Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 346 PM EDT Wed Sep 04 2024 Valid 00Z Thu Sep 05 2024 - 00Z Sat Sep 07 2024 ...Heat wave builds over the Southwest and the West Coast this week... ...Heavy rain and flash flood potential continues for the Gulf Coast states the next couple of days... The forecast is on track for a dangerous heat wave to expand and intensify across the West Coast this week as an upper-level ridge overhead amplifies. As we close out the work week, triple-digit highs will be commonplace from Seattle to Phoenix, which would challenge numerous high temperature records across the Pacific Northwest (including the Seattle and Portland areas) tomorrow and Friday. Widespread heat-related warnings and advisories are in place across much of the West Coast through Friday as this heat will be dangerous to anyone without effective air conditioning or sufficient hydration. Some relief from the oppressive heat will arrive over northern California and the Pacific Northwest this weekend as low pressure moves in from the west, although dangerous heat is expected to continue across the Southwest through next week. Along the Gulf Coast, heavy rain and flash flooding remains the main weather story this week as a stationary front and coastal low drive multiple days of widespread showers and thunderstorms across the region. The placement of the elongated area of low pressure in the western Gulf will keep the focus for the most widespread rainfall over portions of the central and upper Texas Gulf Coasts, and possibly a bit further north into the Lower Mississippi Valley. Extremely moist Gulf air will lead to very heavy downpours (upwards of 2-3" per hours rates) with continued rounds of storms moving onshore. Forecast areal average rainfall totals are in the 3-5" range, with locally higher amounts of 7"+ possible, most likely near the immediate coast. A Slight Risk of Excessive Rainfall (level 2/4) is in place for the region both today and tomorrow given the threat for scattered instances of flash flooding. Storms will also increase along the southeastern Atlantic Coast today and Thursday, and daily thunderstorm chances will continue for the Florida Peninsula. Elsewhere, a brief warm up from the early Fall-like weather is expected across the Mid-Atlantic and Northeast tomorrow and Friday an an upper-level ridge migrates eastward from the Midwest. On the heels of the upper-ridge, an approaching frontal system will usher in transient showers and thunderstorms to portions of the Central/Northern Plains and Upper Midwest today, with moderate to locally heavy rainfall possible in the Upper Midwest and the Central Rockies. The strongest storms this afternoon could produce marginal severe hail and wind gusts, with isolated burn scar flash flooding also possible over the Southern Rockies tomorrow. Asherman/Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php