Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EDT Thu Sep 05 2024 Valid 00Z Fri Sep 06 2024 - 00Z Sun Sep 08 2024 ...A heat wave to continue across large sections of the West and portions of southern Florida... ...Record highs likely to continue over the Pacific Northwest and Northern Great Basin and develop over portions of southern California... ...Heavy rains and potential flooding along the central Gulf coast into the Southeast... ..A cool and dry airmass to spread east from the Plains into the East over the next few days.. A large mid to upper level high centered over the Great Basin and Southwest will continue to drive a heat wave affecting large portions of the western U.S. late this week into this weekend. Much above average temperatures likely from the West coast, east across the Great Basin, Southwest, Rockies and into the Northern High Plains, with high temperatures expected to be 10 to 20 degrees above average. This will support the potential for continued record high temperatures Friday and Saturday over portions of the Pacific Northwest into the Northern Great Basin and for record highs to develop over portions of southern California on Saturday. Excessive heat warning and heat advisories are in effect much of Washington State, Oregon, California, far southern Nevada and into southwest Arizona. Heat will also persist over the next few days across South and Southwest Florida where heat advisories are also in effect. While high temperatures across South and Southwest Florida are not expected to be as anomalous as across large portions of the West, the higher humidity (dew points) will produce dangerous heat indices up to 112 degrees. There are approximately 66 million people under a heat warning and advisories across the West and South and Southwest Florida. In addition to the heat impacts across the West, the dry conditions, low relative humidities will also support fire weather conditions from the Pacific Northwest into California. Wet weather will persist over the next several days in the vicinity of a stationary frontal boundary that is expected to remain in place just to the south of the Gulf Coast and across North Florida. Moisture values are expected to remain anomalously high along the Gulf coast into portions of the Southeast and Florida. Waves of heavy rain are likely in this anomalous moisture axis along and near the stationary frontal boundary from late this week, through this weekend and into next week. The potential for several rounds of heavy rains affecting the same general regions will increase the risk of flash and river flooding. Currently flood watches are in effect across the Upper Texas coast, eastward across southern Louisiana and into far southern Mississippi where rainfall totals of 5 to 10 inches are possible over the next few days. The only other area of rainfall potential over the next few days across the Lower 48 will be associated with a quick moving cold front that will push eastward tonight from the Great Lakes, into the Ohio Valley Friday and across the Northeast/New England Saturday and Sunday. Showers and thunderstorms are possible along and ahead of this front, but the fast movement of the front should keep precip totals from being very heavy. This front will also be spreading southward tonight from the Mid Mississippi Valley into the Central to Southern Plains and into the Lower Mississippi Valley and Tennessee Valley on Saturday. Less favorable conditions for rainfall expected along these portions of the front compared to areas of the Northeast and New England, with only light precip values expected. In the wake of this cold front, below average temperatures and dry conditions likely from the Plains eastward into the East, producing early fall like conditions across these areas. Oravec Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php