Posts

Miguel Pierre

5.22 AM Zones Update: Unsettled Weather Pattern This Week, Memorial Day Weekend Weather

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Good morning! Some showers that have been moving across the region overnight and early this morning were associated with shortwave energy, undercutting upper-level ridge. More rain is likely to overspread the region from the southwest, later this morning and into early this afternoon, as a frontal system with a weak wave of low pressure along it approaches the region.

Latest model guidance indicates some weak instability and strong moisture convergence along a warm/coastal front with precipitable water values between 1.50” to 2.00”. This will likely cause rain, to become heavy at times with some isolated thunderstorms possible over Central and Southern NJ and over parts of Long Island and Coastal CT. These areas are where rainfall totals between 1” to 2” is more likely to fall today. Some locally heavier totals are possible from any thunderstorms with torrential downpours and some localized flash flooding, especially in poor drainage and low-lying areas.

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Steven Copertino

Public Analysis: Calm and Cool Weekend, Turning Unsettled Next Week

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Good afternoon and Happy Friday! 

Today has been yest another hot and relatively muggy day in a strong of abnormally warm, summer-like heat. This heats time is very limited as a cold front is set to move through the region, leaving much cooler and stable conditions for the upcoming weekend. As discussed over the past week or so, high-latitude blocking over Greenland and Atlantic Canada will set the stage for a large upper level trough to set up over the eastern two-thirds of the country. This trough will likely bring a few shots at some heavy precipitation, potentially lasting through much of the work week as we draw closer to the Holiday Weekend!

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Today and This Evening

This afternoon we saw temperatures shoot back up into the upper 80’s and lows 90’s across the entire region, with some stations like La Guardia Airport and Caldwell, New Jersey seeing highs shoot into the mid 90’s (95F)! Despite the clear skies and slight breeze today has also felt relatively muggy as dew-points rose into the lower to mid 60’s. This muggy air-mass has also allowed instability to build over much of the Mid-Atlantic and Northeast states, and combined with some modest wind-shear, has allowed some very isolated showers and thunderstorms to develop across portions of New Jersey and Southeastern Pennsylvania. Due to the fact that the best instability and wind-shear are disjointed from each other, the prospects of widespread, organized thunderstorms is quite low. However, very isolated showers and thunderstorms will be possible, especially over southern New Jersey and Southeastern Pennsylvania. The main threat from these showers and storms will be gusty winds of around 40-50 mph, however small hail and frequent lightning may be possible with some of the stronger storms.

As we head into this evening, a cold front located over southern New England and central New York state will continue to sag south and overspread the region late tonight and into very early tomorrow morning. The flow behind the front will begin to change from very warm southerly winds, to much cooler northerly winds from Canada. These will bring lows down into the 50’s for much of the area, which will be quite the departure from what we have seen over the past few days.

Latest visible satellite imagery, station observations, and regional radar mosaic over the area, showing yet another warm and muggy afternoon. (Courtesy of College of Dupage)

Latest visible satellite imagery, station observations, and regional radar mosaic over the area, showing yet another warm and muggy afternoon. (Courtesy of College of DuPage)

This Weekend

As we start up the weekend tomorrow morning, we should see some relatively cloudy skies behind the cold front as an area of mid-level moisture works in over cool easterly winds coming off of the Atlantic which should produce areas of overcast and scattered clouds throughout most of the day. Temperatures should be relatively cool with highs in the upper 60’s to lower 70’s, which will be 20-25 degrees cooler than the past three days for much of the area. In addition to these cooler conditions, the Canadian/Maritime airmass will limit any chance for measurable precipitation throughout the day. As we head into tomorrow evening, an area of high pressure will be moving to our north and will work to reinforce the maritime airmass over our area. This will allow temperatures to drop into the upper 40’s and lower 50’s across much of the area, with partly cloudy conditions remaining.

We should see more clouds on Sunday as the continued maritime airmass and weak mid-level moisture hold over the area. Temperatures should be in the upper 60 to lower 70 range once again, but these highs should be quite variable as any areas that see prolonged peaks of sun may raise above the lower 70’s, while areas closer to the coast that may see prolonged cloudiness and southeasterly winds could wind up staying in the middle 60’s. Moisture will begin to increase later Sunday as the area of high pressure begins to shift off of the New England coast and as an area of low pressure moves through the Great Lakes region. This area of low pressure will drive a warm front through the Mid-Atlantic region, just south of our area. As time progresses, cloudiness will be on the rise and will likely become overcast towards the end of the evening as winds shift from easterly, to southerly once again. This afternoons model guidance was not in agreement on the exact timing, but the aforementioned cold front will likely not be able to progress east enough to produce widespread showers by Sunday evening. Overnight lows should remain quite moderate, with temperatures likely staying in the low 60’s to upper 50’s for most of the area.

