Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 306 AM EST Sun Feb 04 2024 Valid 12Z Sun Feb 04 2024 - 12Z Tue Feb 06 2024 ...Life threatening flooding likely across central/southern California Sunday and Monday... ...Heavy Snow will cause extreme impacts over much of the Sierra Nevada on Sunday and Monday... ...Showers and thunderstorms expected for portions of the Southeast and Florida Sunday, with the chance for some severe weather in South Florida... ...Anomalous warmth continues across the Northern/Central Plains and Upper/Middle Mississippi Valley... A strong Pacific storm system/Atmospheric River event will bring impactful and dangerous flooding rains, heavy snow, strong winds, coastal flooding, and high surf to California over the next couple of days. The combination of anomalously warm, moist air streaming in from the Pacific, favorable strong onshore/upslope flow, and cool enough air aloft for some instability will lead to widespread, heavy rain producing showers and thunderstorms with rain rates upwards of 1"/hour. There is now a High Risk of Excessive Rainfall (level 4/4) for the Transverse Ranges of Southern California both Sunday and Monday as the Pacific system is expected to slow and allow for a longer duration event with near continuous rainfall over the next 48 hours. A Moderate Risk (level 3/4) encompasses the High Risk along the central Coastal Ranges southward through the LA Basin Sunday, and from the LA Basin southward along the Peninsular Ranges Monday. Expected rainfall totals over the next couple of days range between 3-6" from the central Coastal Ranges southward through the LA Basin and along the Peninsular Ranges in the Moderate Risk area, and 6-12" into the foothills and Tranverse Ranges in the High Risk area. This heavy rainfall will bring the threat for life-threatening flash, urban, and river flooding as well as debris flows and mudslides. Heavy rainfall totals with the potential for some scattered flash flooding are also expected further inland for northern portions of the San Joaquin into the Sacramento Valley and along upslope portions of the Sierra Sunday, and portions of the Mojave Desert Monday, with Slight Risks (level 2/4) of Excessive Rainfall in effect. Heavy snow will be the headline of the event for higher elevations of the mountain ranges of Northern California and the Sierra Nevada, generally above 5000-6000 feet. Snow totals of several feet are forecast for the Sierra through Tuesday morning. Heavy snow rates of 2-3"/hour along with strong winds will lead to whiteout conditions and dangerous, near impossible travel conditions. Higher elevations of the Southern California ranges will also see heavy snow above 7000 feet. In addition to both the flooding rains and heavy snow, very strong, gusty winds upwards of 60-70 mph are expected and may lead to downed trees and power outages. Dangerous, potentially damaging high surf and coastal flooding are also likely along the coast. Moisture associated with the system will spread further northward and inland bringing moderate to heavy snow for the regional mountain ranges of the Pacific Northwest, Great Basin, and Northern Rockies over the next couple of days. Some of the higher elevations could see over a foot of snow, particularly for the Central Great Basin in Nevada northeastward into the Northern Rockies in Idaho/Wyoming. Lower elevations will see a mix of rain and snow, with little to no accumulations expected. To the east, a deep upper-level low and accompanying surface low pressure/frontal system over the Southeast/Gulf of Mexico will continue to draw moist, Gulf air northward leading organized shower and thunderstorms for portions of the Southeast and Florida Sunday. Some locally heavy downpours will be possible with the chance for an isolated instance or two of flash flooding. Locally higher low-level shear from South Florida into the Florida keys may lead to some more organized, supercell storms. The Storm Prediction Center has added a Slight Risk (level 2/5) of severe weather for the threat of some damaging wind gusts and an isolated tornado or two. Elsewhere, some light to moderate showers will linger early Sunday through portions of the Central and Southern Plains, with some light to moderate snow along portions of the Northern High Plains. Precipitation chances should come down through Sunday evening, with mostly tranquil conditions expected Monday. The Northeast will remain dry with near average temperatures. Anomalously warm temperatures will continue for portions of the Northern/Central Plains and Upper/Middle Mississippi Valley. Highs in the 40s and even some low 50s are upwards of 20-30 degrees over early February averages. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php