Heat and humidity will build over the mid-Atlantic this weekend ahead of any influence from Isaac as a tropical rainstorm.
High pressure responsible for the agonizingly slow movement of Isaac in the South will work to build heat from the Midwest to the Atlantic coast during the first part of the Labor Day weekend.
Temperatures will surge into the 90s in Washington, D.C., Baltimore, Philadelphia, New York City, Hartford and Boston on Friday.
While cooler air from Canada will burst the bubble of heat rather quickly across New England for the weekend, 90-degree readings will hold on from Philadelphia through Richmond, Va., during Saturday.
For some, it may feel more like the Fourth of July for a couple of days.
Meanwhile, the center of circulation of Isaac will continue to unwind into the weekend over the Midwest. However, it probably will not completely fade away.
AccuWeather.com meteorologists feel that at least some showers and thunderstorms associated in part with the system will drift in from the Midwest.
It will not be a simple matter of tracking the "blob" of moisture with Isaac as the rainfall will become embedded with a frontal zone sagging across the region.
The front and cooler high pressure pushing into New England will try to slow the forward progress of the rain once again, perhaps causing it to stall over the Ohio Valley and central Appalachians.
However, all things considered, the probability of showers and thunderstorms will increase over the mid-Atlantic Sunday and Labor Day with temperatures trending downward. Much of the time in New England is likely to be rain-free as the second high pressure area moves in.
Timing and how much rain is delivered by the aging tropical system have yet to be determined for the region.
As with any feature of this sort approaching, there is the potential of isolated heavy rainfall and locally damaging thunderstorms.
Isaac has produced a general 8 to 16 inches of rain in southeastern Louisiana and southwestern Mississippi with locally higher amounts. A half a foot of rain is forecast to reach into drought-stricken areas of Arkansas and Missouri into the weekend.
Locally damaging wind gusts are forecast to reach as far as southern Missouri with the aging tropical system.
Repeating and slow-moving storms will raise the risk of flash flooding and damaging winds over the northern and central High Plains into Thursday night.
As July draws to a close, a storm system swinging up from the Deep South will bring downpours to the northeastern U.S. and break the back of an extended heat wave.
Rounds of showers and thunderstorms moving westward off the coast of Africa may pave the way for future tropical systems over the Atlantic Ocean in the weeks ahead.
Highs will run between 10 and 15 degrees Fahrenheit above average across much of the interior western United States into the upcoming weekend.
A budding tropical system threatens to bring flooding rain to the Philippines into this weekend with potential future impacts on China and Taiwan.
The heat felt across the United Kingdom during the middle of July has faded and is not expected to return through at least the first week of August.
Small but intense storm, said to be the worst in about 50 years, hit southern Mississippi (where Camille hit in 1969). U.S. Coast Guard cutter lost with 39 aboard.
New England (1949)
Heat wave in New England; Greenville, RI hit 102 degrees.
Marquette, Il (1988)
99 degrees for a date record.