Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Wed Mar 24 2021 Valid 00Z Thu Mar 25 2021 - 00Z Sat Mar 27 2021 ...A developing low pressure system will bring an increasing threat of severe weather outbreak and flash flooding across the Mid-South to the Tennessee Valley on Thursday... ...Unsettled weather and cool temperatures throughout much of the West but near record warmth in the Northeast and Florida Thursday into Friday... The weather pattern across the U.S. will continue to favor frequent formation of low pressure systems to track from the central/southern Plains towards the Great Lakes. One such low pressure system currently over the Great Lakes will move away into Canada, bringing an end to the wintry weather across the upper Great Lakes by early Thursday morning. Further south near the Gulf Coast, a narrow band of heavy rain and embedded thunderstorms that keeps redeveloping in southern Louisiana should shift slightly to the east toward the coastal section of Mississippi and Alabama by tonight where excessive rainfall remains possible. Meanwhile, another energetic upper level disturbance responsible for periods of heavy snow in the Southern Rockies is currently exiting into the southern High Plains. Additional snowfall is expected in the higher elevations of southern Rockies into this evening. As the winter weather threat concludes late in the day, scattered showers and thunderstorms look to develop this afternoon with some storms becoming severe in some cases. A Slight Risk for severe storms has been issued from the Storm Prediction Center for parts of the Ark-La-Tex region and southern Oklahoma, with heavy rainfall rates within these storms also possible in eastern Texas and the Lower Mississippi Valley Wednesday night. As the upper trough ejects east on Thursday towards the Mississippi Valley, attention turns to the Mid-South where confidence is increasing in a severe weather outbreak transpiring the second half of the day. Intense thunderstorms are forecast to breakout across the Deep South and track towards the Tennessee Valley Thursday afternoon and into the evening hours. All modes of severe weather: tornadoes, damaging winds, and large hail are likely to be on display Thursday afternoon. The Storm Prediction Center has posted a Moderate Risk for severe weather over southern Tennessee, northern Mississippi, and northern Alabama, while an expansive Slight Risk area is in place from the central Gulf Coast on north into the Ohio Valley. In addition to the severe hazards, hydrologic hazards are also a concern as widespread heavy showers and thunderstorms may trigger areas of flash flooding. As a result, a Slight Risk for excessive rainfall is in place from northern Mississippi and Alabama on north into the Tennessee Valley. A myriad of weather hazards; both severe and rainfall, are a recipe for a dangerous weather setup in the Mid-South on Thursday. The severe threat may linger into Thursday night across the Tennessee and Ohio Valleys while the Northeast contends with periods of rain overnight Thursday. Elsewhere, another frontal system ushers in more rounds of rain and mountain snow to the Northwest today. Snowfall accumulations over a foot are anticipated along the Cascades and the highest elevations of the northern Rockies. The front steadily pushes south on Thursday as an upper level trough plunges south into the Great Basin and Intermountain West. Expect more mountain snow to take shape in these regions on Thursday with light rainfall amounts in the lower elevations. Temperature-wise, the Intermountain West and Southwest will remain mired and below normal temperatures due to the active storm track and intrusions of colder air aloft. It is a very different story though along the East Coast, for once a nearby coastal low and its assortment of showers exits Wednesday night, a balmy air-mass rolls in courtesy of warm southerly flow. Daily record warm max and min temperatures may be broken in the Northeast on Thursday with the list of potentially record breaking warmth growing across the region on Friday. Even the Sunshine State may see a handful of record warm highs on Thursday as temperatures soar to above 90 degrees in some locations. Kong/Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php