Leslie headed towards Bermuda; Tropical Storm Michael forms

By: Dr. Jeff Masters , 3:01 PM GMT on September 04, 2012

Share this Blog
41
+

Tropical Storm Leslie continues to suffer from moderately high wind shear of 15 - 20 knots, due to strong upper-level winds out of the northwest. The shear is keeping heavy thunderstorms confined to the southeast quadrant of the storm. Satellite loops show that Leslie has almost no heavy thunderstorm activity near its center, and the storm is crawling north at walking pace, 3 mph. Leslie's slow forward speed means that the storm is staying over the cold water stirred up by the storm's winds, inhibiting intensification. According to the latest SHIPS model forecast, the shear is expected to stay moderately high through Tuesday night, then drop to the low category, 5 - 10 knots, by Thursday afternoon. At that time, Leslie will be over warm ocean waters of 29 - 30°C, and the reduction in shear and warm waters should aid intensification. However, Leslie's motion will continue to be slow, keeping the storm over its cool water wake, and keeping any intensification slow. Once Leslie begins moving more quickly on Saturday, this effect will diminish, and Leslie could be at Category 2 strength on Sunday morning, as indicated in the official NHC forecast. Steering currents for Leslie are expected to be weak through Friday, as Leslie is stuck between two upper level lows. The latest guidance from our top computer models continues to show Leslie making a very close pass by Bermuda on Saturday. Leslie is a huge storm, and tropical storm-force winds are expected to extend outward from its center 250 miles by Friday. Bermuda is likely to see a 48-hour period of tropical storm-force winds beginning Friday night that lasts until Sunday night. The official NHC forecast shows Leslie nearly making a direct hit on Bermuda, but the uncertainty in 4-day NHC forecasts is around 200 miles. Thus, the latest 11 am EDT NHC wind probability forecast calls for just a 12% chance of hurricane force winds on Bermuda on Saturday. Nevertheless, Leslie is capable of bringing an extended period of hurricane-force winds lasting six or more hours to Bermuda Saturday night through Sunday morning, should a direct hit materialize.


Figure 1. Morning satellite image of Tropical Storm Leslie. The low-level circulation center has very little in the way of heavy thunderstorms surrounding it, thanks to strong northwest winds creating 15 - 20 knots of wind shear.

Leslie will stay stuck in a weak steering current environment until a strong trough of low pressure approaches the U.S. East Coast on Saturday. This trough should be strong enough to pull Leslie quickly to the north on Saturday and Sunday, and Leslie may be close enough to the coast that the storm will make landfall in Nova Scotia or Newfoundland, Canada on Monday, September 10. None of the reliable models have shown that a direct hit on New England will occur, but we can't rule that possibility out yet. The storm may also miss land entirely, and brush by the coasts of Nova Scotia and Newfoundland. Large swells from Leslie reached Cape Hatteras, North Carolina last night, and will begin pounding the entire Eastern Seaboard today through Sunday. These waves will be capable of causing significant beach erosion and dangerous rip currents. The Hurricane Hunters are scheduled to make their first flight into Leslie on Wednesday afternoon.


Figure 2. Morning satellite image of Tropical Storm Michael.

Tropical Storm Michael forms in the Central Atlantic
Tropical Storm Michael has formed in the Central Atlantic on Monday, but is not destined for fame. Satellite loops show that this is a very small tropical cyclone, and the storm is well away from any land areas. Michael is under moderately high shear of 15 - 20 knots, and this shear is forecast to remain at 15 - 20 knots through Wednesday. Since Michael is such a small storm, just a modest increase in shear could destroy it. But if Michael survives until Thursday, when shear is expected to fall to the low range, it has the opportunity to strengthen.

