Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 141729
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1129 AM MDT Thu Mar 14 2024

.KEY MESSAGES...
236 AM MDT Thu Mar 14 2024

- Weak cold front brings stratus and patchy fog this morning as
  well as gusty northerly winds
- Dry weather returns Friday with breezy/windy conditions for the
  weekend into the first half of next week leading to elevated
  fire weather conditions

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 236 AM MDT Thu Mar 14 2024

08z surface analysis had main low over the southern Plains with
weak cold front pushing into far northwest SD. Stratus/patchy fog
noted behind front over ND, which was heading southward per
nighttime microphysics RGB loop. Water vapour loop had split upper
trough with northern stream trough sliding across the northern
Plains and main upper low over NV/UT/AZ borders.

Today, northern stream upper trough moves southeast pushing cold
front through CWA. Stratus/patchy fog will slip southward with
daytime mixing potentially arresting the forward progress,
eventually mixing out low clouds. The latest guidance suggests
some areas could be cloudy all day. Thus, have undercut guidance
temperatures a few degrees for this afternoon. Afternoon solar
insolation may take advantage of leftover boundary layer moisture
over the Black Hills creating a few snow showers. Given low level
cold air advection/gradient behind cold front, expect 20-30mph
winds just east of the Black Hills with gusts to 40mph at times
today.

Tonight through the first half of next week, upper level ridge
from the west coast to the northern Rockies expected as a series
of fast moving shortwaves rotate through the upper Midwest,
pinwheeling around Hudson Bay upper low. Result will be northwest
flow aloft over the CWA with oscillating moisture-starved low
level baroclinic zone over the Dakotas. Periodic bouts of
breezy/windy conditions expected as temperatures wiggle around
with each passing front. Ensemble guidance indicates less than 20%
chance of >0.1" QPF through the first half of next week. Much
needed moisture is very unlikely to occur.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1129 AM MDT Thu Mar 14 2024

Widespread MVFR to LIFR conditions in low stratus, some light
snow, and areas of fog should diminish this afternoon through
tonight, with VFR conditions anticipated area-wide by 06z, if not
before. Have opted to hedge towards the more conservative guidance
in terms of timing of improvement given bias among many models in
eroding low stratus too quickly. Nonetheless, given model
consensus of improvement to VFR for most by 00z, I may be a little
too conservative.

At any rate, breezy northerly winds should also diminish this
evening, becoming light and variable for most overnight. Breezy
winds will return tomorrow for much of the area, this time out of
the west and southwest.

&&

.FIRE WEATHER...
Issued At 236 AM MDT Thu Mar 14 2024

Dry/very dry air (minimum afternoon relative humidities in the
20s with some teens at times) in place Friday through the first
half of next week. A series of fronts will bring bouts of gusty
winds at times. The combination will lead to elevated fire weather
conditions.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Sherburn
FIRE WEATHER...Helgeson


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