UWFPS 2017 daily cold-air pool forecast valid Thursday 2/16/2017 10:00  AM MST

 

The weak inversion episode that began Sunday night has mostly mixed out in the Salt Lake Valley but PM2.5 levels around 30 micrograms continues in the Cache Valley. Clean air across the region should be observed by Friday. Periods of stormy weather and no air quality concerns expected from this Friday February 17th through about Saturday February 25th.

This will be the last forecast issued for the UWFPS winter study period. Congratulations everyone on a great field study. Enjoy spring!

UWFPS 2017 daily cold-air pool forecast valid Wednesday 2/15/2017 11:00  AM MST

 

A weak inversion episode continues, with PM2.5 levels creeping up to between 20 and 30 micrograms today in the Salt Lake Valley and Cache Valleys. Levels should decrease somewhat in the afternoon as mixing dilutes the pollution below the capping inversion. Levels should be similar Thursday morning to Wednesday morning, however at least partial mix-out is expected Thursday late afternoon with the increase of southerly winds, with and end of episode expected Thursday night. Periods of stormy weather and no air quality concerns expected from this Friday February 17th through about February 2th.

Tomorrow (Feb 16th) will be the last forecast issued for the UWFPS winter study period.

 

UWFPS 2017 daily cold-air pool forecast valid Tuesday 2/14/2017 1:30  PM MST

A weak inversion episode continues, with PM2.5 levels exceeding 20 micrograms today in the Salt Lake Valley and Cache Valleys. A weak but notable complex late-season inversion has set up across the area.

SLC Airport Sounding 2/14/2017 5 am. Note multiple stable layers

Continuing modest pollution build-up is expected in pollution through Thursday morning as a strengthening capping inversion tries to strengthen in the presence of being modified by heating of snow-free ground in the Valleys.   Partial mix-out is expected Thursday late afternoon with the increase of southerly winds, with and end of episode expected Thursday night. Periods of stormy weather and no air quality concerns expected from this Friday February 17th through about February 23rd.

UWFPS 2017 daily cold-air pool forecast valid Monday 2/11/2017 1:00  PM MST

 

A weak inversion episode in underway, with PM2.5 levels exceeding 10 micrograms today in the Salt Lake Valley. A further small-build-up is expected in pollution through Wednesday as a strengthening capping inversion is modified by heating of snow-free ground in the Valleys.   Partial mix-out is expected Thursday late afternoon with the increase of southerly winds, with and end of episode expected Thursday night. Periods of stormy weather and no air quality concerns expected from this Friday through about February 21st.

UWFPS 2017 daily cold-air pool forecast valid Sunday 2/10/2017 2:00  PM MST

A weak inversion episode will begin Sunday and continue until Thursday. Only 'modest' inversions are forecast given the lack of snow cover and increasing temperatures and solar insolation as we approach mid-February.  Pollution levels will likely peak on Wed and Thurs, but remain below the NAAQS standards all valleys (possible exception being Cache).

Another storm system will likely end the weak inversion episode on Friday 17 February.

UWFPS 2017 daily cold-air pool forecast valid Friday 2/10/2017 12:00  PM MST

Mild weather will continue on Friday, with a significant rain episode forecast Friday late afternoon through Friday night. Light snow accumulations (1 inch or so on grassy and elevated surfaces) are possible late Friday night into Saturday morning in Utah Valleys. 

Conditions will begin to clear Saturday afternoon with much cooler temperatures in the low 40s. Weak high pressure overhead at the climatological "end" of inversion season (sun angle is getting too high to support ongoing inversions) will likely result in a minor inversion episode is anticipated during the Sunday 12 February to  Thursday 16 February time frame. Another storm system will likely end the final inversion of the winter season on Friday 17 February.

