The reason is clear, a modest ridge of high pressure has begun to build northward over the eastern Pacific (see below for 11 PM tonight) and this configuration should stick around for several days. Ironically, a trough is over southern CA, bringing showers and clouds to portions of the southwest--which is good because they needed the precipitation.
The next few days look dry, with a warming trend. As expert forecasters, of course you want to look at the ensemble forecasts to secure some idea of the uncertainty in the forecasts. Here is the U.S./Canadian ensemble output (from NAEFS) for the next two weeks for Seattle. There are about 50 members in this ensemble, with the median value shown by the horizontal lines, the range by the "whiskers", and the inner 50% of values by the yellow boxes.
Temperature slowly increases to about 20C (68F). Little or no precipitation. Few clouds tomorrow, but increasing clouds on Friday.
So forget the "May Gloom" this week.
What about the April precipitation, did Sea-Tac Airport beat the record? Sadly no. With drying during the second half of the month, we ended up with 5.69 inches, 2.98 inches above normal for the month. The puts us in third place for the wettest April on record. Respectable but no cigar. The record is 6.53 inches, which fell in 1991.
A downside of the warmer weather will be increased pollen levels, and thus suffering for those with allergies.
The values in Seattle for the past 30 days show ups and downs, with ups often associated with warmer/drier weather.
And with warming the next few days, pollen.com predicts increasing levels this week. How good are these predictions? I haven't verified them and they don't show uncertainty information. I do see cars being caked by pollen...so there has been plenty of it floating in the air.
