Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 311 PM EDT Mon Jul 01 2024 Valid 00Z Tue Jul 02 2024 - 00Z Thu Jul 04 2024 ...Dangerously hot conditions will continue across the Southern Plains and Lower Mississippi Valley, while simmering heat builds throughout California's Central Valley starting Tuesday... ...Severe thunderstorms and heavy to Excessive Rainfall expected over portions of the Northern Plains and Upper Midwest through Tuesday night... July kicks off with anomalous and potentially dangerous heat impacting the south-central U.S. and portions of the West Coast. As of this afternoon, over 60 million residents are under heat-related watches, warnings, and advisories. Upper-level troughing remains situated over the Northern Rockies/Plains while ridging expands across the southern tier states. For the Central U.S., high temperatures are forecast to soar into the upper 90s and low 100s across the southern Plains through midweek. When combined with elevated humidity levels, heat indices are forecast to rise into the 110s across the Lower Mississippi Valley and Gulf Coast. Excessive Heat Warnings and Heat Advisories currently span from Kansas to the Gulf Coast States. After enjoying a refreshing start to the workweek, the Midwest and East Coast can expect a gradual return to muggy summer warmth by Wednesday as surface high pressure reorients itself off the East Coast and ushers in southerly flow. Extreme heat building throughout the West Coast and more specifically interior California this week will also be particularly dangerous for those without effective cooling. High temperatures away from the immediate coastline are forecast to reach into the 100-110F range, which could break numerous daily records in the San Joaquin and Sacramento Valleys on Tuesday and Wednesday. Excessive Heat Warnings, Watches, and Heat Advisories go into effect as early as Tuesday and stretch from southern Oregon to the low desert of southeast California. The duration of this heat wave is concerning as the current forecast keeps scorching conditions in place through at least the end of the week. This level of heat could pose a danger to the public if proper heat safety is not followed. This includes staying hydrated, out of direct sunlight, and in properly air-conditioned buildings. Additionally, it is very important to check on vulnerable friends, family, and neighbors to confirm their safety. Additionally, a storm system exiting the Northern Rockies this morning is anticipated to create some pre-Independence Day fireworks across the Northern Plains and Midwest through Tuesday as the threat of heavy rain and severe weather slides eastward with time. Severe thunderstorm chances are centered over Nebraska South Dakota tonight, with neighboring states included in the potential for potent thunderstorms capable of containing damaging wind gusts and sporadic hail. Of potentially greater concern throughout the Upper Mississippi Valley is the prospect for more heavy rainfall over saturated soils and swollen rivers. As approaching frontal boundaries provide a focus for several clusters of thunderstorms, areas of intense rainfall rates are possible throughout the Northern Plains and Upper Midwest tonight before sliding gradually eastward on Tuesday, but still remaining centered over the Midwest. Probabilities for at least 1 inch of rain are high (70-90%) for much of Iowa, eastern Nebraska, southern Minnesota, central/southern Wisconsin, and northwest Illinois through Tuesday. This next round of heavy rain could create instances of flash flooding as well as exacerbate ongoing river flooding across areas still recovering from last week's heavy rainfall. There's an Enhanced Risk of Severe Thunderstorms from southern Iowa into northern Missouri and into far northeastern Kansas on Tuesday. Damaging wind will be the most likely threat according to the Storm Prediction Center. Continued sufficient moisture content over the Southwest and southern Rockies will also aid in the development of daily showers and thunderstorms capable of producing localized instances of flash flooding through midweek. Regions most likely to be affected by scattered downpours include Arizona, New Mexico, and southwestern Colorado, with burn scars and sensitive terrain the most at risk for flash flooding. Kebede/Snell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php