textproduct: Salt Lake City

KEY MESSAGES

- Wind gusts in excess of 45 mph will impact the western valleys through late evening.

- Critical fire weather conditions will occur across the Henry Mountains and Grand Staircase regions Wednesday afternoon and evening and again Thursday afternoon and evening.

- With wetting rains impacting fuels across the Tavaputs and San Rafael Swell, the potential for critical fire weather conditions will hinge on the receptiveness of fuels Thursday afternoon and evening.

DISCUSSION

A persistent upper level low will impact the Great Basin through at least Saturday. A shortwave trough rotating around this upper level low combined with mid-level moisture advection continue to support an area of convection across eastern Utah this afternoon. Looking at the few data points available in some of these areas shows three hour totals around 0.25-0.67" (heaviest at Fremont Junction and in Green River). SBCAPE values are expected to peak around 500 J/kg or so (HREF mean) this afternoon, with the highest values of deep layer shear (around 30kts or so) across the north. Main threats will continue to be microburst wind gusts to 45 mph or so and brief, heavy rain.

With a pronounced dry slot shifting into the region Wednesday, attention will then turn to critical fire weather conditions. For more information on this portion of the forecast, see the fire weather discussion.

By Friday into Saturday, the upper level low will finally shift east toward the Utah/Nevada border and lift out the region by late Saturday. Expect additional showers and thunderstorms to impact northern Utah, particularly Saturday afternoon and evening.

Unsettled conditions will continue across northern Utah through the weekend as additional shortwave troughs eject across the region associated with a very active northern stream. By early next week, however, the majority of ensemble members suggest high pressure will become entrenched across the Great Basin and Desert Southwest for much of the rest of the week, bringing a long period with little threat of precipitation. An outlier solution, represented by a significant portion of Canadian ensemble members would keep an upper level low across the Interior West, with some threat of precipitation Tuesday through Thursday.

REST OF UTAH AND SOUTHWEST WYOMING

Scattered high based convection will develop Tuesday afternoon through the evening, particularly for areas along and east of Utah's mountains. This activity will be capable of gusty and erratic outflow winds, and briefly reduced CIGS/VIS with anything that moves over a terminal. Winds at most terminals are favored to maintain a southerly directional component, aside from influence due to precipitation. Western valley terminals will also see moderate gusts through the day, generally around 25-40 mph, with some locally higher gusts possible.

FIRE WEATHER

Showers and thunderstorms with wetting rain will continue across southern and eastern Utah through this evening. Gusty southerly winds will also continue across the western Utah valleys through this evening. A pronounced area of dry conditions will shift into eastern Utah Wednesday into Thursday.

With wetting rains impacting fuels across the Tavaputs and San Rafael Swell, the Fire Weather Watch for Wednesday was canceled. Fuels in this area will be monitored for the next 24 hours or so to see if fuels are more receptive. A Fire Weather Watch remains in effect for these zones for Thursday. Across the Henry Mountains and the Grand Staircase region, wetting rains did not occur...therefore a combination of wind gusts to 40 mph with low humidities will bring critical fire weather conditions for this region both Wednesday and Thursday. A Red Flag Warning is now in effect for these areas.

As the stubborn upper level low moves out of the area Saturday, another round of showers and thunderstorms will impact portions of northern Utah Saturday afternoon and evening. Unsettled conditions will continue across northern Utah through at least late Sunday. The majority solution then shifts to a strong area of high pressure across the Great Basin through much of the next week.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Wind Advisory until midnight MDT tonight for UTZ101-115-122.

Fire Weather Watch from Thursday afternoon through Thursday evening for UTZ484-489.

Red Flag Warning from noon Wednesday to 9 PM MDT Thursday for UTZ494-498.

WY...None.