Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 359 PM EDT Tue Aug 03 2021 Valid 00Z Wed Aug 04 2021 - 00Z Fri Aug 06 2021 ...The heavy rain and localized flash flooding threat continues with Monsoonal showers across the central and southern Rockies through Wednesday... ..Heavy rain and flooding possible along the central Gulf coast northeastward across the coastal Southeast and into the eastern Carolinas... ...Heat returns to the Desert Southwest and Interior Pacific Northwest while the central Plains to the East Coast see below normal temperatures... A mid- to upper-level ridge building from the Southwest into the Pacific Northwest will continue to spread drier conditions across the interior sections of the West Coast while shifting the most active monsoonal showers further eastward into the central and southern Rockies. Heavy downpours associated with some of the thunderstorms could lead to localized flash flooding today and tomorrow. This is especially so in areas with recent burn scars and in regions of steep terrain. A Moderate Risk of excessive rainfall (level 2 of 4) remains in effect through tomorrow morning for portions of south-central Colorado and northeastern New Mexico, while a broader Slight Risk (level 1 of 4) is in place for most of central/western Colorado and northeastern New Mexico. Another inch of rain on average with locally higher amounts is forecast. A Slight Risk is also in effect for Wednesday with another half inch to an inch of rainfall possible over regions that have already seen heavy rainfall the past few days. By Thursday morning, the high pressure ridge is forecast to bring enough stability into the region to suppress the monsoonal rainfall. Meanwhile, the drying trend brought by the building ridge will lead to the return of above average temperatures across the Desert Southwest northward to the interior Pacific Northwest. High temperatures in the 110s will be common in the Desert Southwest Wednesday and Thursday with upper 90s to 100 degrees forecast for the interior Pacific Northwest on Wednesday. A system moving east from the Pacific will begin to bring milder temps to the Pacific Northwest on Thursday. Excessive Heat Warnings have been issued for the Desert Southwest through Thursday evening and a Heat Advisory is in effect for eastern Washington and northern Idaho through Wednesday evening. Fire weather is also a threat as the dry conditions settle in, with an Elevated Risk of fire weather in effect from the Storm Prediction Center for portions of the northern Great Basin on Wednesday. The heat will spread into the northern Plains and upper Midwest as well where high temperatures are forecast to reach into the 80s and 90s the next couple of days. In the East, a frontal boundary is expected to remain nearly stationary over the next few days stretching from the Carolinas southwest across the Gulf Coast and into southern Texas. This boundary, enhanced by waves of low pressure, will be the focus for a continued heavy rain event through the end of the forecast period bringing an increasing threat of flooding and flash flooding. A Moderate Risk for excessive rainfall is in effect through tomorrow morning for the coastal Carolinas for the risk of rainfall rates of 2-3 inches per hour and rainfall totals locally over 5 inches. A Slight Risk is in effect for the most of the same region tomorrow as the threat for the more significant rainfall rates and totals goes down somewhat in comparison to today, but any additional rain will enhance or encourage flooding in locations that have already seen rainfall the past few days. Elsewhere, below normal temperatures are expected from the Central Plains to the East Coast, with highs mainly in the 80s. Portions of the Carolinas under the influence of clouds and precipitation as well as New England will see highs only in the 70s. The dry airmass will also allow temperatures to cool off at night, with lows dipping down into the 60s from north Texas and Oklahoma east to the Mid-Atlantic and coastal Northeast and the 50s for the interior Northeast. Putnam/Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php