There is a weather trade in the works. The increasing threat of showers and thunderstorms is replacing the blistering heat this week. There is a slight chance, however, that, in this current heat wave, the temperature will max out at 90 degrees one more time by the noon hour in some areas including Boston before cooling commences this afternoon under some of the storms. That would make it a 6-day heat wave for a few areas. If it does warm to 90 in Boston, it means that the city will have received all of its July monthly average allotment of six 90-degree days all in a row with 23 days to go! YIKES! This combo of sizzling heat and horrible humidity has been relentless and is unhealthy for long periods of time. We New Englanders are accustomed to 3-day heat waves with some breaks of more cleansing, energizing air in between. There, of course, have been longer spells of hot weather but they become more rare as the days mount. Boston’s longest heat wave lasted 9 days from July 3-11 in 1912. Fortunately, this wave will not extend beyond 6 days as temperatures top out in the lower to middle 80s for most of the rest of this week. The humidity, unfortunately, will be oppressive today and only slightly decrease to the very high range over the subsequent 3 days before a meaningful frontal boundary arrives to change the air mass Thursday night and Friday.
In the meantime, the National Weather Service has issued a Flash Flood Watch northwest of Boston for this afternoon and evening. Some locations are vulnerable to tropical drenching downpours producing flooding in poor drainage areas. There will also be some nasty cloud to ground lightning and perhaps gusty winds and hail in some places. Some intense storms have been rumbling near and just off much of the ME coast this morning. As a pool of unstable air arrives over the region this afternoon, the showers are storms will be triggered. Most of the action will be near and west of the I-95 corridor. The showers and storms will decrease in coverage tonight then redevelop over parts of the area tomorrow.
After that, a developing storm just to the north of the Great Lakes will capture a mass of refreshing air from Canada. This delightful air will be tracking across the Upper Midwest and the Great Lakes to NY on Thursday. Its momentum will probably wane as it approaches New England due to the strong blocking ridge of high pressure offshore and a trough along the eastern seaboard. Presently, based upon the plethora of guidance, there is a 50-50 shot of this pleasant weather arriving in the Boston area southeastward but I will opt to be more optimistic and forecast the high pressure center crossing southern Canada and NY to be a bit more forceful in pushing the disgusting humid air off the coast on Friday. Hopefully, that high center will be more controlling in giving us some decent weather over the upcoming weekend. Keep in mind that the frontal boundary just offshore may try to retreat back into the region with some cloudiness and possible showers before the weekend is over.
A new tropical storm was born yesterday. Chantal is a minimal storm with top sustained winds of 40 mph and is located about 600 miles east-southeast of Barbados. A Tropical Storm Warning is now posted for many of the islands in the Lesser Antilles. For more information, logon to the National Hurricane Center.
Joe Joyce will post his blog early this evening and I shall return early tomorrow morning.
Make it a great day!