Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
1009 PM MST Sat Feb 13 2016

Update...
issued at 1008 PM MST Sat Feb 13 2016

Heaviest snow now pushing out of Haakon/Ziebach counties so will
allow Winter Weather Advisory to expire. Precipitation over scntrl South Dakota will
diminish from west to east overnight.

Update issued at 753 PM MST Sat Feb 13 2016

Compact...yet potent..upper low tracking eastward across western South Dakota this
evening. Freezing rain has transitioned to mostly snow...which is pretty
heavy across Ziebach...Haakon...and far eastern Pennington counties.
Received a report of 4 inches of snowfall just southeast of Faith. Given
the heavy nature of the snow and the timing of its movement...will
extend the advisory for Ziebach County until 05z while also adding
Haakon County to the advisory. Will monitor trends closely further
south/east but believe snow amounts in that area will be below
advisory criteria.

&&

Short term...this evening through Sunday night
issued at 332 PM MST Sat Feb 13 2016

Current surface analysis shows low pressure over far southwest
sk...with warm front extending southeast into western South Dakota. Cold
front extends southward across eastern Montana into northeast Wyoming. Upper
level analysis shows relatively strong shortwave moving east-
southeast across eastern Montana and northern Wyoming...with strong jet
wrapping around it from the northern rockies through South Dakota. Latest
observation show temperatures ranging from around 20 in the Lemmon area to near
60 in far southwest South Dakota. The freezing line right now extends from
southern Harding County to near Faith and then south into south
central South Dakota.

Kudx radar showing showers over much of northeast Wyoming into northwest
South Dakota...with a few lightning strikes also noted with the activity. Precipitation
over far northwest South Dakota into north central South Dakota is likely falling in the
form of freezing rain and possibly some snow. Strong winds have
developed along and just behind the front across northeast Wyoming...with
showers helping to drag stronger winds aloft to the surface. Some
gusts to near 70 miles per hour have been recorded over Campbell Colorado. These
winds will move into the Black Hills area by early evening...with a
few gusts to over 60 miles per hour likely in some areas early this evening.
Winds with the front should diminish as the front moves east of the
Black Hills into cooler and more stable air to the east.

Precipitation with the shortwave will move quickly through the area late this
afternoon and evening. Rain can be expected over most of the County Warning Area as
warm front moves east ahead of the cold front. Some snow is possible
over the Black Hills and northeast Wyoming as the back edge of the
showers moves through. Over the far northeastern County Warning Area into central
South Dakota...some light freezing rain and snow is still possible with light
accumulations. Precipitation will move out of far eastern portions of the County Warning Area
after midnight. Lows will mostly be in the upper 20s to middle 30s.

Sunday will be a relatively quiet day compared to the last couple of
days with relatively mild temperatures and partly sunny skies. Highs
will be in the upper 30s and 40s. A few rain and snow showers are
possible over northeast Wyoming and the Black Hills...especially in the
afternoon and evening...as a weak disturbance slides through western
areas in northwest flow.

Long term...Monday through Saturday
issued at 332 PM MST Sat Feb 13 2016

Northwest flow aloft continues for first part of next week as
western Continental U.S. Ridge begins to flatten. Strong jet streak dives
across the Dakotas Monday/Tuesday and may result some -shra/-shsn.
Best chance will be in upslope areas of northern Black Hills. Dry
weather with very warm temperatures Wednesday/Thursday as ridge
shifts across the plains. Could see some highs in the lower 70s on
downslope areas on east side of Black Hills. Strong shortwave
moves along Canadian border Friday with cold front crossing
forecast area. Strong winds possible with frontal passage.

&&

Aviation...for the 00z tafs through 00z Sunday evening
issued at 332 PM MST Sat Feb 13 2016

MVFR/IFR ceilings over northwest into central South Dakota will
continue through this afternoon and evening as area of snow/freezing rain
develops. The heaviest precipitation will be this afternoon into
tonight. For northeast Wyoming into southwest South
Dakota...showers will develop this afternoon/evening with local MVFR
cigs/vsby. Cold front crosses the area late afternoon/evening
with a period of gusty northwest winds. VFR conditions expected
across the area Sunday morning.



&&

Unr watches/warnings/advisories...
South Dakota...none.
Wyoming...none.
&&

$$

Update...Johnson
short term...26
long term...7
aviation...7

National Weather Service Glossary of Abbreviations