Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 140827

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
227 AM MDT Fri Jul 14 2017

.DISCUSSION...(Today Through Thursday)
Issued at 227 AM MDT Fri Jul 14 2017

Massive western CONUS ridge will bring hot conditions to the
region the next few days. The FA will remain on the edge of the
ridge with topping impulses slated to pass through the region,
supporting ISOLD-SCT Ts at times in the region. One such impulse
will do so this afternoon at peak heating. WAA and height rises
ongoing across the region with a hot day forecast as most places
will see mid 90s to lower 100s on the plains. Lingering low level
moisture coupled with BH terrain will break the cap this afternoon
and support isold TS over the northern and central BH. Convection
should remain on the hills given capping aloft. Otherwise, weak
mid level impulse will shift east and force a sfc trough into the
western fa late this afternoon and evening. Timing at peak heating
will be more than enough to break the cap there and support sct
TS along/near the trough from NE WY into NW SD. Mean CAPE is
forecast to be marginal in the 500-1000 J/kg range in the presence
of very weak deep layer shear. This will support pulse cells with
a strong wind gust threat, esp given dry inverted V profiles. A
few isolated severe cells will be possible with wind gusts of
60-70 mph not out of the question. Have added gusty winds to TS
mention. Any convection should shift east and wane in the evening,
likely not affecting the SE half-third. Sat will see hot conds
with convection limited to NE WY and the western BH where upslope
flow and weak CIN will be in place. Convection may develop on the
WY plains, but would most likely advect in off the Big Horns. Sun
will be similar to today per temps with upper 90s and lower 100s
once again. However, capping will be much stronger with dry conds
forecast all places. Convection may clip the far NW Sunday night
as a cold front forces storms across MT, possibly advecting SE
into NW SD.

The pattern will become more unsettled next week as impulse laden
westerly flow develops. Forecast models are supporting moisture
pooling into the region as a sfc boundary stalls over the area and
wavers. Better CAPE and shear (per faster flow aloft) should
support an uptick in storms and severe chances as this occurs.
Temps are expected not to be as hot, with more seasonal readings
in the 80s and 90s.


.AVIATION...(For the 06Z TAFS Through 06Z Friday Night)
Issued At 1040 PM MDT Thu Jul 13 2017

A front will bring isolated to scattered thunderstorms mid Friday
afternoon through mid evening over northeastern Wyoming and
northwestern South Dakota. Gusty outflow winds are expected from
these storms. Otherwise VFR conditions expected through the




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