Analysis: Two Disturbances to Watch

Good evening! We had a lovely Spring day with sunny skies and temperatures in the 60s, but winds are picking up a bit along the coast as winds turn more onshore and a marine layer develops. For more on these short term changes including the chance for light rain on Wednesday night into Thursday, please be sure to check the dashboard and read our latest zone article updates! This article will be focused on the two upcoming disturbances: one for Thursday night into Friday, and another one for Sunday into Monday. Both could bring periods of heavy rain, but uncertainty is still high as it’s also still possible that little rain falls from either system.

After the periods of light rain on late Wednesday night into Thursday, a stronger storm system will be traversing the Great Lakes. This will allow a warm front to surge northward towards the area, which may place us in the warm sector. There is still uncertainty with how far north this warm front gets — they often can get a bit hung up this time of year and not progress as far northward as model guidance indicates. This is important because if the warm front stays further south, we may not enter the warm sector and thus may remain too stable for heavy showers and thunderstorms.

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All Zones Late-AM Update: More Unsettled Weather, But Some Warmth Late Week?

Happy Tuesday! High pressure will be moving east over Quebec this afternoon. This will cause more northeast winds and a maritime airmass to begin filtering into region. But mostly sunny skies will still help temperatures rise into lower to middle 60s over much of the region, this afternoon.  Areas closer to New Jersey shore, Long Island and Connecticut will more sea-breezes this afternoon keep temperatures upper 50s or around 60.

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Evening PM Zones Update: A Cooler Pattern

Good evening, everyone! Another pleasant and warm day was had today with high temperatures generally in the 70s, with a good amount of mixing behind a cold front. However, surface pressures have begun to rise, which is evidence that Canadian high pressure is building in. This will allow for a cooler airmass to move in, winds to calm, and for skies to generally remain clear. There is a weak shortwave trough that will be passing over the region, which may briefly yield an increase in mid and high clouds in the early and mid-evening hours, but this shortwave trough is extremely positively tilted, so shortwave ridging is right on its heels — combined with the Canadian high pressure, subsidence should outweigh the forcing for lift, so the increase in clouds will be minimal and then should decrease again later in the overnight. Forecast soundings do show some mixing remaining in the low-levels tonight, so while winds will decrease, they may not go completely calm. This could prevent ideal radiational cooling conditions, but we will still have favorable enough radiational cooling for most areas to fall into the low to mid 40s tonight, with some mid to upper 30s in the interior valleys and Pine Barrens.

Tuesday will be a very pleasant day with the high pressure still in control, but its change in positioning will lead to some changes in our sensible weather going forward.

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Public Analysis: Cooler and More Unsettled Pattern Taking Shape

Good Afternoon!

The work week has had a rather dreary start today as cloudy skies and even some rain showers pushed through the area this morning and afternoon. Most of these showers were relatively light in nature, but most of the metro area remained at least under rather thick low level clouds. This area of cloudiness and showers was caused by a weak disturbance in the mid levels of the atmosphere just ahead of a larger system that is still located back in southern Canada.

As of 3pm this afternoon, the clouds and showers associated with this weak system have begun to dissipate and move to the east/southeast, giving way to clearing skies over northeast NJ and portions of Connecticut. Despite the cloudy conditions and the mixed in showers, temperatures have been able to rise into the mid to upper 60’s this afternoon. In fact. the locations that are beginning to see more sun poke through the clouds this afternoon have actually made it back into the low to mid 70’s. Even though these temperatures are still slightly above normal for this time of year, they are still a good 15-20 degrees cooler than the highs this time yesterday afternoon. Temperatures may continue to warm for portions of central and southern New Jersey as gradual clearing takes over, but overall highs should remain in the mid to upper 60’s with some locations able to break into the low 70’s.

As we work our way into later this afternoon and evening, more gradual clearing will begin to overspread the entire area behind the weak disturbance and antecedent cold front.  Some breezy winds of around 25-30 mph may linger into the evening hours, but as we progress towards sunset, winds should begin to subside, eventually giving way to clearer and more calm conditions. These conditions should allow for all locations to see some rather cool conditions once again this evening, as lows drop into the 40’s for coastal locations and possibly down into the upper 30’s for farther inland locations.

