What a Start to August !

Lake Needwood, Derwood, Maryland

DC’s weather during the first half of August has been active.  Measurable rainfall has occurred on nine of the first 15 days of the month for a total of 5.05” – well above the average of 2.93” for the entire month.  Roughly half of that total occurred when the center of Tropical Storm Isaias passed to the east of Metro DC on August 4. 

Isaias made landfall in North Carolina as a Category 1 hurricane and had significant impacts as far north as eastern Canada.  In addition to the record rainfall in the Nation’s Capital, there was an appreciable amount of severe weather.  NOAA confirmed 35 tornadoes were spawned by Isaias, including 16 in Maryland and Virginia.  Landfalling tropical storms and hurricanes often impact areas well inland and not just the coast.  That’s why it’s vital to pay close attention to the latest forecasts when they threaten.

Aside from the impact of Isaias, Washingtonians have experienced a fairly stagnant weather pattern the last seven to 10 days with a near daily potential for scattered showers and thunderstorms.  While the majority haven’t been severe, they have been slow moving and that’s led to some eye-popping rainfall totals and flash flooding across the DC Metro Area.  For example, heavy rain in Manassas, Virginia, led to a sinkhole this past Wednesday, August 12.  Heavy rain also occurred on the east side of town Wednesday, with 3.51” of rain observed at BWI Marshall Airport.  In fact, 8.52” of rain has already fallen in Baltimore this month – more than double the August average of 3.29”. 

Despite the frequent rainfall this month, temperatures have largely remained warmer than average.  There has been only one cooler than average day so far this month and that was yesterday when DC’s high/low temperatures were 80°/70°.  Today will be even cooler with high temperatures remaining in the 70s.  That will be the first time since June 20 that high temperatures have remained below 80°.

Temperatures in the Nation’s Capital were in the 60s for much of this morning and that was also the first time temperatures fell below 70° since June 26.  That’s in contrast to last month, which finished as DC’s third warmest July on record.  Although four of the first 15 days this month featured 90° heat, that pales in comparison to the monthly record total of 28 such days last month. 

Fortunately, for those DC Area residents who are tired of the frequent clouds and rain that have been so prevalent during the first half of August, good news is on the way.  Tomorrow will be a drier day with the return of sunshine and only an isolated afternoon shower or thunderstorm.  Tuesday is setting up to be a simply stellar day in the Nation’s Capital with lots of sunshine, comfortable relative humidity and highs in the mid to upper 80s.