Area Forecast Discussion Issued by NWS Rapid City, SD
000
FXUS63 KUNR 190828
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
228 AM MDT Tue Mar 19 2024
.KEY MESSAGES...
138 AM MDT Tue Mar 19 2024
-Mild and dry today
-Chance of snow across northwest South Dakota Wednesday/Thursday
-Colder this weekend with snow
&&
.DISCUSSION...(Today Through Monday)
Issued at 138 AM MDT Tue Mar 19 2024
Current surface map places low north of Lake Superior with cold
front across souther North Dakota. Water vapor shows northwest
flow aloft with Pacific Northwest/Rockies high breaking down. For
today, cold front slowly slips southward. Highs near
guidance; 50s across northwestern South Dakota to lower/mid 60s
in elsewhere. Low level baroclinic zone stalls out across the
Northern Plains/Dakotas Wednesday/Thursday, with 25-30F spread in
temperatures across the forecast area. Fast moving shortwave in
northwest flow crosses the area late Wednesday/Thursday with
banded snow event. Deterministic and ensemble guidance in good
agreement keeping strongest 850-600mb frontogenisis north of the
forecast area. An inch or two of snowfall is possible across far
northwest South Dakota with higher amounts to the north. Strong
Canadian high continues to build southward in the wake of the
shortwave, with baroclinic zone shunted southward. Weak upslope
flow Friday may bring some light snow around the Black Hills area,
but with shortwave ridging aloft may end up with some freezing
fog and/or light freezing drizzle.
Upper trough digs across the western CONUS this weekend with lead
shortwave tracking across the Rockies into the Dakotas. Shortwave
comes through fairly fast as an open wave, limiting the duration
of strongest forcing. Isentropic lift/frontogenesis will some
enhanced snowfall to the area. While confidence is increasing in
snowfall this weekend, there is still lower confidence is the
placement of higher snow totals. LREF probability of 24 hour
snowfall amounts >2" is 40-90% and >6" is 10-40% across the
forecast area, with the higher probabilities north and east of
the Black Hills.
&&
.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1117 PM MDT Mon Mar 18 2024
VFR conditions are expected through the period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...7
AVIATION...Helgeson