Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 213 AM EST Thu Dec 26 2024 Valid 12Z Thu Dec 26 2024 - 12Z Sat Dec 28 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 Friday... The very active storm track across the eastern Pacific and into the Pacific Northwest will continue to make weather headlines through the end of the week. The next in a series of atmospheric river events is now ongoing across the Pacific Northwest, with moderate to heavy rainfall and a few thunderstorms continuing into Thursday morning. This round will likely result in widespread 1 to 3 inch rainfall totals, 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 and potentially damaging winds are also expected near the coast and the coastal waters given a strong low level jet with these storm systems. The Cascades and the Olympic Mountains will get hammered with heavy snow on the order of 1-3 feet, where winter storm warnings are in effect, and lighter snows heading south into northern California with winter weather advisories. The higher terrain of the northern Intermountain West and the Northern Rockies will also get noteworthy snowfall as moisture from this storm system moves inland. Unsettled weather conditions are also expected for portions of the south-central U.S. going into Thursday, with an amplifying upper trough developing 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. An axis of heavy rain is likely across portions of the Mid-South going into Friday as the storm system slowly moves eastward. Elsewhere across the country, mainly dry conditions are forecast across the Desert Southwest, Northern Plains, and the Northeast U.S. to close out the week. Foggy conditions are once again likely across portions of the Midwest and the Central Plains Thursday and Fridays mornings with warm/moist air advection over cold ground. In terms of temperatures, forecast highs Thursday and Friday 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 middle 60s to near 80 degrees for southern California, the Desert Southwest, much of Texas, and Florida. Hamrick Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php