textproduct: Salt Lake City

KEY MESSAGES

- An active pattern will bring periods of valley rain and accumulating mountain snow across the forecast area through Monday evening. The heaviest precipitation will occur north of I-70/US-50.

- Temperatures will fall below freezing Tuesday morning in the Cache Valley, as well as the Sanpete and Sevier Valleys, western Uinta Basin, and southwest Utah.

DISCUSSION

An upper low currently crossing the central Sierra will evolve into an open wave as it lifts across the central/southern Great Basin tonight before crossing the forecast area Sunday. Ahead of this wave precipitation aloft has spread across southern Utah this evening, and is gradually eroding a dry sub-cloud layer with evaporative cooling aiding in gusty south winds across southern Utah.

As large scale ascent increases over the next few hours and this dry layer erodes, precipitation will become fairly widespread across southwest Utah overnight, spreading into northern Utah before sunrise. This wave will lift through southern Utah Sunday morning, with precipitation diminishing midday as the trough axis passes. Further north, a deformation axis associated with the passing wave will result in a broad band of persistent valley rain/mountain snow across northern Utah and southwest Wyoming throughout much of the day. With ample moisture available (PW values forecast at or above the 95th percentile for late April) many northern valleys particularly north of I-80 as well as the benches of the Salt Lake and Tooele Valleys will exceed 1" of QPF through Sunday afternoon. while central/southern valleys along/west of Highway 89 can expect up to .50". Snow levels will remain above 7000 feet through Sunday, and although QPF values in the 1-1.5" range will be common across the northern mountains, late April sun angle coupled with warm surface temps will significantly limit impact, thus no winter headlines have been issued.

A brief lull in precipitation is expected across northern and central Utah Sunday evening, before a secondary trough axis swings through the area late Sunday night into Monday bringing another round of valley rain/mountain snow. This colder system will drop snow levels close to 6500 feet Monday. With colder air filtering into the region, freezing conditions are expected Tuesday morning across northern valleys away from the Wasatch Front as well as across eastern and central Utah from Cedar City up through the western Uinta Basin.

REST OF UTAH AND SOUTHWEST WYOMING

Widespread precipitation with areas of MVFR CIGS/VIS are expected across the area late tonight through much of Sunday. Heavier areas of rain, particularly north of I-80, may result in IFR CIGS/VIS at times. A gradual improvement in conditions can be expected at southern Utah terminals by early Sunday afternoon, with conditions improving across northern terminals late Sunday afternoon.

SLC WATCHES/WARNINGS/ADVISORIES

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