textproduct: Salt Lake City

KEY MESSAGES

- After a brief break through early Saturday, an unsettled pattern will shift into northern Utah. Showery conditions, with high snow levels, will continue through Monday.

- An upper level low will cross the region Monday into Tuesday, bringing more widespread precipitation to the state.

- Another colder system will impact the Great Basin later Wednesday into Thursday.

DISCUSSION

The forecast over the next seven days across Utah will be one of front perturbation, upper level lows and generally spring-like conditions. No indications of a blocking high or a return to very dry conditions, especially across northern Utah with a significant number of ensemble members suggesting a much more active pattern beginning this weekend and lasting through at least the next weekend.

Early afternoon upper air and satellite analysis indicates upper level ridging remains in place across the eastern Pacific, centered southwest of Baja California. An active jet continues to stream around this ridge across the West into the southern Plains.

As an upper level low approaches the West Coast Friday, ridging will amplify across the region. This will bring net warming and a generally nice day to much of the Beehive State. This ridging will begin to flatten as the influence of a jet max rotating around this upper level low shifts into the West. Saturday will be another warm day with isolated to widely scattered showers developing across the northern half of the state during the afternoon.

Those showers are the result of preferential jet dynamics interacting with a warm front shifting north across northern Utah Saturday afternoon into Saturday night. This front will weaken through the day Sunday...with some ensemble members indicating this front will shift southward as a weak cold front Sunday morning into Sunday afternoon. Either way, the signal for showery conditions to continue across northern Utah near this front remains across the majority of ensemble members.

As the upper level low continues to slowly eject eastward, a period of shortwave ridging and subsidence between shortwave troughs is expected Sunday night before the main upper level low ejects across the Great Basin Monday into Tuesday. A significant shift in model trends has increased the threat of widespread precipitation across Utah with a cold front and falling snow levels (though only to around 7000 feet) Monday night into Tuesday afternoon. Spread in timing remains around 12 hours or so in the timing of this cold front...but consistency in presentation has increased significantly.

In the wake of this departing upper level low, yet another upper level low is forecast to shift into the region by a significant portion of the ensemble members Wednesday into Thursday. Timing variance is the biggest consistency difference...mode is relatively consistent and similar to the previous storm with a strong cold front crossing the region during this period. This second upper level low has a better tap to a colder airmass, with mean snow levels currently around 5000 feet behind the cold front.

Yet another, even colder, upper level low follows in it's wake as is typical in this type of Rosby wave train...and should keep Utah in an active and potentially increasingly cold pattern through at least the next weekend.

Current forecast suggests the next substantial impact from a headline perspective will be with the second upper level low later Wednesday into Thursday. Current 25th/75th percentile snow forecasts are around 6 to 12 inches for the northern mountains, locally up to 18 inches in the upper Cottonwoods, with around a 20% chance of up to an inch on the benches.

REST OF UTAH AND SOUTHWEST WYOMING.

Winds will generally prevail out of the west to northwest across northern Utah this afternoon, with more north to northwest flow this afternoon across southern Utah. Light and variable winds are then forecast at most sites overnight into Friday morning. Stronger/gustier winds from the west are forecast at KEVW through the afternoon, subsiding and becoming more southwesterly this evening through Friday morning. VFR conditions will prevail.

SLC WATCHES/WARNINGS/ADVISORIES

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