Weather Wednesday June 5 2024 Late showers and t-storms New York City excesive delays over the eastern third of the nation.

Severe thunderstorms and heavy rain possible from the lower MississippiValley across the south-central Plains and through the upper Midwestthrough tonight......Growing Excessive Heat concerns over portions of California's centralvalley region as well as the Desert Southwest with Heat Risk persistingover southern Texas...Over the next couple of days, a shift in the weather pattern willgradually push the active weather that has been persisting over themid-section of the country toward the eastern U.S.  This shift in theweather pattern will also bring a heatwave into the western U.S.  A lowpressure system currently advancing across the northern Plains hasprompted High Wind Warnings and Wind Advisories from the northern Rockiesinto the northern Plains.  This system will act as a catalyst for theweather pattern change as the trailing front marches across the countrythrough the next couple of days.  Showers and thunderstorms are expectedto be most active ahead of the cold front across the Midwest and farthersouth where it meets a low pressure wave over Oklahoma, where the chanceof severe thunderstorms and flash flooding will be the highest throughtonight.  By Wednesday, the system will push steadily eastward, endingmuch of the active weather over the mid-section of the country whilebringing widespread showers and embedded thunderstorms across the GreatLakes, Ohio and Tennessee Valleys, and down toward the lower MississippiValley.  The inclement weather will reach into much of the East Coast onThursday as a cold front continues its eastward progress.  There appearsto be a greater chance for New England to see stronger thunderstorms lateron Thursday as a warm front lifting northward meets the eastward-advancingcold front.Much cooler, damp, and windy conditions will gradually spread from thenorthern Plains eastward into the upper Midwest and the Great Lakesthrough the next couple of days behind the cold front and a deep lowpressure system over southern Canada.  On the opposite side of thecountry, a heatwave is in store for the southwestern portion of thecountry as a strong ridge of high pressure intensifies and takes control. Areas of particular concern for the heat include the low elevation regionsof California's central valley, where high temperatures will likely climbwell up into the 100s at the hottest location while 110s will be commonover the interior desert region including Las Vegas, NV especially byThursday afternoon.  There is a good chance for the temperature to top 112degrees in Las Vegas on Thursday, which would become the city's earliestobserved 112 degrees on record.  Widespread temperature records are alsoexpected to be tied or broken elsewhere across much of the aforementionedareas.  Excessive Heat Warnings and Watches extend from the central valleydown through southern California's deserts, southern Nevada andsouthern/western Arizona.  Heat Risk will peak over California's centralvalley on Wednesday before expanding into the Desert Southwest later thisweek.  Little overnight relief will make for dangerous conditions forthose without effective cooling and/or adequate hydration.  Meanwhile,Heat Risk over southern Texas peaks today but is expected to persist forthe next few days.