09/30/2025

 

Welcome to the last day of September.

We have that trough dropping in out of Canada with the cold front over New York State and New England dropping through the region. Radar and satellite show the clouds streaming in from Imelda Into the northern Middle Atlantic and Pennsylvania. With the clouds over Maryland Delaware into southern New Jersey There is a chance for some light rain or drizzle, but it shouldn't be too bad. North and west of there should be dry today.

North of the cold front It's mostly sunny, with temperature starting to cool off. South of the front It is warmer with muggy conditions in the Middle Atlantic. As the cold front continues to drop south it is going to take these warmer temperatures and muggy conditions out of here.

Hurricanes Humberto and Imelda.

image credit Tomer Burg

Humberto has maximum sustained winds of 80 mph, minimum central pressure Of 979 mb, he is moving north northwest at 17 mph . As he's interacting with that trough dropping down out of Canada, that we can see on the satellite is shredding him apart. Imelda also has maximum sustained winds of 80 mph, Central pressure of 980 MB. With the weakened upper level low to her west; she's starting to feel Humberto 's tug and is tracking northeast at 7 mph

Image credit Tomer Burg

The  two hurricanes Together That their respective circulations Are impacting each other With windshield. With the trough dropping out of Canada The added windshield has exposed Humberto's center. Humberto will likely be downgraded to a tropical storm at some point today.  He is going to stay several hundred miles west and then north of Bermuda, so no direct impact there. Imelda Is going to be right in his way wake, straight for Bermuda. Imelda Is going to be aided by the wind Sheer caused by the trough and slightly strengthen s she as she gets close to Bermuda So it's possible she could bring category 2 hurricane conditions to the island. Regardless of how strong she is. Imelda is going to bring powerful winds and dangerous storm surge to the island  late tomorrow into Thursday.  She will be moving quickly so conditions should quickly start to improve later Thursday as she is passing to the east.

back to the Northeast

For the Northeast as the trough that is protecting us from the hurricanes moves in We are going to cool off to average to below average temperatures for a couple of days. But the high pressure Is going to ensure that we stay dry. On Friday the high pressure is going to start to slide towards the coast We will start to see more in the way of a southerly flow that is going to start to warm us up for Friday.  As the high pressure Continues to slowly slide east Saturday and Sunday  we'll see temperatures continuing to warm and become above average. The entire weekend looks to be dry. Monday will be a mirror image of what we saw over the weekend with above average temperatures and dry conditions. Then on Tuesday into Wednesday We will have a weak moisture starve cold front approach and slide through the region bringing back the chance for more in the way of widespread but scattered showers to the region.

Even though we're going to be in October. As we start to think about Halloween we're still going to have quite a bit of warmer temperatures at times during the month.

09/29/2025

 Doesn't feel like Fall

We have high pressure building in out of Canada Behind the cold front dropping south over southern New Jersey into Maryland and Delaware.

Radar shows some rain up around  the Delmarva peninsula back into Virginia. Much of that over southern Maryland and southern Delaware is likely virga but there could be some scattered isolated showers here and there.

Satellite shows Mid level clouds from Imelda's circulation pushing in from the south Over the Middle Atlantic into Pennsylvania. North of there there's much more in the way of sun. Temperatures today will be above average.  Tomorrow is going to be much the same Only a slight chance for some rain in the northern middle Atlantic.

Then on Wednesday as the high pressure overhead pushes north and east A weak and very moisture starved cold front will drop through. So not expecting much rain if anything out of it. The region will cool off a little bit for Wednesday into Friday. That northeast breeze is going to feel quite chilly As temperatures drop back to average to slightly below average For the time of year.  Then the heat heads right back up for later Friday into next week, as High pressure starts drift east changing us to more in the way of a southern flow.

It still looks like the region should be mostly dry for Monday and Tuesday. Our next chance for more in the way of widespread rain showers won't be until late Tuesday or Wednesday of next week. I really don't expect any rain for the northern Middle Atlantic But I can't completely rule it out.  Depending on what's going on with Imelda Maryland and Delaware possibly Southern New Jersey could see some rain associated with her. But any rain should be widely scattered. Southeast Massachusetts The Cape and Off-shore Islands could also see a little bit of rain for late Tuesday into Wednesday, This will have more to do with ocean effect rather than Imelda.

Tropical Storm Imelda and Hurricane Humberto

Image credit Tomer Burg

Humberto is still a major category 4 hurricane with maximum sustained winds of  145 mph, minimum central pressure of 940MB, currently tracking northwest at 13 mph. As he moves into cooler waters He should start to gradually weaken over the next couple of days

Imelda has maximum sustained winds of 60 mph, minimum central pressure of 988 MB tracking north at 9 mph. Imelda Is slowly enveloping over the Bahamas. The satellite image show she looks fairly impressive. As she is taking advantage of that marginally favorable environment.