Michaels's formation on September 4 puts 2012 in third place for earliest formation date of the season's thirteenth storm. The record is held jointly by 2005, which had Hurricane Maria form on September 2, and 2011, which had Tropical Storm Lee form on September 2 (there was an unnamed tropical storm that year before Lee.) None of the models show that Michael will threaten any land areas. Michael is a classic example of the type of storm that likely would have been missed before the advent of satellites, since the storm is small, far from land, and may be short-lived.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1037 - 987

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26Blog Index

1037. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 42261
2012 Atlantic hurricane season naming list

ALBERTO (TS)
BERYL (TS)
CHRIS (C1)
DEBBY (TS)
ERNESTO (C1)
FLORENCE (TS)
GORDON (C2)
HELENE (TS)
ISAAC (C1)
JOYCE (TS)
KIRK (C2)

LESLIE (TS) - Active
MICHAEL (TS) - Active
NADINE
OSCAR
PATTY
RAFAEL
SANDY
TONY
VALERIE
WILLIAM
Member Since: July 6, 2010 Posts: 113 Comments: 32855
Loggerhead sea turtle nest destroyed by storm surge on the SW FL coast. Close-up in water video clip:
Youtube Link
Member Since: Posts: Comments:
1034. 7544
Quoting wxchaser97:

Its part of Isaac and some other energy, would get a new name.


looks like a new name but will always be issac to us lol after all its still hes remains next up nadine lol
Member Since: Posts: Comments:
1033. LargoFl
rainfall model...........................looks like tampa at the end
Member Since: August 6, 2011 Posts: 4 Comments: 42261
Quoting 7544:


so now its going to go ssw not toward fla hmm maybe texas now

It'll be pulled northeast towards Florida in a few days.
Member Since: July 6, 2010 Posts: 113 Comments: 32855
1031. LargoFl
Quoting 7544:


ok isee now its going to be in the gulf longer now moving ssw then the trof comes by and scoops it e ene hmmm how strong could it get sitting in the bath waters before making the turn interesting
yes we really need to watch this one, i sure hope it does not follow debby's path
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1029. 7544
Quoting VR46L:
90L now 20% ... Formerly known as Isaac

In Rainbow


ok isee now its going to be in the gulf longer now moving ssw then the trof comes by and scoops it e ene hmmm how strong could it get sitting in the bath waters before making the turn interesting
Member Since: Posts: Comments:
1028. LargoFl
Quoting mfcmom:
We are already getting pounded again in Panama City and PCB. Five inches of rain, the roads in Bay and Walton Counties are flooded and this "Ghost of Isaac" is not looking like a good thing> Not again.
yes its really dumping lots of rain for sure,maybe into the weekend gee
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1026. LargoFl
Nam has it in the mid gulf for a few days......
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1025. mfcmom
We are already getting pounded again in Panama City and PCB. Five inches of rain, the roads in Bay and Walton Counties are flooded and this "Ghost of Isaac" is not looking like a good thing> Not again.
Member Since: Posts: Comments:
We had terrible storms in Mobile last night, and now I see where they came from. GO AWAY 90L!
Member Since: Posts: Comments:
Quoting VR46L:
90L now 20% ... Formerly known as Isaac

In Rainbow

Its part of Isaac and some other energy, would get a new name.
Member Since: Posts: Comments:
1022. VR46L
90L now 20% ... Formerly known as Isaac

In Rainbow
Member Since: Posts: Comments:
Quoting LargoFl:
ok ty

You're welcome, hopefully 90L doesn't come your way.
Member Since: Posts: Comments:
1020. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 42261
Quoting aislinnpaps:
So they think ex-Isaac will drift west towards Tampa? The people in south Louisiana do not need to see any form of Isaac again.


West would be towards La/Tx wouldn't it? Tampa is East of this blob.
Member Since: Posts: Comments:
1018. LargoFl
Quoting 7544:


so now its going to go ssw not toward fla hmm maybe texas now
they could use the rains im sure
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1017. 7544
Quoting TropicalAnalystwx13:

A LOW PRESSURE SYSTEM LOCATED ALONG THE COAST OF THE WESTERN FLORIDA
PANHANDLE WILL MOVE SOUTHWARD INTO THE NORTH-CENTRAL GULF OF MEXICO
LATER TODAY. ENVIRONMENTAL CONDITIONS ARE MARGINALLY CONDUCIVE FOR
SOME GRADUAL DEVELOPMENT OF THIS DISTURBANCE AS IT MOVES SOUTHWARD
TO SOUTH-SOUTHWESTWARD AT 5 TO 10 MPH OVER THE NEXT FEW DAYS. THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.