Latest surface temperatures, regional radar imagery, and visible satellite imagery showing improving conditions across much of the area this afternoon (Courtesy of GREarth)

Latest surface temperatures, regional radar imagery, and visible satellite imagery showing improving conditions across much of the area this afternoon (Courtesy of GREarth)

Tuesday Into Wednesday

As we move into tomorrow, generally cooler weather is expected once again as offshore flow brings in a cool maritime air mass from the Atlantic. Winds out of the northwest will also usher in drier conditions as well, so expect mainly clear skies during the day tomorrow with rather pleasant conditions. High pressure located to the northeast will also help to keep things relatively calm and seasonable for this time of year as highs stay in the mid to upper 50’s across much of the area, with a few locations seeing temperatures creep into the lower 60’s tomorrow afternoon.  Tomorrow should feel quite pleasant with frequent sun and light winds, but tomorrow should be right around normal for this time of year. 

Tuesday evening should see a gradual increase in clouds as moisture from the offshore winds bring in some low level moisture. Depending on how much cloudiness winds up manifesting tomorrow night will ultimately determine just how cool the low temperatures can get, but right now it seems that most of, if not all of the area will be seeing lows tomorrow evening in the 40’s. There is a small chance that inland locations that are further away from the coast, and therefore have less chance of marine influence, could possible see lows dip in the upper 30’s, but this will have to be monitored.

As we talked about last week, we are headed into what looks to be a more active pattern later this week that is quite reminiscent of late March as multiple storm systems and potential backdoor cold fronts have the possibility to impact our area. As of right now, Wednesday looks to be a rather seasonable day with broken clouds likely throughout the day just ahead of a gathering storm system in the central part of the county. This storm system will continue to head east towards the area throughout the day, and at least bring some enhanced cloudiness towards the evening hours. 

12z GFS 13km model showing a gathering storm system on Wednesday over the central US on Wednesday evening (Image courtesy of GREarth)

12z GFS 13km model showing a gathering storm system on Wednesday over the central US on Wednesday evening (Image courtesy of GREarth)

Thursday and Beyond 

Thursday should be a rather unsettled day as a frontal boundary ahead of the main area of low pressure in the Ohio Valley begins to sink to the south of the region. This should provide a chance at some showers and possibly a thunderstorm or two before the main low pressure approaches on Thursday evening. As of right now, there seems to be two main options for the late week storm, with the first option looking somewhat more likely as of this afternoon’s model guidance.

This option would mean that the main area of low pressure in the Ohio Valley would be able to lift the frontal boundary that was previously to our south, back up to our north. This would bring more warm/moist air into the area Thursday evening and into Friday afternoon. In this scenario, the low pressure would then track along the frontal boundary to our north during the day on Friday, and this would in turn bring the potential for heavier rain, with some thunderstorms also possible if enough instability is able to work its way in.

The other scenario would be that the low pressure system and frontal boundary remains to the south of the region late Thursday and into Friday, thus a cooler and steadier rain would be more likely. While both scenarios have the potential for heavy rain, the first option would be more intense, but also more localized. The second option would obviously be much more widespread and could even have a wind threat associated with it if the system remains far enough to the south.

12z European model showing the main area of low pressure tracking well to our north on Friday morning, bringing in a more moist/unstable airmass with the potential for heavy showers and even thunderstorms (Valid 2am Friday)

12z European model showing the main area of low pressure tracking well to our north on Friday morning, bringing in a more moist/unstable airmass with the potential for heavy showers and even thunderstorms (Valid 2am Friday)

As we head into the weekend, there is a chance things may briefly calm down, but overall temperatures are likely to remain slightly above or near normal through the weekend. Afterwards, there is a chance that a more substantial rain event could take place. This afternoons guidance has been hinting at the potential for a coastal system to impact the region, but this is of course in the long range and there is a great amount of uncertainty right now.

Regardless, it seems that things are going to become active once again with multiple rain chances over the next 7-10 days, so make sure to stay tuned for future updates on the upcoming pattern!

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Have a great afternoon!

Steve Copertino