textproduct: Salt Lake City

KEY MESSAGES

- Moisture remains in place across southern UT tomorrow afternoon resulting in more widespread thunderstorms. Strong to potentially severe wind gusts with isolated flash flooding appears possible with these storms.

- Hot and dry conditions develop Monday as high pressure builds over the region. Widespread valley HeatRisk values develop across valley locations, particularly Tuesday and Wednesday.

- Critical fire weather conditions return to UT Tuesday and Wednesday as winds pick up out of the northwest.

DISCUSSION

Currently, a midlevel shortwave trough is progressing southeast across the MT/ID border with another weaker shortwave stalled over the CA coastline providing persistent SW'erly flow across southern UT. With time, these two waves will phase together into tomorrow afternoon. Showers and thunderstorms will persist in some capacity across southern UT into central UT keeping the airmass moist and reinforcing a thermal boundary further north. This moist and unstable airmass will favor thunderstorm development across central and southern UT tomorrow afternoon as midlevel ascent increases with the troughs phasing together as they move southeast. With CAPE on the order of 500-750J/kg amidst steep 0-3km LR's and DCAPE in excess of 1200J/kg, strong to severe gusts and potentially small hail cannot be ruled out with any storm that forms. Additionally, PWATs ranging from 0.6-0.9" may yield a localized flash flood threat for any slow-moving or terrain enhanced storms. High LCL's on the order of 2500m+ yield some uncertainty with how much precip will make it to the ground, though storm coverage may compensate and moisten the PBL potentially resulting in training storms yielding a heightened flash flooding threat.

Overnight into Monday morning, a dry front will traverse the state as midlevel ridging begins to nudge into the area. Some residual moisture may result in some terrain driven thunderstorms across central and southern UT Monday afternoon, though these will be quite transient and isolated at best.

Throughout the remainder of the period, an upper jet will progress south from Canada into the central plains, establishing a persistent troughing pattern across the central and eastern U.S.. This will keep much of the west underneath a building ridge, amplifying across each passing day. Hot and dry conditions are forecast to develop once again through the long term, potentially persisting into Saturday and beyond. HeatRisk will see an increase as this occurs, with the highest confidence of heat related issues developing Tuesday and Wednesday as HeatRisk enters the moderate range across most valleys.

Additionally, as ridging builds in and tightens the pressure gradient Tuesday and Wednesday, midlevel northwesterly winds are forecast to see an enhancement. Given preceding dry conditions, these winds will mix to the surface with enhanced dry northwest winds overspreading much of UT Tuesday through Wednesday. As such, critical fire weather conditions are expected to return to the state Tuesday and Wednesday afternoons due to gusty surface winds.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions are expected to prevail through the overnight hours across the airspace with generally light and terrain driven winds. A few showers and thunderstorms are expected to continue over portions of southwest Utah during the overnight and early morning hours, with a low chance of gusty winds. Scattered showers and thunderstorms are then expected to develop over southern Utah during the afternoon. Gusty winds will be possible with any storms that develop along with a low chance of brief MVFR conditions in heavier showers.

FIRE WEATHER

High based showers and dry thunderstorms will continue across southern Utah into the evening hours. West of I-15 showers and thunderstorms moving out of Nevada will be capable of producing wetting rain this evening across zones 495, 497, and perhaps western portions of zone 496. Meanwhile areas further north will remain dry and mild through the remainder of the afternoon and evening.

Moisture will increase across southern Utah Sunday bringing another round of showers and thunderstorms across southern Utah. Wetting rain will be likely with these storms along with lightning and gusty outflow winds. North of I-70, isolated high based showers and dry thunderstorms will impact mainly the higher terrain of central and perhaps northern Utah Sunday afternoon.

High pressure will build into the region for much of next week bringing a return to hot and very dry conditions. By Tuesday daytime RH will fall into the single digits across most low-mid elevations, with poor overnight recovery below 30 percent. This high will remain centered to the west of the area through midweek, resulting in gusty northwest winds across areas east of I-15 as early as Monday afternoon, but more likely and widespread Tuesday and Wednesday. These winds coupled with the hot and very dry conditions will result in critical fire weather conditions Tuesday and Wednesday anywhere fuels are sufficiently dry east of I-15.

SLC WATCHES/WARNINGS/ADVISORIES

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