Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 181943
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
143 PM MDT Mon Mar 18 2024

.KEY MESSAGES...
142 PM MDT Mon Mar 18 2024

-Mild, dry, and breezy weather continues Tuesday

-Chance of snow across far northwest South Dakota Wednesday into
 Thursday

-Much colder with increasing chances of snow across the area this
 weekend, especially early next week

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 142 PM MDT Mon Mar 18 2024

Western NOAM ridge will shift west and amplify, supporting a
southwest bias to the central Canadian negative height anomaly.
This will support increasingly active flow the remainder of the
week with a trend to much colder conds by the weekend. A couple NW
flow impulses will support a few rounds of light snow later this
week, with the best chance of snow over NW SD with these systems.
Strong upper trough will then undercut the ridge this weekend,
cross the Rockies, and eject into the plains early next week. This
will support a strong reflected sfc low somewhere in the Plains,
the exact location of which is still unknown.

Temps have recovered quite well today after this morning`s cold
temps with many places now in the 60s across the NW third. Fast
moving clipper type system will drop a sfc trough into the FA
tonight, with winds increasing across most areas, esp NW SD. Still
expect mild conds across the SW half to third with highs in the
60s once again. A secondary cold front will move SW through area
later Tues. This front will stall as a sfc low traverses the
region Wed, supporting FGEN across NW SD. Some light snow accums
will be possible there along with much colder temps, as highs will
struggle into the 30s there. Much warmer conds expected across
the far SW, with highs in the 50s and a few 60s expected. Frontal
boundary will waver over/near the region through the end of the
week and will provide the pathway for additional impulses, which
may allow for bouts of light snow as the pattern becomes
increasingly unsettled. Best chance for accums will continue to be
across the northern third. Deep western CONUS upper trough will
cross the Rockies and support more unsettled and cooler conds late
this weekend into early next week. A winter storm is likely to
affect a portion of the region early next week, with accumulating
snow. The best chance of heavier snow accums will likely remain
east of the FA given the far southwest dig that models currently
offer. In addition, ongoing tendencies for split flow this winter
tends favor this scenario. Still much uncertainty at this time,
and will monitor the pattern until a better handle on the upper
trough becomes established. One thing that is certain is that much
colder temperatures can be expected for the first part of next
week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Tuesday)
Issued At 1051 AM MDT Mon Mar 18 2024

VFR conditions will prevail through the period. Breezy northwest
winds are expected across northwestern SD this afternoon and
evening as a weak front crosses the region. These may reach KRAP
before sundown, but if not, light and variable winds should
prevail this evening into tonight owing to nocturnal
stabilization.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Sherburn


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