Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Thu May 04 2023 Valid 00Z Fri May 05 2023 - 00Z Sun May 07 2023 ...Threat of severe thunderstorms over the southern Plains through tonight followed by heavy rain and threat of flash flooding across the Tennessee Valley on Friday... ...Unsettled weather expanding into the Pacific Northwest will promote snowmelt and flooding across the interior sections while rain and some thunderstorms expand up the northern Plains... ...Cool afternoons across the western U.S. and the Mid-Atlantic will be contrasted with highs into the low 90s in the central Plains by Saturday... Over the next couple of days, much of the active weather will be found across the mid-section of the country, gradually shifting eastward into the southeastern U.S. while unsettled weather will persist across the Northwest and the northern Plains. This is in response to a slow-moving upper trough interacting with a couple of slow-moving frontal boundaries. The frontal boundary currently across the southern Plains will be responsible for a threat of severe thunderstorms over the southern Plains through tonight as it lifts ever so slowly northeastward. By Friday, the thunderstorms are forecast to reach into the lower to mid-Mississippi Valley as a low pressure wave develops on the front over the central Plains. Heavy rain will likely expand eastward across the mid-Mississippi Valley into the Tennessee Valley Friday and Friday night ahead of the low pressure wave where the heavy rain may lead to flash flooding. By Saturday, the threat of heavy rain should decrease as the rain continues its eastward movement into the Carolinas. Meanwhile, thunderstorm clusters are forecast to organize across the lower Mississippi Valley behind the warm front, and over central Texas ahead of a dry line. Meanwhile, unsettled weather will continue expanding into the Pacific Northwest under moist southwesterly flow ahead of the western U.S. upper trough. The moisture will interact with a stationary front near the northern slopes of the northern Rockies. The heaviest rains are forecast across the lower to mid elevations of the interior mountains across Idaho and portions of nearby states tonight into early Friday where snowmelt will promote flooding across the region. Wet snow will be confined to the highest elevation as well as across northwestern Wyoming. For the rest of Friday into early Saturday, the focus of moderate to locally heavy rain will shift northeastward from the northern Rockies into the northern High Plains while moderate to locally heavy rain and some thunderstorms expand up the northern Plains as the stationary front lifts northward as a warm front. Much of the Northwest and into northern California will see unsettled weather continuing into the weekend. Temperature-wise, cool afternoons will prevail across the western U.S. under the upper trough as well as the Mid-Atlantic behind another upper trough. In contrast, an upper ridge is forecast to build across the mid-section of the country where high temperatures are forecast to reach into the low 90s by Saturday. Kong Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php