textproduct: Salt Lake City

KEY MESSAGES

- Critical fire weather conditions will occur where fuels are critically dry across southern and eastern Utah both Wednesday and Thursday during the afternoon and evening as dry and breezy conditions persist.

- A trough meandering over the Great Basin will cross Utah and southwest Wyoming Friday into early Saturday, bringing temperatures back to near seasonal normals and allowing for some showers and thunderstorms. Temperatures will warm again for early next week.

DISCUSSION

A broad low pressure system continues to wobble around the Great Basin this evening. The proximity of this low has brought a steep pressure gradient into western Utah, which brought widespread gusts to 40 mph with isolated gusts to 50 mph across the western third of Utah. Winds have started to diminish and will continue to do so this evening. Going Wind Advisory covers the threat well. Earlier showers and thunderstorms brought some periods of gusty winds, primarily for northern Utah, but these showers have also diminished considerably and should not be a threat overnight. Temperatures were on the mild side once again, particularly over northern Utah where maxes averaged 10F above seasonal normals.

The low is expected to pivot slightly eastward for Wednesday into Thursday, and the position of the low will allow drier air to advect in as gusty winds become more widespread across the area, though peak gusts will tend to decrease. This will temporarily suppress shower and thunderstorms development over the area but will bring increasing fire danger, particularly for southeast Utah. See the fire weather section of the AFD for more details.

Eventually, the low will be on the move again, tracking across Utah and southwest Wyoming. The latest suite of guidance continues to trend slower with when the system will move across the area, with the consensus now looking more like Friday into early Saturday as opposed to late Thursday into Friday. The models generally struggle with closed low features, so confidence in timing and overall impacts is lower than usual for this time period. The main impact of the low will be on temperatures, which will drop to values near or just below seasonal normals by Saturday. Anticipating some scattered convective development on Friday, but as the center of the low moves through, showers will become more widespread and focused over northern portions of the area late Friday into Saturday.

The overall consensus in guidance is to bring a slow warming trend for early next week, with most ensemble members showing a trailing system grazing northern Utah late Sunday into early morning. Beyond that, increasingly dry and warm conditions are anticipated through day seven and beyond as high pressure moves in.

REST OF UTAH AND SOUTHWEST WYOMING

Strong southerly winds will relax through the overnight hours with the exception of terminals on the lee side of significant terrain features (i.e. KCDC) where winds will continue to gust to upwards of 25-30 kts. There is around a 10- 15% chance that isolated to widely scattered showers continue across northern Utah/ southwest Wyoming through around 09-10Z Wednesday, potentially generating gusty and erratic outflow winds. Strong southerly winds resume on Wednesday across a majority of the forecast area.

FIRE WEATHER

The upper low over the Great Basin will wobble slowly east for Wednesday into Thursday. This will bring more widespread breezy conditions across the area, with drier air making its way into the area from the south. These two factors will come together to increase the fire danger, particularly over southern and eastern Utah. Given current fuel conditions, the Red Flag Warning for tomorrow afternoon and evening is limited to the Henry Mountains and Grand Staircase areas. However, there are indications that fuels over east central Utah, including the San Rafael Swell and Tavaputs Plateau, could dry out by Thursday. A Fire Weather Watch is therefore in effect for those areas for Thursday while the Red Flag Warning persists for the southeastern zones. As the low finally tracks across the area late Friday into Saturday, winds will decrease and moisture will increase. However, showers and thunderstorms will impact mainly northern Utah as the system passes. Drier and warmer conditions are expected to develop again early 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.