textproduct: Salt Lake City

KEY MESSAGES

- High-based showers capable of producing gusty and erratic outflow winds to 50 mph will develop across southern Utah Sunday afternoon and evening.

- The threat for thunderstorms and gusty outflow winds shifts into northern Utah Monday afternoon and evening, with additional precipitation anticipated on Tuesday.

- Temperatures dip to near seasonal normals Monday into Tuesday, but building high pressure beginning Wednesday will bring a return to very mild temperatures for Thursday and beyond.

DISCUSSION

Weak ridging is centered near the Four Corners this evening, with Utah and southwest Wyoming under a generally light southerly flow aloft. This is resulting in dry and mild conditions with just some high clouds streaming in from a low off the Pacific coast. Maxes averaged around 10F above seasonal normals today and will be just a few degrees warmer tomorrow.

The Pacific low is expected to meander eastward onshore during the day Sunday, and the strengthening southerly flow over the area will start to draw moisture and instability into the forecast area from the south. By mid to late afternoon, there will be enough instability and high based moisture for the development of scattered showers and thunderstorms over southern Utah. Given the dry lower levels, any storms that develop will be capable of producing gusty and erratic outflow winds, with a decent chance of this convection persisting past the end of daytime heating and into the overnight hours as shortwave energy lifts northward.

For Monday, the low is expected to elongate, with its position moving a dry slot into southern Utah. Northern Utah and southwest Wyoming, however, will be the focus for high based moisture and additional instability from the deformation of the low. Gusty and erratic winds will again be the primary threat with any storms that develop, with overall coverage expected to be more widespread than what is anticipated for southern Utah on Sunday. The low is most likely to track across the Desert Southwest on Tuesday, bringing additional showers and thunderstorms, primarily on the north side of the low over northern Utah. By this point, the high based moisture is expected to have spread into the mid and lower levels, decreasing the gusty wind threat at least somewhat. The passage of the low will also drop temperatures back to or just below seasonal normals for a day.

There is high confidence that the trough will track out of the area on Wednesday, bringing just a few residual showers before another broad Pacific ridge brings the return of dry and very mild conditions for the latter portion of the upcoming week.

REST OF UTAH AND SOUTHWEST WYOMING

Expect high-based showers and thunderstorms to develop across the higher terrain of southern Utah between 18-20Z. A more concerted area of showers and thunderstorms will shift into southwestern Utah near 22Z near SGU and KNB, reaching CDC and BCE between 23-01Z. Ceilings near 5000 feet and gusty, microburst winds up to 50 mph will be the most likely impact.

SLC WATCHES/WARNINGS/ADVISORIES

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