We do have that weakening upper level low sitting over the Southeast US, As Imelda continues to organize and push further north.

That stalled front along the east coast Is going to protect the United States from both of these Systems. Keeping the majority of their impact out over the ocean. Humberto will be passing a few hundred miles west of Bermuda Later Tuesday and Wednesday This will keep most of his impacts out over the ocean but gusty winds and two to perhaps four inches of rain will be possible for the island. 

Imelda is gonna stay well off the southeast coast most of her wind impact an excessive rain issues out over the ocean. Gusty winds of 35-40 mph will still be possible with winds of 20-30 mph north of that along the coast. A few days ago the Carolinas looked to be going to have an issue with excessive rain The possibility of a lot of flooding But with Imelda staying so far-off shore before she gets yanked east, the flooding brisk is no longer an issue. So that is very good news for the Southeast US.

The trough to the north is going to exert influence on Humberto and pull him north and then northeast. At the same time with that weakened upper level low Humberto is going to latch on to Imelda and forced her to follow him. The East Coast's good news is not such good news for Bermuda, Over the next day or so Imelda is going to strengthen into a hurricane. This will make her the 9th named storm with three of those being hurricanes so far for the season. Imelda Looks to make a close pass or make a direct impact on Bermuda later Wednesday and Thursday likely as a category 1 hurricane but possibly a category 2

Image credit Tomer Burg

While the East Coast has no direct impact from these systems. High surf and dangerous rip currents will still be an issue along the coast.

09/28/2025

 This post will be a little longer than my typical Sunday update, due to the amount of what's going on. But you don't have to read the entire thing you can cherry pick what you want to know about.

A quick look at this week's weather...

Surface charts and radar

We have that week cold front dropping down through the region Most of the right region is dry but there are a few very isolated showers. Behind this cold front We are going to see Canadian high pressure drop down into the region for the entire week. Providing the vast majority of the region with dry Conditions and above average temperatures. The question is going to be What happens in the tropics.

Right now future Imelda Looks to keep the bulk of her moisture Over the southeast and south of our region. But it is possible A bit of this precipitation gets into the middle Atlantic region And Wednesday. I do think the Canadian high pressure will keep it south of the region but I can't completely rule that out so I'm gonna throw in the chance for a few rain showers for Maryland and Delaware.

This dry spell looks to last into maybe Mid-Next week When we will have a  stronger cold front come through that will bring a better chance for widespread rain showers.

The tropics...

Humberto:

Hurricanes Hurricanes Hurricanes Have a hard time maintaining category 5 strength For very long Umberto is now a strong category 4 hurricane with 150 mph maximum sustained winds, A minimum central pressure of 934 MB , tracking west northwest at 13 mph. This weakening is due to an eyewall replacement cycle earlier this morning.

Image credit tropical tidbits

We do have the Bermuda high In the Atlantic, Humberto is going to be working on this and most likely will weaken its influence on the steering pattern. This will have implications On TD9 down the road. Humberto still looks to pass a couple hundred miles west of Bermuda. But he looks to bring tropical storm force conditions to the island.

Image credit Tomer burg

Tropical depression 9

TD9 should become Imelda at some point today.

Currently TD9 has maximum sustained winds of 35 mph, a central pressure Of 1002MB Tracking north at 7 mph.

Future Imelda still looks to slow down and stall  north of the Bahamas. We have to trough We have the trough over the southeast that is going to try to hook TD9 and pull it towards the Carolina coast. Then we have the Bermuda high That is going to try to pull TD9 north. This will allow a roadway for TD9 to follow toward the southeast coast.

Image credit tropical tidbits

But because Humberto has weakened the Bermuda high and being as strong as he is, he is going to override the influence of the southeast ridge. So as he pulls to the north, his influence on the steering pattern is going to try and nudge TD9 south, with the net result of stalling TD9  east of the Florida Coast. Why off Florida?  TD9 taking longer to develop than I anticipated and the faster forward pace of Humerto, has TD9 Just south of Humberto's circulation, Preventing TD9 from coming further West and north.  Then  later Tuesday into Wednesday Humberto will pull  TD9 sharply to the east away from the Coast.

Image credit Tomer Burg

Because of the influences will stay Further south and east then she looked yesterday. As a result rain totals are down along the coast. Central east Florida can expect gusty winds From future Imelda, There are tropical storm watches up along parts of the Florida coast in case tropical force conditions make it that far to the west. The east coast of Florida will likely be dealing with some rain locally heavy rain will be possible.

As the rain Plume moisture hits that stalled front over the southeast, moderate  to heavy tropical rainfall will be over far north eastern Georgia and the eastern Carolina's.  general rainfall amounts for these areas look to be 3-6 inches.

