textproduct: Salt Lake City

KEY MESSAGES

- High-based showers and thunderstorms will impact parts of the region, primarily east of I-15, Thursday afternoon and evening, with gusty and erratic winds up to 40 mph possible near any showers or thunderstorms.

- Enhanced easterly canyon winds up to 40 mph will develop along the northern Wasatch Front Thursday night into Friday morning.

- After a relatively dry and increasingly mild weekend, an active pattern will redevelop for much of the upcoming week.

DISCUSSION

An unsettled north to northwest flow remains in place over Utah and southwest Wyoming this evening. Weak high based showers developed today, primarily across northern Utah, but these showers have all but dissipated. Instability is expected to increase just a bit for Thursday as a weakly defined trough continues across the area. Guidance has been trending faster with the exit of this system, which is now expected to occur Thursday afternoon. As a result, there will be an increase in coverage of convection for areas east of I-15, with less coverage over western Utah. Given the dry lower levels, any storms that develop will be accompanied by little rain and will be capable of producing gusty and erratic thunderstorm winds.

As the trough moves out of the area, guidance has been relatively consistent in showing a period of easterly flow across northern Utah and southwest Wyoming late Thursday into early Friday. Such flow would enhance canyon winds in prone areas of the Wasatch Front, with a high chance of gusts up to 40 mph. However, a downslope wind event looks quite unlikely due to a lack of cold advection and relatively weak flow, with guidance showing a 10 percent or less chance of peak gusts exceeding 40 mph.

There is high confidence that high pressure will make its way back over the area on Friday, persisting through the weekend. This will keep conditions dry with a steady warming trend. Maxes, which should be around seasonal normals on Thursday, will rise to in excess of 10F above climo by Sunday. Normally colder valleys such as the Sanpete and Sevier Valley, the Cache Valley, southwest Utah, and eastern Millard and eastern Juab Counties with see minimum temperatures at or below freezing Thursday and Friday mornings. There is a medium chance that the freezing lows will persist in those areas Saturday morning despite modest warming, but the threat of a freeze in these areas should be quite limited by late in the weekend.

It continues to look likely that the ridge will shift east of the area by late Sunday as a broad Pacific low moves onshore. This is expected to usher in a cooler and more unsettled pattern for at least the first part of the upcoming week, though there remains spread with regard to the details.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will persist for the entire airspace through the period. Diurnal cumulus will develop over the mountains during the afternoon and bring a threat of terrain obscuration and isolated MVFR conditions to the mountains east of I-15. The chance of such MVFR conditions impacting nearby valley terminals is highest for KLGU and KEVW, with a diminishing chance at KSLC (20-30%). Other valley terminals have a less than 20% chance. Winds will remain light and diurnally driven, except for showers which could cause gusty and erratic outflow winds up to 25kt.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Freeze Warning until 9 AM MDT Thursday for UTZ107-116-118-119- 122.

Freeze Warning from 8 PM Thursday to 9 AM MDT Friday for UTZ107- 116-118-119-122.

WY...None.