Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 237 AM EST Sat Feb 22 2025 Valid 12Z Sat Feb 22 2025 - 12Z Mon Feb 24 2025 ...Atmospheric River to bring very heavy rain and scattered instances of flooding to the Pacific Northwest and northern Rockies this weekend... ...Showers and thunderstorms with locally heavy rainfall forecast along the Gulf Coast... ...Temperatures begin to slowly moderate this weekend across the southern U.S. following prolonged Arctic Blast... An active Pacific storm track/Atmospheric River will bring very heavy rainfall to the Pacific Northwest east through the northern Rockies this weekend. Showers are already ongoing through the region as an initial Pacific system moves through Saturday morning. Then, a more significant influx of moisture will arrive later Saturday, extending inland through the northern Great Basin and into the northern Rockies through Sunday. Mild Pacific air will keep snow limited to the higher mountain peaks allowing for upslope flow and very heavy rainfall along the coastal Ranges, Olympics, and Cascades. Isolated flooding will be possible Saturday with more scattered instances of flooding by Sunday as rainfall totals continue to increase, and a Slight Risk of Excessive Rainfall (level 2/4) is now in effect. This mild air will continue inland as well with snow levels remaining high through the northern Rockies. Runoff due to snowmelt from the mild temperatures as well as heavy rainfall will lead to isolated flooding concerns on Sunday. Some heavy snow totals will be possible for higher mountain elevations of central Idaho and northwest Wyoming, especially on Sunday. Yet another Pacific system will arrive by early Monday continuing the heavy rainfall into early next week. An area of low pressure over the Gulf will encourage increasing shower and thunderstorm chances along the western Gulf Coast Saturday, moving east along the central Gulf Coast Sunday. Moderate to locally heavy rainfall will be possible. Some light snow showers are expected around the Great Lakes and interior Northeast as a cold front and a couple upper-level shortwaves pass by. Elsewhere, the rest of the country will be mostly dry. Conditions will finally start to slowly moderate across much of the southern U.S. this weekend following the prolonged Arctic blast this past week. Below average temperatures will linger longest from southern Texas east along the western/central Gulf Coast and north through the Lower Mississippi Valley. Highs will increase from the 40s on Saturday into the 50s and 60s by Sunday. Morning lows dropping to near or below freezing will be a concern for more sensitive regions of the South less prone to freezing temperatures. Temperatures will remain a bit below average but see a warming trend along the East Coast as well, with 30s and 40s for the Northeast and 50s and 60s for the Southeast Saturday, and running generally 5 degrees or so warmer Sunday. Increasing upper-level heights from the west will bring a more significant warm up with above average temperatures to the northern Plains and central High Plains Saturday with highs reaching into the 40s and 50s. These above average temperatures will spread eastward on Sunday with 40s into the Midwest and 50s and 60s into the central/southern Plains. Upper-level ridging over the West will continue to lead to above average temperatures across the region, with highs generally ranging from the 40s and 50s across the Pacific Northwest and Interior West, the 60s and 70s for California, and 80s for the Desert Southwest. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php