Wind Advisory and Heavy T-Storm Potential Late Tonight

A wind advisory was posted just a short time ago for Eastern and Southern New Jersey. A wind advisory means that sustained winds of 31 to 39 MPH or frequent wind gusts between 46 and 57 MPH are anticipated. Currently the advisory goes into the late evening hours. With the saturated ground, I have been emphasizing the potential for scattered trees to come down for days and this remains true with the soaking rain in progress and even heavier rain later tonight. Scattered power outages are expected. Wind gusts below the advisory criterion are even capable of bringing down trees with the soaked ground.

The computer model guidance continues to show a well-developed line of thunderstorms pushing through New Jersey between 11:00 p.m. and 3:00 a.m. with torrential rain. Based on the organization of these storms and strong winds aloft, I could even see the possibility of isolated damaging wind gusts with these storms.

A coastal flood warning has been issued for Northwestern Burlington, Camden, Gloucester, and Salem Counties. Tidal effects will aggravate the flooding along the Delaware River and along the coastline. Flood advisories and flood warnings are also posted for various communities and more will be added through the night I am sure. Low-lying areas and areas of poor drainage will flood first and then the water will enter and flood tributaries, creeks, and streams. Finally, the water will enter the major rivers and flood them. This will be a process, so the riverbeds may not flood from rain water until after the tidal flooding. The exception is the ongoing flooding for the Passaic River and also any riverbeds impacted by enhanced rains from thunderstorms which could result in flashier flooding.

Wind Advisory and Heavy T-Storm Potential Late Tonight

Image added shortly

A wind advisory was posted just a short time ago for Eastern and Southern New Jersey. A wind advisory means that sustained winds of 31 to 39 MPH or frequent wind gusts between 46 and 57 MPH are anticipated. Currently the advisory goes into the late evening hours. With the saturated ground, I have been emphasizing the potential for scattered trees to come down for days and this remains true with the soaking rain in progress and even heavier rain later tonight. Scattered power outages are expected. Wind gusts below the advisory criterion are even capable of bringing down trees with the soaked ground.

The computer model guidance continues to show a well-developed line of thunderstorms pushing through New Jersey between 11:00 p.m. and 3:00 a.m. with torrential rain. Based on the organization of these storms and strong winds aloft, I could even see the possibility of isolated damaging wind gusts with these storms.

A coastal flood warning has been issued for Northwestern Burlington, Camden, Gloucester, and Salem Counties. Tidal effects will aggravate the flooding along the Delaware River and along the coastline. Flood advisories and flood warnings are also posted for various communities and more will be added through the night I am sure. Low-lying areas and areas of poor drainage will flood first and then the water will enter and flood tributaries, creeks, and streams. Finally, the water will enter the major rivers and flood them. This will be a process, so the riverbeds may not flood from rain water until after the tidal flooding. The exception is the ongoing flooding for the Passaic River and also any riverbeds impacted by enhanced rains from thunderstorms which could result in flashier flooding.

Heavy Rain Moves In

Round one of the heavy rain is now taking over Southwestern New Jersey and Northwestern New Jersey. The very sharp cutoff line is slowly moving east-northeast and will take more and more areas into the rain as the morning and early afternoon progresses. Flood advisories have already been posted in advance of this line for the majority of New Jersey. A flood watch remains in effect for all 21 New Jersey counties. A coastal flood watch continues for Salem, Camden, Gloucester, and Northwestern Burlington Counties for areas along the Delaware River. Flood warnings remain in effect along the Passaic River basin where the flood waters never receded from the previous heavy rain event on Sunday.

East-southeast winds are so far sustained 15 to 25 MPH with gusts to about 35 MPH. As the low pressure areas strengthen and get closer to our region, the gradient should tighten further. The strongest winds will probably be late this afternoon and early this evening. Gusts should be pretty significant in our eastern counties for a time.

