Tuesday, November 23, 2010

Noon update

The frontal precipitation band has advanced into far NW Utah and both pre- and post-frontal winds are quite impressive.

An interesting aspect of the front is the thermal structure.  There is a nice frontal nose (see below), but the coldest air lags well behind the front.  

What this means is that we'll have an exciting frontal passage, but that it will take several hours for the really cold air to move in.   


  1. Here's an animation of the front approaching I-84 near Snowville:
    UDOT Cam
    The temperature drop is a bit more substantial in this area, around 12-15F in 10 minutes (e.g. UT-30 at Curlew).

  2. Note that the latest (12Z-GFS-initialized) 1.3 km WRF run has a substantial lake band developing tonight and carrying on through tomorrow mid-morning: Simulated Reflectivity

    Some areas near and north of downtown SLC could conceivably see more snow with a lake band than with the front.

  3. If the WRF is right, we're in for 3 hours of snomaggedon and then ????

    It's interesting that the WRF always produces a band and never something broader. I wonder if that is because the PBL is totally parameterized so that the primary updrafts are organized on the land-breeze fronts and if we might see a greater variety of modality if it was run at LES scale.

  4. Occasionally the WRF will show wider areas of more cellular precip, particularly during the SOLPEX IOP2 runs, but there does seem to be a bias toward banded features. It will certainly be interesting to run some 100-m LES cases.