Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 271102
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
502 AM MDT FRI MAY 27 2016

.SHORT TERM...(Today Through Saturday Night)
Issued at 236 AM MDT Fri May 27 2016

08z surface analysis had stacked low pressure over southeast CO
with narrow band of lift northeast into south central SD, which is
in the left exit region of 90kt jet streak over the southern
plains in the in the right entrance region of 90kt jet streak
across the Great Lakes. Model guidance depicts upper low moving
into southwest NE as an area of lift shifts slightly north and
west today, persisting into the early afternoon with an area of
rain and isolated thunderstorms. Have raised pops for these areas.
250-500J/kg MLCAPE will be available this afternoon, so would
expect additional showers and thunderstorms to develop further
northwest by afternoon, especially over the Black Hills. 0-6km
bulk shear weak. Temperatures will be slightly cooler than
guidance given cloud cover.

Tonight, upper low lifts into eastern NE. Diurnal convection wanes
with spotty showers across the CWA overnight. Temperatures will
be slightly below normal.

Saturday, upper low shifts into the Great Lakes as a northern stream
shortwave moves across southwest Canada into MT, dragging a boundary
into the CWA. This boundary should be the focus for shower and
thunderstorm activity with rather weak instability. Confidence low
in how much coverage will occur, so have broad-brushed and matched
with neighbors. Temperatures will be slightly cooler than guidance.

Saturday night, boundary shifts east as weak shortwave ridge moves
in overhead allowing precipitation coverage to decrease.

.LONG TERM...(Sunday Through Thursday)
Issued at 236 AM MDT Fri May 27 2016

Persistent upper level trough over the northwest CONUS will keep
active west to southwest flow across the Northern Plains for the
Memorial Day weekend and into the middle of next week. Periodic
shortwave energy will eject out of the trough, keeping a daily
chance of showers and thunderstorms in the forecast through the
extended period. It still looks like Monday/Mon night could bring
the best chances for storms as an upper low pushes into the
region. A ridge develops over the western CONUS behind the low,
and with northwest flow over the Northern Plains, the end of next
week looks drier. Temperatures will be near seasonal averages,
with highs each day generally in the mid 60s to upper 70s. Lows at
night will be in the 40s to mid 50s.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 501 AM MDT Fri May 27 2016

Numerous showers and thunderstorms will persist across
south central SD this morning into this afternoon, with isolated to
scattered showers/storms developing across the CWA this afternoon.
MVFR to IFR conditions possible in and near any showers/storms.

&&

.UNR Watches/Warnings/Advisories...
SD...None.
WY...None.
&&

$$

SHORT TERM...Helgeson
LONG TERM...Pojorlie
AVIATION...Pojorlie


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