Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 201644
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1044 AM MDT Fri Oct 20 2017

.DISCUSSION...(Today Through Thursday)
Issued at 321 AM MDT Fri Oct 20 2017

Upper ridging continues across the eastern two thirds of the CWA
with a trough moving onshore the Pacific NW coast. Southwest flow
aloft dominates the central Plains. Surface low pressure is
strengthening ahead of the Pacific trough across western Canada
into Montana. Gusty southwest flow over the High Plains will
continue to bring much warmer than average temps to the area today.
Highs will reach the 70s to mid 80s. Upper trough will quickly
approach today into tonight. Surface low will transition into ND
tonight with a strong cold front crossing the area late tonight.
Gusty southwest winds will switch to the northwest with the frontal
passage. Could see some showers develop overnight with the boundary
pushing through...but overall QPF will be light. Drier and cooler
weather is expected Sunday with breezy northwest winds continuing.
Highs will be in the 50s to low 60s. Main upper flow will be north
of the CWA late Sunday...and next shortwave will bring some energy
southward into the northern Plains. This will bring some chances of
showers to mainly southern/southwest portions of the CWA into Monday
morning. Upper ridging will keep the area dry through the middle of
the week with warming temperatures. Cooler and more active
weather will be possible afterward.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1041 AM MDT Fri Oct 20 2017

VFR conditions will continue through the period. Gusty southwest
winds will be found across most of the area today. A strong cold
front will slide across the area this evening into the overnight
hours, with gusty northwest winds behind the front. Winds will
become northwesterly behind the front. A few showers are possible
behind the front, especially east of the Black Hills.

&&

.FIRE WEATHER...
Issued at 321 AM MDT Fri Oct 20 2017

Minimum RH will be very low again today, ranging from 15% across
northeastern WY and western South Dakota to 25% across south
central South Dakota. Gusty southwest winds are expected to re-
develop across northeastern WY, as well as the Black Hills and far
western South Dakota. Low RH and frequent gusts of 25+ mph are
expected across this area along with a strong cold frontal
passage Friday evening. Red Flag Warning headlines will be
expanded eastward.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until midnight MDT tonight for SDZ260>264.

WY...Red Flag Warning until midnight MDT tonight for WYZ259-297>299.

&&

$$

DISCUSSION...13
AVIATION...Johnson
FIRE WEATHER...13



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