First heat wave of 2013 is upon us in Fredericksburg
To quote this morning’s NWS Sterling forecast discussion: “Today marks the first day of what will be the first real heat wave of the summer.” After several weeks of above normal rainfall and cloudiness that held temperatures down Fredericksburg and vicinity must now pay the piper. It is a bit ironic that the heat is occurring this week, which marks the exact middle of meteorological summer (June 1 – August 31).
Temperatures will rise to the mid-90s during the day and slide slowly down to the mid-70s during the wee hours of late night this week while the humidity levels remain high. (The dewpoint this morning is in the low 70s, which is definitely in the uncomfortable range.) Despite the typically dire media warnings that occur during such heat waves you won’t melt into a helpless puddle of protoplasm upon walking outside. However, folks venturing outdoors should take extra care of themselves this week, drinking plenty of extra water and dressing in light-colored clothing as much as possible. Also check on elderly neighbors and relatives, especially those who may not have access to air conditioning.
One weather parameter that gets tossed around during these hot stretches is heat index. That phrase combines the effects of heat and humidity into a number that the National Weather Service uses to provide advisories and warnings about the effects of heat. One result of our growing urbanization is that the concrete, brick, and asphalt prevalent in and around cities absorbs the sun’s heat very efficiently and in turn pushes up temperatures. This effect is known as the “urban heat island,” which has a definite effect on conditions in the Fredericksburg vicinity with all the highways, parking lots and shopping centers.
The good news is that this won’t be a multi-week event. Another in the continuing series of anomalous upper-level troughs will push into the eastern U.S. this weekend, dragging a surface cold front across the region and cooling things off a few degrees as shown in this forecast graphic for Sunday morning.
The combination of the heat and humidity and the cold frontal approach could fire off some severe weather this weekend so keep an eye on the forecast as the week progresses. The air behind this front – assuming the boundary makes it completely through our area and doesn’t stall out – won’t be a lot cooler but the dewpoints should be somewhat lower. That in itself will feel better than the steambath we’ll be in this week.