UWFPS 2017 daily cold-air pool forecast valid Thursday 2/9/2017 1:00  PM MST

Summary: Mild weather will continue on Thursday, with a significant rain episode forecast Friday into Friday night. Light snow accumulations (1 inch or so on grassy and elevated surfaces) are possible late Friday night into Saturday morning in Utah Valleys. Weak high pressure overhead at the climatological "end" of inversion season (sun angle is getting too high to support ongoing inversions) will likely result in a minor inversion episode (and corresponding minor basin pollution build-up with PM2.5 levels staying below 15-20 micrograms/m3 (except perhaps a bit higher pollution levels in Cache Valley) is anticipated during the Sunday 12 February to  Wednesday 15 February time frame.

UWFPS 2017 daily cold-air pool forecast valid Wednesday 2/8/2017 3:30  PM MST

Summary: Mild weather will continue for the next several days, with a significant rain episode Friday into Friday night. Light snow accumulations (1 inch or so on grassy and elevated surfaces) are possible late Friday night into Saturday morning in Utah Valleys. If this occurs, weak inversion conditions are possible Sunday February 12th - Wednesday February 15th. Only minor basin pollution build-up is anticipated during this time frame unless greater snow accumulations occur than expected.  Stay tuned for updates.

UWFPS 2017 daily cold-air pool forecast valid Monday 02/06/2017 10:00 MST (10:00 am local time)

Summary: Windy with showers likely through Tuesday night.  A break period on Wednesday into Thursday.  Another major rain storm Friday now extends into Saturday. Forecast models continue to show a weak inversion setting up across northern Utah on Sunday and Monday  12 and 13 February . 

Tuesday 7 February:

80% chance of showers, rainfall up to 0.50". Windy. Southwest winds at 30 knots at 500 m AGL.

Wednesday 8 February:

Potential flight day, particularly in afternoon and into overnight hours (60% chance of showers in morning, 30% in afternoon). Winds will be more favorable (weaker) than Thursday.

Visibility: no restrictions expected.
Winds: 10 knots southerly to southwesterly across the area on Wednesday afternoon.  Increasing to 15 kts in the Salt Lake Valley Wednesday night, around 10 knots elsewhere. 

Thursday 9 February:

Potential flight day. Partly cloudy.  Southwest winds increasing to 30 knots by afternoon into evening ahead of Friday storm system.

Visibility: no restrictions expected.
Winds: 20 knots southerly to southwesterly across the area on Thursday mid-day.  Increasing to 30 kts in the Salt Lake Valley Wednesday night, around 20 knots elsewhere. 
Friday 10 February: 

Rainfall likely, up to 1.00" total rainfall.  Northwest winds 10-20 knots.

Saturday 11 February: 

Rain or rain/snow mix likely in the morning.

Sunday 12 February - Tuesday 14 February:

Weak inversion conditions forecast at this time with light winds and potential 
for some minor pollutant build-up in boundary-layer starting Sunday night. Pattern uncertain with closed low over Arizona and ridge over northern Utah. Stay tuned.   

UWFPS 2017 daily cold-air pool forecast valid Saturday 02/04/2017 5:40 MST (5:40 pm local time)

Summary: All basins have mixed out and clean air and mild weather has arrived in northern Utah. A series of mostly warm storms systems are expected almost daily through Friday 10 February, although several break periods are likely (the largest looking to be on Thursday).
 
Sunday 5 February:

Partly cloudy. Warm. High around 50 F in Salt Lake Valley,

Monday 6 February:

Rain likely, changing to snow Monday night.

Tuesday 7 February:

Mostly cloudy, high near 40 F. 30% chance of rain/snow.

Wednesday 8 February:

Chance of rain.

Thursday 9 February:

Partly cloudy.

Friday 10 February - Wednesday 15 February

At this time a final storm system is forecast Friday into Friday night/Saturday morning, 

 

High pressure if forecast to build through the weekend into early the following week, although confidence remains low this far out in the forecast cycle.

UWFPS 2017 daily cold-air pool forecast valid Friday 02/03/2017 12:00 MST (12:00 pm local time)

Summary: The decay phase of the ongoing persistent cold-air pool is nearly complete in the Salt Lake Valley with only a shallow 50-100 m deep polluted layer bleeding into the Valley from the Great Salt Lake. PM2.5 has continued to rise in Cache, reaching 100 micrograms/m3 Friday. Complete mix-out is expected in all basins by Saturday afternoon, although there is a small chance of the inversion continuing in Cache until Monday's storm. A series of storms may be followed by a ridge of high pressure Starting Saturday 12 February.

