Posted: 6:55 pm Monday, August 7th, 2017
By Kirk Mellish
In the previous blog posts and on Twitter I already explained in general why we are not having the high heat and dryness so common to many of our summers in recent decades.
The upper level Sonoran and Bermuda high pressure cells have never developed over our region or do so briefly and weakly. Normally they displace the active storm track toward Canada suppressing rainfall and building heat.
Instead we keep getting upper level troughs or gaps in the ridges, allowing fronts and low pressures systems to make there way from the north unusually far south. At the same time and active west to southwest flow has fed in plenty of moist air from the Gulf with occasional disturbances aloft coming along in the flow.
It looks to continue more or less for the rest of the month, probably returning to more normal for only a few days at a time as we alternate between below normal temperatures and very muggy to drier than normal and back again.
So hard to see any extended period of hot dry sunny weather, difficult enough to get a long stretch of of just mostly sunny and warm. Clearly the hottest weather of summer, such as it was, is behind us already!
The Pacific ENSO signal is still basically neutral with a weak La Nina lean. Pacific typhoons have been active feeding energy into the jet stream, the Madden Julian Oscillation, Southern Oscillation Index, Kelvin Waves and Pacific North American Index continue to be active and that lends itself to a continuation of the weather volatility and lack of “normal”.
END OF DAY WEDNESDAY:
UPPER-LEVEL PATTERN 500MB:
DAYS 3-7 SURFACE CHART:
UPPER LEVEL PATTERN 500MB:
The preliminary OUTLOOK for SEPTEMBER calls for temperatures to average out near-normal to above-normal, with rainfall above-normal.
FOLLOW ME on Twitter @MellishMeterWSB.