825
FXUS63 KUNR 171113
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
513 AM MDT Mon Jul 17 2017

.DISCUSSION...(Today Through Sunday)
Issued at 255 AM MDT Mon Jul 17 2017

Current surface map shows cold front creeping through western
South Dakota. There are a few showers lingering across northwest
South Dakota. For today, cold front makes it into central South
Dakota this afternoon. Low level moisture pooling along front will
result in MLCAPE of 1500-2000J/KG. May be a few strong storms with
damaging winds. If storms can obtain some rotation with the
marginal shear, then some larger hail will be possible. Slower storm
movement may result in locally heavy rain. While the main focus
will be along the front this afternoon, a few thunderstorms are
also possible around the Black Hills. Better chance of
thunderstorms tonight into Tuesday morning with increasing
850-700mb theta-e advection in response to right entrance region
of jet streak tracking across the Dakotas.

Front will be stalled out in northern Nebraska Tuesday afternoon
as weak high pressure slides through the Dakotas. Return flow on
back side of high will bring increasing low level moisture in to
northeast Wyoming and Black Hills area, with 1500-2000J/KG MLCAPE.
Thunderstorms will develop across northeast Wyoming and Black
Hills late Tuesday afternoon.

Area will be under flat upper ridge through the remainder of the
week. GFS/ECMWF then amplify ridge over the Rockies over the
weekend with digging trof over the Great Lakes. Forecast area will
be on western edge of northwest flow, allowing for slight cooler
temperatures with back door fronts. Isolated to scattered
thunderstorms possible each day.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 510 AM MDT Mon Jul 17 2017

VFR conditions are expected through the period. Scattered
thunderstorms will form early this afternoon over the Black Hills
and far south central SD, with better chances for thunderstorms
later in the evening and overnight across the entire area.

&&

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

$$

DISCUSSION...7
AVIATION...15