A cold front moving in from the plains is expected to arrive in our area tomorrow evening. The North American Mesoscale Forecast System (NAM computer model), forecasts a line of thunderstorms to develop over central Pennsylvania and New York before making its way over the NYC Tri-State by 8 pm ET.
Weather360 is forecasting frequent lightning, hail, high winds, and potentially a few tornadoes in these storms tomorrow. The Storm Prediction Center (SPC) forecasts an ‘Elevated Risk’ for severe weather tomorrow, meaning that strong storms are likely with the potential for isolated tornadoes.
Already today the main parameters for severe storm development (CAPE, shear, helicity, and ML LCL) are already favorable for strong thunderstorms. Please have access to a cellphone, television, or radio tomorrow in the event that the National Weather Service issues a severe thunderstorm, flash flood, or tornado warning. Tornadoes can and do occur in this area of the country, please take shelter immediately should a warning be issued for your area.
Today marks the first day of Weather 360’s Severe Weather Forecasts for 2017. Through October, we will provide up-to-date severe weather forecasts for the entire NYC Metro Area. More information and graphics can be found on our Weather Outlook page.
Due to atmospheric instability over the next following days, severe weather will pop up (mainly in the afternoons), across the Metro Area. This type of constant instability is not entirely common in the Northeast, as it only occurs when all the ingredients come together during the day (i.e. lifting parcels of moist air as well as a ‘trigger’ of sorts to jump start the storms), but due to a build up of heat and moisture, even winds coming off the Sound can create thunderstorms. Over the past several days, intense lightning storms have made night into day for certain portions of the Tri-State, and it was only several days ago when The National Weather Service confirmed a weak tornado touched down in North Haven, Connecticut.
The primary threat from these ‘pop-up storms’ is flash flooding and lightning, although it would be inadvisable to disregard this threat as nothing, as hail, high winds, as well as the potential for some isolated spin-ups does exist throughout the week.
Remember to stay alert and aware of all current threats and alerts, and make sure you alter your plans accordingly if thunderstorms are in the forecast.
Over the past hour and a half, a line of thunderstorms brought periods of heavy rain, gusty winds, and lightning to mostly northern portions of the Tri-State Area. Although this line of storms may have cooled things down a bit, there is yet another, larger line of thunderstorms that has the potential to bring even more severe weather to the Metro Area later on in the evening. With respect to the first line of storms, although they may not have gotten their act quite together when it comes to supercell development, they still packed a punch able to take down large branches, leaves, and lower visibility to less than a mile in some locations temporarily.
The line of storms that is expected to move into the Metro Area tonight will have even more ingredients necessary for Severe Weather Development in their favor. After the first line of storms earlier, the Mixed Layered CAPE, instead of dropping off, skyrocketed from 700-1,100 joules per kilogram, to 1,500-2,000 joules per kilogram. Along with this, there has been a notable increase in Effective Helicity as well as Effective Shear, indicating that stronger and more developed storms are on the way.
The most important thing to remember today is that the storms are not over, and that it will be important to have access to NOAA Weather Alerts via an NOAA Weather Alerts Radio or via Cellular Phone so you can stay informed if Severe Weather hits.
Starting this afternoon, the potential for Severe Weather exists across the New York City Metropolitan Area. The first storms will begin to appear over the western portions of the Metro Area in the early afternoon, before becoming more numerous and greater in size by the early evening. At the moment, it is beginning to appear that there will be at least one line of storms that will form over The Hudson Valley around 3:00-5:00 PM EST.
It will be important to note that Weather360 is increasing the threat for Severe Weather today to 60% across the Metro Area, with the threat for isolated spin-ups and tornadoes at 22%. The primary threat today will be the threat for small hail, high winds, frequent lightning, and heavy rain. It is advisable to keep a weather radio nearby and to keep a lookout for storms in your area.
Following a round of moderate to heavy rain this morning in and around New York City is the potential for severe thunderstorms in the mid afternoon. With the next round of storms expected to impact the area comes the threat of hail, high winds, heavy rain, and lightning (not ruling out the potential for an isolated tornado or two). In order to stay safe, take appropriate action now if you live in the NYC Metro Area. Make sure that you have a flashlight, water, and a weather radio available in the event of an emergency.
An important factor in forecasting severe weather is the Convective Available Potential Energy or CAPE value. The CAPE is a measure related to the total energy available for convection and the maximum vertical updraft speed. It is important to note that the greater the CAPE, the more likely it is for severe thunderstorm development. It becomes much more common for severe thunderstorms to develop in and around the NYC area when the CAPE value is above 800, give or take a few, and as of now, the SREF ensemble computer models (run by the Storm Prediction Center)are suggesting a CAPE value of around 1,200. Along with this, more short range computer models such as the HRRR are suggesting a line of thunderstorms popping up around 4:00 PM EST today across the area. Remember to be on the look out for severe weather today and heed any and all advice distributed by the National Weather Service.
The National Weather Service has issued multiple Severe Thunderstorm Warnings for the New York City Metro Area. This comes after a day of pouring rain that has saturated the ground. These storms will impact the area over the following several hours and may bring wind gusts of upwards of 60 mph along with lightning and some hail. Weather 360 advises to heed all warnings and to go inside if not already to avoid potential injury.
After a two month developing phase, Weather360 is back up and running even better than ever. Over the following weeks, a new Severe Weather Forecasting System will be implemented to give specialized information regarding the New York City Metro Area. Along with this, we plan to provide more insight into oncoming storm systems that may impact the Metro Area as well as large storm systems that may deliver severe outbreaks across the country.
Over the next several hours, more lines of potentially severe thunderstorms are expected to line up across portions of the Upper Midwest, bringing hail, strong winds, and some isolated tornadoes. As of 2:30 CDT, lines of heavy rain and thunderstorms are developing over portions of Southern Iowa, and are expected to make their way east into Illinois, parts of Wisconsin, and parts of Minnesota. The Storm Prediction Center (SPC), has most of Western Illinois under an ‘enhanced risk’, meaning that the potential for multiple severe storms does exist, and that the threat of tornadoes is elevated as well.
Starting tonight, strong to severe thunderstorms are expected to bring heavy rains, high winds, hail, and potentially some tornadoes from Eastern Oklahoma to Alabama. This same storm system is expected to move across the country and will eventually bring some rain to the East Coast as well.