The number as of 12:02 a.m. stands at 80! 80 tornadoes that is! The largest tornado outbreak of the year continues at this late hour in the Southeast. The majority of these tornadoes occurred so far in Mississippi, Alabama, and Missouri, and Illinois. Tornado watches continue at this hour for additional states and we may be adding to these numbers throughout the early morning hours. Based on the reports, it does appear a few strong tornadoes occurred. There have been fatalities and injuries with some of the tornadoes.
The same potent storm system is anticipated to impact our region today, Saturday. For our region, we will not see the widespread tornado outbreak. However, we may be dealing with thunderstorms that could contain damaging wind gusts. Right now, the Storm Prediction Center has the slight risk for severe thunderstorms only including Southern Delaware. I think it is possible that they will extend the risk area further northward in later outlooks. The North American Model and some of the high resolution models show clearly that a line of convection… pushing from west to east between 8:00 p.m. and 11:00 p.m. …will impact the region. The NAM has widespread purple coloring indicating a quick 1.50 to 1.75 inches of rain in less than six hours during the time frame of convection which I suspect may lead to some localized flash flooding. Total rainfall of 1.75 to 2.50 inches looks to be a good bet for much of the region. Bucks, Montgomery, Eastern Berks, and Eastern Lehigh Counties into North-Central New Jersey need 1 to 2 inches in less than 6 hours for flash flooding to begin. Elsewhere in Pennsylvania…2 to 3 inches of rain would be needed for flash flooding to begin. In Southern New Jersey, rainfall amounts of 3 to 4 inches would be needed for flash flooding to begin and the sandier soil will make this area less vulnerable to flooding. If the NAM is correct, the heaviest rain would be right over the Delaware River and Interstate 95 corridor. I wouldn’t be surprised if some flash flood warnings or a flash flood watch is posted for the more vulnerable counties.
Basically, a low will develop a cold front pushing towards our region. The low will energize the front. Moisture will be streaming in from the fetch off the Atlantic and combine with the Gulf Moisture that is open for business. All of this suggests a super soaking.
We also will be dealing with wind issues that are non-convective related. We have had some decent soakings and this will be another one. The ground will be wet enough to be supportive of an increased risk for trees to become uprooted in strong winds. Unfortunately, it looks like the jet intensifies by mid-evening during the timing of the heavy rain which could transfer the momentum down to the surface. Non-thunderstorm wind gusts of 40 to 50 MPH appear likely, perhaps higher than 50 MPH along the coastline. The National Weather Service has issued a wind advisory which implies sustained winds of 31 to 39 MPH or frequent wind gusts of 46 to 57 MPH are imminent or occurring. This is in effect from noon today until midnight tonight. The gradient looks tight enough that even when it is not raining...gusts of around 45 MPH will occur.
The strong onshore winds will also pose a risk for widespread minor coastal flooding, with scattered areas of moderate coastal flooding. A coastal flood watch has been issued for the tidal areas of the Delaware River and the entire New Jersey/Delaware Atlantic coastline.
We will have continuing coverage of the potential wild weather throughout the day here on phillyweather.net.
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