Posts

John Homenuk

Severe thunderstorms possible this afternoon and evening

/by

12:30pm: This morning, we initially had a strong area of showers and rumbles of thunder in Pennsylvania that was moving toward our area. if it hit us, the atmosphere would have stabilized and the severe threat for thunderstorms would have significantly gone down.

Current SPC Mesoanalysis as of noon shows an area of mid-level lapse rates in excess of 7C/KM in our area. This is very significant, as it leads to plenty of instability in the middle of the atmosphere, as well as providing a capping inversion below it that weakens any weak convection and keeps us sunny and unstable.

Current SPC Mesoanalysis as of noon shows an area of mid-level lapse rates in excess of 7C/KM in our area. This is very significant, as it leads to plenty of instability in the middle of the atmosphere, as well as providing a capping inversion below it that weakens any weak convection and keeps us sunny and unstable.

However, the EML we discussed yesterday was able to work its way into the region and provide a capping area that completely disintegrated this area of showers. This means that clouds will quickly be disintegrating, and we will quickly be able to destabilize the atmosphere, making it very ripe for severe weather.

Current Mesoanalysis from the SPC shows already building values of surface-based CAPE.

Current Mesoanalysis from the SPC shows already building values of surface-based CAPE.

In fact, surface-based CAPE values are already in excess of 3,000 J/KG in many areas, which is actually ahead of schedule. When this is combined with the strong mid-level lapse rates and strong wind shear, severe weather is expected to hit a decent chunk of our area later this afternoon. The primary threat will be damaging wind gusts and vivid lightning, but large hail is also a threat, and a tornado threat is non-zero.

—–

An energetic mid level disturbance, impressive wind shear, and moderate to significant atmospheric instability will combine to create an enhanced threat for organized severe thunderstorms in the Northeast US on Tuesday. While some uncertainties still exist in regards to exactly how the event will unfold, confidence is rising in the heightened threat for severe thunderstorms — even in the NJ and NYC Metro Area. While not everyone will experience a severe storm, the threat for organized thunderstorms is much higher than normal today.

Thunderstorms are forecast to develop over Northern Pennsylvania and New York State, and begin progressing southeastward throughout the day. Meanwhile, atmospheric destabilization will occur over much of New England, the NYC Metro, New Jersey, and the Mid Atlantic. Instability parameters are expected to be quite high, especially by Northeast US standards. With more than adequate wind shear for thunderstorm organization, these storms are expected to spread southeast toward the coast during the late afternoon and evening.

This post will serve as a Live Blog throughout the day for updates and information on the latest analysis as well as a relay point for Watches and Warnings from the Storm Prediction Center and Local NWS offices. A de-brief on the threat is below:

Read more

John Homenuk

Heavy rain, gusty winds early Sunday morning

/by

The remnants of Tropical Storm Bill, currently tracking through the Mississippi and Ohio Valley, will make a move toward our area later tonight into early Sunday morning. The presence of a very moist atmosphere and lots of lift for precipitation will aid in the threat for a period of heavy rain, late Saturday Night into early on Sunday throughout much of New Jersey, NYC, Connecticut and Long Island. Embedded thunderstorms are also possible.

A localized threat for flooding may emerge, as rainfall will become particularly intense along an area of enhanced lift for precipitation. This area of lift will move from southwest to northeast through the area early on Sunday morning. As it does so, very heavy rain with rumbles of thunder are likely — and urban/poor drainage areas will be especially prone to flooding.

Read more

John Homenuk

TS Bill’s remnants still an uncertainty this weekend

/by

Much has been made over the past few days in regards to the potential for heavy rain on Sunday. The remnants of Tropical Storm Bill are anticipated, by many forecast models, to move northeastward from the Ohio and Mississippi Valley’s into the Northeast States. A weak developing surface low near the area of the mid level disturbance is expected to aid in the development of heavy rain from the Mid Atlantic northeastward toward parts of the Northeast as well, as the system shifts toward the coast.

The problem, however, is that remnants of Tropical systems are unpredictable by nature. The high moisture, high energy, and intricate nature of the pattern in the mid levels of the atmosphere makes it very difficult on forecast models to try and pin down specifics. For us, this means an uncertain weekend forecast. And, yes, the potential that Sunday may turn out to be not quite a washout at all.

Read more

John Homenuk

PM Update: Nicer Friday, but unsettled weekend expected

/by

After a “dud” of a day on Thursday, things are at least looking partially “up” for the weekend. Temperatures on Thursday throughout most of the area barely escaped the 60’s and 70’s, with low clouds and drizzle remaining commonplace during the day. A cool, marine flow can be thanked for that. Much of the same is expected through the first half of the evening on Thursday as well, although some increase in humidity should be notable.

By Friday morning, things will start to change for the better. Temperatures will rebound into the 80’s during the day on Friday, with partly cloudy skies anticipated. The marine layer from Thursday will be scoured out of the area, allowing for sunshine to return. The big game changer? Winds turn westerly during the morning — a big difference from Thursday, when they were coming out of the south and east, off the cool area waters.

Read more