Severe thunderstorms and flash flooding expected across portions of thenorthern/central Plains today and into the Midwest Friday......Dangerously hot conditions will continue for parts of the South andSoutheast......Monsoon-like conditions persist today in the Four Corners region...A strong upper level trough is swinging across the Pacific Northwest todayand pushing a surface frontal system southeast across the IntermountainWest into the northern and central Plains. Conditions will be supportiveof severe thunderstorm development this afternoon and evening across thePlains, and the Storm Prediction Center has highlighted portions of thenorthern and central Plains with an Enhanced Risk (level 3/5) of severethunderstorms today. Potential severe storm hazards will include verylarge hail, significant damaging winds, and a few tornadoes. Locally heavydownpours may lead to scattered instances of flash flooding acrossportions of the Plains, especially where soils are saturated from recentheavy rains. The WPC Excessive Rainfall Outlook includes two Slight Riskareas (level 2/4) in the northern and central Plains where flash floodingwill be most likely.The Excessive Rainfall Outlook for today also highlights a Slight Riskarea (level 2/4) over the Four Corners region where persistentmonsoon-like rains are ongoing. Precipitation chances will decrease onFriday for the Four Corners region as the frontal system approaches fromthe north, but the front is forecast to stall and lift back northwards asa warm front over the weekend. This will allow moisture to stream into theSouthwest ahead of the front, continuing rain chances in portions ofArizona and New Mexico through the weekend.The frontal system will push across much of the Central U.S. and lift awarm front north across the Lower Mississippi Valley on Friday.Precipitation chances will spread east as the system progresses, expandingthe severe thunderstorm and flash flooding threats into portions of theMidwest. The Storm Prediction Center has a Slight Risk (level 2/5) ofsevere thunderstorms from the central Plains towards the Middle/UpperMississippi Valley on Friday, and WPC has a Slight Risk (level 2/4) ofExcessive Rainfall for this area as well. Potential storm hazards will belarge hail, damaging winds, a couple tornadoes, and locally heavy rain.This weekend, the broad frontal system will push into the eastern U.S.while the back end lifts north across the Intermountain West.Precipitation chances will extend from the Northeast down across theMid-Mississippi Valley to the central/southern Plains and Southwest. Thepotential for severe weather will decrease as the upper level energybecomes less organized, and the Storm Prediction Center has only a smallSlight Risk (level 2/5) of severe thunderstorms for much of Ohio andwestern Pennsylvania. The risk for flash flooding will decrease as well,and only isolated instances of flash flooding are anticipated along thefrontal system.Temperature-wise, dangerously hot conditions will persist across parts ofthe South and Southeast through the weekend. High temperatures near 100degrees will be common across the southern Plains and Texas, and hightemperatures will likely reach above 90 degrees each day in much of theSoutheast. High humidity will make these temperatures feel even hotter,and heat indices may reach as high as 105-110 degrees. Daily summertimeconvection will bring some relief to the Southeast, but mainly dryconditions are forecast across Texas through the weekend. Overnight lowswill also remain above average in the 70s and 80s, providing little relieffrom the heat.