Heavy mountain snow expands across Four Corners and Southern Rockiesthis weekend.Severe Thunderstorm and Excessive Rainfall chances shift south into theSoutheast and Gulf Coast States.Mild weather continues across the Pacific Northwest and East Coast.A closed upper low will continue spinning over the Southwest this weekend,while an upper ridge builds over the Northwest and a deep trough descendsinto the Great Lakes/Midwest. Shortwave energy will round the base of theclosed low in the Southwest and accelerate through Texas and the GulfCoast leading to heightened Severe Weather and Excessive Rainfall threatsthis weekend. At the surface, a slow moving cold front will eventuallystall out along the Gulf Coast and be the focus for thunderstorms andheavy rainfall. Tonight, scattered to isolated thunderstorms (some severe)will develop along the cold front extending from the Edwards Plateau intosouth-central Texas. An Enhanced Risk (level 3/5) of Severe Thunderstormsis in effect for those areas tonight, while a Slight Risk (level 2/5)extends from there out across the central Gulf Coast and into the Floridapanhandle, where very large hail and isolated damaging winds are expected.In addition to that, a Slight Risk of Excessive Rainfall (at least 15%) isin effect for those same areas where 3-4 inches of rainfall mayaccumulate. The Slight Severe Weather and Excessive Rainfall Riskscontinue over southern Texas on Saturday where the cold front will stallout. Scattered showers and thunderstorms will continue across the centralGulf Coast as well.While heavy snow diminishes later today across the central Rockies, heavysnow will expand and intensify across the Four Corners this weekend and islikely to redevelop over the Southern Rockies on Sunday. For the higherelevations of the Southwest and Four Corners region, including portions ofthe Mogollon Rim north into the southern Wasatch and the San Juans, snowprobabilities for amounts of at least 12 inches are moderate to high(50-90%). Localized totals up to 2 feet are possible. By Sunday, theheaviest snowfall is expected to transition to the Sangre de Cristo andJemez Mountains. Heavy snow rates of up to 2"/hr and gusty winds exceeding35mph (locally higher to 50mph) will cause blowing snow and reducedvisibility, especially across the mountain roads and passes. This willcreate difficult to at times impossible travel, with road closures likely.Disruptions to infrastructure due to power outages are possible as well.Elsewhere, an upper ridge will promote increasing heights and aboveaverage temperatures for the Northwest this weekend. High temperatures inthe 60s and 70s will be 15-25 degrees above average for this time of year.Meanwhile, a deep upper level trough will supply ample southerly flow intothe East Coast through Sunday after which a cold front will sweep throughand return temperatures to seasonal averages. This weekend though, highsshould be 5-15 degrees above average up and down the coast.