Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS65 KRIW 231523
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
923 AM MDT Wed Oct 23 2019

.SHORT TERM...This afternoon through Thursday

Isolated to widely scattered snow showers continue over areas 
east of the Divide this morning, with isolated snow showers over 
the northwest. An inch or two occurred with the heavier showers 
early this morning, in places like western Natrona County. 
Precipitation chances will increase over the Absaroka and Wind 
River Mountains and the Wind River Basin through the rest of the 
morning and into the afternoon. This will be due to the left front
quadrant of the jet moving over northwestern/western WY today. 
This will be in addition to the continuing chances for scattered 
snow showers over the Bighorns and Johnson and Natrona counties. 
Little to no snow accumulation is expected in the lower elevations
with these showers and may even become a rain/snow mix. The best 
chances for snow accumulation (other than in the mountains) look 
to be northern Natrona County, near Midwest and Twenty Mile Hill, 
where an inch could occur. 

Gusty winds will continue across much of the area once again. Gusty 
northwest to northeast winds will occur today across areas east of 
the Divide and southwestern portions. The strongest winds will occur 
in the Bighorn Basin and northern Johnson County, where winds of 25 
to 35 mph with gusts up to 40 mph will occur. 

Snow showers will gradually end tonight, with southern portions of 
the Wind River Mountains and the Lander Foothills finally ending 
early Thursday morning. Winds will decrease across the area this 
evening, becoming light by midnight. Dry and cool conditions, with 
light winds, are expected across the area Thursday. 

.LONG TERM...Thursday night through Tuesday
Issued at 245 AM MDT Wed Oct 23 2019

Weak ridging and north-northwest flow will continue the dry weather 
with cold overnight temperatures in the teens to upper 20s Friday 
morning. The highs on Friday will be the warmest of the period 
across most of the state. Saturday will also see warmer highs, with 
morning lows rebounding as well across the region. 

The next front will move into northwestern Wyoming early Saturday 
morning before moving further south, reaching the Continental Divide 
around 00Z Sunday.  Winds will be gusty and west-southwesterly with 
the approach of the front, before switching to north to northeast 
with, and behind the front. this will keep high temperatures below 
seasonal averages on Sunday and Monday, only reaching the upper 20s 
and 30s. The pattern appears more favorable for upslope flow in the 
central basins, as the surface and 700mb low set-up shop to our 
south-southwest. While this system does not seem to tap into a 
healthy dose of Pacific moisture, there does appear to be sufficient 
moisture for at least a few inches, perhaps 2-4 inches, of 
accumulating snow Sunday and Sunday night and into Monday. The 
pattern does not look very favorable for heavy western mountain or 
valley snow. 

Models continue to disagree on the movement of this system, with the 
GFS being the most progressive. The ECMWF continues to dig the base 
of the trough into the Great Basin Sunday, before swinging over the 
Central Rockies Monday. This will be in response to a second system 
diving southward from the Bering Strait/Gulf of Alaska. That system 
could bring the first plunge of arctic air to northern Wyoming in 
the early days of the work week.

&&

.AVIATION...For the 12Z TAFS through 12Z Thursday
Issued at 245 AM MDT Wed Oct 23 2019

Light shower activity will continue for sites east of the Divide 
today. Snow showers will occur in most mountains. Areas of gusty
wind will continue today, relaxing after sunset this evening.  
Shower activity will be decreasing by 06Z with only isolated
activity after 06Z. VFR conditions will prevail at the terminal 
sites today and tonight. 


&&

.FIRE WEATHER...

Today will be a cooler day, with gusty winds at most locations. 
Snow showers will occur in the mountains today through this 
evening, ending after midnight. Scattered snow showers will occur 
at the lower elevations east of the Continental Divide today into
this evening, ending after midnight as well. Thursday will be dry
and cool, with lighter wind speeds over the area. 

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

National Weather Service Glossary of Abbreviations