A pair of slow moving storm systems are responsible for prolonged periods of heavy rain and thunderstorms in the Southeast and the Northeast.
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Starting in the Northeast, an area of low pressure will carry a plume of rich moisture aloft into the region today.
The heaviest rainfall today will be found from the Catskills on east across much of New England.
By Saturday, the strengthening storm system will track into the Gulf of Maine with a broad swath of heavy rainfall centered over northern New England.
The Northeast will gradually dry out throughout the day Saturday with Downeast Maine seeing the last bands of showers finally depart by Saturday evening.
The latest forecast calls for an additional 1-2 inches of rainfall across much of New England with localized totals over 2 inches possible through Saturday.
With much of the region sporting saturated and sensitive soils, it is possible for instances localized flash flooding and minor to isolated moderate river flooding through Saturday.
WPC has issued a pair of Marginal Risks (threat level 1/4) to highlight the flash flooding potential that will most likely be confined to poor drainage areas and urbanized communities.
Farther south, another dawdling storm system is set to produce rounds of heavy rain and thunderstorms today and into the weekend.
This storm systemwill direct copious amounts of Gulf moisture northward while a stationary front also acts as a trigger for thunderstorms each day.
Today, WPC has an expansive Marginal Risk for Excessive Rainfall that stretches from the Lower Mississippi River Valley to as far east as the Southeast coast.
In addition to the Excessive Rainfall potential, the Storm Prediction Center (SPC) issued a pair of Slight Risks (threat level 2/5) along Florida's Space Coast and in the North Carolina Outer Banks.
Marginal Risks encompasses much of the same areas of the Southeast as WPC's Marginal Risk with severe storms capable of producing damaging winds, large hail, and tornadoes.
By Saturday, the upper low responsible for the onslaught of heavy rain meanders eastward slightly, placing Alabama, the Florida Panhandle, and much of southern Georgia in the best position to receive the heaviest rainfall.
In terms of severe weather, SPC does have a Marginal Risk in place for much of northern and central Florida.
Through Friday and Saturday alone, the rainfall forecast calls for as much as 1-4 inches of rain for much of the Southeast with the Florida Panhandle having the best chances for witnessing the heaviest amounts.
Flash flooding, as well as some cases of river and small stream flooding, are expected through Saturday with more rain still to come both Sunday and into early next week.
With the pair of storm systems causing widespread cloud cover for much of the coastal areas and their associated cold fronts directing cooler temps into the southern and eastern U.S., temperatures will be below normal from the Rio Grande Valley of western Texas all the way to the East Coast.
Temperature anomalies will largely be 5-10 degrees below normal with some parts of the Northeast seeing departures as cool as 15 degrees below normal in some cases.
Meanwhile, a large upper level ridge will park itself over the western and northern U.S. that will foster very warm temperatures for early-to-mid May.
Some record warmth is possible today in parts of northern California and the Great Basin, but the footprint of record-breaking warmth will consume more of the West, including the Northern Rockies and Southern California.
Some parts of Southern California may see high temperatures reach triple digits, while morning lows may also challenge record warm levels for this time of year.
Temperature anomalies throughout the West by Saturday are likely to range between 15-25 degrees above normal and will potentially approach 30 degrees above normal in the Northern Plains by Sunday.
NWS's HeatRisk does depict Moderate to scattered instances of Major heat potential in the Southeast on Saturday, with Moderate heat impacts showing up in the Northern Plains. ■