Weather Chat Megathread

[ProtoJeb21]

According to Tropical Tidbits, both Miriam and Norman are Category 1 hurricanes with 75 mph winds. Typhoon Jebi is also quickly intensifying and is now a Category 2 equalivent storm with winds of 105 mph. 

[SaturnianBlue]

@ProtoJeb21  This is the first site I can find for wind shear in the EPAC, the site also has wind shear maps for other basins.

As for Norman, that's likely. Currently the ECMWF and GFS both have it passing to the north completely, but since that's still 9 days out, there is a high chance of the forecast changing. The EPAC has been tremendously active this year, it has already exceeded the average Accumulated Cyclone Energy in a given year, with half the season to go!

The NHC has upgraded the tropical wave to a 70% chance of formation in 5 days. Cabo Verde is in the path of the storm, should it form fairly early (which seems likely), but it does seem like the storm will remain out to sea, for the time being. The EPAC has an area of its own, which is forecasted to curve north, but in the long range might turn south, and possibly follow Norman.

Edited August 30, 2018 by SaturnianBlue

[ProtoJeb21]

11 hours ago, SaturnianBlue said:

As for Norman, that's likely. Currently the ECMWF and GFS both have it passing to the north completely, but since that's still 9 days out, there is a high chance of the forecast changing. The EPAC has been tremendously active this year, it has already exceeded the average Accumulated Cyclone Energy in a given year, with half the season to go!

Speaking of Norman, it appears to be undergoing very rapid intensification. Over the last six hours it’s gone from an 85 mph Category 1 to a 115 mph Category 3 hurricane (the fifth major hurricane of the season already!). Norman has developed the signature compact, symmetrical, circular shape of rapidly intensifying East Pacific storms like 2016’s Lester, which Norman may end up being like in terms of intensity and track. 

At this time in 2016 — one of the most active EPac seasons overall — it was also at 15 named storms like this year, with the 16th named storm (Newton) less than a week away. This also appears to be the same case for this season. Comparing 2018 so far to 2017 and 2016, it looks like this could end up being a well above average season with 20-22 total named storms, ten or more total hurricanes, and maybe another major hurricane or two (>6 total). Already this year’s ACE is, as you said, well above average, and it’s also 50% higher then all of last year’s ACE!

12 hours ago, SaturnianBlue said:

The NHC has upgraded the tropical wave to a 70% chance of formation in 5 days. Cabo Verde is in the path of the storm, should it form fairly early (which seems likely), but it does seem like the storm will remain out to sea, for the time being. The EPAC has an area of its own, which is forecasted to curve north, but in the long range might turn south, and possibly follow Norman.

Now the wave is up to 80% in the next 48 hours, and if the GFS models are correct, it will become Tropical Depression 6 or Tropical Storm Florence by tomorrow. The NHC has noted that tropical storm watches or warnings may need to be issued for the Cape Verde islands soon, which will be quite a rare occurrence if I’m correct. The East Pacific area of interest is also now more likely to develop, with a 70% chance of development over the next five days. 

[ProtoJeb21]

Hurricane Norman has explosively intensified into a 145 mph Category 4 hurricane, and the lastest NHC forecast cone has it reaching winds of 155 mph. The rate that this storm has intensified is incredible — 85 mph to 145 mph in just nine and a half hours! If this continues, Norman may become the second Category 5 hurricane of the year. 

Mewnwhile, Typhoon Jebi has also become a Category 4, with winds of 130 mph. It too has a shot of becoming a Category 5 and also appears to be undergoing rapid intensification. 

[SaturnianBlue]

@ProtoJeb21 If we ignore the outliers of Major Hurricane Ekeka and Tropical Storm Hali that formed very early in the 1992 season, the 2018 season is on par with the most active EPac season ever, and just one storm behind the second most active, 2015. Additionally, August 2018 has broken the record for the most active (in terms of ACE) month, exceeding September 1992.