This afternoons European model showing moisture beginning to build to the south of the region as a cold front associated with an area of low pressure in the Great Lakes begins to trudge eastward (Courtesy of AccuweatherPro)

This afternoons European model showing moisture beginning to build to the south of the region as a cold front associated with an area of low pressure in the Great Lakes begins to trudge eastward (Courtesy of AccuweatherPro)

Next Week

This afternoons model guidance did differ on the exact timing and placement of the cold front by Monday morning, but indications are that it should be located over eastern Pennsylvania by the morning commute. With moisture surging up to the east of the front, substantial cloudiness is likely to be present over the region, but depending on just where the warm front is located, some isolated peaks of sun will be possible. High temperatures on Monday will be very dependent on where the warm front is located as this will dictate where partial sunshine will be possible. By late morning, the actual cold front will likely move through the region and will likely have the potential to bring some showers and thunderstorms over the region. A strong southerly jet will continue to feed moisture north over the area for six hours or so and there will be the potential for some heavy rainfall with training storms. Although it doesn’t seem overwhelmingly likely, there may be the potential for some localized flooding, so make sure to stay tuned for further updates!

Tuesday will likely be a calm and cooler day as another storm begins to gather to our south with more possible moderate to heavy rainfall for the area on Wednesday. This will continue to be the theme for the week as a large upper level trough will be cemented over the central and eastern states due to another period of prolonged high latitude blocking that will allow multiple systems to slow down and congeal together to our south. While it is possible that this trough produces multiple rain threats over the next week, there is also the potential that we return to another period of below-normal temperatures coming down from Canada. Though it’s around ten days out as of today, there are some indications that this period of cooler and unsettled weather may last into the Memorial Day weekend. Stay tuned for the numerous upcoming rain threat as well as details on the upcoming Holiday Weekend!

This afternoons European model showing a very large and very anomalous upper level trough parked over the Ohio Valley and Eastern US that has the potential to bring multiple shots at heavy rain and below-normal temperatures (Courtesy of Accuweather Pro)

This afternoons European model showing a very large and very anomalous upper level trough parked over the Ohio Valley and Eastern US that has the potential to bring multiple shots at heavy rain and below-normal temperatures (Courtesy of Accuweather Pro)

or more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great weekend!

Steve Copertino

Miguel Pierre

5/8 AM Zones Update: Cool Weather Week, Potential Weekend Coastal Storm

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Happy Monday! It’s been chilly with some sunshine has been this morning. But an large, anomalous cold upper-level low continues to linger over the northeast today. This will cause the atmosphere to become more unstable, with more daytime heating. So more clouds will likely increase again this afternoon, with some isolated or widely scattered showers around. These should be mostly on light side however, with very limited lift and moisture overall. Temperatures will be cooler than normal today with highs in mid-upper 50s to around 60 in most spots.

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Steven Copertino

Public Analysis: Heavy Rains Exit Today, Unsettled and Cooler Next Week

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Good afternoon and Happy Friday!

The large area of low pressure that we have been talking about for over a week now is finally making is way through the Northeast, and is certainly making its presence known. As of 2pm, most of the region has seen anywhere from 1-3.5″ of rain over the past 6 hours or so. All of this heavy rain in such a short period of time has lead to street flooding to be quite common in areas with poor drainage that also saw some of the heavier 2.5-3.5″ amounts. Flash flood warnings are currently out for portions of central NJ, Northeast NJ, Long Island, and southern Connecticut. While street flooding will be possible across portions of northeast New Jersey, Long Island, and Connecticut due to training of very heavy pockets of rain, more significant creek, river flooding is not expected at this time-though a few isolated cases may be possible as totals may approach 4″ in some isolated locations later this afternoon.

