Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 215 AM EST Sun Feb 18 2024 Valid 12Z Sun Feb 18 2024 - 12Z Tue Feb 20 2024 ...There's a Moderate Risk of Excessive Rainfall leading to Flash Flooding over portions of Southern California... ...Heavy Snow likely over Sierra Nevada and Shasta Siskiyous... ...Warming trend continues across Central U.S. through midweek... A closed upper-level low will direct a plume of subtropical moisture into California over the next few days. A low pressure system at the surface will focus the moisture along its attendant surface fronts as it makes it's way into the state. Heavy Rainfall is expected for the coastal areas as well as much of the inland valleys of northern/central California and into the windward foothills of the Sierra beginning this evening. Some instability will work it's way into portions of southern California tonight and continue into Monday morning, which will lead to the chance for thunderstorms and increased rain rates. Thus, a Moderate Risk of Excessive Rainfall leading to Flash Flooding (level 3/4) is in effect for portions of Santa Barbara County tonight and expanding into Ventura on Monday as the heavy rain drifts southward along a cold front. Slight Risks (level 2/4) are in effect for Humboldt down to Ventura today and then expanding down to Orange through Tuesday. Meanwhile, heavy snow will develop over the Sierra and Shasta Siskiyous tonight. This snowfall is expected to continue into Tuesday when the Pacific moisture feed is likely to end. Between 2-4 feet of snow are forecast for the Sierra and Shasta by Tuesday morning with locally higher amounts possible. Elsewhere, a stalled out surface front will focus showers and thunderstorms across the Florida Peninsula today. A stripe of 1-2 inches of rain is probable across central/southern portions of the peninsula. Lake effect snow showers continue downwind of the Great Lakes through Sunday night. An upper ridge with embedded shortwave energy will support a warming trend across the Great Plains, Mississippi Valley and Midwest over the next several days. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php