Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 328 PM EDT Thu Jun 20 2024 Valid 00Z Fri Jun 21 2024 - 00Z Sun Jun 23 2024 ...Heavy rain and flash flooding concerns across the northern Plains to the upper Midwest... ...Focus for record hot temperatures will shift into the Mid-Atlantic by Saturday... ...Heat building over much of the West... Tropical Storm Alberto made landfall in Mexico this morning and continues to spiral rainfall into South Texas, which will slowly diminish into Friday. Some of the tropical moisture from Alberto will be drawn northward and energize the scattered showers and thunderstorms from the southern High Plains to the Four Corners heading into the weekend. These showers/storms will be more numerous during the late afternoon to early evening hours in these areas, and there is a Slight Risk of excessive rainfall in this area late this afternoon and again on Friday. Meanwhile, the National Hurricane Center continues to monitor the potential of tropical cyclone formation over the western Atlantic near the Bahamas as a tropical wave moves west-northwestward in the general direction of northeastern Florida and coastal Georgia. Locally modest rainfall with some breezy winds may affect this region later tonight through Friday. Across the northern Plains to the upper Midwest, rainfall will increase over the area through Friday to the north of a frontal boundary. Rounds of rain, heavy at times, over already saturated soils will increase the threat for flash flooding. A Moderate risk of excessive rainfall has been highlighted for eastern South Dakota into southern Minnesota through Saturday morning. Farther east, scattered thunderstorms are likely across the Great Lakes region and the Northeast near and north of the eastern extent of the front. Some severe thunderstorms are also possible per the Storm Prediction Center. The heat will continue to set records in parts of the Northeast with a shift into the Mid-Atlantic this weekend. Afternoon high temperatures and warm overnight lows will challenge and exceed daily records for many locations in the Ohio Valley eastward. Heat index readings are expected to peak from 100 to 105 degrees in many locations, and Heat Advisories are in effect from Ohio to New Jersey. Those without access to reliable air conditioning are urged to find a way to cool down as very warm overnight temperatures (only in the 70s) will prevent natural cooling and allow the heat danger to build over time indoors without air conditioning. Temperatures may be lower and less hazardous at the coast if/where sea breezes form. On Friday, cooler air will filter into northern New England behind a slowly-moving cold front, but temperatures south of the boundary will soar into the middle/upper 90s Friday and especially Saturday. These temperatures may be the highest observed in several years for some locations. In much of the West (West Coast and Great Basin/Desert Southwest), temperatures will continue to heat up each day with 90s and 100s quite prevalent by Saturday. Some daily record highs may be challenged in Northern California into Oregon. Fracasso/Kong/Tate Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php