Weather Service Report


711 
FXUS65 KRIW 020310
AFDRIW

Area Forecast Discussion
National Weather Service Riverton WY
910 PM MDT Tue Jul 1 2025

.KEY MESSAGES...

- A few showers continue through around midnight tonight, with a
  few lingering wind gusts possible.

- Afternoon showers and thunderstorms chances increase beginning
  Wednesday and continuing through Friday. More widespread
  chances Thursday and Friday.

- Slow moving showers and thunderstorms producing heavy rainfall
  Thursday and Friday could result in localized flash flooding.

&&

.UPDATE...
Issued at 114 PM MDT Tue Jul 1 2025

The forecast remains on track with hot temperatures and mostly 
virga/dry thunderstorm potential this afternoon and evening. Mean 
peak 700-mb temperatures ranging from 14C-18C will continue to 
support widespread highs in the upper 80s and 90s. Locations where 
there is more afternoon cloud cover could see high temperatures a 
few degrees below what is currently forecast and vise versa. This 
cloud cover is originating from mid-level moisture being advected 
into the region by the upper-level high over the Central Rockies and 
upper-level low off the coast of California, evident on water vapor 
imagery. A weak disturbance aloft rounds the high this afternoon and 
provides support aloft, combined with sufficient daytime heating, 
for isolated to scattered convection through sunset. Convection 
initiation is focused across high elevations of western and 
central Wyoming. However, given the dry low-levels with dewpoint
depressions 40-60F degrees, most of this convection will likely
be virga showers/dry thunderstorms. Any virga showers/dry 
thunderstorms has potential to produce dry downbursts with 40-60
mph outflows. If a thunderstorm gets strong enough, a brief 
downpour could occur. Convection remains on track to dissipate 
shortly after sunset, however, lingering high based, light rain 
showers over higher elevations cannot be ruled out through 
midnight. 

The forecast remains on track for increasing shower and thunderstorm 
potential for the second half of the work week.

&&

.DISCUSSION...
Issued at 242 AM MDT Tue Jul 1 2025

June has concluded and today marks the start of July. The upcoming 
weather pattern for the beginning of July is looking warm and 
unsettled across much of the Cowboy State. Warm, above normal 
temperatures are forecast over the next few days. Daily chances for 
showers and thunderstorms are expected through the remainder of the 
week. Southwesterly flow will usher in well above normal PWAT values 
for Wednesday through Friday. Convection chances will increase 
around the same time with daily coverage becoming more widespread 
starting Wednesday.

Today, the first day of July, as mentioned earlier will be warm with 
above normal temperatures. Highs today will range from the mid to 
upper 80s west of the Divide and low to mid 90s east of the Divide. 
An upper level low moving into the Western CONUS today will be the 
key weather maker through the week. Multiple small disturbances will 
move across the area over the week bringing daily chances for 
showers and thunderstorms. Tuesday will see fairly limited 
convection being mainly isolated to scattered in nature during the 
afternoon and evening. One thing to keep in mind is that the 
atmosphere will still be rather dry, which will limit storm 
development and likely produce mainly virga showers. These showers 
and thunderstorms will be capable of producing some strong outflow 
winds due to large dewpoint depressions of 40 to 60 degrees in some 
locations, especially southern WY. Showers and thunderstorms will 
dissipate shortly after sunset.

Wednesday will see much of the same with warm above normal 
temperatures and afternoon showers and thunderstorms. The one 
difference will be the influx of well above normal moisture. The 
aforementioned upper level low over the western CONUS will aid in 
funneling moisture into the region. Models show PWAT values of 0.60 
to 0.90 inches which would be nearly 100 to 150% above normal. This 
moisture will aid in creating more widespread development of showers 
and thunderstorms. The strength of any storms that develop will 
still be fairly minimal as CAPE values only look to be around 500-
800 J/kg. Other favorable dynamics are not expected to be in place 
which should limit any strong storm development.

Thursday will see the warm and unsettled pattern continue. However, 
moisture is expected to increase further with PWATs nearing 1 inch 
translating to almost 200% above normal values. This will increase 
the chances for periods of heavy downpours as showers and 
thunderstorms develop and move across the state during the afternoon 
and evening. While storm motion is not expected to be stationary 
there will still be the potential for some isolated flash flooding 
as a result of this increased influx of moisture. The other concern 
that develops on Thursday will be increased chances for strong 
thunderstorms. These increased chances are due to higher CAPE values 
along with more favorable dynamics as a result of a leeside low 
developing over the Northern Plains. While still a few days out the 
best chances for strong thunderstorms would be across eastern WY 
including portions of Natrona and Johnson Counties.

Looking ahead towards the 4th of July, the unsettled weather 
persists with widespread chances for showers and thunderstorms. 
Temperatures will cool slightly compared to earlier in the week, 
returning to near seasonable values. Above normal PWATs linger which 
would create another day with chances for heavy downpours and 
isolated flash flooding. The best chances are currently looking to 
be across central and northern WY. These may create some 
difficulties when it comes to Independence Day celebrations. While 
the forecast is not set in stone, it is starting to look more likely 
that Friday may be quite unsettled for much of the Cowboy State.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 349 PM MDT Tue Jul 1 2025

Gusty outflow winds will continue to be a concern with any lingering 
convection through the evening. Convection should generally end 
towards sunset. BKN high clouds are expected to persist through the 
evening, but should scatter overnight, generally around 06Z to 09Z. 
Light winds (less than 8kts) will persist overnight through 
Wednesday morning. Widespread spotty showers and thunderstorms will 
then be present across the region Wednesday afternoon once again. 
All terminals with the exception of KJAC have at least a 25% chance 
of seeing shower or thunderstorms. Gusty winds would again be the 
primary threat from any showers and storms. 

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for 
the latest information on smoke, icing, and turbulence
forecasts.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Straub
DISCUSSION...Dziewaltowski
AVIATION...Hensley

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Western Regional Climate Center, wrcc@dri.edu