UWFPS 2017 daily cold-air pool forecast valid Wednesday 01/25/2017 1000 MST (10:00 am local time)

Summary: Fresh snowfall Tuesday night further sets the stage for strong inversion conditions going into the weekend.  A strong cold-air pool will set in during the day Friday and continue through early next week, with pollution build-up starting Friday afternoon and continuing through at least Tuesday. Periods of dense fog and areas of stratus are likely during this episode, particularly in the Cache Valley and will have to be carefully monitored for flight operations.

Current weather synopsis and short-term forecast:

Fresh snow of 1-5" fell overnight Tuesday into Wednesday morning in the Utah Valleys. Current snow depths range from a whopping 30" in Cache Valley to 3-11" in the Salt Lake and Utah Valleys. 

Snow will continue through the afternoon Wednesday across northern Utah. Additional accumulations should be less than 2 inches. Temperatures will remain cold (25-29 F) before dropping to around 20 F Wednesday night.

Thursday 26 January:

30% chance of snow flurries, otherwise mostly cloudy. Cold, highs in the 20s, lows in the 5-10 F range. 20% dense fog at Salt Lake Airport and Logan Airport in the morning.

Visibility/ceiling/clouds: Minimum visibility 2-4 miles in snow flurries, otherwise > 6 miles. Ceilings between 3000-5000 feet in snow flurries.  If dense fog materializes, ceilings will be less than 1000 feet with visibility less than 1/2 mile.

Winds:light and variable 5-10 knots.

Friday 27 January:

30% chance dense fog at the Salt Lake Airport and Logan Airport, favoring morning period.

Otherwise partly cloudy and cold (morning lows 0-10 F, afternoon highs 20-25 F.

Capping temperature inversion will descend during mid-day period. Pollution will probably begin to accumulate in the boundary-layer in the evening commute. 

Visibility/ceiling/clouds: 30% chance low stratus deck or dense fog, with ceilings less than 1000 feet and visibility less than 1/2 mile possible. If this does not materialize, no visibility issues expected.

Winds: northerly, 5-10 knots.

Saturday 28 January - Monday 30 January:

Ongoing strong cold-air pool episode, with pollutant concentrations increasing each day in all urban Utah Valleys. Unknown variables are how much nighttime cooling occurs (clear or cloudy), the amount and persistence of low clouds and fog. Stay tuned. 

Tuesday 31 January - Thurs 2 February:

Forecast models do not agree at this time on the evolution of the cold-air pool after Tuesday, with some calling for a mix-out mid-week and others continuing the cold-air pool until the end of next week.