October Outlook

 

Short term:
The first part of the advertised cool down began yesterday with high temperature about 5-10 degrees lower than they were on Tuesday.  Today is another near average day before temps will dip below average tomorrow through the weekend along the Wasatch Front with the arrival of a reinforcing shot of cold air that will push slightly farther west than yesterday’s.  We, however, will see nothing in the way of precipitation, as all of that action is well to our east.  A few more clouds tomorrow and light breezes is all that will accompany the cooler temperatures.  Night time temps tomorrow night through the weekend will dip below freezing in mountain valleys and some of the colder low valleys as well. Time to cover up or harvest the plants.
Next week, the closed cut-off low pressure system that has been sitting off the California coast will gradually move inland.  Over Southern California, Southern Utah, and Arizona.  Not too much dynamics or moisture associated with this system but it will bring us a slight chance of showers–with the best chance for precip mostly to our south.  The timing on this looks to be about Wednesday of next week.  Southerly flow that develops ahead of the low may warm us up back to near average by Tuesday



Long term:
Everything beyond the next 7 days is very vague at this point but there is nothing to suggest that the blocking high pressure ridge parked off the coast of British Columbia will be going anywhere anytime soon.  So our best chances for snow will remain with cut-off low pressure systems or weak, cool systems that periodically drop down the east side of the ridge.  El Nino, which for a couple weeks, was looking a little stronger in the models, now looks weaker again.  The CPC has now given only 55% chance of development.  I was never as sold on it’s development as they were so I’m not too surprised.  I also believe that an ENSO neutral year or a very weak El Nino is better for Northern Utah’s chances at seeing average or above precipitation.  La Nina has a tendency to favor the Northwest, El Nino – the southwest, but an ENSO neutral year often aims the jet stream more at the mid-latitudes (including the Wasatch).  Teleconnections begin to play a significant role in our weather this time of year, but as of now, most of those are in neutral states and forecasted to stay that way for at least the next ten days or so.  We’ll keep an eye on those as well as the MJO over the next few weeks to see if they show signs of livening up, whether good or bad.
For the month of October, it’s looking mostly dry until at least mid-month.  After that, the CFSv2 suggest near average precipitation through the end of the month. So overall, I think we’ll be below normal precip-wise and near normal temperature-wise for the month barring some drastic change in the pattern.  Not too much excitement as of yet, but remember, things can change in a hurry once the Pacific steps on the gas.


 As far as seasonal outlook, not much reason to change my original snow forecast for the season of about normal.  If a weak El Nino does indeed develop, the southern parts of Utah may be more likely to jump above average with the North slightly below.  But I’m guessing that El Nino will be mostly a non-factor for us this winter so most areas of Utah will have equal chances of seeing above/below average snowfall.  Sounds a bit like a cop-out to say just an average year, but the best we can do is call it as we see it, and right now there isn’t anything out there to suggest otherwise.  Besides, I think after last winter, we’d all be quite happy with an average snow year, right?