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Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
613 FXUS01 KWBC 020757 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 356 AM EDT Tue Jul 02 2024 Valid 12Z Tue Jul 02 2024 - 12Z Thu Jul 04 2024 ...Dangerously hot conditions to impact much of the southern Plains, lower Mississippi Valley, and western U.S. this week... ...Severe thunderstorms and flash flooding possible over portions of the Midwest through midweek... ...Unsettled weather with localized flash flooding chances continue across the Southeast and southern Rockies... Over 60 million residents are currently under heat-related watches, warnings, and advisories this morning as early-July heat swelters much of the south-central and western United States. The weather pattern responsible for the potentially record-breaking heat includes upper-level ridging just off the West Coast and and a separate upper ridge over the south-central U.S. today before sliding to the east by midweek. For the southern Plains, high temperatures are forecast to soar into the upper 90s and low 100s. 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/Missouri 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 be particularly dangerous for those without effective cooling. High temperatures away from the immediate coastline are forecast to reach into the 105-115F range, which could break numerous daily records in the San Joaquin and Sacramento Valleys. Heat begins to build northward on Independence Day as highs into the 90s reach Oregon and interior Washington. Excessive Heat Warnings, Watches, and Heat Advisories go into effect today for some and stretch from southwest Washington to the Desert Southwest. 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 magnitude and duration 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. Active and stormy weather associated with a few storm systems progressing from the northern Rockies to the Midwest this week will create fireworks of their own this holiday week. Initially, a cold front swinging from the upper Midwest to the Great Lakes by early Wednesday is forecast to spark numerous thunderstorms from northeast Kansas to central Wisconsin. Some storms could turn severe and produce damaging wind gusts, a few tornadoes, and large hail from northeast Kansas to southern Iowa. This area is highlighted by the Storm Prediction Center as having an Enhanced Risk (level 3/5) of severe weather. Thunderstorms are also expected to contain intense rainfall rates as elevated levels of atmospheric moisture content remain in place. Flood Watches have been issued for much of Iowa, with the threat of scattered flash floods also encompassing much of the Midwest today. For areas experiencing swollen rivers from prior rainfall, any additional heavy rain could exacerbate flooding concerns. By Wednesday, a cold front is forecast to stretch from the lower Great Lakes to the central/southern Plains and provide a focus for additional potent thunderstorms across the mid-Mississippi Valley. Once again thunderstorms are expected to produce the potential for damaging wind gusts and flash flooding. A separate area of potentially organized convection may impact the central High Plains, where a greater threat for large hail and tornadoes exists. The Fourth of July will feature the aforementioned frontal boundary lingering over the Ohio Valley and lifting as a warm front over the central Plains as an area of low pressure ejects off the High Plains. This will lead to shower and thunderstorm chances from the northern Plains and Midwest to the Ohio Valley and Mid-Atlantic, with the highest chances for severe weather extending from eastern Kansas to central/southern Missouri. 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 southeast Arizona and New Mexico, with burn scars and sensitive terrain the most at risk for flash flooding. Meanwhile, a dying stationary front entering the Southeast from the western Atlantic will also aid in daily widely scattered thunderstorms across the Gulf Coast, Florida, and the Southeast coastline/southern Georgia. Snell Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$