A plume of moisture surging northward from the Gulf of Mexico and Caribbean Sea will bring widespread tropical downpours to a large part of the Southeast through the holiday weekend.
Some cities that have the highest potential for flooding on multiple days through the weekend include Tampa, Pensacola and Tallahassee, Fla.; Atlanta, Ga.; Birmingham, Ala.; Greenville, S.C.; Knoxville, Tenn.; London, Ky.; Charleston, W.Va. and Pensacola, Fla.
Some locations have seen as much as eight inches of rain since Thursday from this moist flow from the Gulf of Mexico.
AccuWeather.com meteorologists are especially concerned for dangerous flash flooding along the western Florida Panhandle and across parts of central Tennessee and central Kentucky.
While widespread river flooding is not likely from this event, there is considerable concern for rapid, dangerous flash flooding of low-lying areas, urban areas, areas with poor drainage and along smalls streams.
Numerous blinding downpours will cause severe restrictions to normal driving speed as low visibility and water-logged roadways bring the risk of hydroplaning.
Those traveling I-65 in Alabama, I-40 in Tennessee or I-10 in the Florida Panhandle will likely endure significant delays this afternoon and evening.
Arrival and departure delays at major airports like Atlanta's Hartsfield International may also be common, especially as drenching storms engulf the region in the afternoon and evening hours.
This situation has the potential to be particularly dangerous in some areas. It is important to remember that flash flooding can be life-threatening. Not every location will have flash flooding, and some areas may not receive much rainfall at all, but that will not be the case in other, less lucky locations.
Tremendous rainfall in a short amount of time can cause flooding in areas that you might not even think can flood. Yards and basements can become more like lakes and swimming pools. In towns with hilly terrain, streets can easily be turned into rushing rivers.
It only takes a few inches of swift-moving water to sweep a person from his feet and only 18 inches to lift a vehicle and wash it away.
Hawaii will escape the worst, but not all of Guillermo's impacts as the tropical storm passes north of the islands Wednesday through Thursday.
A line of violent thunderstorms tore across Massachusetts, including the Boston area, Tuesday afternoon.
A developing storm system will track from the Missouri Valley to the mid-Atlantic through Thursday and produce rounds of showers and thunderstorms with locally heavy rain.
The Northeast will catch a break from heat and humidity for the remainder of the week.
Typhoon Soudelor in the western Pacific Ocean will remain a powerful tropical cyclone this week eventually threatening Taiwan and eastern China.
Two spectators were killed and at least another 32 people were injured Monday evening, as strong storms forced a circus tent to collapse in Lancaster, New Hampshire.
Ice Harbor Dam, WA (1961)
Temperature of 118 degrees - hottest ever in Washington state.
Casper, WY (1980)
39 degrees, broke 1974 record for the date by 9 degrees.
Norfolk, NE (1989)
Early morning thunderstorm brought sustained winds of 60 mph with gusts to 92 mph.