Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Tue Sep 03 2024 Valid 12Z Tue Sep 03 2024 - 12Z Thu Sep 05 2024 ...Areas of heavy rain and the potential for flash flooding continue in Texas and along the Gulf Coast the next couple of days... ...One more day of late-Summer heat for the north-central U.S. Tuesday before focus shifts to a building heat wave in the West Wednesday... Thunderstorms capable of producing heavy rainfall will persist across portions of Texas and along the Gulf and southeastern Atlantic Coasts this week as very moist Gulf air pools around a quasi-stationary frontal boundary lingering through the region. A passing upper-level disturbance will lead to more widespread storms once again today (Tuesday) over portions of central Texas where a locally greater threat for some flash flooding will exist, with a Slight Risk of Excessive Rainfall (level 2/4) outlooked for the region. Further east along the central Texas Gulf Coast, very moist, onshore flow aided by a stubborn coastal low and continued rounds of storms moving inland will bring further heavy downpours that could lead to several inches of rainfall. A Slight Risk of Excessive Rainfall has been included here as well as wet antecedent conditions from rainfall over the past few days will increase the threat for some additional instances of flash flooding in the area. The upper-level disturbance will lift northeastward on Wednesday, increasing storm coverage over the central Gulf Coast and possibly north into the Lower Mississippi Valley. Another Slight Risk of Excessive Rainfall is in place given the threat for heavy downpours and scattered flash flooding. Storms will also increase along the southeastern Atlantic Coast by Wednesday, and daily thunderstorm chances will continue for the Florida Peninsula. Further north, an upper-level trough and associated surface cold front will bring showers and thunderstorms to the northern Rockies today. Some locally heavy downpours will be possible with an isolated threat of flash flooding over central Idaho and southwestern Montana. Ahead of this system, an upper-level ridge over the northern/central High Plains will lead to another day of well above average, hot late-Summer temperatures, particularly over the northern High Plains. Forecast highs are into the 90s, with some upper 90s possible for the western Dakotas. The approaching system from the west will help to bring temperatures back down to average Wednesday, with highs in the low to mid-80s. Showers and storms are expected with the passage of the system, particularly over the central High Plains. Storms chances will also spread into the Upper Midwest as the system continues east Wednesday night. Attention in the mid- to late week will turn to a building heatwave over the West. A strong ridge will settle in over the West Coast following the passage of the upper-trough over the northern tier, with highs on Tuesday already beginning to climb into the upper-90s and low 100s over interior California and 100s to 110s in the Desert Southwest. Then, on Wednesday, temperatures will soar into the low 100s over interior California and into the 90s in the Pacific Northwest. While not as hot, much above average temperatures are expected for coastal areas too, with highs into the low 80s for some locations. Heat-related warnings and advisories have been issued for the Desert Southwest and central/southern California outside of the immediate coast given a heightened risk for heat-related illness, especially for those without access to effective air conditioning. Elsewhere, most of the eastern U.S. outside of the the South will be dry with generally mild temperatures. Early Fall-like highs in the 70s are expected throughout New England, the Mid-Atlantic, and Carolinas. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php