Monday, April 13, 2015

Excitement At Last!

Tuesday and Wednesday look to be the most meteorologically exciting period we've had around here in some time as a strong cold front develops over the Intermountain West.  There's something for everyone including strong winds, blowing dust, mountain snow, and then, for Tuesday night and Wednesday morning, the chance of mountain and valley snow depending on how everything comes together. 

The forecast for 1800 UTC (1200 MDT) today shows a Pacific cold front making landfall along the Pacific Northwest coast.  Ahead of the landfalling cold front, however, temperatures increase fairly dramatically from the Pacific coast to the Intermountain West (circled).

As the Pacific cold front pushes into the interior, a new cold front forms ahead of it from that temperature gradient that currently exists from the Pacific coast to the Intermountain West.  By the time we get to 2100 UTC (1500 MDT) tomorrow, the front pushing through Utah is essentially a new front, with the Pacific airmass well behind it over Nevada and central and western Idaho.  

Meteorologists refer to this as discrete propagation and it is a common occurrence over the Intermountain west, especially in the spring.  See if you can pick up on it in the loop below.

As a result, tomorrow will likely bring a two part system.  We will have a cold-frontal passage in the early afternoon.  This frontal passage could bring some showers, but will otherwise probably be dry with the possibility of blowing dust (both ahead of and behind the front depending on how things come together.  The bulk of the precipitation will lag the surface front and come in two or three hours later.  

Precipitation forecasts for this system have been all over the place (see There's Always a Storm in the Extended) and they continue to give me heartburn.  The latest NAM is calling for 0.8" of water and 16 inches of snow for a storm total at Alta through Wednesday evening.

A few inches in the mountains late tomorrow afternoon and evening looks pretty likely, but Tuesday night and early Wednesday are the really hard part of this forecast.  The latest runs call for moist, northwesterly flow and very cold air for mid April, with the potential for the lake to get going as well.  Right now things look good for mountain snow, with the potential of some action in the valley too, but we are right on the edge of the action and a slight shift could change that.  We'll take a closer look tomorrow.

1 comment:

  1. If it snows hard enough to limit travel to and from the ski areas, don't forget that U of U's version of the multiple Tony award winning Broadway musical sensation "A Funny Thing Happened on the Way to the Forum" will be making its last weekend of performances on Thursday, Friday, Saturday and Sunday at the Babcock. Forget about the weather -- "Forum" is harder core than the corn and it's indoors!!

    This is a high energy, barn burning comedy put on by the students and staff of the U of U (with me playing trumpet in the background).