textproduct: Salt Lake City

KEY MESSAGES

- Showers and thunderstorms focused over southwest Utah will shift gradually to the northeast overnight through Tuesday morning as a weak Pacific trough crosses the area. The convection will continue through Tuesday afternoon before diminishing.

- Generally dry conditions with temperatures near seasonal normals will persist for much of the area Wednesday through the remainder of the week. The exception will be far southeast Utah where some deeper moisture will remain in place, resulting in some diurnal convection through the weekend.

DISCUSSION

A Pacific low is making its way into the Great Basin this evening. The resultant southerly flow is drawing deeper moisture northward into Utah, particularly southwest portions of the state. Satellite derived PWs indicate values up to 0.8 inch over southwest Utah, with values in the 0.5 to 0.7 inch range elsewhere. That moisture combined with instability on the front edge of the low is bringing some patchy showers and thunderstorms to southwest Utah.

Tonight into tomorrow, the low will track roughly northeast as it opens up and splits. One piece should retreat back southwest off the coast, while the large piece moves through Utah and into Idaho by Tuesday evening. Associated showers and embedded thunderstorms will tend to increase in coverage through Tuesday morning before the area that is most likely to see showers continues to move northward with the movement of the trough. Thus, precipitation in the late morning through the afternoon will be most widespread over northern portions of the forecast area. As the low exits late Tuesday afternoon into Tuesday evening, coverage of convection will quickly decrease.

For the remainder of the work week, much of Utah and southwest Wyoming will stay dry with generally light flow owing to broad ridging over the area. Southeast Utah, however, is expected to retain some monsoonal moisture over the next several days. Most of the moisture and instability will be over Colorado, with Utah on the periphery seeing primarily isolated convection, but if the main ridge nudges a bit more westward than what is indicated in guidance, showers and thunderstorms could be noticeably more widespread. Across the area, temperatures are expected to stay roughly near seasonal normals through the weekend.

AVIATION

KSLC...Moisture increasing from the south will yield increasing clouds overnight with a 30% chance for showers to impact the terminal between 06-12z. While winds remain generally light out of the southeast through the morning, these showers may produce periods of variable winds. Additional shower activity is possible through the afternoon before chances for thunderstorms increase after 20z. Storms tomorrow afternoon will be capable of producing heavy rainfall and gusty and erratic outflow winds in excess of 35 kts.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions prevail overall for all regional terminals into Tuesday morning. Winds remain generally light and diurnally driven across northern Utah into Tuesday, while gusty southwesterly winds develop across southwest Utah Tuesday afternoon. Shower activity currently ongoing across central Utah will continue to spread northward through the evening and overnight, with showers impacting most northern Utah and southwest Wyoming terminals through Tuesday afternoon. Thunderstorms are expected to develop mainly across the northeastern portion of the airspace after roughly 20-21z, with potential to produce gusty and erratic outflow winds in excess of 40 kts and heavy rainfall that could drop VIS to MVFR/IFR at times.

FIRE WEATHER

A few showers and thunderstorms continue over southwest Utah this evening due to increased moisture and instability ahead of an approaching storm system. This system will weaken as it moves northeast across the area tonight into Tuesday morning. This will result in gradually more widespread convection with the focus of showers and thunderstorms gradually shifting northward. Any storms that develop will be capable of producing gusty winds and lightning as well as a low chance of wetting rainfall. Storms will continue into Tuesday afternoon before diminishing Tuesday evening. Thereafter, most of Utah will stay dry with light winds and temperatures near normal for this time of year. Over far southeast Utah, moisture will stay elevated, allowing for the potential for afternoon convection over the next several days.

SLC WATCHES/WARNINGS/ADVISORIES

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