Anomalous Ridging and a January 'monsoon'

Black Hole · January 22, 2015

I thought I would start a new thread to talk about a few interesting things I see going on across the west right now.This has been a pretty benign winter for most of the west and that isn't about to change, but at least from a large scale perspective something pretty interesting is happening early next week.

Starting out with the next few days we will briefly see ridging before a longwave upper level trough digs in again. Its not particularly powerful but it splits pretty hard to the SW and absorbs quite a bit of energy in the process forming a strong cut off low to the southwest of the USA. Meanwhile a deep trough off the coast will pump up a strong ridge over the top of us. This is a classic rex block pattern.

Some of the modeled temperatures are crazy with this thing. For my area I have seen 700mb temps as high as +7C on the models which would produce mid 70s at the surface if we weren't going to be inverted. So very warm and nice 'Junuary' weather in the mountains and any valleys that mix out.

Then comes the really intriguing stuff. This cut off low taps into tropical moisture and starts to push north as the trough off the coast nudges inland. This sends it racing north. Notice on models the heavy precipitation over Arizona Tuesday before it moves into Utah on Wednesday as it fades away. This very much resembles a summer monsoonal push. How will the atmosphere respond in January? I guess we will see in a few days. Thoughts?

snow_wizard · January 22, 2015

Certainly a very odd setup. I guess we can't rule out the chance of a reversal before the winter is over. Hard to imagine such an extreme anomaly not being made up for at some point.

As for the shorter term it's pretty hard to imagine any real convection so early in the year over the SW, but who knows.

Dan the Weatherman · January 22, 2015

I wonder if this anomalous pattern is a sign of a significant pattern change in the not too distant future.

I hope that it brings some rain to CA in the short-term, but what I really want to see for February is a more normal mid-winter pattern featuring storms with lower snow levels to help build the snowpack across the West.