textproduct: Salt Lake City

KEY MESSAGES

- High temperatures will remain 10-15F above seasonal normals on Friday, with isolated afternoon showers and thunderstorms developing over portions of northern Utah.

- A weakening Pacific storm system will move across northern and central Utah during the day Saturday bringing cooler temperatures and more widespread precipitation with the potential for strong winds across western Utah.

- A stronger Pacific low will impact the area early next week, bringing greater potential for strong winds as well as below normal temperatures and a chance of significant mountain snow.

DISCUSSION

High pressure remains parked over Utah and southwest Wyoming this evening, resulting in continued mild temperatures and generally light flow aloft. There is enough instability from a weak frontal boundary over northern Utah to keep a few light showers going at this time, with CAMs indicating very isolated coverage (less than 15 percent) of showers through the overnight hours. The mild temperatures and potential for northern Utah showers will continue tomorrow.

A low pressure system is currently spinning off the California coast. The system is expected to open up and move onshore tomorrow, resulting in increasing southerly flow across the area, particularly over western Utah. Right now, the potential for gusts in excess of 40 mph is 30 percent or less per the latest guidance, but the winds will be noticeably strong.

Over the past couple of days, guidance has been trending weaker with this first system and continues to do so this evening, with confidence becoming high that it will weaken significantly as it enters the Great Basin Saturday morning before continuing to weaken as it tracks across northern Utah and southwest Wyoming during the day. Of greatest impact with this system will likely be the gusty winds over western Utah, which now have a 40 to 60 percent chance of wind gusts in excess of 40 mph. There will be slight cooling and some more widespread valley rain and mountain snow, at least for northern and central Utah, but associated accumulations are looking increasingly unimpressive.

By Saturday night another low is on track to approach the California coast, looking very similar to the previous one. Its eventual fate, however, is looking a bit more uncertain. Some guidance weakens the system in a similar fashion to the first one, while a large portion of the guidance weakens it little if at all.

There is also noticeable spread with regard to the timing and the track of the system, which is typical for low pressure systems of this nature, many of which we've seen during this cool season. It does appear, however, that southerly winds with the approach of this system will be stronger than those expected on Saturday, with NBM probabilities showing a 60 to 80 percent chance of wind gusts in excess of 40 mph during the day Sunday. And it does seem reasonable to say at this time that there will be greater mountain snow accumulations with this system than the previous, with at least a low chance for mountain snow that could impact travel. Overall, there is increasing confidence in continuing unsettled weather for early next week and temperatures returning to near or below seasonal normals, but less confidence than usual on potential details.

Behind that second low, most guidance indicates at least some break in the action for the middle of next week with temperatures warming again. However, there are some indications of unsettled weather returning for day seven and beyond.

REST OF UTAH AND SOUTHWEST WYOMING

Light winds and VFR expected overnight. Winds will increase from the south tomorrow as the next system moves in. There will be some afternoon rain shower chances, but chances remain too low for PROB30 inclusion. It will be later as we head into the weekend when precipitation chances become likely.

SLC WATCHES/WARNINGS/ADVISORIES

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