Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EST Wed Mar 06 2024 Valid 12Z Wed Mar 06 2024 - 12Z Fri Mar 08 2024 ...Wet Wednesday in store from the Ohio/Tennessee Valleys to the East Coast, with locally heavy rainfall and the risk of scattered flash flooding along the I-95 urban corridor... ...Showers and thunderstorms expected along the California coast Wednesday... ...Strengthening storm system in the Plains to bring showers and thunderstorms with the threat of severe weather Thursday... ...Above average temperatures persist for much of the central/eastern U.S. as conditions remain below average in the West... Wet weather will continue for portions of the eastern U.S. from the Ohio/Tennessee Valleys eastward to the East Coast in a complex pattern. Ongoing showers will continue along a slow moving cold front stretching from the Interior Northeast southwestward through the Ohio Valley, expected to make little eastward progress today and eventually stalling along the Appalachians. Meanwhile, a combination of upper-level energies and associated waves of low pressure along a quasi-stationary frontal boundary draped along the East Coast southwestward through the Southeast will spread showers and thunderstorms northeastward through the day Wednesday from the Southeast into the Mid-Atlantic and New England. A couple axis of locally heavier rainfall are forecast to occur to the east of the low pressure waves where enhanced very moist, onshore flow from the Atlantic will exist. Slight Risks of Excessive Rainfall are outlooked for the North Carolina Outer Banks and for the coastal Mid-Atlantic into southern New England, from New Jersey northeastward to far southwest Maine. Areal average rainfall totals of 1-2", locally 3", may lead to some scattered instances of flash flooding, especially for urban areas along the I-95 corridor. In addition, some locally heavy downpours will be possible in South Florida ahead of the trailing frontal boundary. The front/low pressure waves will begin to push away from the coast overnight Wednesday into Thursday morning, with rain chances lingering longest into the day Thursday in New England. Some wintry precipitation will mix in for portions of New England as colder air spreads southward behind the departing system, and some light snow accumulations will be possible into Maine. In the West, an upper-level low/Pacific frontal system will move southward along the California coast and eventually inland, bringing showers and storms to the area Wednesday. Some locally heavy rainfall will be possible through southern California, which may lead to some isolated flash flooding concerns given the very sensitive conditions still in place over the area after recent heavy rainfall events. Some snow showers will linger through portions of the higher elevations of the southern Pacific Northwest/northern California but will come to an end as moisture flow follows the Pacific system southward. A light wintry mix for the Great Basin and showers for the Desert Northwest will follow the system as it progresses eastward on Thursday. Precipitation chances will also increase for the center of the country as a couple different systems pass through the region. To the north, an upper-level wave will help to deepen/organize a low pressure system over the Northern Plains, forecast to lift northeastward through the Upper Midwest and into Canada Wednesday-Thursday. Some light showers will be possible ahead of the system, but more precipitation is expected to follow in the colder air on the backside of the system track along the Canadian border. Some light to moderate snow accumulations are expected through Thursday morning from northern North Dakota into northwestern Minnesota. Further south, the upper-level trough/frontal system over the West will approach the Central/Southern Plains from the West, helping to induce lee cyclogenesis along the Rockies and organize/strengthen a frontal system over the Plains by Thursday. A broad area of showers and thunderstorms is expected in the warm sector ahead of the system over the Central/Southern Plains into the Middle/Lower Mississippi Valley as moist Gulf return flow spreads northward. Strengthening deep layer shear as stronger winds arrive with the approach of the upper-level trough may lead to some severe thunderstorms, with the Storm Prediction Center highlighting western Oklahoma into northwest/central Texas in a Slight Risk (level 2/5) for the threat of some large hail as well as damaging winds and an isolated tornado. Some locally heavy downpours and an isolated risk of flash flooding will exist as well more broadly across the region. Finally, some moderate to heavy, higher elevation snow will be possible for portions of the Central Rockies, with some snow mixing in for the central High Plains as well. A familiar pattern of above average temperatures for central/eastern portions of the country and below average temperatures in the West looks to continue for at least the next couple of days. Highs for many locations will be upwards of 10-20 degrees above average from the Plains to the East Coast. Forecast highs generally range from the 40s and 50s from the Upper Midwest east through the Great Lakes and New England; the 50s and 60s from the Central Plains east through the Middle Mississippi/Ohio Valleys and into the Mid-Atlantic; and the 60s and 70s from the Southern Plains east through the Lower Mississippi Valley into the Southeast and Florida. A pocket of much colder temperatures in the 20s and 30s behind a cold front in the far Northern Plains will begin to spread southward following the front, with highs dropping into the 30s and 40s for portions of the Northern/Central Plains Thursday after a warmer Wednesday. Forecast highs in the West range from the 30s and 40s in the Pacific Northwest and Great Basin, the 50s and 60s in California, and the 60s and 70s in the Desert Southwest. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php