Both the GFS and NAM agree that there will be torrential rain falling in the evening or 12 hours from now.

3/9/2011 Extended Forecast: Flood Watch for All of NJ Now/ Strong Winds Expected

UPDATE @ 3:25 p.m.: Coastal Flood Watches have been posted for rather unusual, but significant tidal flooding along the Delaware River from Trenton and points south (let alone the rain flooding that may occur) for Northwestern Burlington, Camden, Gloucester, and Salem Counties...


The east-southeast wind is already cranking across our region today. Winds are sustained 10 to 15 MPH with frequent gusts of 20 to 30 MPH. These winds will only increase as the storm system evolves and moves closer to New Jersey. Vigorous negatively tilted trough and the position of the double-barrel low pressure areas will provide a nice setup for a strong fetch off the Atlantic Ocean and it will also provide a nice setup for strong wind gusts. There is no doubt this will be a windswept rainfall. A low center may exist across the Great Lakes with another forming along the Middle Atlantic. The one across the Middle Atlantic now appears it will move from east into the interior of Central Pennsylvania. This track will really bring in that stream of moisture. Meanwhile, high pressure will be to the north and east of Maine, and that will really work to tighten the gradient. I think the strongest wind gusts will be along our coastlines of Monmouth, Ocean, Southeastern Burlington, and Cape May Counties. Wind gusts past 55 MPH wouldn’t surprise me in these eastern counties during the height of the storm. They will drop off inland, but gusts will still be in excess of 40 MPH. There is the potential for structural damage to the trees and utility poles as the ground is so saturated that these wind gusts would be capable of knocking them down. . I think we will see so much rain that many of the weakened trees even without the wind could fall with the loosened soil. Of course flood waters can also be powerful enough to take down trees. The bottom line is strong easterly to southeasterly winds can be anticipated. Behind the departing system, northwesterly to westerly winds will occur on Friday. With a high pressure area building in, some more windy conditions can be expected, albeit not as intense. The previous Sunday storm, which did not have as strong of an east-southeast setup was able to get wind gusts to 56 MPH in New York City with widespread frequent gusts of around or above 40 MPH in New Jersey. So I do have reason to believe this will be a more impacting strong to high wind event.

Coastal flooding is going to be another concern with a persistent easterly flow. I think the water will pile up fairly well along our coastal communities. Widespread minor tidal flooding looks like a good bet. Some communities should experience moderate coastal flooding with my wind projections.

It appears as though the models want to now show to distinct rounds of heavy rainfall. The one round will be the moisture that streams up from Louisiana and the Florida Panhandle where tornado watches are currently in effect. Then the second round will be the evening and nighttime round which should put many low-lying areas and eventually waterways over their banks. In-between these rounds, there could even be a brief few hour lull (lighter rain?) in the action. Two to three inches of rain will likely fall from Thursday Afternoon into Friday Morning. Some areas will see localized amounts of four to six inches. Historic flooding is quite possible in Northern New Jersey where there is still ongoing flooding around the Passaic River Basin. The water levels will drop some, but perhaps not below flood stage prior to this event. Just imagine the rises in this area this time around as last time around we at least started below flood stage. Elsewhere, even if there is not ongoing flooding, should three inches fall, significant flooding is expected if the rainfall predictions are realized. Some of the flooding could be of moderate to major severity.

Tidal effects will aggravate the flooding along the Delaware River and along the coastline. I remain persistent that anyone living in an area that has flooded in the past few decades should prepare for flooding this go around. Move furniture to higher ground and have an evacuation plan in place. During the heavy rain, flooding in most areas will occur in low spots, around ditches, streets with areas of poor drainage, and at smaller creeks and streams. Then all that water on Friday will head towards the major creeks and major rivers. The rises here will be perhaps slow as it will take time for the runoff to make its way there, although if four inches of rain falls, a much faster rise can be expected, perhaps a flashier flood. The ground is so saturated that this rain cannot be absorbed. Trees are also not sucking in the water since there are no canopies to support. Numerous road closures are expected Thursday Night and Friday Morning.

