textproduct: Salt Lake City

KEY MESSAGES, Issued 1137 AM MDT Wed Jul 8 2026

- High based convection will again develop this afternoon, primarily over northern portions of the forecast area. Any storms that develop will be capable of producing strong outflow winds to 60 mph.

- Gusty winds and low relative humidity will combine to produce areas of critical fire weather conditions during the afternoon and early evening. Critical fire weather conditions will continue Thursday over southern Utah.

- A notable heat wave will develop over the weekend with high temperatures challenging daily and monthly records Saturday and Sunday. Most valleys and some mountain valleys have a greater than 60 percent chance of seeing HeatRisk values in the red (major) range, bringing an increased chance of heat related illnesses.

- Confidence is increasing the monsoonal moisture will move into the area by the middle of the upcoming week.

DISCUSSION, Issued 1137 AM MDT Wed Jul 8 2026

High pressure is centered roughly near the Utah/Colorado border late this morning, putting Utah and southwest Wyoning under a breezy west to southwest flow aloft. High based moisture remains in place over northern Utah, while drier air advects in from the southwest. High temperatures will stay on the mild side with maxes running up to 5F above seasonal normals.

A weak shortwave is expected to move through the ridge and across northern portions of the forecast area late this afternoon into the evening, with the feature looking a bit better defined than the one that moved through yesterday. Overall, seeing less in the way of shear compared to yesterday, but a bit more CAPE, up to 500 J/kg most likely. Thus, already starting to see showers and thunderstorms developing, currently focused over northwest Utah, with areal coverage and extent both increase late this afternoon into the evening. Any storms that develop will be capable of producing strong and gusty outflow winds, with the possibility of at least isolated severe gusts later today.

The ridge axis is expected to redevelop off the southern California coast on Thursday, bringing a more westerly component to the flow and allowing additional drier air to make its way into the area, particularly over southern Utah. With some moisture continuing to linger and another shortwave on track to move through during the afternoon, anticipate the development of at least a few showers and thunderstorms, though coverage will likely be a bit less than what is anticipated for today.

As the airmass continues to dry and strong high pressure builds substantially over the western United States, confidence is high in temperatures across Utah and southwest Wyoming shooting up to record challenging levels for Saturday and Sunday. Guidance continues to show the center of the ridge over Utah on Saturday and just east of the area on Sunday. Guidance has, if anything, gone up with regard to the forecast compared to yesterday, with the majority of valleys and mountain valleys showing at least a 60 percent chance of red (major) HeatRisk for both Saturday and Sunday. It seems all but certain that daily temperature records will be broken, with some monthly and (in the case of the Cache Valley) all time records forecast to be broken. Given this and many valley low temperatures staying in the 70s overnight, this will predictably bring a quite increased chance of heat related illnesses over the weekend. Given the high confidence in the forecast, have gone ahead and issued an Extreme Heat Watch for all of those areas with at least a 60 percent chance of seeing HeatRisk values in the red, which includes just about all valleys (lower Washington county excluded) and many mountain valleys. As the forecast comes in clearer focus over the next couple of days, upcoming shifts will make decisions about advisories and warnings.

With southerly flow expected to increase over the area for the early and middle part of the upcoming week, models continue to indicate a high likelihood of monsoonal moisture returning to the area, bringing temperatures down and rain chances up. While this would decrease the fire danger, it brings an increased potential for flash flooding, particularly for southern Utah.

AVIATION

KSLC...There is low confidence in wind direction this afternoon and especially this evening given isolated to scattered showers and thunderstorms in the area. The main lightning threat will be limited to before 00z, however gusty outflow winds will remain a major question through 08z or so. Outside of any localized outflow winds, northwesterlies should prevail through the afternoon, becoming reinforced around ~02-04z with gusts to 20-30kts as broader outflow from storms over northwest Utah reach KSLC. Otherwise, VFR conditions will prevail.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and thunderstorms capable of producing gusty outflow winds will continue to develop this afternoon primarily across northern Utah and portions of eastern Utah. The main lightning threat will be mostly during the afternoon hours, though outflow winds will remain a threat through 08z or so across the north. Thus, confidence is low in wind direction for the northern TAF sites. VFR conditions will prevail.

FIRE WEATHER, Issued 1137 AM MDT Wed Jul 8 2026

The airmass will trend drier today under a west- southwesterly flow as high pressure shifts west off the northern Baja coast. Afternoon relative humidities will drop below 15% across most of central and southern Utah, down to the single digits in some valley locales. Meanwhile, across northern Utah, lingering moisture will maintain isolated to scattered mainly high-based showers and thunderstorms, with isolated dry lightning and gusty outflow winds being the main threat. While chances of showers and thunderstorms across the central mountains and adjacent valleys are nonzero, they are expected to be much more isolated there today. Meanwhile, enhanced winds combined with the low humidities will once again drive critical fire weather conditions across portions of central and southern Utah today.

The drying trend will continue across the area through the rest of the week, with humidities continuing to trend downward across the area and overnight recoveries become increasingly poor especially across central and southern Utah. Convection will become increasingly isolated during this time as well. Breezy conditions are expected to persist into Thursday and perhaps Friday as relative humidities continue to decrease. For now, have extended the Red Flag Warning for southern Utah into Thursday, and will keep an eye on trends for Friday.

As high pressure builds back into the area for the weekend into the beginning of next week, dry and very hot conditions can be expected. Temperatures are very likely to reach at least 100 degrees in most valleys over the weekend, while relative humidities in the single digits will be common. However, the pattern still looks favorable for moisture to increase into the area beginning early next week.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Extreme Heat Watch from Saturday afternoon through Sunday evening for UTZ101>108-114>116-118>122-128>131.

Red Flag Warning until 9 PM MDT this evening for UTZ492-493-497.

Red Flag Warning until 9 PM MDT Thursday for UTZ495-496-498.

WY...None.