textproduct: Salt Lake City

KEY MESSAGES

- As temperatures climb through Saturday, the threat for heat- related illness increases for those who are sensitive to heat, without adequate cooling or hydration, or have chronic health conditions.

- More widespread critical fire weather conditions develop across central and southern UT Saturday, lasting through at least Wednesday as widespread wind gusts look to develop statewide.

- The threat for isolated to scattered dry thunderstorms capable of strong to severe wind gusts and isolated lightning exists tomorrow across northern UT. This will result in a conditional fire weather risk for northern UT as well.

- Given preceding dry conditions and gusty conditions, blowing dust is expected across much of UT and southwest WY tomorrow afternoon.

DISCUSSION

Today, generally benign conditions persist as height rises gradually build into the region. Modest surface winds with diurnal shifts are expected with clear and sunny skies for the rest of today.

Starting tomorrow, confidence regarding the fire weather threat across central and southern UT continues to increase as a deepening midlevel trough progresses toward the Great Basin. A strengthening pressure gradient amidst strong mixing favors strong winds translating to the surface out of the southwest. Chances for gusts greater than 30mph range from 50-80% across most central and southern UT valleys on Saturday and 90%+ across southwest UT. Additionally, chances greater than 40mph remain around 20-40% across most of southern and central UT with 60%+ across southwest UT. With poor overnight recoveries and widespread single digit humidities Saturday afternoon, critical fire weather conditions will exist across central and southern UT Saturday.

On both Saturday and Sunday, there is at least some potential for isolated scattered dry thunderstorms with attendant strong to severe microbursts. Widespread PVA amidst height falls and inverted-V soundings across northern UT may favor the development of these storms across northern UT Saturday afternoon. Lightning is also possible with these storms in the presence of some instability aloft, potentially yielding a more localized fire weather threat across northern UT Saturday afternoon with lightning probabilities maxing out around 15%. The threat shifts more toward central UT on Sunday as multiple shortwave perturbations traverse across the state, serving as ascent for these storms. There is high uncertainty surrounding an initiation signal at this time for Sunday afternoon, though hazards would remain similar to the storms on Saturday if they do form.

On Sunday across southern and central UT, a frontal boundary will slowly move east with time keeping the gusty wind threat more confined to southeast UT. Critical fire weather conditions will remain in place across central and southern UT, though winds are expected to taper off with a midlevel trough lifting north of the area displacing synoptic wind support from the region somewhat. Despite this, confidence continues to exist regarding critical fire weather conditions due to ample coverage of expected wind gusts greater than 30mph (greater than 60% chance) and humidities in the single digits to low teens.

Monday and Tuesday, however, bring a somewhat different fire weather setup. While humidities may rebound somewhat into the low teens, there is high confidence in widespread winds greater than 30mph across central and souther UT (generally 60-90%+). Additionally, the signal for gusts greater than 40mph is relatively widespread, ranging from 40-60% and increasing somewhat with eastern extent. In particular, this signal is most pronounced on Tuesday when the midlevel pressure gradient tightens with the eastward progression of a midlevel trough across the Great Basin. Lastly, there is also some signal for dry thunderstorms once again on Tuesday, though exact location is extremely uncertain at this time.

Wednesday will bring another round of fire weather conditions to central and southern UT, though somewhat muted compared to the prior two days as a frontal boundary will begin progressing through the region as the midlevel trough begins to lift away from the forecast area. There is some potential that near-critical fire weather conditions extend past Wednesday, though high uncertainty surrounds this.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions prevail for all regional terminals, with generally clear skies across the southern airspace and increasing mid to high level clouds across the northern airspace. Generally light diurnal winds are expected through this evening, gradually increasing out of the south to southwest early in the morning, with widespread gusts 20-30 kts through the evening.

FIRE WEATHER

High confidence exists with a prolonged period of critical fire weather conditions developing this Saturday, lasting through at least Tuesday due to a combination of gusty winds and very low humidities with poor overnight recoveries. Widespread gusts from 30-40mph will develop across central and southern UT starting tomorrow with poor overnight recoveries keeping humidities in the single digits to low teens. A cold front will sweep the area by Sunday morning, pushing the threat more toward southeast UT, though gusty winds in excess of 30mph and low humidities will still exist across central and southern UT.

On Saturday and Sunday afternoons, an isolated to scattered threat of dry thunderstorms will exist starting with northern UT on Saturday. Gusty and erratic strong to severe wind gusts will be possible with any storm that forms as well as occasional lightning (15% chance). The dry thunderstorm threat shifts to central UT this Sunday, though uncertainty regarding storm formation exists and will be ironed out in future forecasts.

On Monday and Tuesday, coverage of wind gusts increase with a higher signal for gusts greater than 40mph. Confidence in this occurring is particularly high, given the signal for gusts greater than 40mph ranges from 40-60% at this time with very low humidities.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Red Flag Warning from 6 AM Saturday to 10 PM MDT Sunday for UTZ484-489-492>498.

Fire Weather Watch from Sunday evening through Wednesday evening for UTZ484-489-492>498.

WY...None.