so now its going to go ssw not toward fla hmm maybe texas now
Member Since: Posts: Comments:
Quoting TomballTXPride:

Yes! I'm under a slight risk of severe weather today.
Member Since: Posts: Comments:
1015. LargoFl
Quoting wxchaser97:

90L does have to be watched for tropical development and Tampa could still get whatever 90L develops into.
ok ty
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1014. VR46L
Quoting TomballTXPride:

Still being sheared very heavily from the west.


..and she still has half her clothes missing ....




Member Since: Posts: Comments:
1013. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 42261
Quoting LargoFl:
boy we have to watch this one closely, does it still look like Tampa bound?

90L does have to be watched for tropical development and Tampa could still get whatever 90L develops into.
Member Since: Posts: Comments:
1011. LargoFl
Quoting TomballTXPride:
alot of storm warnings up there this morning too
Member Since: August 6, 2011 Posts: 4 Comments: 42261
Quoting WxLogic:


Typically when I tend to give a time for an update of some sort I tend to be a bit too conservative and it ends up happening earlier. :)

Well today is a new day and you timed it perfectly.
Member Since: Posts: Comments:
1007. LargoFl
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
622 AM CDT WED SEP 5 2012

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* FLASH FLOOD WARNING FOR...
SOUTH CENTRAL JACKSON COUNTY IN SOUTHERN MISSISSIPPI...
THIS INCLUDES THE CITY OF OCEAN SPRINGS...

* UNTIL 745 AM CDT

* AT 619 AM CDT...THE PUBLIC REPORTED FLASH FLOODING FROM A
THUNDERSTORM NEAR GULF PARK ESTATES...OR NEAR OCEAN SPRINGS...
MOVING SOUTHWEST AT 5 MPH.

* THE STORM PRODUCING FLASH FLOODING WILL MAINLY IMPACT OCEAN
SPRINGS AND GULF PARK ESTATES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE IN THE
WARNED AREA. RADAR ESTIMATES THAT NEAR 6 INCHES OF RAIN HAS ALREADY
FALLEN.

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1006. WxLogic
Quoting wxchaser97:

You got it right, 20%.


Typically when I tend to give a time for an update of some sort I tend to be a bit too conservative and it ends up happening earlier. :)
Member Since: Posts: Comments:
How does the GFS consistently get the best track even though it always has the worst pressure initialization? It's often off by 8 to 12 millibars!

The whole point of this steering map was that pressure was supposedly dictating steering.




So how does it get the right result when it's pressure initialization is off by one, sometimes two mean steering layers?!
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Michael is also spinning out in the Atlantic with 50mph winds and a 1005mb pressure.
Member Since: Posts: Comments:
1002. LargoFl
Quoting wxchaser97:

You got it right, 20%.
boy we have to watch this one closely, does it still look like Tampa bound?
Member Since: August 6, 2011 Posts: 4 Comments: 42261
1001. WxLogic
Quoting TropicalAnalystwx13:

A LOW PRESSURE SYSTEM LOCATED ALONG THE COAST OF THE WESTERN FLORIDA
PANHANDLE WILL MOVE SOUTHWARD INTO THE NORTH-CENTRAL GULF OF MEXICO
LATER TODAY. ENVIRONMENTAL CONDITIONS ARE MARGINALLY CONDUCIVE FOR
SOME GRADUAL DEVELOPMENT OF THIS DISTURBANCE AS IT MOVES SOUTHWARD
TO SOUTH-SOUTHWESTWARD AT 5 TO 10 MPH OVER THE NEXT FEW DAYS. THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.


Nice... :)
Member Since: Posts: Comments:
Model approach Intensity for Bermuda

Model raw / adjusted

00z GFDL 960mb / 957mb
00z HWRF 946mb / 950mb
06z GFS 972mb / 962mb
00z Euro 936mb / 934mb*

avg raw: 954mb
avg adj: 951mb

* reconstructed for off by half a frame in time.

