Weather across America

(NATIONAL) Periods of light to moderate snow in the north, and a low-pressure system to bring rain showers and thunderstorms to the Gulf Coast beginning Monday. Moderate temperatures are forecast across much of the southern and eastern U.S. but mild afternoons over the Northern/Central Plains will be followed by arctic air intrusion Monday into Tuesday.

An arctic air mass that has settled across the southern and eastern U.S. will bring another night of colder than normal temperatures before a moderating trend sets in on Monday. Meanwhile, a series of shortwaves diving across western Canada will round a broad trough stationed over eastern Canada. This pattern will result in a couple of fast-moving low-pressure waves to track across the northern tier states and Northeast over the next couple of days, bringing periods of snow to the region followed by the intrusion of arctic air from Canada. 

The first clipper will depart into the Atlantic Sunday evening but will generate light snow across parts of the Northeast, Lower Great Lakes and Central Appalachians. The second clipper will deliver a quick round of mainly light snow across the northern Plains to the upper Midwest and into the Great Lakes on Monday, before reaching New England by Tuesday morning. Lake effect enhancement should result in somewhat higher amounts downwind of the lake waters from both systems.

Meanwhile, a closed upper-level low is forecast to track eastward toward southern Texas over the next couple of days and will trigger the formation of a surface low system just off the Texas coast Monday night. This system will then tap into Gulf moisture and trigger a round of showers and some thunderstorms along the Gulf coast through Monday before moving into the Florida Peninsula on Tuesday. The heaviest rainfall is forecast to stay just off the coast. Another shortwave impulse will dive down the spine of the Rockies on Monday and Tuesday. This bit of energy will trigger snow showers from the Rockies into western Kansas with heavier snow likely over the higher elevations.

Elsewhere, the Northern/Central Plains warmed up considerably before the second clipper system tracks into the Northern Plains Sunday night. The arctic front in the wake of the second clipper will plunge into the Plains with much colder temperatures surging south Monday night into Tuesday.