 Due to future Imelda, South of the Chesapeake bay and along the southeast coast High surf and rip currents will pose a danger. Some Coastal flooding at high tide is possible. Because of Humberto, north of there along the  Middle Atlantic will also be dealing with higher than average surf and  rip currents. So be careful going into the water.

Humberto  will bring  Bermuda some impacts We will have to see if future Imelda does as well.

A little bit of this and that...

The Atlantic basin has become active since my last post the accumulated cyclone energy index has made great improvement.

Because of Humberto reaching category 5 and future Imelda the ACE index could reach 93-100 by the end of September. That is right around average for this point in the season which means We have seen a huge upward adjustment from the last post I did on the ACE index. My hurricane outlook I posted early this year might not be in as much jeopardy as I thought it might be. We will see

A quick look at the upcoming winter pattern

Siberian snowfall so far this September is notable due to its unusually heavy accumulations and large extent. This could have large implications for our weather here for winter 2025-2026. As I said in the last upcoming winter post; the increase in snowfall is a result of increased atmospheric moisture. With the larger snow extent increased earlier cold across Alaska into northern Canada is likely, with a better chance for more cold fronts bringing in more colder air into our region early on. 

There is a correlation between Siberian snow extent and the strength of the polar Jet. The more snow we see in Siberia the greater the chance for a weaker northern jet, leading to a much better chance of disrupting the polar vortex allowing for colder and snowier conditions for the northern and eastern United States including the Northeast and Middle Atlantic region, As the weakened polar jet Polar vortex allows colder air to penetrate further into our region. It can also create a disruption in the winter pattern leading to a chance for severe winter storms.

It looks like we're off to a fairly decent start we'll see if the pattern continues

The tag team Humberto and Imelda

 In yesterday's post I laid out the scenario as to how things looked to unfold based on my understanding  of the general pattern and how elements in that setup could adjust the pattern further. Today the pattern has evolved with the interaction between these elements. 

Humberto is now a category 4 Hurricane with maximum sustained winds of 145 miles Per hour and a minimum central pressure of 938MB. Conditions are such that further  Intensification is very possible allowing him to become a borderline  category 5 or a category 5. He is tracking west northwest at 8 mph. Humberto Is the 8th named storm of the season and the 3rd major hurricane so far this season.

Currently his hurricane force winds extend 30 miles from his center with tropical storm force winds extending 105 miles from his center. He is going to stay away from the East Coast and looks to pass just west of Bermuda.  This makes tropical force conditions maybe even hurricane force conditions possible for the island.

Image credit Tomer Burg

But in spite of his relatively small size He is very powerful And is disrupting the circulation pattern in this part of the Atlantic. The Northeast Caribbean islands, The Bahamas and the East Coast of the United States can expect dangerous surf and  deadly rip currents. Due to his proximity to the still unnamed storm to his west, He will exert a steering influence on that disturbance.

Potential tropical cyclone #9

Image credit Tomer Burg

I-94L became designated PTC #9 yesterday evening.  This will likely become a tropical depression later today as it heads for the Bahamas. Given the warm waters around the Bahamas, the lowering wind shear and generally supportive upper level conditions. PTC 9 will likely become Imelda over the Bahamas later today or by early tomorrow.

Over the last several days I've been talking about the interaction between these two features. Yesterday I said Humberto's strength and position would have a lot to say about future Imelda's track.  Because Humberto quickly strengthened into a powerful category 4. He is exerting enough influence that he could cause PTC 9 to stall just off the Carolina Coast before pulling it out to sea. I  also talked about that possibility yesterday. Most of the models are now supporting that idea today.

Image credit Tropical tidbits.

The NHC has also adjusted its tracking cone, to show this approaching close to the Carolina coast before sharply being tugged back out to sea. The question  is will she continue to follow Humberto out to sea  or try to be left behind and wander around the western Atlantic.

If PTC  9 doesn't make an official landfall and instead stalls just off the Coast, for a day or so. She could bring 5-10 inches of flooding rain to the Coastal Plain of the Carolinas back into Georgia and up into virginia. If this occurs It would limit rainfall for western parts of the Carolinas to 3 to 6 inches of rain, which is a much better scenario for the mountainous terrain of North Carolina. But while the landfall scenario is lower today It doesn't mean that it can't happen.

The WPC rainfall QPF amount are based on how close to the coast the current national hurricane center track forecast for PTC 9 indicate. So of course If she gets closer to the coast or is further east than the track indicates these rainfall amounts will adjust accordingly.

That's about all I can cover at this time.  I will likely do another tropical post tomorrow at some point.

Will the southeast coast Take a hit?

 

During yesterday's  drought condition post. I said the Madden Julian Oscillation (MJO) is going to be favorable. This could lead to more tropical activity as we move further through the second half of the season. I wanted to go into little more detail on what it is and why it's important.

Basically The MJO is a wave that moves west to east across the equatorial tropics.

