Weak storm Friday night/Saturday morning will bring light snow amounts to the Northern Wasatch. It will also temporarily scour out inversion for a day or two of cleaner air. Pattern change looking likely now for next week.
Finally what we’ve been waiting for…. A decent looking forecast. Most posts over the last 7-10 days have been short due to a combination of a busy holiday period for myself and benign weather. But today’s post is not short, so get ready for some heavy reading.
Inversions will persist for another 36 hours before a system moves through tomorrow night. This is a decent cold front, but it lacks moisture, so precipitation amounts will be on the light side. It is also grazing Northern Utah with the majority of precipitation heading to our north and east. Still, snow should start late Friday night and continue into early Saturday morning. Amounts look to be in the 1-4″ range with perhaps up to 6″ in favored areas like the Cottonwoods if we get real lucky. The big win for us valley folk will be getting rid of inversion for at least a day.
Saturday afternoon thru Monday night look dry. The next system is also fairly weak but will be the first in what could be a series of storms. It will move into the area late next Tuesday, Jan 7 into Jan 8. This could be followed by another storm Thursday/Friday and possibly another next Sunday/Monday. Of course, this is stretching the limits of our forecasting abilities, but the point is we may be entering a period of several storms rather than just a one and done.
Since we like pretty pictures to illustrate this point, take a look at the ECMWF’s total forecasted precipitation through the evening of January 7:
Our only precip in Utah is from the weak system this weekend. Now, lets look at the totals thru Jan 12 (this includes the first two storms in the series):
Much better, storms are progressing from the PNW east into the Great Basin and the Wasatch. This is a very good sign. Although it is still too early to say anything about how much snow we can expect — I’m excited because any change is a good change. For the past two weeks, you’ve heard me spew a bunch of info about ensembles and the CFSv2. If you’ve been a regular reader, you know that when you start hearing about ensembles, the CFS, and teleconnections like MJO/PNA/AO/QBO/etc, then you know we must be desperate. No need for that now as there is finally something tangible in the operation and deterministic runs of the models.
Like I said, we are still early in the pattern change forecast and there is still a lot that can change between now and when this is supposed to take place, so don’t get too excited just yet. But hopefully this will be the start of something good.
With all that being said, let’s take a look at where we stand heading into 2014 snowpack-wise . . .
Because it’s a reliable location and a fairly accurate reflection of the Wasatch as a whole, I’m using the Snowbird Snotel site. Here is a look at the current snowpack for Jan-1 compared to last year (2013) and the year before (2012):
You can see us this year (green line) — currently we are at 68% of the normal snowpack (dark blue line) for this location. We’ve seen about 21% of the average annual snowfall so far. Usually by now, we’ve received just over 30% of our average annual. So while we are noticeably behind normal, if history is any indication, we still have 70% of the season left to go, which is plenty of time to make up ground. You can also see with the above graph that we’ve seen significantly less snow than last year at this time (red line). Last year, however, we had a very poor January-March period after a decent start to the season — so again, plenty of time to catch up. We have seen worse, however, with the winter of 2011-12 as a recent example (light blue line).
Forecasting is often about identifying correlations and patterns. If we look at similar years in which we started out okay but then tailed off for the second half of December, we get this graph:
In two similar years (2007 and 1992), we saw ok starts to the season then long periods of dry weather. In both of these years, we finally broke this pattern in mid-February, but it was far too late to catch up to normal. Hopefully this year won’t be the same, but unfortunately, when we get into dry patterns this time of year, they can be very difficult to dislodge.