A peek into August...(7-26-13)

<B>(9:15 pm Friday July 26th)</B> The month of July is rapidly coming to and end so people are already looking ahead to what August may bring. Here are some clues I'm seeing for the opening third of the month.
It has certainly been an interesting summer across central New York. Of course, we had the heat and humidity of early July but outside that our weather, has been dominated by a general troughiness at the jet stream level here in the eastern United States.  The trough that set up earlier in the summer was unusually far south for this time of year and led to the record rains of late June and early July.

We have slipped back into that pattern of a trough trying to set up in the East, although not as extreme as what we saw earlier. The latest trough is going to end up as a closed area of low pressure at the jet stream level. Here is what it is supposed to look like by this Sunday morning:

With this low becoming ‘cut-off’ from the main flow at the jet stream, it makes for a slow moving system and it looks like we will have to deal with it 3 ½ maybe 4 days. In fact, by the time this low weakens and pulls out to our northeast Tuesday the air aloft will be cold enough and the winds favorable for some lake effect rain showers like we saw this past Wednesday.

Still, this is an unsettled pattern for us and a tough one to forecast for.  Within these troughs, you have travelling through it small jet stream disturbances and it is very tough for our computer models to get a handle on them more than a couple of days in advance.  We try to hedge a bit in our forecasts knowing this but be forewarned that this is a pattern that leads to more day to day changes in the 7 day forecast than you would normally see in the middle of summer.

Beyond this trough/closed low that we will deal with the next 4 days, are there signs that the pattern will change again causing us to get back into heat?  Well, here are a couple of maps. They are both ensemble means from the European model and the GFS (American) model centered on Wednesday August 7th:

The answer would be ‘No.’ The first thing that stands out to me is how remarkably similar these patterns are given this is roughly a week and a half in the future. You have high pressure aloft (and heat) centered over the 4 corners region of the desert Southwest while the axis of a trough of low pressure through the Great Lakes.  This doesn’t mean we are going to necessarily see weather like earlier this week (daytime high in the mid 60s) but this map and the ones preceding it (not shown) don’t scream 90 degree weather for central New York or the Northeast.  I would say mid to upper 70s weather dominates in this type of regime with occasional bouts of 80s.  If you needed more convincing, here is what the National Weather Service 8-14 day temperature forecast looks like:

Like I said above, timing our chances of precipitation beyond a couple of days in the future will be tough at times, too.  Still this is not necessarily a ‘bad’ pattern. We just endured a couple of days of mid to upper 70 degree weather and I would dare to say most folks would say it was some of the nicest weather of the summer. In addition, any tropical systems out in the Atlantic would have a real hard time making it into the Northeast. The trough would deflect any potential storms out and away from the Northeast coast.

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