Please pay close attention to you local National Weather Service office for any information on Flash Flood Warnings or statements over the next few hours. Additionally, exercise caution when driving through heavy downpours and if you do encounter flooding of roadways-DO NOT attempt to cross that area of water no matter how deep you think it may be. We have seen upwards of 10 reports already of people trapped in vehicles, which required rescuing! Turn around and don’t drown!

As we work our way through the rest of the afternoon, dry air will begin to work its way in from the southwest and will work to effectively shut down the heavy rains. Mostly cloudy conditions are expected the rest of the afternoon as the rain tapers off from west to east by around 3-4pm. Temperatures may be able to rebound slightly into the low to mid 60’s across the area as a warm front begins to work its way up from the south just behind the bulk of the rains. As this warm front continues to move north through this evening, some more shower will be possible over the region, but heavy rainfall with these showers appears unlikely as the atmosphere will contain significantly less water vapor than it did this afternoon. Temperatures this evening will remain quite warm as the area will be within the warm sector of the low pressure area moving through Pennsylvania.

Latest regional radar mosaic, surface temperatures, visible satellite imagery , and NWS Flood Warnings (in green) showing the heavy rains finally pushing out of the area (Courtesy of GREarth)

Latest regional radar mosaic, surface temperatures, visible satellite imagery , and NWS Flood Warnings (in green) showing the heavy rains finally pushing out of the area (Courtesy of GREarth)

Saturday and Sunday 

The unsettled pattern will continue through the evening hours and into tomorrow as the negative NAO block helps the storm’s remnants stall out and decay over our area for at least the rest of the weekend. Tomorrow should start off relatively warm underneath partly cloudy skies and light southerly winds as the warm front continues to move north of our area. Depending on how much clearing we see tomorrow, some areas could reach highs into the middle to upper 60’s by late afternoon, while the rest of the region sees highs generally in the low to mid 60’s. Some residual energy associated with a cold front will likely move through the area late tomorrow afternoon or early evening, and bring the potential for some more showers and even an isolated thunderstorm depending on whether or not the area sees enough clearing earlier in the day to support some buildup of instability.

Cool and drier air will funnel in behind the cold front early Sunday morning, so any remaining showers and thunderstorms will likely taper off from west to east once again. As we get to daybreak on Sunday, another cold front will be working its way east, so expect some broken clouds to start off the day, but cloudiness should gradually increase as a the cold-core of the upper level low that will have stalled over the region begins to sink to the south and towards our area. This pocket of colder upper level temperatures will harbor a more unstable environment, so some showers will be possible during the afternoon. With the cooler air being reinforced by two cold front on Sunday and cloudier weather likely, highs should remain in the upper 50’s to lower 60’s during the day.

This afternoons high resolution NAM model, showing unstable conditions underneath with rain/snow showers possible for locations to the North and West (Valid 8pm Sunday)

This afternoons high resolution NAM model, showing unstable conditions underneath with rain/snow showers possible for locations to the North and West (Valid 8pm Sunday)

Extended Range

The latest computer model guidance consisting of the American model, the Canadian model, and the European model, all show the negative NAO continuing into next week and even strengthen the block while bringing it back further west. This will keep a large upper-level low trapped over the Northeast, which will ensure that cooler weather stays locked in place. This large upper level low locked in over the region will also be capable of swinging multiple disturbances around the base of the low, and possibly back into our area.

For the most part, each day early next week should be relatively similar, with early morning sunshine giving way to cloudier conditions with the threat of some showers by later afternoon and evening. Given the cooler temperatures in the upper levels of the atmosphere, some ice pellets or event wet snowflakes may be possible for locations to the north and west. Otherwise, each day is mainly looking at highs in the mid 50’s to lower 60’s for highs, with lows ranging from the low 40’s to 30’s possible for inland locations.

No real significant precipitation events are expected in the medium range, however we are beginning to watch the period around Mother’s Day for a potential coastal system. The time to really watch for larger storms or heavier precipitation events in this type of pattern is typically when the NAO block begins to weaken and move away. At this time, we don’t really see the possibility of this happening until around late May. Stay tuned for further updates on the unusually cool pattern over the foreseeable future!

This afternoons European model showing below-normal temperatures over the next week for the Northeast US, courtesy of a large upper-level low parked over the region (Image Credit: Ryan Maue)

This afternoons European model showing below-normal temperatures over the next week for the Northeast US, courtesy of a large upper-level low parked over the region (Image Credit: Ryan Maue)

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great weekend!

Steve Copertino