9:50 AM | *Excessive heat on the way*
Paul Dorian
00Z Euro ensemble forecast map of temperature anomalies for late Sunday in the lower part of the atmosphere (850 mb); map courtesy tropicaltidbits.com
Overview
We are now slightly more than halfway through the summer season period of June, July and August and temperatures have averaged at above normal levels in the I-95 corridor (Philly: +0.9° June, +2.2° July; DCA: +1.0° June, +1.2° July; NYC: +0.8° June, +0.7° July) and there is no reason to believe this overall warmer-than-normal pattern will stop anytime soon despite the nice break we are experiencing here at mid-week. In fact, after this current break in the heat and humidity, excessive heat appears to be headed our way for the Friday, Saturday, Sunday, Monday time frame and this one could actually result in some isolated 100° readings in the Mid-Atlantic region. Indeed, the nation as a whole will be quite hot by the weekend which is rather typical weather for a summer featuring an El Nino-to-La Nina transition in the tropical Pacific Ocean.
00Z Euro ensemble forecast map of 500 millibar height anomalies for late Sunday; map courtesy tropicaltidbits.com
Excessive heat on the way
High pressure sits right on top of the Mid-Atlantic region today providing us with very nice overall conditions; however, once this high pressure system pushes off the east coast, the stage will be set for hot air to pour into the eastern US from the middle of the country. By the weekend, high pressure will dominate all levels of the atmosphere across much of the nation and temperatures will soar to well above normal levels. Last night’s 00Z European ensemble model run shows widespread well above normal temperatures in the lower atmosphere of the Mid-Atlantic region by late Sunday (oranges) along with above normal 500 millibars height anomalies focused right on the same area (oranges). As far as humidity is concerned, it should be quite high on Friday and Monday, but a weak frontal passage on Friday night that could spark a few showers and thunderstorms may bring slightly lower levels into the area for the weekend.
The upcoming weekend heat wave could actually result in 100° readings in isolated spots in the Mid-Atlantic region, but widespread record-breaking heat may be difficult to achieve as this is “statistically-speaking” the hottest time of the year with some impressive records in place. In fact, on this date in 1934 - in a decade full of record-breaking heat waves and some of the hottest summers ever in the US - 100° readings were quite commonplace across the country (below). The overall warmer-than-normal weather pattern in the Mid-Atlantic region is likely to continue through the rest of the summer and perhaps even well into the fall season.
High temperatures across the nation on July 20th, 1934; map courtesy Steve Goddard, Google
Meteorologist Paul Dorian
Vencore, Inc.