For much of the Northwest, it hasn't rained since mid-June, when we had an unusually heavy one-day deluge of over an inch (see accumulated precipitation at Seattle Tacoma Airport over the past four week, red is observed, blue is normal). Interestingly, because of that one-day amount, the last four weeks had nearly normal rainfall!
A map of the total precipitation over the past two weeks shows less than .1 inches over most of the western U.S., with most locations getting nothing.
The departure from normal shows .75 to roughly 2 inches below normal over western Washington. The departures from normal are not large because we get very little precipitation this time of the year.
In fact, we are now entering the driest time of the year in the Northwest, with the lowest precipitation amounts the last week of July and first week of August (see climatology for Seattle)
The models are forecasting little or no precipitation for the next few weeks.
For example, the 21-member NOAA/NWS GEFS ensemble (many forecasts made to explore uncertainty) show virtually nothing for the next 192 hours.
The even larger NAEFS (US plus Canadian) ensemble shows the same thing through the 21st (second panel)
And the larger European Center ensemble indicates no precipitation or a few hundredths (gray colors) during the next ten days. The bottom panel is the ensemble average... maybe a slight misting on Monday.
With above normal temperatures and no rain, the demand for water in Seattle has increased substantially (see Seattle SPU graphic)--see the red line.
This year has certainly been one of contrasts: the wettest winter for many and now a very dry early summer.
from Cliff Mass Weather and Climate Blog http://ift.tt/2uUU0fL
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