Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 120906
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
306 AM MDT Tue Jun 12 2018

.DISCUSSION...(Today Through Monday)
Issued at 306 AM MDT Tue Jun 12 2018

Current surface analysis still shows high pressure centered over
the Northern Rockies, with west to northwest winds around the high
extending east into the high plains. Upper level analysis shows
low pressure over central Canada, with near zonal flow across our
region. Strong upper jet extends from the Pacific NW to the
Northern Plains. Embedded jet energy is bringing some light rain
showers to northwest SD. Temps right now are mostly in the mid 40s
to mid 50s.

Cooler conditions will persist across the area for one more day,
with highs in the upper 60s and 70s. Isolated showers will spread
east into parts of central SD early this morning before dissipating
by mid morning. Decent boundary layer mixing by midday will allow
for breezy westerly winds to develop across northwest SD. Surface
high moves over the area tonight with relatively light winds and
cool temperatures.

South to southeast winds develop on Wednesday as high moves east of
the area and weak ridging builds over the region. This will bring
warmer air into the area for Wednesday and especially Thursday. Low
level jet will extend north into western and central SD on Wednesday
with fairly strong mid-level theta-e advection also expected. Weak
energy aloft sliding east across the area will likely allow isolated
to widely scattered showers and storms to develop from parts of
southwest into central SD during the day, likely lingering into the
evening over south central SD. Increasing low level moisture will
bring sufficient instability for stronger storms to potentially
develop, especially in the afternoon and early evening.

Hot conditions are expected Thursday ahead of a cold front moving
across the Rockies. Highs will be in the 90s across much of the
plains. The front still looks to be mostly dry as it crosses our
area late Thursday and Thursday night, with better energy aloft
staying north and west of the region. However, a few thunderstorms
could skirt far northeast WY and northwest SD in the evening.
Slightly cooler and dry conditions are expected during the day on
Friday.

Large upper trough will sink south across the western US early in
the weekend, with a more unsettled and cooler pattern developing.
The system will be cutoff to the west of the region through at least
the first part of next week, meandering around the the Great Basin
region and western Rockies. Shortwave energy rotating around the
system will bring chances for showers and storms at times, with
timing very uncertain at this point. The better chances for rainfall
still look to be Saturday into Sunday, especially over northeast WY
and the Black Hills area in closer vicinity to the main upper
system. The threat for any stronger storms over the weekend would
likely be more favorable across northeast WY and southwest SD.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1025 PM MDT Mon Jun 11 2018

VFR conditions expected.

&&

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

$$

DISCUSSION...26
AVIATION...JC



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