Area Forecast Discussion
Issued by NWS Riverton, WY
FXUS65 KRIW 121648
Area Forecast Discussion
National Weather Service Riverton WY
948 AM MST Sun Feb 12 2017
.SHORT TERM...Today through Tuesday night
Imagery shows split flow across the west with a deep closed, nearly
cut-off, low and associated trof helping in separating air-masses
centered over southern California. Upper trof that moved through the
FA Saturday is now east of WY moving over the northern and central
Plains. Ridge upstream coming into the PAC NW. SFC has high pressure
across the NW Quad of the CONUS (including WY), with low pressure
and a front well to the east and south moving into the southern
Plains. No precip falling anywhere across WY this morning.
After a cold start to the day, most of the rest of the forecast
will remain seasonal or on the cool side of seasonal, with
relatively light SFC winds and low flow aloft. With little
moisture and no good upper level forcing...few clouds and no
precipitation is expected through the end of the forecast period.
Near the very end of the forecast period, strong upper level
ridging and building high pressure will be in place across the
Great Basin with lower pressure off over the High and Northern
Plains and a decent P GRAD starting to grow between the two along
the Continental Divide. This may produce some gusty southwest
winds across the usual areas Tuesday night.
.LONG TERM...Wednesday through Sunday
Dry Wednesday and Thursday. Breezy to windy areas on Thursday. A
weather system spreads some snow into the west late Thursday
night. This system passes through the Northern Rockies Friday and
exits Fri night. A chance of snow in the mountains with areas of
rain and snow for the west and north Friday. Saturday afternoon
and night look unsettled as well with a south southwest flow
aloft and a weather disturbance in the flow. GFS model is stronger
with this than the ECMWF model. Will have a chance of rain and
snow for now and see how things evolve over time. Next Sunday will
continue with a moist south southwest flow aloft. Seems like the
west and south would see the best chance of precipitation with
less coverage in the north and east. Again will have to see how
the weather pattern next weekend unfolds with time. Temperatures
will stay on the mild side Wed and Thurs, then gradually colder
from Fri through next Sunday.
High pressure both aloft and at the surface will bring prevailing
SKC conditions through 06z Monday. A weak cold front will push
some mid and high level clouds south across north and central
Wyoming Sunday night with no significant impacts to aviation.
Patchy morning fog will again be possible Monday morning, partially
obscuring terrain in the lower river valleys through 16z.
Fire Danger low for all of WY through the next week as a good
existing snow pack will combine with seasonal to below seasonal
temperatures and less wind to keep fire danger low for most of the
next week. Smoke dispersion poor through Tuesday.