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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
1034 am MST Tuesday Mar 3 2015

issued at 1028 am MST Tuesday Mar 3 2015

Conditions continue to improve on most of the South Dakota plains...far
northeast Wyoming...northern Black Hills. Latest guidance continue to
show secondary shortwave dropping to our west which will support
-sn over parts of northeast Wyoming through this afternoon. Downstream
convergence signature noted on radar and model guidance for far
southwest South Dakota. Headlines adjusted to account.

Update issued at 753 am MST Tuesday Mar 3 2015

Looking at latest web cams...radar loops...and 12z rap...will shave
some of the northern part of the Winter Weather Advisory. Good
drying coming in and less snow than expected across northwest
South even with gusty winds...blowing snow should be limited.


Short through Wednesday night
issued at 236 am MST Tuesday Mar 3 2015

Merging upper level troughs and associated reflected
fgen response continuing to traverse the region this morning. A
decent band of moderate snow is in place as of 09z across western
South Dakota...where fgen/uvm/lsa are currently coupled and maximized with
this system. This band will quickly shift NE early this
morning...with general light snow continuing in is wake through
most of the morning. Sig bl drying will occur this afternoon as
Arctic high pressure builds into the region. Save for a weak
upslope response tonight in the Northern Hills...dry weather expect to
prevail most places tonight through Wednesday.

Today...primary shortwave and associated lobe of ascent will shift
quickly NE of the forecast area. This will support a quick wane to snow...with
generally 1-3 additional inches expected where advisories/warnings
are currently in place. Biggest impact will be gusty northwest winds on the
South Dakota plains. Sustained winds of 15 to 25 miles per hour with gusts over 40 will
continue through morning. However...latest model guidance favors a
quicker wane to wind speeds this afternoon than previous forecast
model suites suggested. In addition...upslope snows will quickly
wane as bl drying highly impacts snow production there by late
morning. Hence...many of the headlines could likely be dropped
late this morning...on track with most headline expirations. Will
drop the far northwest South Dakota zones from the winter weather advection. Snow has not
really materialized there and at most only a couple tenths
expected in areas that do see snow. The only location that looks
to see snow accums into the afternoon is the southern Black Hills
where eddy convergence is expected...although only a couple
additional inches at most would be expected there into the
afternoon. Otherwise...cold conds on track with temperatures falling
through the day.

Tonight...dry conds expected most locations. Main northern steam
trough axis will traverse the region tonight...possibly supporting a
weak upslope response in the Northern Hills. Bl moisture is pretty
limited...hence snow probs remain very low. Isallobaric wind will
prevail tonight across the region...supporting sustained northwest winds.
This will support near windchill advection conds across the northwest South Dakota zones.

Wednesday...surface ridge will build into the region with dry weather and clear
skies expected. Cold conds will prevail with most locations
struggling out of the teens. Warm air advection will ensue Wednesday night...with typical
downslope locations seeing rising temperatures after midnight.

Long term...Thursday through Monday
issued at 236 am MST Tuesday Mar 3 2015

Arctic high slides well upper flow becomes more westerly.
Warmer air will begin to build into the region on Thursday. Medium
range models generally in good agreement for the rest of the week
and the weekend as mainly dry northwest flow aloft remains through
the period. A ridge over the western Continental U.S. Will slowly move east
into The Rockies over the weekend. Temperatures will be above
average Friday through Monday...with highs in the 40s and 50s.


Aviation...for the 18z tafs through 18z Wednesday
issued at 1028 am MST Tuesday Mar 3 2015

Snow has tapered off and ended in most areas this
morning...except for across far southwest South Dakota and portions of
northeast Wyoming. Snow will end across northeast Wyoming early this
afternoon...including at kgcc...while areas of snow will linger
across the southern Black Hills and far southwest South Dakota through the
afternoon. Areas of MVFR conditions will persist across northeast
Wyoming into southern South Dakota through the afternoon...with local IFR
conditions over far southwest South Dakota. Gusty northwest winds to 35 kts
will persist into the early afternoon across the South Dakota plains...then
gradually diminish late this afternoon and early evening. VFR
conditions are generally expected tonight.


Unr watches/warnings/advisories...
South Dakota...Winter Weather Advisory until 5 PM MST this afternoon for sdz027-

Wyoming...Winter Weather Advisory until 5 PM MST this afternoon for wyz054-



short term...jc
long term...15

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