textproduct: Salt Lake City

KEY MESSAGES

- Isolated showers and thunderstorms are possible each afternoon through Tuesday, mainly across central and southern Utah.

- Widespread precipitation returns late Wednesday across southern Utah, with coverage expanding northward through Friday. Many areas will see precipitation accumulations between 0.5-1.0" through this period, with locally up to 2.0-2.5".

- The late week storm will also bring modest snowfall to the high terrain across northern Utah on Friday, with 3-6" possible mainly above 9500 feet.

DISCUSSION

Overall benign conditions are expected across the region today. Some isolated rain showers are ongoing early this afternoon mainly across portions of southeast Utah, courtesy of a modest influx of moisture associated with a weakening cutoff low lifting through the Four Corners region today into Monday. A bit more instability is expected across the region on Monday, which will favor a bit more organized storms capable of producing lightning, especially the higher terrain across southern and central Utah. Similar conditions are expected Tuesday, though potential for afternoon showers and thunderstorms will extend further north into northern Utah and southwest Wyoming.

A more active pattern is expected mid to late week as a trough deepening off the west coast ejects into the southern Great Basin through this period. Southerly flow increasing ahead of this system will yield enhanced south to southwest winds across the region by Wednesday afternoon and continue into Thursday. Strongest winds are anticipated across southwest Utah late Wednesday and Thursday afternoon, with widespread gusts 30-35 mph. An efficient tap of tropical moisture will accompany this system, with deep moisture overspreading southern Utah and resulting in increasing coverage of widespread precipitation capable of producing heavy rainfall across the area as early as Wednesday afternoon. Precipitation will continue to spread northward overnight into Thursday, becoming widespread across all of Utah and southwest Wyoming through the day.

Precipitation coverage will favor northern Utah and southwest Wyoming on Friday as the aforementioned system phases with a northern stream trough, consolidating much of the deep moisture across this area. As such, coverage of showers and storms will taper off across central and southern Utah gradually through Friday morning. While snow levels will hover around 10500-11000 feet through most of Wednesday and Thursday, this northern stream trough will usher in a cooler airmass on Friday, allowing snow levels to drop to around 8000 feet by late Friday night. As such, modest snow accumulations are expected across the high terrain of northern Utah, with 3-6" expected generally above 9500 feet.

This extended period of rainfall between Wednesday and Friday will likely be beneficial rain for many areas that aids our soil moistures before heading into winter. Flooding will still be a threat, especially for sensitive terrain across central and southern Utah, given the potential for an extended period of moderate to heavy rainfall. Models show quite a bit of spread in precipitation accumulations between this period. Across central and southern Utah, there is a 75% chance for precipitation accumulations to exceed 0.5-1.0", and a 25% chance to exceed 1.0-2.0". Across northern Utah, there is a 75% chance for precipitation accumulations to exceed 0.2-0.6", and a 25% chance to exceed 0.6-1.2". Heaviest precipitation is favored for the southern mountains, where there is a 10% chance for accumulations close to 3".

AVIATION

KSLC...VFR conditions will continue to prevail over the KSLC terminal through the valid TAF period under increasing mid- and upper-level cloud cover. Light southerly winds will remain in place before switching to diurnally-driven northwesterly winds around 20- 21Z. Southeasterly winds will return around 03Z this evening. The chances of some showers and thunderstorms bringing lightning, some erratic gusty winds, and a brief mountain obscurity will increase as we head late into the TAF period around 20Z.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail across the area through the valid TAF period. Areas of light rainfall are expected across southeastern Utah and east-central Utah this afternoon through the evening. The chances of some showers and thunderstorms bringing lightning, some erratic gusty winds, and a brief mountain obscurity is possible in Southern Utah late this evening before spreading into Northern Utah late in the TAF period.

SLC WATCHES/WARNINGS/ADVISORIES

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