Some isolated strong to severe thunderstorms cannot be ruled out. There appears to be some marginal instability. Some embedded thunderstorms will be associated with the low as it rides up the cold front. The convection will be mainly low-topped. Strong easterly winds may be enhanced by the convection just like last March when there was a few rumbles of thunder with the monster Nor’easter. With such a well-organized rain shield, detecting microbursts and weak tornadoes are difficult and it may not necessarily happen. It will all be about the parameters in place as the convection approaches from the south. The severe weather threat will be very limited, but not impossible. Any squall-lines that form to our south will have to be watched to see if they move into our region. Lightning could be limited with any convection that does form.

The flood watch now includes all of New Jersey’s 21 Counties. I couldn’t agree with this decision more. My wind forecast is presently more robust than the National Weather Service’s wind forecast. I am well aware. The stronger winds I am expecting is like a domino effect because it is related to tidal flooding in many aspects leading to a more dramatic coastal flood forecast from me. Eventually, in time, I suspect wind advisories and coastal flood statements will be issued for the eastern counties, even if it is issued during the storm. In the March 2010 storm, there were plenty of last minute issuances and upgrades. I have enough confidence in the overall setup to take a step away from cautiousness. If there are already 29 MPH gusts in interior Burlington County, how can I go wrong with the wind forecast during the peak of the storm?

Anyway, I will be updating the forecast again late tonight and all day tomorrow I will have extensive coverage.

Flood Watch Issued for Thursday into Friday

The National Weather Service earlier this morning already placed a good portion of New Jersey under a flood watch from Thursday Morning into Friday Morning. Usually a watch would be issued slightly closer to the event. However, the model guidance continues to yield high confidence that another significant…if not excessive…rainfall event will impact the region on Thursday. The heaviest rain may wait until later on Thursday with cresting of waterways occurring approximately twelve to twenty-four hours later.

I am still confident in a widespread two to three inch rainfall, with locally higher amounts between four and six inches. I wouldn’t be surprised that some of sandier soil counties are added to the watch as the event gets closer. These rainfall amounts will result in moderate to major severity flooding. Some of the waterways in Northern New Jersey are still under a flood warning and some are awaiting a crest that will not occur until late tonight or Wednesday Morning at major flood stage. Since I do not believe these rivers will recover in time, historic flooding is a possibility for the Passaic River areas under the current warnings.

Very Heavy Rain and Thunderstorms On The Way

The threat for heavy rain this evening and overnight continues across New Jersey. While we have had some scattered heavy showers this morning, the main course is waiting to impact us. The radar picture just after noon showed a surface low beginning to develop and intensify along a slow moving cold front moving eastward. Rich gulf moisture and moisture from the Atlantic can be seen injecting itself into the surface low. The low is currently around the Southern Appalachians. The low will move into the Carolina Piedmont and eventually eject northward into our region. As the system gets closer to our region, both the front and the low will begin to develop some heavy, steady rainfall. The heaviest axis of rain will setup in Northwestern New Jersey down through Eastern Pennsylvania. The NAM and GFS models show even heavy rain in Cape May, but I am still expecting lesser amounts in our southeastern counties. The higher resolution models aren’t as robust as the morning GFS and NAM on torrential rain at the shore points.

With New Jersey in the right guardant of this low, I expect it to turn windy for at least a short period of time. Wind gusts of near or in excess of 50 MPH certainly are possible as the front pushes through and the surface low moves to the north and east. With the wet ground, these wind gusts may be able to uproot trees. The heavier rain could be able to transport the stronger winds to the surface. The right quadrant also means that there could be some marginal instability for some thunderstorms. The models indicate low-topped convection with the actual surface low itself, regardless of if you will be on the right side. Any convection will be underneath all of this heavy rain. These situations pose a challenge to detect wet microbursts or a weak tornado, but these are certainly possible with any thunderstorm given the setup.