Without Euro:

avg raw: 959mb
avg adj: 956mb
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting WxLogic:
Given on what I'm seeing... decent low level convergence and divergence (aloft). I would bump it up to a 20% by 8AM:




You got it right, 20%.
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
Leslie actually looks healthy this morning. Watching the loops from last night, it briefly showed its eye.





At least is trying.
Member Since: Posts: Comments:
Good morning everyone, I see we have 90L, Leslie actually looking pretty good right now, and Michael has grown some.
Member Since: Posts: Comments:
Post 990:

Nadine would be furious to be mistaken as a boy


Post 993:
Expect slow intensification for Leslie, until the MLC is completely aligned with the LLC. Once they do, RI is possible as the pressure is already quite low.

Member Since: Posts: Comments:
Quoting WxLogic:
Given on what I'm seeing... decent low level convergence and divergence (aloft). I would bump it up to a 20% by 8AM:




A LOW PRESSURE SYSTEM LOCATED ALONG THE COAST OF THE WESTERN FLORIDA
PANHANDLE WILL MOVE SOUTHWARD INTO THE NORTH-CENTRAL GULF OF MEXICO
LATER TODAY. ENVIRONMENTAL CONDITIONS ARE MARGINALLY CONDUCIVE FOR
SOME GRADUAL DEVELOPMENT OF THIS DISTURBANCE AS IT MOVES SOUTHWARD
TO SOUTH-SOUTHWESTWARD AT 5 TO 10 MPH OVER THE NEXT FEW DAYS. THIS
SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.
Member Since: July 6, 2010 Posts: 113 Comments: 32855
Leslie actually looks healthy this morning. Watching the loops from last night, it briefly showed its eye.



Member Since: July 6, 2010 Posts: 113 Comments: 32855
Miami NWS Disco

A little bit of this and a little bit of that...

LONG TERM...SATURDAY THROUGH TUESDAY
THE LOW PRESSURE AREA...FROM THE REMNANTS OF ISAAC THAT HAS HOVERED
OVER THE N CENTRAL GULF OF MEX THE PAST FEW DAYS...SLOWLY MOVES EAST
NORTHEAST AND ACROSS N FLA THIS WEEKEND AS SW WINDS AHEAD OF A COLD
FRONT MOVING INTO THE SE U.S. INCREASE. THIS INCREASES PRECIPITABLE
WATER OVER THE S FLA EARLY NEXT WEEK AND A BETTER CHANCE OF RAIN.
BUT AT THIS POINT...WILL FOLLOW GUIDANCE. LONG RANGE MODELS INDICATE
THAT THE ABOVE MENTIONED COLD FRONT WILL POSSIBLY MOVE THROUGH S FLA
NEXT TUESDAY DRYING S FLA OUT SOME AND REDUCING THE CHANCE OF RAIN.
Member Since: Posts: Comments:
Quoting leftlink:



140mph, or 121.7 kts was the number provided by RTSplayer. You are right it was erronous, but unfortunately the NHC did not bother to update its archive material with any disclaimer: http://www.nhc.noaa.gov/archive/storm_wallets/atla ntic/atl1992/andrew/public/pal0492.033



Liar?


I've never used either of those numbers, 140mph or 121kts, in the past 3 days.

I don't know who you're quoting, but it isn't me, unless you're quoting me quoting someone else.



I used 165mph for all of my Andrew landfall calculations, and made that absolutely clear repeatedly.

I used 175mph for all of my Andrew over-water calculations, and also made that perfectly clear.

You can even go back to the previous blog where this whole thing started.

Quit lying about me or anything I said or did.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Son of Isaac (90L) returning to the scene of the crime:

Member Since: Posts: Comments:
Given on what I'm seeing... decent low level convergence and divergence (aloft). I would bump it up to a 20% by 8AM:



Member Since: Posts: Comments:
none.90l.to.texas.or.mex
Member Since: Posts: Comments:
Member Since: Posts: Comments:

Viewing: 1037 - 987

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
38 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron