Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 151720
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1120 AM MDT Fri Mar 15 2024

.KEY MESSAGES...
142 AM MDT Fri Mar 15 2024

- Red Flag Warning hoisted for northwest SD
- Dry weather expected through next Wednesday with periodic bouts
  of breezy/windy conditions at times resulting in elevated fire
  weather conditions

&&

.DISCUSSION...(Today Through Thursday)
Issued at 142 AM MDT Fri Mar 15 2024

07z surface analysis had high over the CWA as leftover stratus
shrinks per nighttime microphysics RGB. Water vapour loop had
upper low over southern CA, northern stream shear axis slipping
through through the northern Plains, and speedy shortwave trough
chugging across northern SK. The next 6 days look to be dry with
breezy/windy periods.

Today/tonight, surface high moves south under upper level shear
axis. Back side of high will feature westerly flow enhanced by
3-5mb/3hr pressure falls over the eastern Dakotas per low level
warm air advection. Downslope warming will promote temperatures
near guidance this afternoon as very dry air mixes to the surface.
Northern SK shortwave trough drops moisture-starved back door
cold front into northeast reaches of the CWA tonight. Temperatures
will be near guidance tonight.

Saturday through Wednesday, ensemble guidance depicts upper ridge
building into the northern Rockies from the west coast as
southwest US upper low spins eastward/slowly weakening. Mean
upper trough over eastern North America. CWA will be under dry
northwest flow aloft with periodic back door cold fronts and
breezy/windy spots. Chance of >0.1" QPF <20%. Cooler air will be
noticeable Saturday and Sunday particularly east of the Black
Hills, but most guidance (although spreads increase) indicate
temperatures 10-20F above normal for the first half of next week.

The end of next weeks turns colder and potentially more active,
assuming moisture return is sufficient.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1120 AM MDT Fri Mar 15 2024

VFR conditions should prevail area-wide through the period.
Westerly to southwesterly wind gusts exceeding 30 kt are
anticipated across northwestern SD this afternoon before
diminishing this evening. More widespread northwesterly gusts of
25 to 35 kt are expected after 15z tomorrow.

&&

.FIRE WEATHER...
Issued At 142 AM MDT Fri Mar 15 2024

Very dry air will mix out over northwest SD this afternoon per
increasing westerly downslope flow. Minimum relative humidities
<=15% likely with frequent gusts of 25mph or greater, especially
near the ND border. Will hoist Red Flag Warning to account and
extend a bit further south, although mainly for areas from Belle
Fourche to Milesville. A series of fronts will then bring bouts of
gusty winds at times Saturday through Wednesday along with minimum
relative humidities dropping to 15-30%. The combination will lead
to elevated fire weather conditions.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 7 PM MDT this evening for SDZ327>331.
WY...&&

$$

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


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