The high resolution models show cold air catching up with the precipitation on Monday Morning prior to and during the morning commute. It could be cold enough to change the precipitation to sleet and wet snow in our Northwestern Counties. The setup leaves me still with some doubts, but it can happen and one must maintain an eye on the credible models suggesting this possibility.

3/5/2011 Extended Forecast: Flood Threat, T-Storms

For more on the heavy rain threat, see the previous post.

The latest high resolution modeling is in agreement with the more general modeling that the steadiest and heaviest rain will not be affecting the Garden State until Sunday Afternoon and Sunday Evening. I still also believe that the lowest rain amounts will be recorded around Cape May with the highest amounts in Northwestern New Jersey.

Recent heavy rainfall in February, especially north and west of Philadelphia, and all of the melting snow has caused our waterways to run above normal. Therefore, flash flood guidance is low across a good portion of the Northern and Central New Jersey. According to the updated guidance, one to two inches of rain in six hours or less is all it would take to cause flooding in the Raritan Basin region. For Southern New Jersey, three to four inches of rain would begin to cause flooding. Unfortunately, the latest model guidance has the heaviest rainfall axis where the guidance shows the lower values. This is the reason a flood watch remains posted for Northern and Central New Jersey. Two to three inches of rain with locally higher amounts are possible in Northern and Central New Jersey. One to two inches of rain is expected elsewhere in Southern New Jersey. Cape May could see amounts under an inch. We need to watch to see if any training or terrain effects result in a narrow corridor of 3-6 inches of rain.

For the New Jersey counties within the flood watch, there is a strong potential to see creeks and streams rise and exceed flood stage. The watch area could also have numerous road closures and washed out roadways if amounts exceed two inches. Outside of the watch area, while the road closures may not be as widespread, some street flooding and poor drainage flooding is quite possible. The entire forecast area will likely see hydroplaning conditions by nightfall. Ditches will also fill to capacity.

By evening, everyone should be into steady moderate rain with those pockets of heavier rain. The low developing on the front will be so strong that low-topped convection may develop in the entire region, despite a true lack of instability. In our eastern counties, the lack of rain initially during the day could allow for temperatures to spike up into the sixties and this may add marginal instability in those areas. Don’t be surprised to see some thunderstorms Sunday Evening and Sunday Night. The higher resolution modeling wants bring a line of convection through the area from 4:00 p.m. to 9:00 p.m. The low pressure center will allow for Garden State to be within the right quadrant and any unforeseen instability would be able to trigger potential severe thunderstorms. Sometimes these events could cause a wet microburst or a hard to detect, weak tornado embedded within the heavy rain.

Let’s know get the wind potential. The cold front will cause a strong southerly flow to develop in advance of it. The heavier rain could certainly transport stronger winds to the surface. The winds aloft do not look the most impressive, but there is enough of a kick aloft to be concerned about. With the low crossing our region, the gradient does tighten enough to suspect that a period, perhaps short-lived, of windy conditions could occur. With the saturated ground, the wind potential must be monitored. South winds could be sustained 20 to 25 MPH with gusts of up to 45 MPH. I could even see some areas, especially in the coastal counties; see wind gusts of near or in excess 50 MPH during the frontal and low pressure passage. The wind will be dependent on the exact low pressure center movement and there is low confidence about the wind threat.

Some of the model guidance wants to show this ending as wet snow and sleet Northwestern New Jersey. It will be dependent on whether the cold air catches up with the precipitation behind the cold front. It is not impossible to see this happen, but I have my doubts. I don’t see the best setup for this to occur. The primary impact in these areas will be the flooding and even mudslides in the higher terrain.

