.Intensifying storm system to bring the threat of severe weather overthe Plains on Monday followed by the Mississippi Valley on Tuesday..Well above average temperatures across the Central/Eastern U.S;Critical Risk of Fire Weather for the Central/Southern High PlainsMonday..A low pressure system responsible for producing heavy snow over themountains of California on Saturday will move into the Intermountain Westtonight and bring with it some scattered rain/snow showers. In the OhioValley/Northeast, scattered showers and thunderstorms may turn severeearly this evening as a low pressure system moves across the region. TheStorm Prediction Center issued an Enhanced Risk (level 3/5) of SevereThunderstorms for eastern Ohio into western and northern Pennsylvania.Severe storms storms will track southeastward across the region thisafternoon/evening with the potential for damaging winds being the mainthreat. Severe hail and a couple of tornadoes are also possible tonight.An emerging area of low pressure over the Front Range/High Plains onMonday will quickly intensify into a significant mid-latitude cyclone bythat evening. Showers and thunderstorms will develop across the GreatPlains on Monday afternoon. The severe weather threat begins Monday nightwhen scattered to severe thunderstorms are likely to initiate across theSouthern to Central Great Plains, according to SPC. Thus, they have issuedan Enhanced Risk of severe storms in western Oklahoma and parts ofnorthwest Texas, due in part to the threat of large to very large hail,damaging wind gusts and a few tornadoes. A broader Slight Risk (level 2/5)is in effect across the Great Plains. Severe weather threats shifteastward on Tuesday. Showers and thunderstorms expand into the MississippiValley within the warm sector of the deep Great Plains storm. SPC issuedanother Enhanced Risk area for portions of southern Iowa into northernMissouri where scattered severe thunderstorms are likely Tuesday intoTuesday night from the Corn Belt to the Ark-La-Tex. Significant severehail and tornadoes are forecast over the Enhanced Risk area.Meanwhile, as the Plains storm intensifies on Monday, so will winds overthe Central/Southern High Plains. Dry air will work it's way into theregion accompanied by strong winds. These factors will contribute to aCritical Risk of Fire weather over portions of eastern Colorado, westernKansas, western Texas and eastern New Mexico. Dust storms are alsopossible over portions of southern New Mexico where winds gusts will peakaround 55-65 mph on Monday. High Wind Warnings are also in effect for thisarea. Red Flag Warnings are in effect for the Central/Southern High Plainson Monday due to the fire threat. Strong southerly flow out ahead of thePlains storm will promote well above average temperatures across theCentral and Eastern U.S. over the next couple of days, but tomorrow inparticular. High temperatures in the 80s in the Northern/Central Plainswill represent a 20-30 degree departure from normal on Monday.Temperatures moderate a bit but remain above average in those areas onTuesday. Highs will be well below average over the Southwest andIntermountain West on Monday.