Hello again, everyone! It has been awhile since I have used this platform because time has been at a premium for me. I will be using this site on an as needed basis for complex weather events when I have time. Please follow me on Twitter or on Facebook (links on the right) for my latest forecasts and analysis. My hope is that I will be using this site more when time allows.
Now, onto the weather.
SEVERE THREAT FOR WEDNESDAY, JULY 23RD
Where the region was subject to a tornado in St. Albans and a microburst in York last week, this week the atmospheric dynamics are more potent, and more concerning. As with any of these types of events, timing is critical in what may happen. I strongly suggest that you stay updated with this event. What I am about to present is not the final word, just an idea based on current trends.
The first player involved here, is 2-meter temperatures. This is from the 18z GFS model from Monday afternoon:
The heat factor near the surface is key in all of this as it is part of the equation in a severe event. Forecast highs at 2 PM will be in the 80s for much of the region, 90s over interior sections, and 70s along most of the shorelines. No doubt this will be the best seaside beach day of the summer, but under the impression that severe weather looms. Best to arrive early, and leave mid-afternoon, so not to get caught.
The second player, is moisture. To that, we look at the 18z Canadian RGEM model from Monday Afternoon:
This a look at precipitable water forecast for the northeastern United States at 2 PM Wednesday. Many areas over much of Western Maine are pushing 2″ by this model idea. This is similar to the event of the previous week. FLASH FLOODING is going to be a concern here once again as very heavy downpours will be likely with this event.
Take the sum of those two ingredients, and it helps form Convective Available Potential Energy. This from the 12z NAM:
CAPE is essentially the gas needed to drive thunderstorm activity. In this model run, it suggests that there will be plenty of CAPE around for fuel. In all honesty, I think this run is a bit on the rich side, but to give you an idea, this is very potent. Many of the storms over the Plains have this kind of CAPE to work with, and it can be quite destructive. In perspective, last week’s severe outbreak was with roughly HALF of the energy that this model idea is putting out.
Now that the gas has been configured, in order for combustion to occur, a spark needs to happen:
Heat rises, cold air sinks. When the two come together, they cause friction between the two, molecules get moving around and things start to happen. This is the forecast temperature lapse rates between 10,000 feet to the surface at 2 PM on Wednesday. A big range like this often spells trouble. While the mid-level lapse rates aren’t that severe, the difference is enough in this case for cause for concern.
Wind shear helps get the storms moving…
Thus we have the low-level jet. This is projected wind speed at roughly 5,000 feet at 5 PM Wednesday. Strong southwesterly flow aloft with strong south flow at the surface, and the atmosphere begins to spin a bit. This too, is a bit more amped than during the severe outbreak from last week.
TIMING & CONCERN AREAS
This idea is SUBJECT TO CHANGE but this is as it appears for now. Not only is this a timeline, but also can be viewed as areas of most concern to moderate concern. This could be a rough go of it in the mountains again. The foothills will likely get nailed in areas quite hard as well. Coastal areas may escape the worst of it, BUT temps over the interior will likely be the warmest. Given that dynamic, the threat for the coastal interior areas will last later into the evening Wednesday until the front pushes through overnight Thursday.
PLEASE KEEP YOURSELVES UPDATED ON THIS EVENT. I will do my best to keep you updated, but don’t depend on just me. Please consult with local media as well as the National Weather Service / NOAA Weather Radio for the latest information.
My next update will be in Facebook in the morning,
Stay updated, stay alert & stay safe! – Mike