Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 246 AM EST Wed Dec 25 2024 Valid 12Z Wed Dec 25 2024 - 12Z Fri Dec 27 2024 ...Continued rounds of heavy rain and mountain snow for the Pacific Northwest... ...Heavy rain and strong thunderstorms return for eastern Texas into Louisiana on Thursday... ...Relatively mild conditions across the majority of the country through Thursday... The very active storm track across the eastern Pacific and into the Pacific Northwest will continue to make weather headlines through Thursday. After a brief break in the action, steady rainfall reaches the Washington and Oregon coasts by midday Christmas, and then reaches northern California by evening. Periods of heavy rainfall are likely Wednesday night as the atmospheric river intersects the coastal terrain, with perhaps a few thunderstorms. This round will likely result in widespread 1 to 2 inch rainfall totals, and potentially more on the west facing slopes, and there may be some instances of flooding where rainfall rates are highest. Once this first system moves inland, there will be a short-lived break Thursday afternoon before the next round arrives Thursday night for many of the same areas, bringing an additional 1-2 inches of rain by Friday morning. Strong winds are also expected near the coast and the coastal waters given a strong low level jet with these storm systems. Snow levels are likely to be lower with the second round, with the Cascades getting hammered with heavy snow on the order of 1-3 feet, and lighter snows heading south into northern California. The higher terrain of the northern Intermountain West and the Northern Rockies will also get noteworthy snowfall, particularly across eastern Oregon and into Idaho. Unsettled weather conditions are also expected for portions of the south-central U.S. with a loitering surface low over Texas and a meandering stationary front over eastern Texas and into Louisiana. There will likely be a decrease in the shower and thunderstorm coverage on Christmas Day, but an amplifying upper trough will develop a new surface low and moisture plume from the western Gulf, heralding the development of scattered to widespread showers and thunderstorms. Both wind shear and instability parameters appear to become increasingly favorable for some severe weather on Thursday, and therefore the Storm Prediction Center has portions of the ArkLaTex region in a Slight Risk for severe storms. Heavy rainfall could also be an issue where these storms train over the same areas, and there is a Slight Risk of flash flooding from eastern Texas to central Arkansas. Elsewhere across the country, mainly dry conditions are forecast across the Desert Southwest, Northern Plains, and most of the East Coast states with the exception of some showers near the Florida East Coast. Foggy conditions are likely across portions of the Midwest and the Central Plains both Christmas morning and Thursday morning with warm air advection over cold ground. In terms of temperatures, forecast highs on Christmas Day and Thursday generally range from the 30s and 40s for the northern Rockies/Plains eastward to the Great Lakes and New England/Mid-Atlantic; the 40s and 50s for the Pacific Northwest and northern California eastward across much of the Intermountain West, central Rockies/Plains, and extending eastward to the Ohio Valley; the 50s and 60s for the Mid-South and the Southeast U.S. states; and the 60s and 70s for southern California, the Desert Southwest, Texas, and Florida. Hamrick Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php