textproduct: Salt Lake City

KEY MESSAGES

- After a historically hot day, temperatures will become less hot tomorrow, averaging 5-10F above seasonal normals.

- Temperatures will gradually become less hot through the week as monsoonal moisture moves into the area. This will increase the threat of precipitation and thus flash flooding, particularly over southern Utah, throughout the week.

DISCUSSION

A strong ridge is centered over the Dakotas this evening, putting Utah and southwest Wyoming under a rather hot southerly flow aloft. The presence of this ridge resulted in historically hot temperatures for northern Utah and southwest Wyoming today, with Salt Lake City setting a new all-time record high at 109F. Other locations such as a Logan, Park City, and Duchesne at least got close to setting monthly and all-time records as well, but will need to wait for morning reports to come in to confirm. The 00Z sounding also showed the hottest 700mb temperature for SLC on record with a value of 21.0C.

The southerly flow has already started to draw moisture into southern Utah, with satellite derived PWs showing values up to 0.8 inch. This moisture allowed for the developed of strong to severe showers and thunderstorms over southwest Utah, one of which brought severe gusts to Cedar City airport and another one which knocked a large tree branch onto a road in Zion National Park. The monsoonal moisture will continue to increase and spread northward through Tuesday, with guidance indicating widespread PW values in the 0.8 to 1.2 inch range across all but northeastern portions of the area by Tuesday afternoon. This moisture combined with daytime heating and some embedded shortwave energy will bring increasing coverage of showers and thunderstorms, primarily over the higher terrain. Best coverage will be over southern Utah, particularly tomorrow, though there will be at least some possibility of showers across the area by midweek.

For the middle to latter part of the week, guidance indicates that the flow aloft will most likely become generally light and variable due to the influence of the rebuilding broad ridge. This will limit the advection of additional moisture into the area, but will allow the existing moisture to remain in place for the remainder of the week into early next week. Thus, the threat of precipitation will continue, continuing to decrease the potential for wildfires but keeping the potential for flash flooding heightened.

AVIATION...KSLC

The SLC terminal will see VFR conditions through the night with some high clouds. Southerly winds are expected to shift to the northwest between 18Z and 20Z. There is a 20 percent chance that outflow winds from nearby thunderstorms will produce periods of gusty and/or erratic winds late tomorrow afternoon into the early evening.

REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR conditions through the night. High clouds will dominate over northern Utah, with some lower clouds over west central and southwest Utah in association with thunderstorms. These storms are most likely to diminish around 06-08Z or shortly thereafter. Additional showers and thunderstorms will develop tomorrow afternoon into the evening, primarily focused over the higher terrain of southern Utah. Any storms that develop have a medium chance of producing gusty and erratic thunderstorms winds, and a low chance of brief visibility restrictions in heavier showers.

FIRE WEATHER

Southerly flow has already brought some monsoonal moisture into southern Utah this evening, and the influx of moisture and spread northward across the remainder of the state will continue through Tuesday. This will bring somewhat less hot temperatures, increasing relative humidities with improved overnight recoveries, and an increasing chance of wetting rainfall. The moisture is expected to remain in place for the remainder of the week and into early next week, acting to decrease fire danger but increase the threat of flash flooding, particularly over southern Utah.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Extreme Heat Warning until 6 AM MDT Tuesday for UTZ101>108-114- 116-118>121.

Extreme Heat Warning until 6 AM MDT Monday for UTZ115-122- 128>131.

WY...Extreme Heat Warning until 9 PM MDT Monday for WYZ021.