The MJO has a strong impact on tropical activity in many areas across the tropical oceans. It's a big  factor in precipitation patterns, variations in sea surface temperature, low level winds, vertical wind shear, variations in atmospheric temperature and humidity levels. All major factors when it comes to tropical cyclone development.

A very basic overview Of the MJO.

There are 8 phases in the MJO.  The MJO originates in the Indian ocean then it travels east across the pacific. When the MJO gets into the far eastern pacific heading towards the Gulf of America, It Disrupts the pattern  and causes lower height leading to general lower pressures to develop. As the wave propagates eastward across the Atlantic these conditions continue to follow it. This ends up causing precipitation resulting in storms. If  there's enough energy these storms can develop a spin and we can see a tropical cyclone develop. Generally when the MJO is in phases 1,2 and sometimes into 3. It creates conditions that are favorable for tropical cyclone development in the Atlantic basin.

Humberto:

He looks very healthy on satellite. But he is still dealing with a little bit of wind shear, But that is going to continue to  lessen

Humberto underwent rapid intensification and now has maximum sustained winds Of 90 mph, with a minimum central pressure of 979MB. Because he sees 94L he is slowing down and currently is moving northwest at around 5 mph .

Image credit Tomer Burg

Humberto has been dealing with wind shear of 25-30 knot, But that is relaxing. So, Humberto will likely become a major hurricane over the weekend.  If that occurs, all three hurricanes that have formed so far this season, will also have become major Hurricanes. 

Because of I94L the western extent of Humberto's track is limited. The center of circulation between the two systems will anchor him off the coast and force him to pivot and the move north and east away from the East Coast. Right now Humberto looks to pass west of Bermuda. It is possible he could pass close enough to bring tropical storm conditions to the island.

Invest 94L:

The National Hurricane Center is giving this 2 day development odds of 90%

94L has been dealing with the mountainous terrain of Haiti and eastern Cuba. Therefore it looks rather messy at the moment.  But today it will be pulling away from all that and head towards the Bahamas. On the satellite 94L's convection is looking much better than it was yesterday

Image credit Tomer Burg

The sea surface temperatures (SST) In the northeast Caribbean and around the Bahamas are 85-86° Fahrenheit. Wind Sheer has also been a moderate 25-30 knot.

Image credit tropical tidbits.

Image credit university of Wisconsin.

Over the weekend the wind shear is going to relax and the upper level pattern will begin to become favorable for the development of I94L. Given the conditions 94L will likely become Tropical Storm Imelda over the weekend.

We have low pressure in the Tennessee valley,  along with that trough near the Southeast. We also have that high pressure out over the Atlantic. All of these create a flow that would normally allow I-94L to approach from the south and east and make a landfall on the Carolinas. Humberto Is also going to help steer I94L towards the coast. Due to it helping to pump the ridge to the east of I94L. This will act as a block keeping or at least delaying 94L from trying to slip out to sea.

Image credit Tomer Burg

The overall setup keeps I94L  away from the coast of Florida as this churns north and west. If 94L approaches the Coast, wind shear will be increasing closer to the coast But it will be out of the south and west.  The water is going to be warm and the wind shear coming from this direction could allow a storm approaching from the south and east a chance for even more intensification. So it's very possible the Southeast coast could have an approaching hurricane. As 94L gets closer to the coast it will be dealing with dry air. This should keep it from rapidly intensifying over the warm waters of the Gulf stream. So the most likely scenario would have a strong tropical storm or a category 1 hurricane making landfall Monday into Tuesday.

Normally a setup like this with the overall steering current would be a slam dunk for this to plow into the Carolinas. But that's not the case this time. The fly in the ointment is going to be Humberto. Depending on his strength and location It's possible he could influence the circulation pattern enough to slow I-94L and stall or turn it to the north and northeast and out to sea. 

Right now Based on the setup I see I think the odds of a landfall on the Carolinas is 75%-80% with the odds of this staying just off the Coast and going out to sea 20%-25%.

Any landfall would likely be between the Georgia/South Carolina border and the Outer Banks of North Carolina.

As I said in the earlier weather update. The Northeast and northern Middle Atlantic are going to be protected by the northern stream. Regardless of a landfall, the flow is going to limit the northern extent of 94L's track forcing it to to recurve out to sea, or forcing it to sit over the interior southeast where it would weaken and dissipate.

Regardless of this becoming a hurricane or not, This scenario is not good news for the Southeast. If I-94L makes a landfall 6-14  inches of rain is a likely bet. This will be especially tough for the mountainous terrain of the western Carolinas. The worst case scenario I94L ends up sitting and spinning for awhile. Right now rainfall amounts don't look to be as bad as Irene was. So that's at least a sliver of good news.

Gabrielle brought significant wind and wave action to the Azores. She will continue to move towards Portugal. This is likely my last post dealing with Gabrielle