Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 191053

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
453 AM MDT Thu Oct 19 2017

.DISCUSSION...(Today Through Wednesday)
Issued at 224 AM MDT Thu Oct 19 2017

Broad upper ridge covers much of the CONUS, with partly cloudy
skies over the northern plains. Surface trough stretches over the
region. Southwesterly winds are generally around 10-15 kts, and
some areas are gusting to 25-35 kts. Temperatures at 2 AM are in
the 40s and 50s.

Very warm and dry weather will continue today and Friday, with highs
in the mid 70s to mid 80s. Some locations may break records,
especially on Friday. Southwesterly winds will be gusty across
northeastern WY and south central SD both days.

An upper level trough will cross the Rockies Friday night with a
cold front. South central SD may see some light rain showers Friday
night into Saturday, but most places will remain dry. Northwest
winds will become strong, especially across northwestern SD, and
highs will cool to the 50s and lower 60s. Sunday will be dry and
warmer as upper ridging builds behind the trough. However, a fast-
moving wave Sunday night could bring another chance for light
rain/snow to the area into Monday. Models are still showing another
upper ridge building over the west coast early to mid week; however,
they disagree towards the end of next week regarding the timing of
another upper wave and potentially much cooler air.


.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 451 AM MDT Thu Oct 19 2017

VFR conditions will continue through the period. Gusty south-
southwest winds will develop over northeastern Wyoming and south
central South Dakota today. The gusty winds will continue tonight
across northeast Wyoming. Low level wind shear is expected across
the plains of western South Dakota tonight.


Issued At 224 AM MDT Thu Oct 19 2017

Minimum RH will be very low today, ranging from 10%
across northeastern WY to 25% across south central SD. Gusty
southwest winds are expected to develop across northeastern WY, as
well as the Black Hills this afternoon. With 10-15% RH and frequent
gusts of 25+ mph across northeastern WY and the Black Hills, have
issued a Red Flag Warning for this afternoon. Min RH values should
be slightly higher on Friday, but winds will be stronger, so may
need to reassess the potential for headlines on Friday.


SD...Red Flag Warning from 11 AM this morning to 6 PM MDT this
     evening for SDZ260-262.

WY...Red Flag Warning from 11 AM this morning to 6 PM MDT this
     evening for WYZ259-297>299.



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