Steven Copertino

Warm and Unsettled Pattern Returns, Cool Shot This Weekend?

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Good Evening! 

Today was another beautiful day over the vast majority of the Northeast and Mid Atlantic regions as a large area of high pressure centered over the Ohio valley continues to press eastward, continues to dominate our weather. With relatively clear skies, low humidity, and warm mid level temperatures, highs today across the region were able to find their way back into the mid to upper 80’s. This is another step back up to seasonal temperatures after highs took a pretty large hit late last week and during the first half of this past weekend. These warm temperatures, clear skies, and light winds will last into the evening hours, and should be quite favorable for radiational cooling to take place during the overnight and early morning hours. This should allow low temperatures to fall into the mid to upper 60’s across the area, leading to another comfortable evening across the entire region.

As of six o’clock, there were some heavy showers and thunderstorms located over western New York and central Pennsylvania associated with a weak mid level disturbance. Shear and instability is marginal at best in this region, and as you get further from these storms, atmospheric conditions become very unfavorable to sustain these showers and thunderstorms Therefore, we do not expect any significant shower/thunderstorm activity to move into the region this evening.

This evenings latest high resolution radar mosaic, visible satellite imagery, and surface observations, showing a very nice and clear day over much of the Northeast. Some showers and thunderstorms were ongoing over portions of PA and NY. but these are expected to dissipate later this evening (Courtesy of Simuawips)

This evenings latest high resolution radar mosaic, visible satellite imagery, and surface observations, showing a very nice and clear day over much of the Northeast. Some showers and thunderstorms were ongoing over portions of PA and NY. but these are expected to dissipate later this evening (Courtesy of Simuawips)

Tuesday and Wednesday

Tuesday morning will likely start off relatively clear, with any low level clouds and residual early morning fog quickly dissipating. The area of high pressure over the Ohio Valley will continue to move to the east and get closer to the region, which should also allow for temperatures to increase a bit more as mid level ridging increases aloft. In addition to warmer mid level temperatures, the high pressure system to our south should allow winds from the west/west-southwest to take over during the day on Tuesday. This will in turn allow for dewpoints to increase to the lower to middle 60’s across the entire region, making for a more muggy feel tomorrow afternoon. Clear skies should allow for highs to quickly rise into the middle to upper 80’s tomorrow-with some locations possibly creeping into the lower 90’s.

With the increasing dewpoints over the area, instability will be on the rise, and we may have to watch for some afternoon shower and thunderstorm activity. At this time, it appears quite likely that any thunderstorm activity will likely be located over portions of Pennsylvania and New York state once again, due to an overall lack of coherent forcing, unimpressive mid level lapse rates, and weak shear values over the NYC metro area. As we head into the evening hours tomorrow, things should remain quite warm as the increased mid level moisture/temps really put a cap on any potential radiational cooling. Lows will likely be stuck in the low to middle 70’s, with more humid conditions taking over. Some patchy fog may try to develop near coastal locations, but widespread fog is not likely at this time.

On Wednesday, we can expect yet another sunny start to the day with any early morning clouds and fog quickly burning off by the late morning hours. A weak shortwave trough in the mid levels of the atmosphere will be loving to our west during the afternoon hours, and this trough will have to be watched during as the area begins to destabilize on Wednesday. This afternoons model guidance is not too impressive with shear or overall forcing over our area, but a few small changes over the next 36 hours would yield some different results. At this time, it appears that capping may hold on long enough on Wednesday afternoon to allow for some weak mid level energy to pass to the west of the region, thus setting off the development of some showers and heavy thunderstorms over portions of Pennsylvania, New Jersey, New York, and Connecticut. Wind shear and lapse rates look very marginal at this time, so any storms that do form will likely be “pulse” storms that oscillate in intensity without begin able to move much. This may result in locally heavy downpours in some areas in addition to some brief gusty winds. Regardless, highs should be in the middle 80’s to lower 90’s once again on Wednesday, with another warm and humid evening on tap as well.

This afternoons RPM model showing the development of showers and thunderstorms over portions of the Mid Atlantic and Northeast on Wednesday. Overall, these showers and thunderstorms should remain below severe limits due to weak shear and poor mid level lapse rates.

This afternoons RPM model showing the development of showers and thunderstorms over portions of the Mid Atlantic and Northeast on Wednesday. Overall, these showers and thunderstorms should remain below severe limits due to weak shear and poor mid level lapse rates.