Here is the latest loop of Hurricane Norman's rapid intensification, courtesy of Tropical Tidbits:

Edited August 30, 2018 by SaturnianBlue

[ProtoJeb21]

9 minutes ago, SaturnianBlue said:

@ProtoJeb21 If we ignore the outliers of Major Hurricane Ekeka and Tropical Storm Hali that formed very early in the 1992 season, the 2018 season is on par with the most active EPac season ever, and just one storm behind the second most active, 2015. Additionally, August 2018 has broken the record for the most active (in terms of ACE) month, exceeding September 1992.

Here is the latest loop of Hurricane Norman's rapid intensification, courtesy of Tropical Tidbits:

I hope this won’t end up like 1992, because remember what happened in the Atlantic during that year? The activity of the Atlantic often depends on the activity of the East Pacific, and if this EPac season is like 1992, then the Atlantic could be similar to that year as well. Thankfully, it’s not guaranteed. Hopefully there’s no devastating Atlantic hurricane this year like in 1992 or 2017.

[ProtoJeb21]

@SaturnianBlue The tropical wave has now been designated Potential Tropical Cyclone Six and tropical storm warnings are now up for the Cape Verde islands. It is forecast to become at least a Category 1 hurricane. Hurricane Norman in the Pacific now has winds of 150 mph and is expected to become the second Category 5 of the season by the next NHC advisory. 

[ProtoJeb21]

After some of the fastest intensification I’ve ever seen, Hurricane Norman has halted and kept its intensity of 150 mph/937 mbar. It still could become a Category 5, but I’m thinking it might be getting ready for an eyewall replacement cycle. Meanwhile, Super Typhoon Jebi has exploded into a Category 5 with winds of 160 mph and a central pressure of 925 mbar. It’s expected to intensify even more, and is forecast to reach winds of 180 mph by tonight. 

[ProtoJeb21]

@SaturnianBlue where’s the wind shear map you mentioned? I need to check to see if that’s what’s causing Norman to weaken (although its connective structure appears to be improving over the last few hours).

[SaturnianBlue]

1 minute ago, ProtoJeb21 said:

@SaturnianBlue where’s the wind shear map you mentioned? I need to check to see if that’s what’s causing Norman to weaken (although its connective structure appears to be improving over the last few hours).

This should be the link. The NHC reports that Norman's weakening was the result of an EWRC. 

Miriam has managed to intensify, despite being under 40 knots of wind shear.

Tropical Tidbits reports that PTC 6 is a Tropical Depression—we will find out momentarily with the next advisory if this is officially the case.

[ProtoJeb21]

2 hours ago, SaturnianBlue said:

This should be the link. The NHC reports that Norman's weakening was the result of an EWRC. 

Miriam has managed to intensify, despite being under 40 knots of wind shear.

Tropical Tidbits reports that PTC 6 is a Tropical Depression—we will find out momentarily with the next advisory if this is officially the case.

Tropical Tidbits is right, PTC 6 is now a Depression. 

I’m wondering about two things right now: why is Norman weakening so much from just an EWRC while in a very favorable environment, and how is Miriam even still alive?

[SaturnianBlue]

4 hours ago, ProtoJeb21 said:

Tropical Tidbits is right, PTC 6 is now a Depression. 

I’m wondering about two things right now: why is Norman weakening so much from just an EWRC while in a very favorable environment, and how is Miriam even still alive?

The newest NHC advisory says that Norman is getting sheared, interestingly enough. Hurricane Lane managed to hold fairly well against heavy wind shear, but I don't know if what happened there applies to Miriam.

Tropical Depression 17-E has formed, and Tropical Depression 6 will probably become Florence tomorrow.

Earlier today, I read a tweet mentioning that what was formerly Lane has become what appears pretty clearly like a subtropical cyclone. Interestingly enough, the CPHC is directed not to issue public advisories for subtropical storms (as written in this directive here).

