Whew … It’s Hot!!!

As of 4:45pm, Monday, July 11, the highest hourly temperature recorded at BWI-Marshall was 92 degrees. A breakdown of the minute-by-minute readings today may add a degree or two for the final word on the Monday high temperature but it will likely fall short of the record of 100 degrees for the date set in 1988. Factoring in the humidity levels, the 92 degree reading feels like 99 degrees.

(NOTE: At 5:28pm the National Weather Service stated that the Monday high reach 93 degrees at 3:38pm.)

The amount of moisture in the air makes these 90+ temperatures exceptionally uncomfortable and potentially dangerous. The dewpoint temperature is and expression of the moisture content of the air and readings in the 70s are very high, similar to a tropical rainforest.

The high temperature forecast for Tuesday will be well into the 90s and the dewpoint temperatures will once again be in the 70s, demonstrated in the maps above and below.

By Thursday, air temperatures and dewpoints will be dropping.

The Thursday dewpoint forecast map above shows readings falling into the 50s and 60s (green shading) for most of the Chesapeake Bay area. Relief is in sight.

Record temperatures are vulnerable on Tuesday.

Source: National Weather Service, Sterling, VA

Air pollution is an issue in these sultry conditions. The maps below display the forecast ozone concentrations over the area for today and Tuesday.

A Code Red Orange Air Quality Alert is in effect for Baltimore.

The late Monday afternoon satellite image shows the scattered clouds and storm free weather over the Mid Atlantic region. Just to the west is a storm complex that hammered the Chicago area with severe weather earlier in the day. Its’ track will stay mostly west of the Chesapeake Bay but it may brush close enough to produce rain or  contribute enough energy to help trigger some mountain storms this evening or overnight.

On Tuesday, a weak disturbance and eventually a weak cool front will increase thunderstorm chances but any activity will most likely be widely scattered. The bottom line is that less humid air will begin to filter into the area Wednesday and temperatures should ease up by Thursday. In the meantime, take it easy.

John Collins


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