Current weather synopsis and short-term forecast for Friday 3 February:

An extremely shallow polluted layer continues on day 8 (Thursday) of the cold-air pool over the Great Salt Lake. In the Cache Valley, a 200m deep pollution layer continues.

60% chance scattered rain showers after 4 pm. High 44 in Salt Lake Valley. High 35 in Cache.

See the following link for real-time ceilometer data https://asn.synopticdata.com/vis/time-height/

See the following link for Mesowest air quality data (including UDAQ monitoring sites)
http://meso2.chpc.utah.edu/aq/

Utah Division of air quality:
http://air.utah.gov/


Saturday 4 February

The last of the shallow polluted layer should be mixed out over the Great Salt Lake Friday night. There is a 30% chance Cache does not mix out with this system.

Most of the rain now looks to occur overnight Friday night, with scattered light snowers Saturday morning. 50% chance of rain with up to .25" rainfall totals (most Friday night). Some snow is possible in Cache is cold-pool does not mix out. 

High: 45, Low: 32
  

Sunday 5 February:

Mostly cloudy. Clean air all basins, except slight chance Cache remains polluted if does not mix out Friday night/Saturday morning. 

High: 47, Low: 35

Monday 6 February:

Rain with snow possible Valley benches. Clean air all basins.

Tuesday 7 February:

Looks like this may be a break period between storm systems at this point centered from Monday night through late afternoon Tuesday, will gain more confidence in this forecast by Saturday update.

Wednesday 8 February:
 
Rain likely.

Thursday 9 February:

Mostly sunny. 

Friday 10 February:

Rain possible.

Saturday 11 February - Tuesday 14 February

Possible building in of ridge of high pressure.

  

 

UWFPS 2017 daily cold-air pool forecast valid Thursday 02/02/2017 1:00 MST (1:00 pm local time)

Summary: The decay phase of the ongoing persistent cold-air pool continues in the Salt Lake Valley Thursday while pollutants continue to rise in Cache. Utah Valley appears to have mixed out.  Complete mix-out is expected in all basins by Saturday afternoon. No major pollution episodes are on the horizon at this point after Sunday.

Current weather synopsis and short-term forecast for Thursday 2 February:

A weakened and very shallow temperature inversion continues on day 7 (Thursday) of the cold-air pool. A weak weather system is also bringing light precipitation that is falling into the ongoing shallow polluted layer. Ceilometers show that the depth of the polluted layer as of noon Thursday is now only around 200 m in the Salt Lake Valley and 250 m in the Cache Valley.

See the following link for real-time ceilometer data https://asn.synopticdata.com/vis/time-height/

See the following link for Mesowest air quality data (including UDAQ monitoring sites)
http://meso2.chpc.utah.edu/aq/

Utah Division of air quality:
http://air.utah.gov/

Friday 3 February

Mix-out in the southern Salt Lake Valley expected Friday morning. A push of polluted air back into the Salt Lake Valley from the Great Salt Lake possible Friday afternoon. Cache is expected to remain in a cold-air pool Friday at this time.

Saturday 4 February

80% chance of rain with up to .25" rainfall totals. 90% chance of complete mix-out of cold-air pool in Salt Lake Valley, 70% in Cache Valley.
 

Sunday 5 February:

Partly cloudy. Clean air expected all basins, although slight chance Cache remains polluted.

Monday 6 February:

Rain or rain/snow mix likely. Accumulations possible in Cache at this time, unlikely in Salt Lake/Utah.

Tuesday 7 February:

Looks like a break between storm systems at this point centered from Monday night through early afternoon Tuesday.   Rain starting in late Tuesday afternoon/evening and continuing through Wed.

Wednesday 8 Feb.
 
Rain likely.

Thursday 9 Feb. -Fri 10 Feb

Weak inversion possible. Would only expect minor pollutant build-up given snow will have all been melted (except in Cache) and short duration.