Posts

Steven Copertino

Public Analysis: Remnants of Cindy Likely to Bring Heavy Rain, Seasonable Conditions Return Next Week

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Good Afternoon and Happy Friday! 

Getting right into things, earlier this week we highlighted the potential for some heavy rain associated with the remnants of Tropical Storm Cindy, which made landfall along the Texas coastline early Thursday morning. At that time, we stated that there were two scenarios that were likely to play out, one being that the remnants of Cindy would not hold up all that well after landfall, and the other being that they would. Over the past twelve to eighteen hours or so, it has become apparent that the remnants of Cindy have remained quite robust as they traveled over the Ozarks and into the Tennessee Valley, at least in the mid levels of the atmosphere. With very deep, tropical moisture streaming north from the Gulf of Mexico, the significance of having a more coherent remnant system means that the leftover energy will spark widespread showers and thunderstorms through this evening and into Saturday. In addition to the remnants of Tropical Storm Cindy, which has been downgraded to a remnant low pressure area, we also have a cold front surging through the Ohio Valley.

This cold front has been working to funnel all of the moisture from the Gulf of Mexico to the north and east, allowing it to pool up over the eastern third of the nation over the past two days. This has made for a very soupy and humid day today across the majority of the Northeast. We saw some very subtle lift manifest itself over Pennsylvania around noon today, which allowed for some showers to move eastward through eastern Pennsylvania, New Jersey, and New York. Occasional breaks in the clouds and very warm temperatures a few thousand feet off the ground allowed temperatures to spike back into the low to middle 80’s across the entire region, despite sudden temperature drops with any gusty showers that passed through some locations.

As of 630pm, a convective complex was evolving over the eastern half of Pennsylvania, and this complex will continue to head eastward through the evening. With adequate amounts of wind shear, instability, and an extremely moist air mass in place, torrential downpours, frequent lightning, and some gusty winds seem quite likely for those in the path of these showers and storms. Synoptic winds (winds not associated with small scale features) have already been quite impressive this afternoon, so we are quite confident that the probability for tropical-like downpours and gusty winds could cause some localized flooding with debris from trees likely clogging sewers. In lieu of this slight risk for severe thunderstorms, the Storm Prediction Center in Norman Oklahoma has issued a severe Thunderstorm Watch until 10pm this evening. The rest of the evening should remain quite unsettled, with the potential for more showers and thunderstorms behind this complex, so make sure to pay attention to your local NWS office for any potential warnings!

Animated regional radar mosaic, showing the evolution of a complex of showers and thunderstorms approaching the area. The main threats appear to be heavy downpours and gusty winds (Courtesy of College of DuPage)

Animated regional radar mosaic, showing the evolution of a complex of showers and thunderstorms approaching the area. The main threats appear to be heavy downpours and gusty winds (Courtesy of College of DuPage)

Saturday Morning to Evening

As we head into tomorrow morning, things look to remain quite unstable as the energy from the remnants of Cindy approaches the area while the cold front to our east compresses all of the rich tropical moisture into a focal point, located right over our area. During the day today, the high resolution models have been keying in on a very heavy band of rain moving over portions of Pennsylvania, New Jersey, New York, and Connecticut by 7-10 am tomorrow. This band of heavy rain is directly associated with a mid level piece of energy currently located over portions of Kentucky, which will likely continue NE throughout the evening hours. A crucial point here is that since the energy already exists and is well sampled, the models likely have a decent grasp on the situation over the next 12-18 hours. Regardless, as this piece of energy nears our area tomorrow morning, we will have to monitor the situation very closely since any rainfall with this system will likely be quite intense, which could produce localized flash-flooding, and exacerbate and potential flooding issues caused by tonight’s storms.

Thankfully, the rain threat looks to quickly diminish later tomorrow morning, into the early afternoon hours. Any residual showers and thunderstorms look to press off to the east and offshore, leaving much drier conditions in their wake. With clearing skies, westerly winds, and warm low to mid level temperatures, temperatures should be able to climb into the middle 80’s with ease by late tomorrow afternoon, making for a nice rebound. Weak high pressure will be over the region Saturday night. Clear to partly cloudy skies are expect with lows in the 60s in many of the suburbs to lower 70s in NYC and urban areas.

Rapid Precision Models deception of this evening and tomorrow mornings heavy rain threats (Courtesy of WSI)

Rapid Precision Models deception of the possible heavy rain threats this evening, lasting into tomorrow morning (Courtesy of WSI)

Sunday and Beyond 

Sunday looks to be quite beautiful early on, with increasing sunshine during the early morning and afternoon hours and light winds from the west/southwest due to high pressure exiting off the Mid Atlantic coast. With the mid/upper level trough moving over the region during the day, slightly cooler temperatures aloft will limit just how warm temperatures can get, with highs likely reaching into the lower to middle 80s over much of the area. There is some potential for sea-breeze activity to knock temperatures down into the 70’s during the afternoon hours, but this will likely happen on a very small scale. Later in the day, a weak cold front looks to move through the area, and bring at least an increase in cloudiness, with an outside chance at a shower or weak thunderstorm towards the evening hours.

By Monday, troughiness will increase once again over the northern section of the Great Lakes region, which will likely usher in a cooler and much direr air mass compared to what we have been experiencing over the past few days. This area of below normal temperatures looks to continue into at least Tuesday, before we have to watch for the potential of a ridge building over the east, possibly by Wednesday. Mid level ridging may continue to build into the Northeast and Mid-Atlantic through end of the week, with more heat and humidity possible over the east.  As of right now, no significant precipitation or convection is expected, until the trough over Rockies finally shifts east into Northeast/Mid-Atlantic region by next weekend.

This afternoons European Ensembles showing a rather high likelihood of below normal temperatures for the first half of next week.

This afternoons European Ensembles showing a rather high likelihood of below normal temperatures for the first half of next week.

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Have a great evening!

Steve Copertino

 

Miguel Pierre

5.24 Midday Zones Update: Heavy Rainfall, T-Storms, Coastal Flooding Possible Thursday

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Good afternoon. Low pressure that brought some light early this morning, is moving further offshore. This will allow for clouds to clear for more sunshine this afternoon. This will help temperatures rise into the upper 60s to lower 70s over much of the region, especially inland. A northeasterly flow may keep some coastal sections a little cooler in the lower to middle 60s.

Then clouds will increase again this evening and overnight, as larger storm system from the Ohio and Tennessee Valleys , that we’ve been discussing over the past few days with these zone forecast updates, finally begins moving into the region. As more lift with mid-level warm advection and isentropic lift increases ahead of warm front, some may start developing form southwest to northeast across the region, very late tonight. Cloud cover will likely support low temperatures drop into 50s over most of the region.

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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