Scientific Forecaster Discussion
fxus65 kriw 202320
Area forecast discussion
National Weather Service Riverton Wyoming
issued by National Weather Service Billings Montana
520 PM MDT Fri Sep 20 2019
Short term...tonight through Sunday night...
A strong upper low will move over the forecast area tonight into
Saturday. This will bring scattered showers and thunderstorms this
evening becoming isolated late this evening. Snow will be likely
through noon Saturday for the western mountains with significant
Expect just light showers during the day Saturday with the
activity decreasing during the day. High pressure ridging will
build over the forecast area Saturday night into Sunday night.
This will result in dry conditions along with warmer temperatures.
High temperatures will be cooler Saturday with mainly 50s and 60s
for the lower elevations. Temperatures will be slightly warmer
Sunday with 60s to around 70 degrees.
Long term...Monday through Friday...
A split flow aloft will be over the forecast area Monday with
more of a zonal flow Tuesday and Wednesday resulting in dry
conditions and seasonal temperatures. An upper low moves southeast
out of the Pacific northwest Thursday and across the northern
rockies Friday. This will provide an unstable southwest flow aloft
on the Thursday with a chance for showers and isolated
thunderstorms. The system will bring in cooler temperatures and
better chances for showers on Friday along with higher Elevation
Partly to mostly cloudy skies will prevail through tonight.
Scattered showers and isolated thunderstorms can be expected
through 02z with isolated showers for the remainder of the night
through Saturday morning. Expect MVFR conditions in any
shower/thunderstorm activity. Otherwise, VFR conditions will
prevail through the night. The mountains will be obscured
throughout the night with heavy snow likely.
Showers and isolated thunderstorms will continue through the
evening with the showers becoming more isolated after midnight.
Expect cooler temperatures along with a chance for showers
Saturday. Expect warmer and drier conditions on Sunday. Afternoon
humidities will be above 30 percent for the lower elevations
Saturday and mainly in the 20 to 35 percent range Sunday.
Winter Weather Advisory until noon MDT Saturday for wyz001-002-