Heavy snow over parts of Northern/Central Rockies.There is a Slight Risk of excessive rainfall over parts of Southern NewEngland/northern Mid-Atlantic on Wednesday.There is a Slight Risk of severe thunderstorms over parts of theSouthern Plains on Thursday.Low pressure along the northern Mid-Atlantic Coast will move northeastwardinto Southeast Canada by Wednesday morning. The low will develop lightrain over New England through Wednesday morning.Additionally, a front extending from the Lower Great Lakes to the SouthernPlains will move eastward off the East Coast by Thursday evening. Moisturepooling along the front will aid in developing showers and thunderstormsover parts of the Lower Mississippi Valley northeastward to the LowerGreat Lakes through late Tuesday evening. Overnight Tuesday, the showersand thunderstorms will be over parts of the Central Gulf Coast andSoutheast. The showers and thunderstorms will move off the Southeast Coastovernight Wednesday. Further, light rain will develop over parts of theOhio Valley into parts of the Northeast by Wednesday morning.On Wednesday, the system will produce rain over parts of the Northeast andMid-Atlantic. The rain over Southern New England/northern Mid-Atlanticwill be heavy. Therefore, the WPC has issued a Slight Risk (level 2/4) ofexcessive rainfall over parts of Southern New England/northernMid-Atlantic from Wednesday through Thursday morning. The associated heavyrain will create mainly localized areas of flash flooding, with urbanareas, roads, and small streams the most vulnerable. On Thursday, rainwill continue over parts of New England, with snow over northern Maine.  Moreover, a wave of low pressure along a front over the Northern/CentralRockies will produce heavy snow over parts of the area through Wednesday.The associated boundary will linger through late Wednesday afternoon,producing light snow at the higher elevations. In addition, weak onshoreflow will aid in creating light rain over parts of Northern Californiathrough late Wednesday night.Overnight Tuesday, the onshore flow will move southward, producing rainover parts of Central California through early Thursday morning. Moreover,the onshore flow will move southward over Southern California, creatinglight rain through Thursday evening. Furthermore, the wave of low pressure moves eastward into the NorthernPlains by Wednesday morning and into Central Canada by Thursday. OnWednesday, the low will produce light to moderate snow over parts of theNorthern Plains and the Upper Mississippi Valley.The associated front will move southeastward over the Central Plains intothe Southern Plains by Thursday. On Thursday, the boundary will createshowers and severe thunderstorms over parts of the Southern plains.Therefore, the SPC has issued a Slight Risk (level 2/5) of severethunderstorms over parts of the Southern Plains on Thursday. The hazardsassociated with these thunderstorms are frequent lightning, severethunderstorm wind gusts, hail, and a few tornadoes.