Sunrise 6:49 AM   Sunset 8:13 PM Moonrise 3:23 PM   Moonset 4:00 AM

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FXUS65 KSLC 192145 AFDSLC

Area Forecast Discussion National Weather Service Salt Lake City UT 345 PM MDT Fri Apr 19 2024

SYNOPSIS
Isolated rain and higher elevation snow showers will continue Saturday for central and southern Utah. Dry and warmer conditions will push in to end the weekend. Dry conditions will last through the start of the week. More active weather is forecasted later in the week.

.SHORT TERM (Through 12Z Sunday)...A weak shortwave trough positioned near the southern California and Nevada border has brought enhanced cloud cover to Utah. It has provided enough lift for isolated rain and snow showers for portions of central and southern Utah. Precipitation has largely been within the mountains. Some of that has spilled into adjacent valleys to the east, but with a dry subcloud environment, much or all of the moisture has evaporated before reaching valley floors. Showers will taper off through the evening.

Similar conditions are forecasted Saturday. Synoptic flow will transition to the northwest as an incoming ridge builds closer to Utah. The aforementioned shortwave trough will push into Arizona and New Mexico. Isolated rain showers, with snow showers above roughly 9500 feet, are expected. Showers will taper off early in the evening as a ridge pushes in. Temperatures will jump to 5-10F warmer than normal throughout southwest Wyoming and northern Utah, while southern Utah stays around 5-10F warmer than normal.

.LONG TERM (After 12Z Sunday)...Weak ridging and a warming air mass on Sunday will bring another warm day - e.g. 70s to near 80 for northern Utah valleys and near 90 in St. George. The ridge will be somewhat short-lived as the overall synoptic flow remains more zonal and by Monday a trough moving through the Northern Rockies will depress heights slightly and bring slightly cooler conditions to at least northern Utah Monday. The weather will remain quiet otherwise with the cooler air arriving in the form of a weak dry front struggling to even generate clouds. Another short-lived ridge axis Tuesday/Wednesday will bring temperatures back to 10-15 degrees above normal. By this time, global models are showing signs of a more spring-like convective pattern, with potential for showers or even a thunderstorm over the higher terrain of northern Utah as a trough digs upstream of our area over the West Coast.

Looking at the range of ensemble solutions, there is high confidence in unsettled weather (cooler with higher chances of precipitation)
over the Great Basin somewhere around the latter half of next week.
As is common this time of year, there is a lot of uncertainty as to whether the mean trough will manifest as a closed low somewhere in the Desert Southwest or a consolidated wave. Either way, ensemble meteograms show a notable shift to at least normal temperatures if not below normal as well as elevated precip chances from the end of next week into the following weekend. Indeed, the CPC 6-10 and 8-14 day outlooks echo the same themes of above-normal precipitation chances, while our area lies on the edge of high chance of below- normal temperatures to our west - likely due to the uncertainty of the longwave trough evolution as it moves inland. If such an unsettled pattern does develop, cannot rule out thunder given the time of year. Early 25th-75th percentile NBM projections are in the neighborhood of 0.25-1.25" liquid for the mountains and trace to 0.5" for valleys, with amounts increasing from south to north across the area.

From a snowmelt runoff perspective, we should see several melt periods for the first half of next week followed by a slowing of the melt with potential for accumulating mountain snow.

AVIATION
KSLC...VFR conditions are expected to prevail through the TAF period under mid and upper level cloud cover. Winds will persist out of a northerly direction, reverting back to a southerly flow around 08Z. Between 03-08Z, there will likely be periods of light and variable flow of 5kts or less. There is a 30% chance that winds will revert to southerly before 08Z.

REST OF UTAH AND SOUTHWEST WYOMING
VFR conditions are expected to prevail across the forecast area through the TAF period.
Predominantly northerly winds are expected to prevail through the late evening hours, reverting back to light drainage flows during the overnight hours. Otherwise, scattered to broken mid and upper level cloud cover will prevail through the early morning, briefly clearing, then clouding up again late tomorrow morning.

SLC WATCHES/WARNINGS/ADVISORIES
UT...None.
WY...None.

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