Though D.C. managed to get the 8th in a row 90+ day under its belt, this one has been a comparative break compared to recent high heat. But more widespread relief in the way of showers and storms have also shown themselves throughout the afternoon, providing at least a temporary cool down as a “cold” front approaches and readies to pass through. In some parts of the area, like Howard, northern Montgomery and northern Prince Georges counties, rainfall has been enough to prompt flash flood warnings through 6:15 p.m..
Through Tonight: Showers and storms, some dropping briefly heavy rain and localized flooding, should continue to head southeast heading into the evening. Even if there is a break, we may still run a risk of an additional shower or storm (40%) through about midnight as the front is still up in Pennsylvania. Eventually, with drier air filtering in on a northwest breeze, low temperatures may dip into the upper 60s well north and west, to the mid-70s downtown.
Tomorrow (Tuesday): After the recent past, this might feel somewhat comfortable even though it’s still above average. Mostly sunny skies promise ample opportunity for another 90+ day as afternoon highs head for the low 90s. A northwest wind around 5 to 10 mph continues to pump in drier air, and dew points may even fall into the 50s which would be quite a humidity-lessening treat.
How hot’s it been? With 32 days 90+ behind us we are just a handful away from the yearly average of 36. 2011 is running 10 behind the top to-date years of 1994 and 2010. Still, there are only five years with more than 32 through July 25, in addition to three others also with 32. July has become a standout warm month in D.C. already and may become more so. To date, the 19 90+ in July is equal to last year and three behind 1994’s 22. Both last year’s monthly total of 21 and the overall July extreme of 24 are in play.
Pollen update: Susan Kosisky from Walter Reed writes, “Tree pollen is LOW at 0.32 gr/cubic meter, grass pollen is MODERATE at 4.79 gr/cubic meter and weed pollen is LOW at 1.6 gr/cubic meter. Mold spores are in the MODERATE range at 8899.95 spores/cubic meter”