textproduct: Western and Central Wyoming

KEY MESSAGES

- Snow continues across the Bighorns, northern Johnson County, and Casper Mountain Wednesday.

- Showers Thursday and Friday but less widespread.

- Warming and dry trend over the weekend and into next week.

DISCUSSION

Issued at 106 AM MDT Wed Apr 2 2025

Areas of snow showers moving across the Wind River Basin down into eastern Sweetwater County ongoing through near sunrise Wednesday morning. The NAMNest is handling this pretty well, although other HiRes models not too far off having it dissipate by this timeframe. Otherwise, the near stationary boundary to the north will bring in another round of snow showers out of Montana along the shortwave skirting around the main upper level trough dipping to the south of the CWA. By early afternoon, the Bighorns and northern Johnson County will see continuous snow showers. Additional accumulations of higher confidence up to 4 to 8 inches (70-80%) for the Bighorns and 1 to 3 inches for northern Johnson (50-60%). As winds increase through the afternoon with the stronger gradient from the aforementioned surface boundary, expect north to northwesterly gusts up to 25 to 35 mph that will limit visibility for these stretches of interstate out of Buffalo. Mid to late afternoon, the highest snow rates across Casper Mountain as the boundary sage south, east of the Bighorns, also coupled with the stronger winds. Elsewhere, some sporadic snow showers across the Absarokas and Yellowstone, and more organized through the Wind River Basin. By 4-5PM, expect a subtle low to push a rain/snow mix through about sunset before lingering as snow into the late evening hours as it pushes southeast into Sweetwater County once again. Regardless, the showers will dissipate towards midnight lingering for Yellowstone by sunrise Thursday morning.

With the lingering surface boundary near the Montana state line, another round of developing showers by mid afternoon, mainly across the northern parts of the CWA. With a bit stronger daytime heating, some instability off the Absarokas into the western Bighorn Basin could see some isolated thunder chances with 100-200 J/kg expected. This is where the stronger of the PVA anomalies will be from the more elongated upper level trough progressing a bit further east. Coverage a bit more limited, mainly driven by daytime heating with more limited accumulations expected for the higher terrain. With the upper trough continues eastward dipped well to the south, more limited coverage for eastern counties for any shower activity Friday afternoon.

Overnight Friday into early Saturday morning, expect the main finger of the PFJ finally eject the upper trough to the east of the CWA allowing for the cold front to drop southeastward into the high plains. This will give way to the more seasonable and slightly cooler Saturday afternoon high temperatures with improved conditions expected. Strong ridging builds into the CWA from the west with increasing convergence aloft. The PFJ remains well north and eastward aiding in dry weather into next week, despite the more meridional upper level pattern. This ridge will set in place through about mid next week giving way to a warming trend, resulting in above average temperatures. A couple shortwaves look to pass to the north with the southward moving PFJ but impacts look to be limited with minor precipitation chances for northern zones Tuesday through Thursday. Otherwise, long term outlooks trend towards stronger ridging, and dryer/warmer than average conditions expected heading into the middle of the month.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1109 PM MDT Tue Apr 1 2025

The current weather continues to impact the area through the TAF period, but there will be less convective showers on Wednesday. Focus is on banded showers in the Wind River Basin to start the period, with MVFR/IFR conditions at KRIW/KLND at times. Some graupel occurred at KRIW around 03Z, so these showers are convective at times. Other terminals should remain dry tonight, with more convective snow/rain showers developing late Wednesday morning. As previously stated this convective activity will be more scattered than the previous two days. It also should not be as intense, so conditions will predominantly drop to IFR if/when showers impact terminals.

Most of these convective showers will end after sunset, but may linger at KCOD/KWRL into Wednesday evening. PROB30 groups have been continued or added for the convective showers on Wednesday due to the lower chance (20-40%) it will occur at a specific terminal. Wind will be gusty at most terminals beginning Wednesday morning and ending Wednesday right around sunset (00-02Z). Occasional mountain obscuration will occur through the TAF period.

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

RIW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 PM MDT this evening for WYZ008>010.

Winter Weather Advisory from 6 AM this morning to 6 PM MDT this evening for WYZ022.