Summer may be winding down as we near the unofficial end to the season on Labor Day Weekend, but Mother Nature has different plans up her sleeve in the form of some potentially record breaking heat midweek in the Northeast. So far this August, it has been relatively hot in the region, with widespread average temperatures between 1 and 5 degrees above normal. This week’s heat will only increase that average.
This latest warmup will be brought to you by a building ridge of upper-level high pressure centered over the Eastern Seaboard of the US. Geopotential heights at 500 millibars, or about 18,000 feet in altitude, will exceed 594 millibars in select areas, indicating a rather strong dome of heat pressure. When heights reach this magnitude, it is usually a good indicator of above-average temperatures and intense heat.
It was a nice and rather seasonable weekend, but that will change as the new week begins. On Monday, the heat wave will begin in some areas as high temperatures rise up to about 90 degrees in the I-95 corridor while the remainder of the Northeast deals with highs into the mid to upper 80s, which is up to 10 degrees above the typical high temperature for this time of the year. The offshore flow of the wind will even allow for coastal areas to heat up about the same as the inland locations.
Once we get to Tuesday, the heat will really crank up as the high pressure continues to intensify in the mid levels of the atmosphere. If you are anywhere in the Northeast, the chances are rather high you deal with an actual temperatures in the 90s and heat indices approaching 100 degrees. The hot spots will be in the urban areas, especially near Boston, New York City, and Philadelphia, where the actual high temperature will near 100 degrees. This will put daily record highs in jeopardy in numerous locations. The sunny skies in most areas will also help for temperatures to reach their maximum potential, as there won’t be any cloud cover or precipitation.
By Wednesday, a few showers and storms may begin to sneak into the Great Lakes and northern New England late in the day. This will keep temperatures down by a few degrees while the Northeast megalopolis continues to deal with the intense heat. By this point in time, some cities will meet heat wave criteria (at least 3 consecutive days of 90 degree heat or greater). High temperatures across the interior Northeast will be in the upper 80s to around 90 degrees, while the coastal areas and I-95 corridor will be even warmer. A few locations may even sneak into the upper 90s, and with dew points into the 70s it will feel even warmer than that.
An approaching storm system will weaken before it approaches the coast on Thursday, so while temperatures and humidity will return to more seasonable levels, the chance for rain will be quite low.