[ProtoJeb21]

10 hours ago, SaturnianBlue said:

The newest NHC advisory says that Norman is getting sheared, interestingly enough. Hurricane Lane managed to hold fairly well against heavy wind shear, but I don't know if what happened there applies to Miriam.

So a strong Category 4 hurricane gets completely wrecked by <20 kt shear, but a Category 1 hurricane is able to strengthen in 40-50 kt shear.

....I have no comments on that. 

10 hours ago, SaturnianBlue said:

Tropical Depression 17-E has formed, and Tropical Depression 6 will probably become Florence tomorrow.

It looks like 17-E will also become a hurricane. The current NHC forecast cone has it reaching Category 2 intensity, but it’s  in an even more favorable environment than Norman when it exploded into a Category 4. I think it’s safe to say that 17-E will also end up being much stronger than expected. 

 

Meanwhile in the West Pacific, Super Typhoon Jebi peaked yesterday with 175 mph winds and...well, the JMA says it had a pressure of 915 mbar, but Tropical Tidbits said it bottomed out at 910 mbar. Either way, it became the strongest storm this year in terms of wind speed. Over the last 12 hours, though, it’s weakened to a 155 mph Category 4 and has maintained that intensity for about six hours. On satellite imagery, it looks like Jebi is undergoing an EWRC, so it’s possible that it could strengthen briefly again today before encountering less favorable conditions as it accelerates towards Japan. 

[ProtoJeb21]

On 8/31/2018 at 11:01 PM, SaturnianBlue said:

Earlier today, I read a tweet mentioning that what was formerly Lane has become what appears pretty clearly like a subtropical cyclone. Interestingly enough, the CPHC is directed not to issue public advisories for subtropical storms (as written in this directive here).

It looks like the CPHC is tracking it now, as Invest 96C has been designated, and from the looks of it, it is Subtropical Storm Lane. 

 

Both Typhoon Jebi and Hurricane Norman have finished their eyewall replacement cycles, but the two storms have very different futures from this point on. Jebi has weakened to a high-end Category 3, and because of its current path, it will be unable to restrengthen at all. Norman, on the other hand, like is strengthening again. Its convective structure has greatly improved, becoming more symmetrical with a tighter ring of strong thunderstorms. While the eye hasn’t entirely cleared out yet, it should within the next six hours, and I expect Norman to regain major hurricane status sometime later today. 

Also Tropical Depression 17-E is now Tropical Storm Olivia. Unlike Norman, it looks like it will be slow to develop into anything major. For now, Norman will remain the system to watch in the Pacific (considering how Miriam is basically nonexistent right now).

In the Atlantic, that tropical wave heading towards the Gulf is getting more likely to develop. The NHC gives it a 50% chance during the next two days, and an 80% chance during the next five days. I still don’t think it’ll become anything major due to land interaction — even if the European models suggest otherwise — but if it becomes a tropical storm, it will get the name Gordon (which really should’ve been retired after the destruction caused by Hurricane Gordon in Haiti back on the 90’s).

 

UPDATE: Tropical Tidbits now says that Norman is back to Category 4 intensity with winds of 130 mph and a central pressure of 948 mbar. 

...that was quick. 

Edited September 2, 2018 by ProtoJeb21

[ProtoJeb21]

Hurricane Norman intensifying from a Category 2 to a Category 4 hurricane, with winds increasing from 105 mph to 130 mph over a 6-hour time frame.

https://imgur.com/a/BDf15Nu

[ProtoJeb21]

Potential Tropical Cyclone 7 has been designated near the Bahamas and Florida, and is expected to develop into a tropical depression or storm between later tonight and early tomorrow. Labor Day sure is going to be fun for the people in south Florida  

PTC-7 will be nothing more than a rainy inconvenience until it gets into the Gulf of Mexico. It will have about 1.5-1.75 days to intensify in VERY warm waters around 29-30 degrees Celsius. Wind shear will also be favorable or, at the very least, tolerable. The current NHC forecast predicts this becoming a storm tropical storm with winds of 60-65 mph before making landfall in Louisiana, but it could become stronger, especially if it develops a surface low quicker. Tropical Storm Watches are already up for the Gulf coasts of Louisiana, Mississippi, and Alabama. Thankfully, this is going to be a much faster storm than Harvey, so people shouldn’t have to worry about massive flooding like last year. 

