Drenching downpours to slice through hot, humid air in Northeast
The deluge could cause travel problems from late this weekend into early next week. In some areas, several inches of rain could lead to flooding issues.
Drenching downpours will bring the risk of flash flooding and travel delays to the Northeast through this weekend and into early next week.
The weather pattern in the Northeast has been a tale of all or nothing so far this summer. A remarkable dry spell was followed by unrelenting rain, bookended by waves of wildfire smoke and poor air quality. And, as if right on cue, the first heat wave of the summer got underway for parts of the Northeast during the first full week of July. AccuWeather meteorologists warn residents not to get used to that either, as a surge in moisture could evolve into flooding downpours and travel disruptions into early next week.
Widespread high temperatures ranging from the mid-80s to the mid-90s F have been a regular occurrence for the northeastern United States much of this week. But, even on Saturday, summery conditions will continue over much of the region with highs in the 80s to near 90. AccuWeather RealFeel® temperatures will tend to run 5–10 degrees higher than the actual temperatures.
The AccuWeather RealFeel Temperature is more realistic than the actual temperature or heat index as it incorporates the effect of the sun on how hot it feels, along with impacts on the body from humidity, wind and other conditions.
After rounds of rain and thunderstorms on Friday, the atmosphere will tend to slowly reload across the region this weekend as the core of the hot and humid air prepares to exit.
Spotty thunderstorm activity will be possible once again in part of the I-95 zone as well as over northern and western New England and part of eastern New York.
However, moisture will gather over portions of the middle Mississippi, Ohio and Tennessee valleys on Saturday thanks to a strong ripple in the jet stream. That feature will set off severe thunderstorms and torrential downpours over the middle of the nation.
Travel conditions are likely to deteriorate from southwest to northeast across the Northeast states from Sunday into Sunday night.
As this disturbance takes a northeastward turn Sunday morning, it will be in a position to grab extra moisture from both the Gulf of Mexico and the Atlantic Ocean. The storm has the potential to be a very efficient producer of heavy rain due to the high amounts of moisture available in eastern portions of Kentucky and Tennessee, as well as West Virginia and the western portions of North Carolina, Virginia and Maryland.
The timing on the heaviest rain on Sunday is likely to be during the afternoon and evening in Washington, D.C. In Philadelphia, the heaviest rain is likely to last from late Sunday afternoon to early Sunday night. Around New York City, the greatest risk of flooding downpours will occur from Sunday evening to after dark.
"Rainfall rates could reach 2 inches per hour in some locations as the system moves along on Sunday from the southern Appalachians and mid-Atlantic to eastern New York and central and western New England from Sunday night to early Monday," AccuWeather Senior Meteorologist Adam Douty said.
"Infrastructure in the metro areas may not be able to handle rainfall of this magnitude, and as a result, rising water could quickly inundate some locations," Douty warned.
The exact timing and orientation of the heaviest rain will depend on the track of the storm system.
Motorists should expect significant slowdowns as a result of poor visibility and possible road closures due to high water. From Sunday to Monday, a broad area of 2-4 inches of rain will fall with an AccuWeather Local StormMax™ of 10 inches in the wettest spots. Rainfall of this magnitude may not only lead to street flooding, but rapid rises along small streams is likely as well.
"The heaviest rain may slide just to the west and north of Boston later Sunday night to Monday, but commuters over the Hudson Valley of New York and in western, central and northern New England could experience significant travel delays for the Monday morning drive," AccuWeather Meteorologist Alex DaSilva said.
Another component of the storm system is the potential for thunderstorms with strong wind gusts and frequent lightning strikes along the leading edge of the heavy rain from midday Sunday to Sunday evening, Douty added. Localized gusts could be strong enough to knock over trees and lead to sporadic power outages.
Warmth ahead of the disturbance will tend to boost the thunderstorms to the point that localized severe weather with gusty winds could occur during the daylight hours on Sunday. Then, after dark, the gusty nature of the thunderstorms will tend to ease, but energy will be squeezed out in the form of thundery torrential downpours, forecasters say.
The incoming rain will slash temperatures on Sunday by 10 degrees or more.
In the wake of the disturbance, a corridor of moisture is likely to remain from the southern Appalachians and the coastal Carolinas northward to the mid-Atlantic and New England regions next week.
High temperatures much of next week in the Northeast will tend to run below historical averages with widespread highs ranging from the upper 70s to the mid-80s.
Additional disturbances are likely to roll along in this moist zone and increase the likelihood of more rounds of downpours and locally gusty thunderstorms.
Could smoke from Canadian wildfires return?
The ongoing pattern next week will be created by a large, strong storm that will develop near Hudson Bay, Canada. The counterclockwise circulation of this massive storm may direct thick smoke from wildfires in western Canada into the North Central states from later this weekend into next week.
It is possible that some of that smoke could reach part of the Northeast next week.
Smoke at higher levels of the atmosphere could produce hazy sunshine. If it were to reach lower levels, it could cause air quality to deteriorate, especially in areas from the Appalachians to the Great Lakes and Ohio Valley.
As long as these fires continue to burn across vast areas of Canada, the risk of an invasion of wildfire smoke will persist in the northern U.S., AccuWeather forecasters say.
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