textproduct: Salt Lake City

KEY MESSAGES

- Isolated to widely scattered showers and thunderstorms will impact the central and southern mountains Friday afternoon into Friday evening. There is a 10 percent chance of microburst wind gusts up to 45 mph near any of these showers or thunderstorms.

- There is a 50% chance of wind gusts in excess of 45 mph across western Utah on Tuesday.

- Locally critical fire weather conditions will occur across much of southern Utah Tuesday into Wednesday in areas where fuels are critical.

DISCUSSION

The upper level low responsible for light precipitation across northern Utah and Uinta County, WY this afternoon has shifted into the central Rockies this evening. The associated front is currently across the southern third of Utah.

Utah will largely remain in northwesterly to westerly flow into Friday. A weak shortwave trough embedded in this flow will bring a threat of high-based showers and thunderstorms to mainly the higher terrain of central and southern Utah near the boundary Friday afternoon and evening. While SBCAPE values will be meager, with the HREF mean around 100-250 J/kg, deep layer shear will be around 30 kts or so. Given a relatively dry sub-cloud environment, expect a few microbursts with wind gusts up to 45 mph. This is reflected well in the latest HRRR with wind gusts fields indicating isolated microbursts with this activity. There is around a 10 percent chance of microburst winds near to above 45 mph, especially east of the terrain in communities such as Ferron, Emery, and Torrey.

Mean upper ridging will shift into the Interior West Saturday, with temperatures surging to around 10 degrees or so above normal across the region. This warming trend will continue through the remainder of Memorial Day Weekend, with temperatures reaching the mid to upper 80s across the Wasatch Front, low 90s for St George.

Guidance continues to struggle with the pattern for early to mid- next week. As a weak southern stream trough ejects across the Desert Southwest, a northern stream trough will shift into the Pacific Northwest Monday into Tuesday. Around 40% of ensemble members eventually cut-off this northern stream trough and retrograde this cut-off low westward. Around 60% of ensemble members now favor a more progressive trough, with the southern stream shortwave trough ejecting ahead of the main northern stream trough in stronger southwesterly flow. Main point is that conditions look unsettled early to midweek next week, but synoptic details remain far from certain.

REST OF UTAH AND SOUTHWEST WYOMING

Diurnally driven winds are expected across the area overnight and throughout the day Friday. VFR conditions will be the rule across northern sites. Across southern Utah, isolated afternoon convection will bring a 20% chance for gusty outflow winds exceeding 25 kts in the vicinity of KCDC after 20Z Friday.

FIRE WEATHER

Isolated to widely scattered showers and thunderstorms will develop along the stalled front across central Utah tomorrow, mainly over the high terrain. Locally gusty and erratic outflow winds cannot be ruled out with those storm. Otherwise, the rest of the area will be on warming and drying trend through the weekend with temperatures trending to about 10 degrees above average by Sunday into Monday.

There is increasing confidence in increasing southwesterly winds by Tuesday across western Utah along with low humidity. There is now about a 60% chance of critical fire weather conditions developing over western Utah by Tuesday afternoon from a combination of low humidity and wind. There is even about a 50% chance that winds will exceed 45 mph across western Utah during this period of low humidity. By Wednesday there is increasing spread in how quickly the low pressure system will track eastward, but the overall trend will be the spread the windy and dry conditions in eastern Utah by Wednesday.

SLC WATCHES/WARNINGS/ADVISORIES

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