Tropical Storm Florence weakened slightly today, but thanks to a recent burst of convection it may get a little stronger by the next NHC advisory. While it won’t be a threat to anybody now, some models — including the CMC and ECMWF — are now suggesting it could track further south and impact the US East Coast or Bermuda. Since such a scenario is at least a week out, these predictions shouldn’t be taken with full certainty yet. At least one other tropical cyclone is expected to form behind Florence next week and the week after, with various models having various solutions. Some say a singe tropical storm will form, others say a depression and a hurricane, and a few say three or four tropical storms and hurricanes. 

In the East Pacific, Hurricane Norman continues to improve on satellite imagery, and may be strengthening even more. The eye is just about fully cleared now with a ring of powerful thunderstorms surrounding it. Norman will have no more then 2 days left to intensify before it encounters the same wind shear that (finally) tore Hurricane Miriam apart today. Speaking of wind shear, Tropical Storm Olivia is right next to some 15-20 knot shear, and most of its convection is displaced from its center of circulation. As it moves further north over the next day or so, it will enter very favorable conditions to rapidly intensify like Norman did when it first formed. 

[Just Jim]

32 minutes ago, ProtoJeb21 said:

Potential Tropical Cyclone 7 has been designated near the Bahamas and Florida, and is expected to develop into a tropical depression or storm between later tonight and early tomorrow. Labor Day sure is going to be fun for the people in south Florida  

Actually it's been raining pretty much every afternoon for the last couple weeks here, so this isn't going to make that much difference for us... I hope.

I just pray Louisiana is OK, that's where our local weather is projecting it to hit land sometime Wednesday:

http://www.baynews9.com/fl/tampa/weather/tropical

Edited September 3, 2018 by Just Jim

[ProtoJeb21]

2 minutes ago, Just Jim said:

Actually it's been raining pretty much every afternoon for the last couple weeks here, so this isn't going to make that much difference for us... I hope.

I just pray Louisiana is OK, that's where our local weather is projecting it to hit land sometime Wednesday:

http://www.baynews9.com/fl/tampa/weather/tropical

It shouldn’t be too bad. Land interaction is likely to keep this from getting too strong, and it’s speed will make sure it won’t drop tremendous amounts of rainfall.

Off topic: you’re part of the Squad staff now?

[Just Jim]

30 minutes ago, ProtoJeb21 said:

It shouldn’t be too bad. Land interaction is likely to keep this from getting too strong, and it’s speed will make sure it won’t drop tremendous amounts of rainfall.

Off topic: you’re part of the Squad staff now?

Yeah, it became official a month ago, right in the middle of the summer rainy season.... to bring it back on topic... lol  

 I hope this one doesn't get too bad... What worries me is it's already so hot and wet here, and the gulf is quite literally a sauna... There's a lot of energy just waiting to get sucked up into a storm. I hope it doesn't stall, or it could get really big, really fast,.

Edited September 3, 2018 by Just Jim

[ProtoJeb21]

20 minutes ago, Just Jim said:

I hope this one doesn't get too bad... What worries me is it's already so hot and wet here, and the gulf is quite literally a sauna... There's a lot of energy just waiting to get sucked up into a storm. I hope it doesn't stall, or it could get really big, really fast,.

Thankfully, as I mentioned before, this system is going to be moving rather quickly. It’s wedged inside a trough that’s moving east into the Gulf, taking PTC-7 along with it as the same pace. Once the trough breaks apart, the system will be steered in the same direction by the high pressure system that’s been creating some great weather here in New England. So no matter what, this thing is going to be moving too fast to explode into something like Harvey. 

