textproduct: Salt Lake City

KEY MESSAGES

- Isolated showers and thunderstorms will develop again over portions of northern and central Utah Sunday afternoon into the early evening.

- There is an increasing chance of critical fire weather conditions developing where fuels are dry over southwest Utah on Tuesday, with a low chance of wind gusts in excess of 40 mph. Winds will be stronger with higher gusts more widespread on Wednesday, with the potential of critical fire weather conditions for eastern Utah lingering Thursday into Friday.

DISCUSSION

Weak high pressure remains centered over Utah and southwest Wyoming this evening, with embedded shortwaves providing enough instability for isolated weak showers this afternoon, which have mostly diminished this evening. Temperatures were quite mild, with maxes approaching 10F above seasonal normals. The ridge axis is expected to shift east for Sunday, with shortwave energy moving over the top of the ridge expected to act as the focus for another round of isolated weak convection, this time focused over southwest Wyoming and near the Utah/Idaho border, with some storms also possible over central Utah.

The eastern movement of the ridge will open up Utah and southwest Wyoming to more unsettled conditions beginning Memorial Day as a storm moves onshore along the Pacific Northwest coast. The initial effect of this system will be to bring increasing southerly winds. Breezy conditions will be primarily focused over western Utah for Tuesday as the trough drops into the Great Basin. These winds could combine with critically dry conditions over southwest Utah to produce critical fire weather conditions, with a low (20-30%) chance of some gusts in excess of 40 mph.

The majority of guidance shows the Pacific Northwest system closing off over the Great Basin, wobbling around west of the area for Wednesday. With it being a little closer to the area, associated breezy winds should be more widespread over Utah and southwest Wyoming, bringing a broader risk of critical fire weather conditions. By Tuesday into Wednesday, the influence of the storm system will also act to make temperatures a few degrees less warm.

Spread starts to increase for the latter part of the work week as models typically struggle with the evolution of closed low features. Most guidance shows the system opening up beginning Thursday and ejecting out of the area, with spread being introduced with its strength and track at this point. So while confidence is relatively high in unsettled and less warm conditions during this period, things are more uncertain regarding the location and coverage of any associated precipitation. However, given the weakening nature of the system, totals and potential cooling don't look particularly impressive in the vast majority of solutions. It seems most likely that the trough will have exited the area in whatever form it does by the upcoming weekend.

REST OF UTAH AND SOUTHWEST WYOMING

Light showers will largely diminish by 08z, though there is a chance that some hang on, moving through the Wasatch Front 11-16z or so. Scattered showers and isolated thunderstorms will develop across much of Utah and southwest Wyoming after 19z. Any showers will be capable of producing gusty and erratic outflow winds up to 30-40kts. Outside of any outflow, expect largely diurnally-driven winds, with a slight preference for breezy southwesterlies during the afternoon.

FIRE WEATHER

Dry and mild conditions with light winds are expected across much of the state tomorrow, with some isolated showers developing over far northern Utah as well as portions of central Utah. These storms will be generally weak with little to no chance of wetting rainfall. The approach of a Pacific Northwest trough will bring an increase in winds Tuesday into Wednesday. The winds will be strongest over western Utah on Tuesday, combining with very dry conditions over southwest Utah to bring an increasing potential of critical fire weather conditions. As the low moves slowly closer, the extent of breezy winds and the potential for critical fire weather conditions will increase for Wednesday. As the trough moves out of the area, winds are expected to bring at least some potential for critical fire weather conditions for eastern Utah Thursday into Friday.

SLC WATCHES/WARNINGS/ADVISORIES

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