The rain will end rapidly on Monday and we will deal with lingering runoff causing flooding. The wind will be stiff with the departing low and incoming high. Tuesday looks seasonable. Wednesday will be mostly cloudy as a warm front passes through and this front perhaps could create some showers. By Thursday, another strong front with low pressure will bring a heavy rain threat. More thunderstorms and windy conditions are possible.

Flood Watch for Northern and Central New Jersey

At this point, it appears as though this heavy rainfall threat will have to be monitored from a radar standpoint. The computer model guidance continues to shift the axis of heavy rain around with every model run. It is now returning to the solution of having the core of heavy rain over Pennsylvania and Northwest New Jersey. Refer to the earlier posts to compare the latest model images below with earlier runs.

I have now included future precipitation which shows that the region will get at least one and one half inches of rain, with less southeast and more northwest. The flood watch has been posted for much of Northern and Central New Jersey and this is where future precipitation indicates the best potential for two to three inches of rain over a widespread area. The model guidance is blended in to future radar from this morning. The big question south and east of Trenton will probably be if thunderstorms develop and if they produce localized heavy rainfall.

I think everyone is vulnerable to poor drainage flooding, street flooding, and ditches overflowing. Areas in the flood watch will be most vulnerable to stream and creek flooding. Certainly if Northeastern Pennsylvania and Northwestern New Jersey see heavy rainfall, that water will move downstream on the Delaware River and combine with heavy downpours around Trenton to cause large rises on the Delaware. The worst case scenario with this particular solution would result in a rise to near or slightly above the capacity. Should more than three inches fall (more liquid to work with), then we would have to watch for more significant flooding on both the Delaware and Raritan.

The bottom line is that hydroplaning and road closures appear quite possible Sunday Night and Monday across New Jersey with the greater chances the more north and west one lives or travels. Less rain may fall towards Cape May and this is where we have sandier soil anyhow.

I’ll have more on the wind and any potential severe weather (since we may be on the right side of the surface low) tonight.

High Wind Warning, Flood Watch, and Severe T-Storm Threat Friday

The National Weather Service has placed the region under a high wind warning for Friday Afternoon and Friday Evening. A high wind warning is not issued to often, as severe wind events are fairly unusual for the Garden State. However, this is the second high wind warning product issuance in less than one week. A high wind warning is issued when sustained winds of 40 MPH or greater and/or wind gusts of 58 MPH or greater are imminent or occurring. A warning implies dangerous conditions are imminent or occurring. For Northeastern New Jersey, a high wind watch is in effect.

The high winds will obviously once again lead to a situation where many trees and tree branches could come down. This may close several roadways and lead to widespread power outages. One difference with this high wind event will notably be the ground saturation. The ground will be absolutely saturated after receiving two to three inches of rain, possibly more. The saturated ground will increase the chances for whole trees, even healthy ones, to come down.

A high wind warning does not include the wind gusts that could come with any potential thunderstorms. The other wind threat will come thunderstorms that could develop ahead of the warm sector in the mid to late afternoon hours, as the cold front sweeps through. There appears to be favorable conditions for the development of thunderstorms that can transport strong winds aloft down to the surface in the warm sector. The areas in the warm sector have the possibility of tapping into rich moisture, shear, and instability…especially if some clearing takes place for a few hours prior to the frontal passage. I have more confidence of this occurring south of Interstate 195, but even north of this line we will have to watch for thunderstorms to develop. One higher resolution model shows a severe cell even making it into Mercer County.

Meanwhile, a flood watch is in effect for Northern and Central New Jersey. Our higher resolution models are indicating the bulls-eye of heavy precipitation in the watch counties. I would not be shocked if flood watches or warnings include areas not under the current flood watch as I think everyone will see heavy rain and while it may not be the heaviest axis, it will be drenching.

Temperatures could fall more than thirty-degrees in just three hours from 5:00 p.m. to 8:00 p.m. for areas that get into the warm sector and rise to near 65-70 degrees. Quite a contrast once again from North to South.