TS/Hurricane Leslie

M.T. Cranium

Leslie began life as T.D. 12 and became the second-earliest twelfth named storm on 29 August (Luis, 1995, was a day earlier). Since then, Leslie has become a large but relatively disorganized tropical storm moving gradually northwest past the Virgin Islands. Current guidance suggests a period of stronger shear that may make it difficult for Leslie to maintain current 55 knot sustained winds, but then an interval of more favourable conditions as it slowly drifts N (slightly NNW) towards a point that in about seven days may be quite close to Bermuda (the model consensus says 100-200 miles east but this could change). At this point the storm could be a cat-1 to cat-3 hurricane depending on how much it can intensify.

By about 11-12 September Leslie will be accelerating northeast past Newfoundland and this morning's GFS run has the outcome of a very strong extratropical storm making a direct hit on Ireland on Friday, 14 Sep (288h panel). Since exact verification of 12-day GFS forecast maps is unusual, this is only a vague indication of any severe weather to come from Leslie, but something that we will have to monitor if the track does take this evolution.

Changes in the past two or three model runs (only GFS goes beyond 10 days) have brought Leslie across the Atlantic both a little earlier and further south. A few days ago we were being shown 15-16 day maps of extratropical Leslie near Iceland on Sunday 16th. Now it would be closer to the Gulf of Bothnia at that time.

Iancar29

ANd here is its remnants right out in FI effecting the West Coast... shall be interesting to watch it unfold!




Plus... Whats THIS!?


Hurricane for the Med?!

Su Campu

Yes ESTOFEX mentioned about a med hurricane in this morning's forecast

maquiladora

Long way to go with Leslie. I don't have much faith in the models for her at the moment. An awful lot can change with a tropical system, especially one encountering high shear and forecast to slow down to a crawl in an area of weak steering.

maquiladora

Haha, 12Z ECM develops Leslie into a huge extratropical system in FI.

Sponge Bob

V_Moth

maquiladora wrote: »

Haha, 12Z ECM develops Leslie into a huge extratropical system in FI.

Its... hypnotic. ALL GLORY TO THE HYPNOWEATHERCHART!

Iancar29

maquiladora wrote: »

Haha, 12Z ECM develops Leslie into a huge extratropical system in FI.

maquiladora

Iancar29 wrote: »

Well the 12Z GFS had it down to 958 in Donegal Bay. Pure FI of course.



It was just the huge expansion in size on the ECM that I thought was funny.

Iancar29

maquiladora wrote: »

Well the 12Z GFS had it down to 958 in Donegal Bay. Pure FI of course.



It was just the huge expansion in size on the ECM that I thought was funny.

:rolleyes:

Sponge Bob

Sponge Bob

Deep Easterly

Slow weather day. :cool:

maquiladora

Thread derailed.

I hope Ian won't be too disappointed when we just end up with a wet day with a breeze instead of a hurricane in 10 days time. :pac:

Bermuda on the other hand, could be facing a hurricane, if Leslie manages to strengthen like the models show.

catch.23

If the storm were to maintain Hurricane/TS strength winds, would it still be classified as such or as post-tropical/random depression?

M.T. Cranium

Probably, the NHC classifies on the basis of storm organization rather than maximum wind speeds. Once the tight core, eye feature and lack of frontal patterns that are indicative of a tropical cyclone are dispersed, the storm would become extra-tropical no matter how strong, although in marginal cases they would probably hold on for public safety reasons. By modern naming standards, Debbie (Sep 1961) would probably have been extra-tropical after passing 48N and before reaching Ireland.

However, the more important point is how strong the winds might be in whatever type of storm exists at the time where it passes Ireland.

The 18z GFS was also quite intense although somewhat later, passing Donegal around Saturday 15th. This is only an indication of potential until we get to about 144-168 hours and the major models still showing an intense storm near Ireland. Then it would start to become a real forecast issue instead of a "what if" discussion. Nobody should be too surprised if this entirely disappears from model runs later today or tomorrow, then comes back later, etc. It is a bit ominous seeing that much agreement between ECM and GFS on such a development in 10 days.

Worth keeping in mind also that the new moon occurs on the night of 15-16 Sep (03z 16th) and almost perigeean. So any region impacted by strong winds 14th to 16th would have storm surge issues.

maquiladora

Models for Leslie. UKMO taking it pretty far west.

maquiladora

Bermuda directly under the gun with the new official track. Huge cone of error though.

maquiladora

12Z ECM goes crazy with Leslie.

916 mb west of Bermuda.

cherryghost

Getting close to the 892 hurricane record, and not far off Hurricane Katrina's 902.

maquiladora

cherryghost wrote: »

Getting close to the 892 hurricane record, and not far off Hurricane Katrina's 902.

I think the ECM just went a bit bananas with it to be honest. I'm pretty sure there's never been a Cat 5 hurricane that far north in the Atlantic in recorded history.

It's crazy that it gets Leslie down to 917 at just 120 hours and not way off in FI. But no other model is close to that in intensity, so I'm not buying it. I'm sure there will be a climbdown on the 0Z.

Sponge Bob

Still forecast by the ECM as a large and mean ( but by then fast moving) system with a 955 low in its centre as it barrels between Iceland and Scotland next week. I'd watch out for a visit by the new TS/Hurricane Michael before then once the models start to get a handle on it.

maquiladora

0Z ECM still wants to make Leslie into a very strong hurricane.

928mb center, the type of pressure you'd see typically see in an extremely dangerous Cat 4, less than 200 miles off the coast of Rhode Island.



0Z GFS, a close call for the Canadian Maritimes.

Sponge Bob

The unusual thing about Leslie is that it could hang about largely static for a week off the Virginias and kick up a severe sea state along the US East Coast without ever making land. It has been a large system for some time now and with TS winds out to 200 miles from the centre.

Certain 06z runs place it further west ...making landfall in Nova Scotia or Newfoundland perhaps on Mon or Tue of next week.

maquiladora

Majority of 0Z GFS ensembles go for some kind of Canadian landfall.



5 or 6 days out though, a lot can change.

maquiladora

US East Coast is pretty safe now. Looking like a Canada landfall though.




Edit : We don't have a thread of Hurricane Michael (no threat to land) but he is now a Cat 3, the first major hurricane of the season. And the NHC has this interesting piece of trivia :

WITH MICHAEL BECOMING THE SEVENTH HURRICANE OF THE SEASON EARLIER
TODAY...IT MARKS THE THIRD EARLIEST FORMATION OF THE SEVENTH
HURRICANE IN A YEAR...ONLY BEHIND 1886 AND 1893.

Redsunset

And here is Michael who won't be rowing any boat ashore.

maquiladora

Models are shifting further east with Leslie now. Good news for Bermuda and if trend continues Leslie could end up missing Canada too.

(shorter tracks are the most recent runs)

Iancar29

Interesting 5 day Track of Leslie and Michael ....
makes me wonder what would happen if 2 hurricanes were to collide? ...
" THE PERFECT STORM " haha :rolleyes:

catch.23

Would the wind shear from the other storm not prevent development of each storm instead of enhancing it?

maquiladora

catch.23 wrote: »

Would the wind shear from the other storm not prevent development of each storm instead of enhancing it?

And for Ian's post above.

http://www.chbcnews.ca/explainer/6442709962/story.html