Thursday and Beyond 

Later in the week, a strong cold front associated with a large northern stream disturbance will begin to track to the south and east. Before the frontal boundary reaches the area, precipitable water values will likely surge once again, possibly edging over the 2″ mark over portions of the Mid Atlantic. This moisture surge will be similar to the one that occurred last week, but with a completely different upper level setup this time. As the front approaches the region on Friday and Saturday, there is the possibility of numerous showers and thunderstorms breaking out as the parameters for thunderstorm development become much more favorable, with a strong upper jet maximum, increased forcing, and better lapse rates. Depending on how this system evolves over the next few days, we may have to watch for another localized flooding event over portions of the NYC metro area.

As this frontal system pushes through on Saturday and Sunday, a large area of high pressure dropping down from Canada will begin to take control, which should provide a nice end to the weekend, with cooler conditions and much lower humidity. At this time, this period of mid temperatures and decreased humidity looks to last into the middle of next week, before we have to worry about our next rain chances.

This afternoons European ensembles, showing relatively good agreement on a brief cool down after a frontal passage this upcoming weekend (Courtesy of Tropical Tidbits)

This afternoons European ensembles, showing relatively good agreement on a brief cool down after a frontal passage this upcoming weekend (Courtesy of Tropical Tidbits)

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Have a great evening!

Steve Copertino

Miguel Pierre

Premium PM Update: Very Warm, More Humid Midweek…More Unsettled Late Week

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After some cooler than normal and dreary weather much of last week, more summer-like weather returns this week. This afternoon we already saw temperatures in the mid-upper 80s. The next few days will feature warmer than average temperatures. However, more unsettled weather may be arriving by the end of this week, as a large trough and frontal boundary approaches from the west. Meanwhile, Tropical Storm Emily over Florida today, will be moving out to sea later this week.

First for tonight, mostly tranquil and comfortable conditions are expected. A few isolated showers or thunderstorms that developed over Interior NY and PA, will diminish this evening, as a surface trough and instability weakens. Then skies will be clear to partly cloudy for the rest of tonight, with low temperatures ranging from the 60s over the Interior to lower 70s near the coast. If skies clear enough, some of the interior valleys and Pine Barrens may drop into the mid-upper 50s by daybreak, with more radiational cooling. Some areas of patchy fog may also develop over Interior valleys overnight.

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Doug Simonian

Video: Outlook over the Next 7-10 Days

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Good morning! After a very cool start to the day, temperatures should rebound nicely this afternoon into the upper 80s — perhaps touching 90 in the warm spots. Humidity will remain mostly low today, but will increase later this afternoon. We can’t completely rule out an isolated shower or thunderstorm, but any storms that do form look weak and should stay to our west and north. Thus, we should mainly remain mostly sunny today. The same general story looks to continue on Tuesday, though with more persistent humidity for the entire day. Wednesday will be similar as well, but with perhaps a slightly better chance of showers and thunderstorms. Some sea-breezes are likely along the immediate coast, keeping temperatures a few degrees cooler.

A bigger trough will be forming in the Central US on Thursday and make a trek towards our area. Our pattern will thus become more “troughy”, which could mean a few more clouds and a slightly better chance of showers and thunderstorms on Thursday and Friday afternoon than in the first half of the week. But we do not anticipate anything particularly hazardous at this point. The core of this big trough will arrive on Saturday, when perhaps a bit more widespread shower and thunderstorm activity is possible — with heavy downpours potentially being a threat. But once this front moves through, a shot of Autumn air is likely. This general trough will stay in the region from Sunday through at least a decent chunk of next week — though the core of the “chillier” air will probably stay to our west.

The above video has all of the details!

John Homenuk

Sunday PM Update: Warming, transitional weather ahead

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Good evening! We hope you had a wonderful Sunday. The weather today was impressively pleasant – especially by late July standards – with low humidity values and plentiful sunshine. High temperatures in the lower 80’s were fairly common throughout the Northeast states, although it did remain a touch cooler in parts of the interior. The low humidity and pleasant weather will continue into the evening tonight and through Monday morning.

Gradually, this week, higher heights are expected to build into the region in the mid levels of the atmosphere. This denotes the presence of a mid level atmospheric ridge, and while its presence will remain most stout in the Central United States, it will briefly extend its reach towards the Northeast during the middle part of this upcoming week. The result will be building surface high pressure and warmer surface low — with warmer temperatures each day that goes by.

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