A large-scale blocking pattern over North America is leading to a series of upper level disturbances tracking across the southern tier and off the East Coast this weekend, while a robust ridge of high pressure forms over the North Central U.S, and southern Canada.
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This pattern aided in the formation of Tropical Storm Arlene today, which is located in the eastern Gulf of Mexico.
Fortunately, the storm will track south and pose no threat to Florida, eventually dissipating later this weekend as it tracks towards northern Cuba.
However, daily rounds of heavy showers and thunderstorms will be common each afternoon across the Florida Peninsula this weekend.
There is a Marginal Risk (threat level 1/4) in southern Florida, as well as in New England as a cold front makes its way south this afternoon.
The stormiest weather will reside from the southern and central High Plains to the northern Rockies.
Southeasterly flow continues to usher in anomalous moisture content into these regions, who have also received well above normal rainfall over the past 2-4 weeks.
Given the combination of sensitive soils and downpours within thunderstorms, a pair of Moderate Risks (threat level 3/4) for Excessive Rainfall are in place over eastern Montana and the Texas Panhandle today.
There are also Slight Risks (threat level 2/4) in the southern High Plains and both central Montana and northern Wyoming.
Regarding severe weather, the Storm Prediction Center has an Enhanced Risk area (threat level 3/5) in west Texas, with a larger Slight Risk area (threat level 2/5) encompassing more of the southern High Plains.
Severe storms may contain a combination of tornadoes, large hail, and damaging wind gusts.
By Saturday, the Excessive Rainfall Marginal Risk footprint stretches from the Rio Grande River on north through the central Plains/Rockies and into northern Montana.
The area most at-risk for flash flooding is in the southern High Plains where a Slight Risk is in place.
Temperature-wise, following a day of record heat in the Northeast and Great Lakes, hot conditions will persist through the weekend from the Northern Plains and Mississippi Valley to the Great Lakes.
Record warmth is anticipated in the Upper Mississippi Valley and parts of the Ohio Valley on Saturday.
While not as many records are set to be broken on Sunday, daytime highs will continue to range between 10-20 degrees above normal from the Dakotas to the Great Lakes.
The West Coast, particularly areas farther inland, can also expect hotter than normal conditions, while the immediate coastline stays on the seasonably cool side.
After a rather hot Friday in the Northeast, a cold front will race south along the Eastern Seaboard and deliver a cooler than normal air-mass to coastal New England on Saturday, then into the Mid-Atlantic on Sunday.
Cooler than normal temperatures look to stick around in the southern and central Rockies and Plains due to the ongoing cloudy and stormy stretch of weather. ■
An upper level high pressure system is expected to continue aiding well above average and potentially dangerous temperatures throughout the West into the first full weekend of September.