Doug Simonian

Video Analysis: Potential Nor’Easter on Friday into Saturday

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Good evening, everyone! We hope you all enjoyed this lovely Wednesday. We have a lot to talk about with this potential upcoming Nor’Easter on Friday into Saturday. Late July may be the hardest time of year to get a Nor’Easter, with the main jet stream generally being protracted towards the Arctic rather than diving down towards the mid-latitudes. But with a strong blocking pattern with a -NAO blocking ridge in Greenland as well as a ridge forming out west, we are able to get some of the necessary ingredients we normally see in the Fall and Winter months for a potential Nor’Easter.

A strong shortwave will be diving on the downstream side of this ridge and into the Great Lakes on Thursday into Friday. Thanks to this blocking pattern, it will be able to slow down and amplify as it does so, turning into a very strong shortwave that closes off at 500mb and even at 300mb. The blocking pattern and subsequent vortex in Southeast Canada will also allow for a strong jet streak to form in New England, placing us in the right-entrance region of this jet streak, which is great for lift and precipitation. But what makes this forecast tricky is that the interplay between the main shortwave and the Canadian vortex is very tricky and has a lot of nuances, and the fact that some energy crashing into the West Coast will be flattening the PNA ridge and make our shortwave take on a positive tilt. This may make it hard for the low pressure to truly climb the coast, and instead it may slide ENE when it reaches our latitude.

The above video explains all of the details and potential complications to the forecast, as well as the very unique set of ingredients that could come together to make this a powerful storm with high impacts for our area. As of now, we think the heaviest rain may be to our south, but the jet streak aloft and deepening storm may allow enough precipitation to spread out well ahead of the low to still give our area over 1″ of rain. But if all of the ingredients come together and consolidate, a large portion of our area could easily get 2″ or more — even locally much more — of rain.

Miguel Pierre

Premium: Coastal Storm with Heavy Rainfall Possible Late Week

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After the heat wave last week, more cooler, unsettled weather has returned to the region, as a trough moves through the Northeast.  More clouds and onshore flow this week have kept high temperatures well below average over the region — it certainly doesn’t feel like the middle of summer. High pressure will support more pleasant, warmer weather on Wednesday. Then it looks like something we often see during the fall and winter months: a coastal storm with the potential for heavy rainfall by Thursday night and Friday and perhaps into this weekend as well. But uncertainty is still quite high with exactly how this storm evolve, its timing, and how much impact it will have on the region.

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Doug Simonian

Medium Range Analysis: Severe Weather Chances this Weekend

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Good evening! We hope you all had a great Monday. For the most part, the area had a beautiful, summer day, but some western suburbs of NYC had some strong thunderstorms and flash flooding. These storms quickly weakened as they headed towards NYC, as the pattern right now is generally not favorable for severe weather in our area. But that may change come this weekend, when the general synoptic pattern may start to favor strong to severe thunderstorms.

It’s pretty far out in time, so plenty can change — but at this range we like to look at general features of the pattern and what they signal, since there is inherently less noise in broader signals. One thing we like to look at is a pattern that can favor advection of an EML (Elevated Mixed Layer) into the region. The EML is a layer of very hot and dry air from around 700mb (around 10,000 feet) and up that originates in the desert southwest. This hot and dry air air is not contaminated with moisture and thus it can cool quickly with height, creating a lot of mid-level instability. These EMLs often combine with rich, tropical Gulf of Mexico moisture in the low-levels of the atmosphere in tornado alley and lead to some of the biggest severe weather outbreaks.

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Miguel Pierre

Premium Weekly Outlook: More active, progressive pattern this week

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Good morning and happy Monday! Overall it was a beautiful weekend, especially as lower humidity settled into the region on Sunday. But a more active, progressive weather pattern is expected this week. This comes as a strong heat ridge begins building over the Rockies and Western Plains this week and the AO/NAO remains positive with lack of high-latitude blocking. This pattern will allow some ridging to build into the region this week with heat and humidity building. Multiple disturbances are expected to move from the Great Lakes/Ohio Valley through the Northeast and Mid-Atlantic, with threats for showers and thunderstorms this week.

First off,  high pressure will be moving off the Mid-Atlantic coast, with a return southerly flow developing over the region today. Mostly sunny skies are expected this morning, then some clouds will be increasing and filtering the sunshine as a warm front approaches.  Humidity will begin increasing later this afternoon as dew points rise into 60s. More lift and instability ahead of warm front may lead to a few isolated showers or thunderstorms popping up over the region later this afternoon. Temperatures will rise into lower to middle 80s area wide. South-southwest winds today will allow for sea-breezes to keep coastal sections in the 70s much of this afternoon.

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