textproduct: Salt Lake City

KEY MESSAGES

- High temperatures trend a few degrees cooler today, but overnight temperatures remain elevated across the region, yielding continued heat health impacts through Tuesday morning.

- A monsoonal surge has brought deep moisture across central and southern Utah today, and will become widespread across the region by Tuesday.

- Temperatures will gradually become cooler through the week with a daily threat for showers and thunderstorms capable of producing locally heavy rainfall through the remainder of the week.

DISCUSSION

The strong ridge that brought us anomalously hot temperatures across the region yesterday has shifted east and is currently centered across the Dakotas. Southerly flow on the western periphery of this ridge has brought an influx of deep monsoonal moisture, especially across central and southern Utah this afternoon. This increasing moisture and attendant overspreading of clouds across the region has resulted in temperatures cooling a few degrees for most of the area this afternoon. A hot day is still in store for many across northern Utah and southwest Wyoming with highs 100-105 degrees for many lower valley locations and 95-100 across higher valley locations. This increased cloud cover will also result in very warm overnight lows across the region, which will exacerbate heat impacts through at least Tuesday morning, especially for those without adequate cooling or hydration.

Afternoon convective development will kick off this afternoon across portions of central and southern Utah as PWATs rise to 0.8-1.2 inches across the area from the monsoon surge. Initiation of storms is favored along the high terrain of the central and southern Utah mountains, with coverage gradually expanding northwest through the evening. Storms taper off by the late evening. Any cells that develop through this evening will be capable of producing locally heavy rainfall capable of producing isolated flash flooding. Areas of highest concern include recent burn scars (including the Cottonwood Fire), normally dry washes, slot canyons, and steep terrain. Those outdoors this afternoon across the area should have multiple ways to receive warnings in case a flash flood threatens your area.

Deep monsoon moisture becomes widespread across the entirety of Utah and southwest Wyoming on Tuesday, which will result in even more widespread coverage of showers and thunderstorms. Again, storms will be capable of producing locally heavy rainfall. This deep moisture will linger across the region into at least this weekend as the ridge remains stoutly in place through the period. As such, expect continued chances for widely scattered showers and thunderstorms with an increased risk for flash flooding each day through this week areawide.

AVIATION

KSLC...VFR conditions are expected throughout the TAF period, although visibility may be occasionally reduced slightly due to smoke from nearby wildfires. West to northwest winds will return to southeast around 03Z. There is a 20% chance outflow winds gusting to 25 kts push into the terminal from the south during the 00-03Z timeframe.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered afternoon showers and thunderstorms will develop across southwest Wyoming as well as areas south of I-80 this afternoon, developing across high terrain areas and then drifting off to the northwest. Showers and thunderstorms will be accompanied by gusty outflow winds and lightning. Aside from this, winds will largely follow a typically diurnal pattern at area terminals. Conditions expected to remain VFR through the period, though any stronger storm directly atop a terminal may result in brief reductions to CIGS/VIS. Smoke from nearby wildfires will result in a hazy sky across northern Utah, and occasional, slight reductions in visibility.

FIRE WEATHER

Hot and overall dry conditions prevail across most of northern Utah today, though humidity will trend upward as monsoon moisture continues to spread northward. Deep monsoonal moisture is already in place across central and southern Utah, which will allow for widely scattered showers and thunderstorms to develop this afternoon. Convective development favors the central and southern mountains, with coverage gradually expanding northwest through the evening. Localized flash flooding will be the main threat from any storms that develop today, with main areas of concern being recent burn scars, normally dry washes, and steep terrain. As deep monsoon moisture becomes widespread across the state on Tuesday, daily chances for widely scattered storms capable of producing localized flash flooding will continue each afternoon and evening through the remainder of the week.

SLC WATCHES/WARNINGS/ADVISORIES

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

WY...Extreme Heat Warning until 9 PM MDT this evening for WYZ021.