Hot Summer

Temperatures in Spanish Fork Since May 1, 2018

Summer Thunder

I woke up last night at 11:40 to strobing lights. A long line of thunderstorms stretched from Richfield to the Utah-Idaho border. This morning I measured 0.26 inches of rain in south Provo.

Radar 11:50 PM, Local Time

It was a forecast miss for the HRRR model, which didn't simulate this particular line of thunderstorms until the analysis hour. This is an important lesson on not using weather models as deterministic forecasts for thunderstorm prediction. This loop of HRRR forecasts shows all 18 forecasts and the analysis valid at 0600 UTC (local midnight). Beyond the first two hours, there is no warning of this particular line of storms.

Started a small fire on Y-Mountain: https://www.heraldextra.com/news/local/central/provo/lightning-sparks-small-brush-fire-on-y-mountain/article_ad4d2531-58a6-5b62-800e-0e38e3be22ca.html

Gusty winds were observed across the state. The Salt Lake International Airport and many other locations along the Wasatch Front recorded winds exceeding 50 MPH between 11 and Midnight last night.

In Spanish Fork, recorded winds gusted ranged between 17 and 30 MPH.

UKBKB (bench): Max gust 17 MPH at 11:35 PM

C9348 (bench): Max gust 18 MPH at 11:33 PM

UCC13 (river bottoms): Max gust 30 MPH at 11:15 PM

KSLC (Salt Lake City International Airport): Max gust 50.6 MPH at 11:20 PM

Quarter-Sized Hail

Quarter-sized hail was observed in this quick-moving thunderstorm that moved across the Salt Lake Valley before noon...

Radar 10:45 AM

Camera 10:55 AM

GOES-16 True Color Image and Lightning data 10:43 AM

It looks to me that the lightning data is skewed a little south of there it actually occurred. The center of maximum reflectivity is in the heart of Salt Lake County, but the lightning mapper positioned the flashes along the Salt Lake-Utah county line.

HRRR model statistics compared to NWS weather warnings

The orange in Texas represents the extreme heat warnings in Texas issued by the National Weather Service on May 30, 2018.

This area of hot temperatures corresponds well to the HRRR temperature statistics I computed on the Open Science Grid. Below is a HRRR zero-hour forecast valid 1800 UTC on May 30, 2018. The black contour is the 500 hPa geopotential height and the red shading shows how many degrees the HRRR forecast was greater than the 95th percentile temperature for the previous 3 years.

Changing Seasons

Time-lapse video is taken on top of the William Browning Building at the University of Utah. By stitching images together we can see the sun positon change with the changing seasons. The dates below are for the year 2018 and the time is the local time.