[ProtoJeb21]

PTC-7 has become Tropical Storm Gordon just a few miles south of the southern tip of Florida, and already it’s slightly stronger than anticipated, with winds of 45 mph. As of now it’s still expected to peak as a 60-65 mph tropical storm, but I’m starting to have my doubts. It’s entirely possible Gordon can become a Category 1 hurricane thanks to the unstable, moist air and high SSTs of the Gulf. 

In the East Pacific, Hurricane Norman has started feeling the effects of less favorable conditions the closer it gets to Hawaii. Its eye has collapsed and its thunderstorm activity is starting to diminish as it drops to low Category 3 status. Tropical Storm Olivia is having a better day — convection is finally starting to wrap around the entire center of circulation, and according to Tropical Tidbits it has just intensified into a 60 mph storm. Relatively rapid intensification may be starting soon.

We’re now entering a new phase of activity in the Pacific and Atlantic hurricane seasons, where activity between the basins flips due to the Madden-Julian Oscilation (I hope I got the name right). For the next month/month and a half, conditions in the Atlantic will become more favorable as thunderstorm activity begins to diminish in the East Pacific. The MJO for the last two-ish months has been responsible for enabling storms like Hector and Lane to pop up, and now it’s moving over to the Atlantic. Olivia is likely to be the last major system in the EPac before a decrease in activity. Meanwhile, the MJO will help the various tropical waves coming off of Africa to gain some steam and potentially develop into multiple tropical cyclones over the next few weeks. Whether or not they ever impact land has yet to be seen. 

[SaturnianBlue]

Here is the view from the Key West NWS radar (as of 13:33 EDT).

Tropical Storm Gordon appears to be forming an eyewall. While it isn't speeding along like Hurricane Nate, it is a good thing the storm is moving fairly quickly at 16 MPH—it would otherwise spend a disturbing amount of time over very warm water at a slower speed.

Edited September 3, 2018 by SaturnianBlue

[ProtoJeb21]

46 minutes ago, SaturnianBlue said:

Here is the view from the Key West NWS radar (as of 13:33 EDT).

Tropical Storm Gordon appears to be forming an eyewall. While it isn't speeding along like Hurricane Nate, it is a good thing the storm is moving fairly quickly at 16 MPH—it would otherwise spend a disturbing amount of time over very warm water at a slower speed.

It may not been spending a whole lot of time over warm water, but it is organizing at a very disturbing pace. If this trend continues it likely will become a hurricane by tomorrow.

Some posts from the Tropical Tidbits twitter that highlight the rapid organization and potential intensification of Gordon: 

https://mobile.twitter.com/TropicalTidbits/status/1036667641409228800?ref_src=twsrc^google|twcamp^serp|twgr^tweet

https://mobile.twitter.com/TropicalTidbits/status/1036670711664992257?ref_src=twsrc^google|twcamp^serp|twgr^tweet

https://mobile.twitter.com/TropicalTidbits/status/1036674648904294400?ref_src=twsrc^google|twcamp^serp|twgr^tweet

I know I’ve been saying that Gordon isn’t going to be anything major...but now, with each new update, I’m starting to fear that I will be wrong. 

[SaturnianBlue]

@ProtoJeb21  The apparent eyeball has collapsed for the time being.

[ProtoJeb21]

2 hours ago, SaturnianBlue said:

@ProtoJeb21  The apparent eyeball has collapsed for the time being.

That’s not too surprising. Gordon is still pretty close to land, and that, along with its tiny size, means that it’s sensitive to interference. 

The meteorologists at The Weather Channel are saying that there’s at least a decent possibility of Gordon rapidly intensifying due to its small size and the extremely favorable conditions in the Gulf of Mexico. I’m starting to think that may end up being the case — or, Gordon becomes at least a Category 1 hurricane, like the NHC says. 

Edited September 3, 2018 by ProtoJeb21