textproduct: Salt Lake City

KEY MESSAGES

- Mild temperatures with highs around 10 to 15 degrees above normal will persist through the work week.

- The onset of a more unsettled pattern is expected by Saturday, bringing periods of rain and high elevation snow. This pattern is likely to continue into early next week, along with the intrusion of some cooler temperatures.

DISCUSSION

Morning mid-level water vapor loop shows a weak shortwave departing eastward through the Desert Southwest as ridging builds into the Great basin. Visible satellite in turn shows mostly clear skies with only some high clouds filtering in around the crest of the ridge. While arguable pleasant, temperatures are starting out above normal once again, with afternoon highs expected to peak around 10 to 15 degrees above seasonal normal. With the ridge in proximity, dry conditions will be maintained.

Anomalously warm temperatures are expected to continue on through the work week, with afternoon highs each day generally reaching similar marks. A trough digging into the northern Plains will send a very weak and dry boundary southward into the area, knocking those temps down a degree or two across northern Utah and southwest Wyoming. As the boundary stalls and washes out, Thursday it will help serve as a focus for slightly enhanced lift given modest destabilization ~50-250 J/kg SBCAPE. Best chance of isolated to scattered afternoon showers and thunderstorms (~20-40% chance) will be in the high terrain near the front across northern Utah. A lower chance (~10-20%) is noted at lower elevation windward areas adjacent to the terrain. With limited moisture and moderately strong heating, a well-mixed boundary layer will support any such showers being higher based in nature, bringing potential for some modest outflow wind gusts. Activity will quickly cease after sunset with loss of heating.

The forecast pattern will start showing some modest signs of change by as early Friday as mid level heights fall in response to a Pacific trough pushing ashore in California. As such, will once again see some isolated to scattered afternoon showers and thunderstorms, with the highest coverage over higher terrain. With the approaching system, some showers may persist overnight into Saturday.

The pattern changes more in earnest starting Saturday as the aforementioned trough shifts further through the Great Basin, and another deepening trough advances southward along the Pacific coast. The combination in further increases of moisture and forcing will result in more widespread coverage of precipitation areawide. Given limited cool air initially, snow levels will start around 8500-9000 feet, and only foster some modest snow accumulations at the highest elevations. Models then show modest agreement that the deepening trough pushes a cold front through around Sunday/Monday, allowing snow levels to drop more into the 6000-7000 feet range. That said, there is still some uncertainty in exact track/timing/strength. For example, around 20% of ensemble members never phase the two troughs, and instead we end up with the initial trough cutting off and sliding by to our south, and only bringing modest QPF at best along with little intrusion of cooler air. Will certainly be a trend to watch. Still, for now the NBM has around a 20-40% chance of more than 1" of liquid for much of Utah's mountains, and 70-80% of at least 0.25". So long as the tap of cold air does get established, we'd also see daytime highs drop back below normal for a change.

REST OF UTAH AND SOUTHWEST WYOMING

A nearby ridge will help to maintain clear to mostly clear skies and VFR conditions at area terminals. Winds are favored to follow a diurnally normal directional pattern, with some modest gusts (~15-30 kts) primarily at higher elevation and exposed terminals.

SLC WATCHES/WARNINGS/ADVISORIES

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