Sunrise 6:28 AM   Sunset 8:23 PM Moonrise 12:00 AM   Moonset 8:22 AM

  Print   HELP   Reset   Save   Recall

FXUS65 KSLC 282124 AFDSLC

Area Forecast Discussion National Weather Service Salt Lake City UT 324 PM MDT Sun Apr 28 2024

SYNOPSIS
Utah and southwest Wyoming will see mild and breezy conditions during the day Monday before a cold front moves through late Monday into early Tuesday, bringing cooler temperatures and some showers to northern portions of the area. Another mostly dry cold front is expected to impact the area midweek.

.SHORT TERM (through 12Z/6AM Tuesday)...West to northwest flow has brought some modest warm advection to Utah and southwest Wyoming this afternoon. As a result, maxes are averaging 5-7F above what they were yesterday, within 5F of seasonal normals. Other than a few light popcorn showers over northern Utah, conditions are fairly benign over the area. Any lingering showers should diminish early this evening.

As the work week begins, attention turns to a trough forecast to move onshore along the Pacific Northwest coast tonight until tomorrow morning. There is high confidence that this system will track east during the day, grazing northern Utah late Monday afternoon into early Tuesday. The trough looks to be relatively moisture starved, but northern Utah should still see some showers during the afternoon and evening, as instability is somewhat favorable. Any accumulations will be light and confined to the higher elevations.

The front will bring a greater impact to northern Utah temperatures, which are expected to run up to 10F above climo on Monday. The passage of the front is expected to drop those maxes back to near seasonal normals by Tuesday. A tightening pressure gradient ahead of the front will lead to some breezy winds, and would not be surprised to see some gusts in excess of 40 mph just ahead of the frontal passage, most likely over northwest Utah.
However, anticipated flow aloft does not support widespread or long lasting gusts in excess of Wind Advisory criteria, so have held off on any headlines at this time.

.LONG TERM (After 12Z/6AM Tuesday)...

...Cool through mid-week then warming trend by the weekend...

Tuesday through Thursday will be dominated by an active pattern across the Northern Rockies as a low pressure system remains over Montana. Northern Utah in particular will feel the influence of this troughing to our north, while southern Utah largely remains south of the boundary stalled across the state.

Looking at the specifics, there is high confidence in a shortwave trough grazing northern Utah Monday night, which will be quickly departing to our east by Tuesday. The resulting cold advection and subsidence behind the shortwave passage will support a cooling temperature trend across northern Utah, while also acting to produce dry and mostly clear conditions (mainly early in the day). However, cloud cover will start to increase again across northern Utah later Tuesday ahead of the next wave to impact the region. Meanwhile, southern Utah on Tuesday will remain south of the stationary front and will see steady to slightly warmer temperatures than Monday.

By Wednesday, confidence among ensemble members is increasing about bringing a trailing shortwave pinwheeling southward around the influence of the low centered over Montana. This will swing a deeper trough axis into Utah on Wednesday, however, the magnitude of its depth now remains the primary point of contention among the ensembles - with the main consequence being how far south the cold front makes it across Utah. Now approximately 75% of ensembles have a slightly more robust trough which will eventually push the cold front into southern Utah - of these 75% a little less than half have a slower and even deeper solution that would hold the cold air off until later Wednesday into Thursday. Otherwise, only approximately 25% of ensembles have a shallower trough which stalls the frontal boundary across central Utah resulting in milder temperatures remain in place across southern Utah. Otherwise, while some showers will accompany this trough, it will be a relatively dry system. Only about 10% of solutions produce more than 0.1" of water in the valleys and more than 0.25" of water in the mountains, all mainly across northern Utah. Much of southern Utah has a high chance of staying completely dry.

Late week into the weekend, there is increasing confidence in a warming trend, although the exact details of the large scale pattern evolution are a little dicey yet. However, the main trend in the ensemble solutions into the weekend is for a weak ridging to build particularly down stream of the forecast area. There remains some solutions that are a bit slower to evolve this pattern, but by Sunday every cluster supports this downstream ridge with a building thermal axis over Utah now. For KSLC, there is an 80-85% chance of exceeding 70 degrees by Saturday and Sunday. For St George, there is a 60% chance of exceeding 85 degrees Saturday and Sunday.

AVIATION
KSLC...Trailing energy from departing system to maintain some VFR cloud cover and limited chance (less than 20%) of isolated showers through Sunday evening. Diurnally typical winds expected, with switch to S drainage flow between ~03Z-05Z, and a return to NW flow between ~18z-21z Monday. Another passing impulse will yield some isolated shower chances Monday afternoon which could result in brief variability to winds in addition to slightly degraded conditions at the terminal, but largely anticipate VFR to prevail.

REST OF UTAH AND SOUTHWEST WYOMING
At northern terminals, a few isolated showers possible through this evening, but expect VFR conditions to prevail. A relative lull is then anticipated overnight, but another quick and fairly weak impulse will trigger some isolated to scattered shower activity during the day Monday.
Even then, largely expect VFR conditions outside of any heavier showers. At southern terminals, clearer skies and VFR conditions anticipated. Areawide winds will largely follow something of a diurnally typical pattern, though could see passing showers at northern terminals yield some slight variability at times.

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

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Salt Lake City, UT,