturbed westerly flow through the Northern Rockies/Northern
Plains. At the surface, broad low covers the Dakotas. Convection
from yesterday`s short wave is mostly east/south of the area
early this morning, with next upstream short wave already spreading
convection across southeastern MT/northeastern WY and into
northwestern SD.

Heat remains the main focus through the weekend, although isolated
severe storms remain possible. Highs well into the 90s and lower
100s will continue through Sunday, with heat indices into the
lower 100s south/east of the Black Hills and into south-central
SD. Current Heat Advisory through Sunday looks good. Elevated
convection currently over northeast WY and parts of northwest SD will
spread eastward across western SD this morning. Additional
activity will fire around the Black Hills in the afternoon and
expand/spread east through the evening hours. A few supercells
possible with activity coming off the Black Hills, although
effective shear not overly impressive. Given high storm bases,
biggest threat with any storms will be strong wind gusts.
Disturbed flow overhead will lead to continued chances for a few
nocturnal storms Saturday night, with additional surface based
convection again Sunday afternoon/evening as a cold front pushes
into northeast WY and northwest SD.

Upper trof dives southeast across southern ALTA/SASK Sunday night,
and through the Northern Plains Monday, pushing the associated
cold front through our entire zones by Monday morning. Best chance
for post frontal storms Monday will be around and south of the
Black Hills within convergence zones. Highs will cool into the mid
80s to mid 90s for Monday.

Northwest flow through mid week will result in on/off storm
chances along with cooler weather (closer to average), but western
CONUS ridge will reamplify through the Northern Rockies for late
in the week with temperatures heating back up.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Sunday Morning)
Issued At 513 AM MDT Sat Jul 13 2024

Scattered showers and storms will continue to move from west to
east across the Black Hills into the western South Dakota plains
this morning. Storms should be out of the area by noon. Isolated
to scattered thunderstorms will return this afternoon through this
evening. Locally gusty winds and MVFR conditions will be possible
with any storms. Otherwise, VFR conditions will continue through
the TAF period.

&&

.FIRE WEATHER...
Issued At 104 AM MDT Sat Jul 13 2024

Hot temperatures will continue through the weekend with elevated
to near critical fire weather conditions at times. Expect RH`s
dipping in the teens both today today and Sunday from northeast WY
into far western SD, with slightly higher RH`s further east.
Winds still do not look to be particularly strong (outside of any
thunderstorms), but there is some chance that breezy northwest
winds could develop across parts of northeast WY and far northwest
SD Sunday afternoon as a cold front moves in, and bring near
critical fire weather conditions. Storm chances will continue
through the weekend, some with little rainfall and strong winds.

Cooler and slightly more unsettled conditions will develop for
early next week.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory from noon MDT /1 PM CDT/ today to 8 PM MDT /9 PM
     CDT/ Sunday for SDZ030>032-041>044-046-047-049-075>077.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Johnson
AVIATION...Wong
FIRE WEATHER...Johnson