Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 254 PM EST Tue Dec 24 2024 Valid 00Z Wed Dec 25 2024 - 00Z Fri Dec 27 2024 ...Another round of heavy lower elevation/coastal rain and high elevation mountain snow returns to the Pacific Northwest Christmas Day... ...A couple rounds of showers and thunderstorms in the south-central states through Thursday... ...Relatively mild, average to above average conditions across the majority of the country Christmas day... It will be a tale of two weather patterns for the country heading through the Christmas holiday, as portions of the West and south-central U.S. see a couple rounds of unsettled weather while most other locations remain dry. In the West, moderate to heavy lower elevation rain will remain possible with showers and thunderstorms in California though Christmas Eve as a Pacific system moves inland, with heavy higher elevation snow for the Sierra. Some isolated flooding will remain possible along upslope regions of the Sierra. The precipitation focus will spread inland over the Great Basin and northern/central Rockies through Christmas Eve night and into Christmas morning as the system continues eastward, with a mix of rain and snow for lower elevations and snow into the mountains. Any accumulations should light for lower elevations with a few inches possible in the mountains. Another Pacific system will approach the Pacific Northwest/northern California on Christmas day bringing another round of moderate to heavy lower elevation/coastal rain and heavy high elevation snow. Some isolated flooding will be possible along upslope regions of the coastal ranges, and Winter Storm Watches have been issued for the Cascades south through the Mt. Shasta region in California for snow totals of 1-2 feet through Thursday. The system will continue inland into the day Thursday bringing more lower elevation rain/snow and high elevation snow to the Great Basin and northern/central Rocky Mountains. Heavy snow totals of 4-8 inches, locally 12"+, are also expected through many ranges of the northern Great Basin/Rockies. Any accumulations at lower elevations should remain light. Strong, gusty winds will spread inland with the system and lead to blowing snow at higher elevations. To the east, showers and thunderstorms remain in the forecast for portions of the south-central U.S. the next couple of days as a couple upper level waves/surface systems pass through the region. Showers and thunderstorms will continue through this evening over eastern Texas and into the ArkLaTex ahead of the first system. Some severe thunderstorms producing mainly hail and isolated damaging winds are possible, as well as some locally heavy downpours and isolated instances of flash flooding. This system will make little progress eastward and weaken Christmas day as a supporting upper-level wave departs the region, which fortunately means more scattered chances of storms into the Middle/Lower Mississippi Valley. Then, by early Thursday, another upper-level wave dropping southward will lead to lee cyclogenesis and a second frontal system pushing eastward into the southern Plains. Plentiful Gulf moisture lingering just along the coast will quickly return back northward over Texas/Oklahoma and into the Arklatex, leading to a renewed round of showers and thunderstorms. Severe weather will once again be possible with a Slight Risk (level 2/5) issued from the Storm Prediction Center for the threat of damaging winds as well as the potential for tornadoes. In addition, widespread storms producing locally heavy downpours will also once again bring the threat of some isolated flash flooding. Some more scattered showers and storms will be possible further northeastward into the Middle and Upper Mississippi Valleys as well. Elsewhere, some lingering showers will be possible this evening along the coastal Carolinas. Scattered showers and thunderstorms will be possible across Florida through Christmas day and into Thursday. Conditions will generally be at or above average temperatures-wise through Christmas, with some of the higher anomalies of 5-15 degrees most likely for the central U.S. Forecast highs Christmas Day and Thursday generally range from the 30s and 40s for the northern Rockies/Plains east through the Great Lakes and New England/Mid-Atlantic; the 40s and 50s for the Pacific Northwest/northern California east through the Great Basin, central Rockies/Plains, and the Middle Mississippi and Ohio Valleys; the 50s and 60s in the Southeast; and the 60s and 70s for southern California, the Desert Southwest, Texas, and Florida. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php