The main weather story this weekend will be the progression of a low-pressure system tracking through the southern tier of the country, producing beneficial rains for areas such as the Southern Plains, lower Mississippi Valley, and Southeast, where moderate to severe drought has been ongoing.
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A widespread 1-2" of rainfall, with locally higher amounts, is forecast through the end of the weekend along a broad stripe ranging from eastern Texas through the Gulf Coast and into the Tennessee Valley.
Areas of heavy rainfall associated with developing bands of showers and thunderstorms could trigger isolated flash flooding.
However, the threat will be marginal due to the progressive nature of this system.
Much of the active weather will shift into the lower Mississippi Valley tomorrow, where severe thunderstorms are possible in the warm sector of the system as warm, moist air advecting from the Gulf of Mexico clashes with cooler air moving eastward behind an associated cold front.
As a result, a Slight Risk of Severe Thunderstorms has been issued by the Storm Prediction Center for southeastern Louisiana and coastal sections of Alabama and Mississippi.
An area of moderate to heavy rain with embedded thunderstorms is also anticipated farther north ahead of the low-pressure center.
Associative showers will begin to spread northward into the Ohio Valley and interior Mid-Atlantic on Sunday as the low-pressure system tracks northward, with the thunderstorm threat steadily decreasing as the system moves into cooler, more stable air.
Widespread precipitation is expected this weekend across the Pacific Northwest as a frontal system moves ashore late Saturday into Sunday in the wake of the system that is currently pushing inland.
While much of the region is forecast to dry out this afternoon, rain chances will increase tomorrow for lower elevations before becoming more steady tomorrow evening.
The precipitation may be heavy at times in northwestern Washington, leading to the issuance of a Marginal Risk of Excessive Rainfall on Sunday.
High-elevation snow will also be possible across the Olympic Peninsula and northern Cascades.
The majority of the U.S. mainland should enjoy tranquil weather conditions this weekend as a couple of strong high-pressure systems dominate the Intermountain West as well as the Northeast.
Above-average high temperatures are forecast to span the Northern Tier from the Plains to New England, with highs into the 50s and 60s through the final weekend of October. ■
A hyperactive weather pattern will bring an expansive low pressure system across mainland U.S., resulting in widespread impactful weather to progress from west to east across the country through the next few days.