- Prevailing weather pattern
It feels as though we've moved to Seattle or Portland with this stretch of gray and damp weather, but even they have seen a more sun than us lately. The last time we had a good deal of sunshine in the D.C. metro area was on Wednesday the 14th, so it has been eleven days (and counting) with at least seven tenths of our sky shrouded in clouds according to the observations at Reagan National Airport (DCA). In those eleven days, seven have contained at least a trace of rain with 1.25 inches measured at DCA and 0.86 inches at Dulles (IAD). You may have noticed a plethora of mushrooms sprouting in area yards, gardens and parks due to this weather pattern. Not to mention mold spores are in the high range as well.
Our weather pattern is lodged in a holding pattern with an area of low pressure stuck in the Midwest and high pressure offshore in the Atlantic. This essentially wedges the D.C. are in between these two systems and within a moist wind out of the Gulf of Mexico due to the rotation around the two systems (see graphic). In turn, mostly cloudy skies, high humidity, and spotty showers will continue through the middle part of this week. As of now, it looks like changes are on the horizon as our weather pattern becomes progressive towards Thursday and Friday. At that point, a series of cold fronts are expected to move through and set the stage for widespread sunshine by Thursday, and fall-like temperatures (and humidity) into the weekend.