Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 300 AM EDT Tue Jul 13 2021 Valid 12Z Tue Jul 13 2021 - 12Z Thu Jul 15 2021 ...Heavy rain and potential flooding for parts of the Eastern U.S. and the Desert Southwest... ...Heat wave continues for much of the western U.S. through mid week... The active summertime pattern of mainly afternoon/evening intense thunderstorms with heavy downpours will continue to make weather headlines through the middle of the week. This especially holds true for portions of the Northeast U.S., Florida, and the Northern Plains to the Upper Midwest. A quasi-stationary frontal boundary will be nearly anchored in place across New York and southern New England, and this in combination with multiple mid-upper level impulses will fuel additional rounds of storms with high rainfall rates, and any storms that develop will have the potential to produce flash flooding. The threat for flooding will be even greater across those areas that have observed well above normal rainfall over the past few days. Afternoon and evening showers and storms are expected to be in place across the Four Corners region, and especially southern Arizona and New Mexico, as the southwest monsoon kicks into high gear. Given relatively weak steering flow aloft, many of these storms will likely be slow moving and result in flash flooding for canyons, across burn scars, and other vulnerable areas. Showers and storms are also expected to increase across portions of the Dakotas and extending eastward across much of the Upper Midwest as a cold front intercepts a moist and unstable airmass ahead of it. Training of convection may also lead to flooding concerns for this region, mainly on Wednesday. In the temperature department, the heat wave is beginning to show signs of abatement across the Southwest as the stubborn upper ridge begins to break down some and monsoonal moisture increases. However, readings are still expected to remain above mid-July averages from California to the Great Basin, and heat-related NWS bulletins remain in effect for many of those areas. Hot and humid conditions will also be present across much of the southern and eastern U.S. with heat indices reaching above 100 degrees at times. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php