Category: Forecasts

Flooding will continue through the night and into the morning hours Monday as additional rounds of showers and thunderstorms move into southeastern Pennsylvania.  Some areas will see upwards of 6 inches of rainfall. Additionally, rounds of heavy rain and thunderstorms will move from Pittsburgh to Scranton into the early morning hours Monday. This corridor will receive 1-3 inches of rain overnight, with some areas seeing up to 5 inches of rain. Flooding will be likely across this area into tomorrow morning. According to local media, Woodlayne Court Apartments in Middletown, Pennsylvania, are being evacuated as about five feet of water have flooded into the basement. First responders are on the scene to

Scattered thunderstorms are expected to develop across this region in patchwork fashion, along and ahead of the surface cold front today into this evening. Activity will offer mainly damaging wind, with isolated severe hail also possible. The risk area remains rather broad-brushed and generalized at this time due to the messy, nuanced character and mesoscale dependence of potential convective foci. (blue area shows a 40% chance of thunderstorms for today) On Monday, Isolated strong/severe storms may occur over portions of the northern Plains vicinity, as well as across parts of the central Appalachians and mid Atlantic region. Strong storms may be ongoing at the start of the period across portions of the southern

The pattern responsible for sparse severe thunderstorm activity and heavy rainfall the past few days will energize and increase the risk to lives and property across the northeastern United States this weekend. Those sweltering in recent days from blazing sunshine, heat and high humidity will get relief but at a price. Motorists and those spending time outdoors should be on the lookout for rapidly changing weather conditions. Airline passengers are likely to face delays as storms approach their departure, arrival or connection hubs. A couple of storm systems will roll eastward from the Midwest this weekend. These storms will tap the high level of moisture in the region as well as

A few areas of showers and thunderstorms will likely be ongoing within zone of warm advection and isentropic ascent north of the warm front from parts of the Dakotas into the upper MS and OH Valley regions. This activity will be elevated above a stable surface layer, but could pose at least a marginal risk for hail as it shifts eastward. The moist warm sector in vicinity of the warm front will destabilize during the day with moderate to strong instability possible during the afternoon. A capping inversion associated with eastern extension of the elevated mixed layer may limit more robust initiation over western portion of region until mid-late afternoon when

A few severe storms with wind or hail are possible across the northern High Plains, and from parts of the Midwest into the Northeast this afternoon. An upper high will be centered over the mid MS into the OH Valley with belt of stronger 40-50 kit midlevel flow across the northern tier of states. The strongest flow will exist from the Great Lakes into the Northeast, with a progressive embedded shortwave trough. To the west, another shortwave will move from across the northern Rockies late in the period, with a slight flattening of the upper ridge into the northern High Plains. Early storms are expected across Lower Michigan and vicinity this

A batch or train of thunderstorms was responsible for the Johnstown, Pennsylvania, flood of July 19-20, 1977. Close to a foot of rain fell in 24 hours over the mountains north of the city. A series of dams failed with sent a wall of water into the city. Dozens were killed and damage topped $100 million. A similar setup mostly likely was the cause of the Smethport, Pennsylvania, record rainfall and flood of July 17, 1942. In just 12 hours, 34.30 inches of rain fell. The torrential rain caused catastrophic mudslides and flooding that took the lives of more than a dozen people. Rounds of thunderstorms with torrential rain and gusty winds will

Synoptic upper pattern will change little Tuesday with belt of stronger winds over the northern tier of states. Embedded within this regime, a low-amplitude shortwave trough now moving into the northern High Plains will continue east into the upper MS Valley and Great Lakes. In wake of this feature heights will rise over the northern High Plains during the day. However, a secondary impulse is forecast to reach central and eastern MT later Tuesday night. At the surface a cold front will continue southeast through WI and MN with trailing portion of this boundary likely to become quasi-stationary across NE. A general risk is in place for parts of central and

A few severe thunderstorms are expected Monday afternoon and evening from South Dakota into northern Minnesota, and during the day from Pennsylvania into New York and Vermont. Isolated severe storms are expected from Wyoming into Nebraska, across the Appalachians, and across southern Arizona. Supercell formations are possible, given the weak capping convection and instability. This means that damaging storms are possible, as well as hail and gusty wind. Isolated tornadoes cannot be ruled out in the slight risk area. Stay up to date by following the Pennsylvania Weather Authority and the NWS for any alerts that may be issued.

A few severe thunderstorms are possible from the middle Mississippi Valley northeastward toward lake Erie, across the northern Rockies and High Plains, and over southern Arizona. Scattered weaker storms will occur during the afternoon across much of the Southeast. Severe thunderstorms are not likely to occur from Jul 16-17 across the state. Isolated storms will mainly be pop-ups and pose no threat for wind related damage. The severity remains below five percent as of right now. Storm activity along a cold front should increase throughout the day as heating commences, resulting in moderate instability from MO into southern Lower MI. A belt of 30-35 kt northerly mid-level low will exist across