textproduct: Salt Lake City

KEY MESSAGES

- A storm system moving through northern Utah Saturday will bring more widespread coverage of showers and thunderstorms, especially along and east of the I-15 corridor. In addition to the potential for gusty winds, these storms will bring the threat of flash flooding to any rain sensitive areas over which they track.

- Southerly winds will remain elevated on Saturday, with a 20 to 30 percent chance of wind gusts in excess of 40 mph over the West Desert. The approach of a second storm system will increase winds further for Sunday, with a 60 to 80 percent chance of West Desert winds exceeding 40 mph.

- The storm system will bring unsettled conditions Sunday into Tuesday bringing much cooler temperatures as well as periods of valley rain and accumulating mountain snow.

DISCUSSION

A broad storm system is moving onshore along the California coast this evening, putting Utah and southwest Wyoming under a breezy southwest flow aloft. This flow is drawing enough moisture northward for the development of scattered showers and thunderstorms early today, with many of these storms producing gusty winds, some in excess of 40 mph. A few light showers remain and will continue to dissipate into the overnight hours.

The California trough is on track to weaken significantly as it moves onshore, eventually crossing northern Utah Saturday afternoon and evening. The flow aloft is no longer expected to increase much with the passage of the trough, so the potential for wind gusts in excess of 40 mph has dropped to the 20 to 30 percent range. While it would not be surprising to see isolated gusts in excess of 40 mph, the areal extent and anticipated duration of these winds would not warrant a Wind Advisory. Associated showers and storms will be a bit more widespread compared to the last couple of days, but the best coverage will be confined to areas east of I-15, primarily over northern Utah. Still, any storms that move over rain sensitive areas could bring the threat of flash flooding.

As the weakening system exits the forecast area, another broad low will approach the California coast. Guidance appears to be converging on a solution for this low that would slowly track it across the Great Basin and eventually into Utah and southwest Wyoming Sunday into early Tuesday. There is high confidence that this will bring substantial cooling to the area, with highs below seasonal normals by Monday. The storm and associated cold front will also bring unsettled conditions and the potential for accumulating mountain snow, though totals overall look a bit less impressive than they have the past couple of days. This is because the system ultimately becomes a bit moisture starved and more guidance is showing the system weakening somewhat as it moves through, though not to the extent of the first system.

A drier zonal flow is expected to develop for the midweek period, but long range guidance is showing the potential for a colder storm system impacting the area by late in the work week, bringing a chance of snow for most valleys as well as the mountains for day seven.

REST OF UTAH AND SOUTHWEST WYOMING

Winds have been calming this evening and will continue to be from a a generally southerly direction overnight. Saturday will see a shift to the southwest with a return of gusty winds again as this shift occurs. Scattered rain showers will be starting mid morning into the evening mainly east of the Wasatch. Some chance for thunderstorms as well in the afternoon and evening.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.