Latest Forecast

A Jet Stream ridge, or "heat dome," will extend from the Ohio Valley into the mid-Atlantic States through the end of the week. Downsloping, west-to-northwesterly winds off the Appalachians will combine with mostly sunny skies to boost high temperatures into the low-to-mid 90s this afternoon and upper 80s to low 90s on Friday. Maximum heat indices will top out between 98-102 degrees this afternoon. Drink plenty of non-alcoholic beverages to stay hydrated, limit time in the sun, and take frequent breaks from the heat in an air-conditioned room or building. Never leave children or pets unattended in a vehicle! The internal temperature of a car can reach lethal levels in a matter of minutes on a 95-degree day. Periodically check up on relatives, friends, and neighbors, especially the elderly and those without air conditioning or with underlying medical conditions. A weak cold front will sag southward through the Commonwealth this evening, but no showers or thunderstorms are expected to accompany its passage. Behind it, northwesterly winds will usher much drier air into the region on Friday. However, smoke from distant wildfires in northeastern Minnesota and southern Canada will dim the sun late this week and cause a significant reduction in air quality. The poor air quality will cause adverse health effects for sensitive groups such as children, the elderly and those with heart/lung diseases today and everyone on Friday. A Code Red Air Quality Alert is in effect this afternoon with a Code Orange Alert in effect for Friday, but these should be reversed for the Lower Susquehanna Valley. Avoid strenuous exercise or outdoor activity to minimize the effects of air pollution. The smoke concentrations should lower on Saturday and lead to an improvement in air quality, but sensitive groups may still be impacted. In addition, a storm system will track from the Great Lakes region into New England spanning Saturday to Saturday night, and a trailing cold front will trigger widespread showers and heavy, drenching thunderstorms across northern MD and southeastern PA during that time. The worst storms will likely occur during the afternoon and evening hours and bring torrential downpours, localized flash flooding, damaging wind gusts and hail to the hardest-hit areas.