Dry Period Record Tied Today

There has been no measurable rain at Seattle-Tacoma Airport  for fifty-one days.   This ties the record for number of consecutive days without measurable rain, which occurred from July 7 to August 26, 1951.

And considering the current weather situation and the latest model forecasts, we are going to break the record tomorrow.    In fact, we are going to smash this record, with no rain in sight for the lowlands for the remainder of the week.

To illustrate our summer precipitation situation, here is a plot of the normal (blue line) and actual (purple line) precipitation at Sea-Tac for the last 12 weeks.   We had one very wet day in mid-June, but after that precipitation basically ended.

Now it can't be stressed enough that the summer are generally dry around here, and as shown by the figure, we are only about an inch below normal for the 12-week period.   So in terms of real impacts, the lack of summer precipitation doesn't mean that much, particularly after a very, very wet winter and spring.

Meteorologists like records though, and I am no exception.

Our temperatures this summer have been a few degrees above normal, as illustrated by this temperatures plot at Sea-Tac for the same period (average high is purple, average low in light blue)

And the deviation of the average max from normal for the last 60 days indicates that western WA is roughly 0 to 2 F above normal.   The West Coast has clearly been warmer than normal.

Why warmer and drier?    Because of persistent high pressure (ridging) over the West Coast,  which is demonstrated by the anomaly (difference from normal) of the heights of the 500 hPa pressure surface for the past 30 days:

OK, the big question folks are asking are asking is when this warm/smoky situation is going to end? 

 Well, I have good news for them.....the latest forecast ensembles suggest a shift to a cooler, wetter pattern over the weekend.    Here is the latest National Weather Service global ensemble forecasts (GEFS) for 2-m air temperature.  We actually warm up this week (sorry), followed by a distinct cool down on the 13th-15th.  Yes, uncertainty increases (the variability amount the ensemble forecasts), but all go for cooling.

from Cliff Mass Weather and Climate Blog http://ift.tt/2uhrzZK