John Homenuk

Nor’easter, cooler air, and the latest on Dorian

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A weakened frontal boundary settled off the Mid Atlantic coast will serve as a highway for a developing low pressure system today. Despite being weak and progressive, the Nor’easter will shift from the Mid Atlantic coast to a position near or off of Cape Cod through Friday. The result, in terms of sensible weather, for our area? More clouds, a cooler northerly flow, and a chance of showers especially along the coast.

The cooler temperatures, clouds and dew points that settled into the area on Thursday have created quite a stir throughout the meteorological community. Not without reason, thought as temperatures fell into the 40’s in much of the interior Northeast early Thursday morning. Parts of elevated New England saw temperatures drop into the upper 30’s! (Just a reminder, it’s July 24th).

After the system shifts northeastward this weekend, temperatures should rebound more towards normal with highs in the low to middle 80s. Conditions look to become more pleasant, with the return of more sun, by this weekend as well.

Dorian still chugging westward: Tropical Storm Dorian, which formed officially Wednesday morning, continued to move west through the Atlantic on Thursday. Maximum sustained winds increased slightly to 60mph, and the system remained compact and small but rather well organized.

Major questions still exist in regards to the eventual track and intensity of Dorian as she shifts west. Forecast models agree that a large and expansive Atlantic Ridge will remain in place. But the important feature, instead of the ridge itself, will be the periphery of the said ridge — as the center of Dorian will likely slide along its fringes. Model guidance indicates that the system may have a slightly higher than normal chance of impacting the US Coast as she is forced west into the Southwest Atlantic and then may potentially recurve northward around the west side of the ridge.

Intensity forecast continue to remain mostly meager on forecast guidance through the next 3-5 days, with most models keeping Dorian at moderate Tropical Storm levels. Increased wind shear by Day 3 may hinder further development of the system as it shifts west — adding further uncertainty to the forecast.

As always, stay tuned over the next few days. Despite the fact that the system is several days away from potentially impacting land, we will continue to provide updates both on our web page and social media outlets.

Doug Simonian

Big heat on hold for the foreseeable future

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We finally saw a nice break today from the high humidity values, as dewpoints dropped into the low 60s this afternoon, making it feel quite comfortable outside this afternoon. With the lower humidity, this means that temperatures have more room to drop tonight — mid 50s in colder, inland areas to mid 60s in more coastal sections. This is quite the stark contrast from the constant stream of 70s for lows that we have had all month.

European Ensemble Mean Valid for tomorrow evening shows a frontal boundary being stalled as it runs into the stubborn Western Atlantic Ridge. Image courtesy of the WSI Model Lab.

European Ensemble Mean Valid for tomorrow evening shows a frontal boundary being stalled as it runs into the stubborn Western Atlantic Ridge. Image courtesy of the WSI Model Lab.

As far as what is going on with the synoptic weather pattern, the heat wave has broken as that huge ridge has finally dissipated and split into two ridges — one in the southwest, and one in the NW Atlantic. The NW Atlantic ridge is the same one that has been plaguing us all summer with humidity, showers, thunderstorms — and at times, heat. Although it has fluctuated in position at times, it has generally remained in the western Atlantic.

This 500mb image valid for tomorrow evening gives a good general summary as to what is going on now and what we can expect over the next few days. There is a trough in the northeast, as a cold front made its way through the area yesterday, giving us drier conditions. However, there are still clouds around as the front has stalled just to our east. Because of the tremendously strong western Atlantic ridge of 600 decameters  (!), the front was forced to stall, as it ran into a “wall”, instead of clearing the coast. This leads to a tight 500mb height gradient along the eastern seaboard (which in this case is pretty much a frontal boundary). This leads to the potential for waves of low pressure to develop along this front.

Since the front is just to our east, the biggest rainfall threat would be east of NYC, with NYC itself being on the gradient. For now, we will mention the relatively high chance of showers, with periods of moderate rain at times — especially in eastern sections of the region (such as Long Island) — in an otherwise relatively mostly cloudy regime for tomorrow. With surface winds more northerly, instability should be too low for much in the way of thunderstorm activity, as temperatures may not get out of the 70s tomorrow.  A stark change from last week, considering our lows were often in the mid to upper 70s!

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John Homenuk

Forecast: Cooler breeze, lower dew points finally arrive

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It has been a two week stretch of high dew points, fueled by a persistent West Atlantic ridge which has continually built towards the Eastern 1/3 of the US. Finally this morning, a frontal boundary pushed just off the area coasts helping to lower dew points with winds out of the northwest.

In addition, a cooler airmass aloft will settle into the area late this week with high temperatures falling into the 70s and lower 80s. The break in hot and humid weather may be somewhat short lived, but should still feel enjoyable.

Forecast models have been hinting at the potential for showers late this week, despite the cooler airmass, with a weak coastal system moving offshore. Thereafter, temperatures should return to near normal levels by this weekend — but chances of showers and storms may continue.

Dorian could form today: The NHC is carefully watching Tropical Depression 4 in the Eastern Tropical Atlantic this morning — and the system may soon form into Tropical Storm Dorian based on satellite appearance. The storm is forecast to continue on a slow westward heading over the next several days. Intensity forecasts remain rather low and the storm’s strengthening is expected to be mitigated at some point by strengthening atmospheric shear. Regardless, stay tuned for updates as the system continues its slow jog westward over the vast Tropical Atlantic waters.

John Homenuk

Excessive heat peaks Friday

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A week characterized by excessive, in some cases record setting, heat will come to a climax on Friday as temperatures and dew points are maximized ahead of a cold front. West-southwesterly winds will reinforce an already moist and hot airmass – and temperatures are expected to climb near or over 100 degrees in much of the NYC Metro Area and New Jersey on Friday afternoon. The combination of this surface heating and staggeringly high dew points in the mid to upper 70’s will lead to Heat Index values as high as 100 degrees.

The National Weather Service has issued an Excessive Heat Warning for the entire NYC Metro Area through 8pm Friday. The aforementioned combination of heat and humidity will make this final day of the heat wave especially dangerous. Make sure to take all heat related precautions and be prepared for any heat related emergencies. Keep a close eye on the elderly, children and pets. Avoid prolonged exposure to the sun as well as outdoor exercise. Wear loose fitting and light clothing if possible. Most importantly — stay hydrated at all times.

Along the area shores, some relief is expected by late Friday afternoon as a seabreeze develops. Then, finally, later on Saturday a cold front will make its approach towards the area — and is expected to sweep out the excessive heat. Until then, however, try your best to stay cool!