Sunday, April 6, 2014

Potential for Hottest Day of the Year (So Far)

We have one more day of unsettled weather today and then the big warmup begins.

By Tuesday, a high-amplitude ridge will be parked right over Utah.  The weather should be splendid and the Bonneville Shoreline Trail packed with mountain bikers.

Although the ridge is parked over us in Tuesday, right now Wednesday looks like it may be the warmer afternoon.  The latest GFS suggests that on Wednesday as the ridge weakens, a weak surface trough approaches from the north and northwest.

This typically results in enhanced southerly flow and, with 700-mb temperatures near +6ºC, maximum temperatures on Wedensday afternoon may reach the upper 70s at the Salt Lake Airport (the highest maximum we've had so far this year was 75ºF on March 25th).

The way things have been going so far this spring, maybe we'll hit 80 at the airport, where once again the temperatures appear "jacked."  In other words, they seem to be a couple degrees warmer than I would expect, and also higher than I would anticipate from observations from surrounding sites.  This is something that we discussed last summer (see What's Up @ KSLC) and remains inadequately resolved.  Perhaps we will try to revisit this issue in the coming days or weeks.


  1. Something also seems fishy with KSLC's precipitation gauge, appearing to report lower than surrounding sites, and very little amounts when sizable cells have moved over recently, but maybe that will be a discussion for another time...

  2. I've noticed the same thing. Along with the the small amounts, the precipitation observations seem to lag. There are many times when radar echoes move over the airport 10-15 minutes before moving over the downtown area where I live, and very often the precipitation at the airport only begins accumulating after it's been pouring at my place for several minutes.

  3. Last year that the KSLC obs seemed about 2 degrees too high. More recently they have been about 3 or 4 degrees (F) higher than surrounding sites. If it is just a siting issue (blacktop, etc) you would expect the difference to be less during windy or stormy conditions, but this has not been the case.

  4. Trevor and I have discussed this recently. It does seem to be getting worse. Yesterday, it recorded a high of 60F when the NWS office hit 54F and locations on the freeway at almost the same location that should be high biased, if anything, hit 55-56F. The U hit 54F, which would yield a 30F/km lapse rate using the airport's temperature!!! Physically impossible lapse rates are present on very windy days and days when we are moist adiabatic during storms as well. How can you have a 20F/km lapse rate in a saturated atmosphere and not convect and cool? I know when I drive by the airport, my car, which should be high biased in recording temperature on the freeway, is always lower than the airport and agrees more closely with the NWS office. There is no way the airport temperature can be correct and the NWS is going to have to go back and correct the climate record. The sooner, the better.

    1. Adam - I agree that things seem worse this year than last.

    2. Jim, it appears that the temperature went haywire today and the National Weather Service said they were doing maintenance on it. Now the temperature appears to be much more reasonable. It'll be interesting to see if it was actually fixed, but so far appears to be so.