Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

FXUS63 KUNR 220511

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1111 PM MDT Fri Oct 21 2016

.SHORT TERM...(This Evening Through Saturday Night)
Issued at 252 PM MDT Fri Oct 21 2016

Current surface analysis shows low pressure over south central
Canada, with a surface trof stretching south through the western
Dakotas. A cold front extends southwest from the low across
northeast and central MT. Breezy northwesterly winds have
developed across the western SD plains behind the trof. Upper
level analysis shows ridge over the western US, with large scale
trof over the Great Lakes region. Some high clouds are passing
overhead, otherwise mostly sunny skies with temps in the 60s and
lower 70s this afternoon.

Mainly quiet weather to continue into the weekend, though there will
be some fire weather concerns Saturday afternoon from portions of
northeast WY to southern SD. Models are in good agreement through
the short term period. For tonight, skies will remain mostly clear
with winds decreasing around sunset. Lows will mostly be in the mid
30s to mid 40s.

Low pressure will develop along the front over MT later tonight and
Saturday, with winds turning south to southwest and increasing on
Saturday ahead of it. Highs will be slightly warmer than today,
especially to the south and east of the Black Hills, mid 60s over
far northwest SD and the Black Hills to the upper 70s over far
southern SD. The dry cold front will move through during the
afternoon and early evening hours, with breezy conditions in some
areas ahead and behind it. High pressure will settle over the
Northern Plains overnight, with light winds and lows in the 30s and
lower 40s.

.LONG TERM...(Sunday Through Friday)
Issued at 252 PM MDT Fri Oct 21 2016

Eastern pac troughing will persist through the period as fast
westerly disturbed flow over the northern pac supports trough re-
loading there. This will continue to support downstream mean
ridging. Flow will remain progressive with periodic disturbances
ejecting out of the persistent trough. This will support mild
weather in the period, esp ahead of each impulse in sw flow, with
50s-70s for highs and 30s/40s for lows. Mean storm track looks to
remain just north of the fa, which supports dry weather locally.
The only concern in the period will be fire weather with very dry
westerly flow and potentially breezy conds at times.


.AVIATION...(For the 06Z TAFS Through 06Z Saturday Night)
Issued At 1110 PM MDT Fri Oct 21 2016

VFR conditions are expected through the period. LLWS due to a
30-40kt low level jet will occur on the SD plains overnight into
Saturday morning. Gusty winds make it to the surface by Saturday
afternoon across the south.


Issued At 252 PM MDT Fri Oct 21 2016

Dry westerly flow will develop over the area on Saturday. Minimum
relative humidity values will be low over much of the CWA. The
driest locations are expected to be across parts of northeast
Wyoming...and southwest to south central South Dakota especially
southwestern SD and parts of northeastern WY where the minimum
relative humidity will reach 15 percent or lower. Westerly winds
of 15 to 25 mph with higher gusts are also likely there. These
conditions will produce critical fire weather conditions Saturday
afternoon. A Fire Weather Watch and red flag warning has been


SD...Fire Weather Watch Saturday afternoon for SDZ262-264-265.

     Red Flag Warning from noon to 6 PM MDT Saturday for SDZ263.

WY...Red Flag Warning from noon to 6 PM MDT Saturday for WYZ259-298.



FIRE WEATHER...JC is the U.S. government's official web portal to all federal, state and local government web resources and services.