Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
140 FXUS65 KRIW 031103 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 503 AM MDT Wed Jul 3 2024 .KEY MESSAGES... - Scattered rain showers and thunderstorms Wednesday afternoon with severe weather possible across the Bighorn Basin and Johnson County. Large hail and gusty outflows the main concerns. Elevated fire weather risk across the southern half of the CWA. - More isolated rain showers and thunderstorms Thursday afternoon, but severe weather is not expected. - Mainly dry and a warming trend into the weekend and next week with increasing fire weather concerns moving forward. && .DISCUSSION... Issued at 1224 AM MDT Wed Jul 3 2024 IR currently depicts mainly clear skies through much of the CWA with some mid level clouds for northern parts along the Montana state line. This is where some weak rain showers are currently that will push east and dwindle through the early Thursday morning hours. Another shortwave will push through by late morning that will increase the gradient to 6-7mb across the state leading to some gusty winds, especially for areas along the I-80 corridor up to 30-40 mph likely. Points north should see 15-25 mph during peak heating of the afternoon before diminishing towards sunset and into the overnight hours. By noon to 1PM Thursday afternoon, isolated thunderstorms will develop off the Absarokas and push into the Bighorn Basin becoming more widely scattered by mid afternoon around 3-4PM. Some gusty outflows and larger hail are possible with the main concern for Johnson County after around 5PM. This is where the better ingredients are located. CAPE values over 600-700 J/kg and wind shear up to 35-40kts, along with better low level moisture as well. The weak surface boundary will help aid in the lift off the Bighorns after this time through the evening hours before pushing to the east by 8PM or so. Overall, a marginal severe afternoon is projected with Johnson County once again the area to watch as per usual. Some isolated thunderstorms possible further south along the front with most CAMS depicting activity staying north of Riverton to Casper with low confidence (20%) for anything that far south. Otherwise, points to the south, elevated fire weather concerns will be had during the afternoon and early evening hours. Behind the weak cold front, expect slightly cooler temperatures for the Fourth with only 70s east of the Divide and 60s to the west. A weaker shortwave is projected during the afternoon Thursday that will see more of an isolated scenario across northern portions of the CWA once again for the same area, but severe weather is not expected at this time. Weaker winds and cooler temperatures will see good fire weather conditions for fireworks later that evening and into the nighttime hours. Friday and into the weekend through much of next week, expect mainly dry conditions with a warming trend in store through the long term forecast. Higher heights centered to the southwest will build greatly during this time period with increasing convergence aloft extending ridging into the upper Rockies. With this, will come a weaker upper level flow allowing for only some isolated higher terrain airmass storms to develop each afternoon with some possible outflows to the lower terrain. No impacts expected except for increasing drought and fire weather concerns going forward through the month of July. Longer term outlooks show warmer and dry than average conditions going forward not looking too well going forward in these areas. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 501 AM MDT Wed Jul 3 2024 Gusty winds return across the state today, with frequent gusts above 30kts at most sites, especially KBPI/KPNA/KRKS. More numerous showers and thunderstorms will build up across northern WY in the afternoon, with gusty winds and lowered cigs possible at KCOD/KWRL/KGEY/KBYG. The chance of any convection at KRIW and KLND remains less than 1 out of 6, so have kept any precip notes from TAFS at KRIW and KCPR. Precip will end early evening with loss of daytime heating, but gusty winds will likely continue until 06Z/Thu. && .FIRE WEATHER... Issued at 1224 AM MDT Wed Jul 3 2024 Elevated fire weather concerns for southern areas along the I-80 corridor and extending through Fremont and Natrona Counties Wednesday. Winds will be strongest for Sweetwater county with westerly winds gusting up to 30-40 mph through peak heating of the afternoon. Points north will see breezy conditions 15-25 mph. Relative humidity values will drop into the 10-15 percent range for this entire area but with green-up conditions continuing, only an RFD will be issued from noon Wednesday through the afternoon and early evening hours. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Lowe AVIATION...Hattings FIRE WEATHER...Lowe