Yet another day of tracking the same storm as it continues to slowly make its trek across the country. This Friday, there will be renewed concern for flooding rains as well as severe weather, especially in the Southeast and southern Mid-Atlantic regions.
Flash flooding will be possible across the eastern Ohio River Valley, southern Mid-Atlantic, Tennessee River Valley, and even the ArkLaTex region. Across many of these areas, the soil is quite saturated, and any additional heavy rain that comes down in a short period of time will likely bring flooding to some towns. This morning, there is a round of scattered showers and thunderstorms, some of which are heavy, that will slowly move to the north and east through the duration of the day. This rain spans from the southern Great Lakes through the Mid-Atlantic. These storms will become more scattered later in the day as they reach much of Pennsylvania, New Jersey, and western New York.
There will also be a severe aspect to some of these storms, especially from the ArkLaTex through the Tennessee Valley as well as in the southern Mid-Atlantic, during the afternoon and evening hours. In the morning hours, there are lines of scattered storms affecting parts of the Ohio River Valley down into the Lower Mississippi River Valley. As lobes of energy become injected into the region paired with modest wind shear and instability, this will spark off the development of scattered storms and will allow for some of these storms to turn severe. Not only will damaging winds and large hail be possible, but a few tornadoes will also be a concern both in the Southeast and Mid-Atlantic. These storms will then weaken in the wee hours of Saturday morning due to the loss in daytime heating.
The action will begin to shift into the Northeast thanks to this storm. A few severe storms will be possible near the Mid-Atlantic coast as well as localized flash flooding, but the main focus will be how ugly and unsettled this weekend will be in the Mid-Atlantic and Northeast as clouds and moisture stream in. As we’ve been discussing, this system will feature rounds of showers and storms, acting like spokes on a wheel, which in this case is the low pressure.
The most widespread of the rain will be at the onset. In the morning on Saturday, showers and embedded thunder is expected across western New England and portions of the northern Mid-Atlantic. Farther south and west, storms will be more scattered in the hit or miss variety. This is the region where there will be more in the way of sunshine and warmer temperatures, which will allow for a few of these storms to turn robust. Then in the afternoon, scattered showers and thunderstorms will overspread into the rest of New England while a new line of scattered thunderstorms possibly forms over the Mid-Atlantic coast and into eastern New York and western New England. These hit or miss storms should then track into eastern New England during the late-afternoon and evening hours. The best risk for any heavy rain will be at the coast, which is where the highest precipitable water values will be found. As a reminder, precipitable water measures the amount of available moisture in the atmosphere. When there is more water in the atmosphere for the clouds to use, that increases the risk for heavy rain.
Overnight Saturday, storms will weaken and become isolated by early-Sunday morning. The best risk for rain Saturday night will be across northern New England and the interior Northeast, which is the region experiencing the lower pressure thanks to the passing large-scale storm system.
Sunday will be the better day across the region overall. More of the Great Lakes, Ohio River Valley, and southern Mid-Atlantic will dry out with just a few spotty storms possible. In the northern Mid-Atlantic into central and northern New England, there will be additional rounds of rain and thunder that move through. It’s these areas that will experience the rainiest of conditions — plus the ugliest with low clouds around for much of the day. Down toward the I-95 corridor, there will still be the risk for rain, especially north and east of New York City, but the precipitation will be in the form of hit or miss thunderstorms, mainly in the afternoon. It will also be a warmer and sunnier day with partly cloudy skies forecast.
By Sunday night, the weather will begin to quiet down as high pressure comes in from Canada. High pressure makes it difficult for clouds and precipitation to form due to the sinking air. Before it moves in, however, there will still be a few lingering showers and storms moving eastward across Upstate New York and northern New England. Through this time period, a widespread half an inch to one and a half inches of rainfall is forecast. Some areas will receive over two to three inches, however, especially in the Mid-Atlantic and Ohio River Valley.
By Monday morning, other than a few lingering showers in northern New England, conditions will dramatically improve across the Northeast overall. High pressure will sit overhead early in the week. It’s not until the next storm, which will be moving at a much faster pace, brings a round of thunderstorms to the western Mid-Atlantic on Wednesday, then a few storms to the east, affecting the rest of the northeastern US on Thursday. By Friday, the region should dry back out as impressive heat begins to build into the East.