Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 281754
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1154 AM MDT Tue Mar 28 2017

.UPDATE...
Issued at 1051 AM MDT Tue Mar 28 2017

Area of rain continues to push slowly northwestward as it
overcomes drier air to the north. Expect that trend to continue
through the afternoon. Expect some light snow to develop in the
highest elevations of the Black Hills this afternoon with light
accumulation possible.

&&

.SHORT TERM...(Today Through Wednesday Night)
Issued at 238 AM MDT Tue Mar 28 2017

08z surface analysis had a low over central CO and another over
the four corners area. Couple of troughs extended from lows into
southeast MT and south central SD. Water vapour has upper low
spinning over central AZ, which is a bit further south than
previous guidance showed. Northern branch of upper trough moving
across MT. IR had cooling tops moving into the CWA from the south
with radar showing increasing returns. Effects of this system main
concern in the short term.

Today and tonight, upper low moves into the TX panhandle by 12z
Wednesday which is a bit slower and further south than previous
guidance. Inverted trough feature extending north into the CWA will
be focus for precipitation today and tonight given modest synoptic
scale lift and low level frontogenesis. Further south track of low
has resulted in less dynamic cooling, upslope flow, and jet
dynamics. Boundary layer temperature forecast shows wet bulbs 1-2C
warmer than yesterday and thus, snowfall looks to be limited to
the very highest elevations. Have adjusted QPF and snowfall down
about 25%. Otherwise, high PoPs warranted with adjustment for
latest timing. It`ll be a refreshing day for those who would like
moisture and duck-like if you prefer liquid sunshine.

Wednesday, system pulls away with lingering precipitation ending
from west to east. Temperatures will rebound to 5-10F above normal.

.LONG TERM...(Thursday Through Monday)
Issued at 238 AM MDT Tue Mar 28 2017

Transient upper ridge Thursday replaced by another splitting
upper trough Thursday night through Saturday afternoon with good
chances for rain. A bit of snow may occur over the higher elevations
at night. Drier weather is expected the rest of next weekend, but
a bit of rain still possible given weakly unstable flow.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1152 AM MDT Tue Mar 28 2017

Widespread IFR CIGS will continue today across much of western SD
into parts of northeastern WY as rain pushes in. LIFR CIGS
expected across the Black Hills area. Conditions will improve VFR
late tonight into Wednesday morning as drier air moves back in.

&&

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

$$

Update...10
SHORT TERM...Helgeson
LONG TERM...Helgeson
AVIATION...13



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