In the last two weeks alone, we’ve seen anywhere from 100-450% above normal the climate average across the Northeast. It has been active and persistent throughout this region since June, with almost no sign of stopping. We have another potential threat coming this weekend, especially on Sunday from CT to MA, NH and ME in bull’s eye at this point.
The most noticeable thing with this setup this weekend will be the moisture boost. The source area that the moisture is being “pulled” from is the Gulf, which is currently “boiling” with sea surface temperatures much higher than normal. Below, we see a relatively wide range of 2.2” – 2.5” PWAT values, well above the climate average across New England. No shortage of steam will be ready to condense in no time. Notice how this increases overnight from Saturday to Sunday. This humidity increases as a warm front will approach from the south through Saturday through Sunday.
On Sunday, the synoptic setup will have another shortwave track that will move through the Northeast. In front of it, this surface is described as a cold front, which will be the main forcing mechanism. Sunday afternoon, this front will slowly push eastward and will push warm floating air in front of it, upward to coincide with its hottest time. Now, what makes this another powerful flood generator is the alignment of the low and medium winds with the front. When you have low winds approaching the humidity becomes parallel to a front, this presents an extremely favorable environment for rain rebuilding and training.
Compare the snapshot above with the animation of “Synthetic thunderstorms” below where it combines CAPE and wind vectors at each level respectively: 10m, 850mb (~5,000 ft), 500mb(~18,000 ft) and 300mb (~30,000 ft). What we see here verbatim is the increase in CAPE (probably not modeled at this point and will certainly spike when we are sunny) into New England from PA to ME through Sunday . However, the most important thing here is the direction of our wind vector. Note that if you take the average by just observing the vectors at different levels, you will get an average wind direction of south/southwest. This is consistent with our surface cold side which will also push unstable air forward. We combine these components to get back-building convection, heavy rainfall and the possibility of severe thunderstorms as well as due to wind shear and our unstable profile on Sunday.
Given the aforementioned discussion regarding previous rain around this general area, flash flood guidance will be particularly low, meaning there will be very few certain areas subject to rain-induced flooding by the end of the year. this week. Use flash-flood-indexwe find that values rounded to close to 1.0 and higher indicate an impending intensely saturated environment as the warm front lifts northward.
All together, we’re currently looking at anywhere between 2 – 4”+, with higher numbers potentially localized, especially with elevated terrain and topography that increase precipitation from the Catskills to the Berkshire mountains. While VT is not necessarily targeted as the main “black spot”, it is very close to the axis of the largest rain band forecast and there could be adjustments leading up to this event.
In terms of timing, this appears to have mainly occurred late Sunday morning when showers and minor storms began, then intensified as the front moved closer to the coast and worsened in the morning. Sunday afternoon. The front will then clear New England after Sunday night into Monday before depleting when we start next week.
If you live in this area and are located in a flood sensitive area, please be prepared for flooding. More importantly if on the road, you know how it goes – Turn around, Don’t Drown! It takes 6 inches of water to stall the vehicle and one foot to move the vehicle.
About the author
Armando Salvador
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands
