Leslie headed towards Bermuda; Tropical Storm Michael forms

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

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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

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Member Since: Posts: Comments:
1086. LargoFl
THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...SOUTHERN
DELAWARE...NORTHEAST MARYLAND...CENTRAL NEW JERSEY...NORTHERN NEW
JERSEY...NORTHWEST NEW JERSEY...SOUTHERN NEW JERSEY...EAST CENTRAL
PENNSYLVANIA AND NORTHEAST PENNSYLVANIA.

.DAY ONE...TODAY AND TONIGHT.

LOCALIZED HEAVY RAINFALL AND FLOODING IS POSSIBLE.
Member Since: August 6, 2011 Posts: 4 Comments: 40960
1085. 7544
Quoting Neapolitan:
90L's winds are up 5 knots, and pressure is down another millibar:

AL, 90, 2012090512, , BEST, 0, 307N, 864W, 25, 1010, LO, 0, , 0, 0, 0, 0, 1013, 100, 60, 0, 0,


intresting and once its gets in the water im looking for a td soon ?
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...and Michael still listed at 45 knots, with no change in pressure from the previous update:

AL, 13, 2012090512, , BEST, 0, 282N, 436W, 45, 1005, TS, 34, NEQ, 50, 30, 20, 30, 1016, 140, 20, 0, 0, L, 0, , 0, 0, MICHAEL, M,
Member Since: November 8, 2009 Posts: 4 Comments: 13604
1083. LargoFl
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE WILMINGTON NC
516 AM EDT WED SEP 5 2012

AMZ250-252-254-256-060930-
SURF CITY TO CAPE FEAR NC OUT 20 NM-
CAPE FEAR NC TO LITTLE RIVER INLET SC OUT 20 NM-
LITTLE RIVER INLET TO MURRELLS INLET SC OUT 20 NM-
MURRELLS INLET TO SOUTH SANTEE RIVER SC OUT 20 NM-
516 AM EDT WED SEP 5 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT.

LONG PERIOD SWELLS FROM TROPICAL STORM LESLIE WILL CAUSE BREAKING
WAVES IN PLACES WHICH MAY NORMALLY NOT SEE BREAKING WAVES. INLETS
MAY EXPERIENCE STANDING WAVES AND TURBULENCE DURING OUTGOING TIDES.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

LONG PERIOD SWELLS FROM TROPICAL STORM LESLIE (PERHAPS BECOMING
HURRICANE LESLIE) WILL CAUSE BREAKING WAVES IN PLACES WHICH MAY
NORMALLY NOT SEE BREAKING WAVES. INLETS MAY EXPERIENCE STANDING
WAVES AND TURBULENCE DURING OUTGOING TIDES. THESE CONDITIONS WILL
PERSIST THURSDAY THROUGH AT LEAST SUNDAY.
Member Since: August 6, 2011 Posts: 4 Comments: 40960
1082. WxLogic
Quoting Neapolitan:
90L's winds are up 5 knots, and pressure is down another millibar:

AL, 90, 2012090512, , BEST, 0, 307N, 864W, 25, 1010, LO, 0, , 0, 0, 0, 0, 1013, 100, 60, 0, 0,


90L is trying.
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1081. VINNY04
Quoting WxLogic:


Not much (at least from what we can see).
hopefully it will at least bring us some rain and break us from this drought here in florida.
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1080. LargoFl
Quoting Neapolitan:
90L's winds are up 5 knots, and pressure is down another millibar:

AL, 90, 2012090512, , BEST, 0, 307N, 864W, 25, 1010, LO, 0, , 0, 0, 0, 0, 1013, 100, 60, 0, 0,
my guess is TS by the weekend
Member Since: August 6, 2011 Posts: 4 Comments: 40960


Michael's getting bigger and spiky hedgehog looking, which is a good sign.
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1078. SLU
Quoting CybrTeddy:


They might even make it a hurricane if new data comes in supporting such.
CI# /Pressure/ Vmax
4.3 / 980.9mb/ 72.2kt

T3.5/3.5

A reasonable blend of the two would be 3.9, which is 74mph.


... and Michael is at 3.0.

05/1145 UTC 28.0N 43.5W T3.0/3.0 MICHAEL -- Atlantic

Safe to say that if all things remain equal, this could be the 3rd straight season with 19+ named storms.
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1077. WxLogic
Quoting VINNY04:
Thanks. dont look like much potential out there.


Not much (at least from what we can see).
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1076. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 40960
90L's winds are up 5 knots, and pressure is down another millibar:

AL, 90, 2012090512, , BEST, 0, 307N, 864W, 25, 1010, LO, 0, , 0, 0, 0, 0, 1013, 100, 60, 0, 0,
Member Since: November 8, 2009 Posts: 4 Comments: 13604
1074. LargoFl
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
ALABAMA...SOUTHWEST ALABAMA...NORTHWEST FLORIDA AND SOUTHEAST
MISSISSIPPI.

.DAY ONE...TODAY AND TONIGHT

NUMEROUS SHOWERS AND THUNDERSTORMS...MOSTLY OVER LOWER PORTIONS OF
FORECAST AREA...WILL MOVE SOUTH TOWARDS THE COAST AND OFFSHORE THROUGH
EARLY TONIGHT. PERIODS OF HEAVY RAIN COULD GIVE WAY TO MORE FLASH
FLOODING MOSTLY OVER COASTAL SECTIONS OF ALABAMA AND MOST AREAS OF
NORTHWEST FLORIDA THROUGH EARLY TONIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A MODERATE TO STRONG COLD FRONT WILL MOVE ACROSS THE FORECAST AREA LATE
SATURDAY THROUGH EARLY SUNDAY. SHOWERS AND THUNDERSTORMS ARE EXPECTED
AHEAD AND ALONG THE FRONT. A FEW STRONG TO POSSIBLY SEVERE THUNDERSTORMS
WILL BE POSSIBLE AHEAD AND ALONG THE FRONT...MOSTLY SATURDAY AND
SATURDAY NIGHT.
Member Since: August 6, 2011 Posts: 4 Comments: 40960
Quoting VR46L:


Have a good day at school

THE WATER IN THE WESTERN GULF IS ROCKET FUEL !!!

But not in the North East !!

Thank God!
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Quoting SLU:


No surprise. Leslie's got a well defined eye now.


They might even make it a hurricane if new data comes in supporting such.
CI# /Pressure/ Vmax
4.3 / 980.9mb/ 72.2kt

T3.5/3.5

A reasonable blend of the two would be 3.9, which is 74mph.
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1071. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 40960
1070. SLU
Quoting SLU:


No surprise. Leslie's got a well defined eye now.


Mike's not to far from being a hurricane either ....
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Leslie is starting to take advantage of the better conditions all ready.
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1068. SLU
Quoting Neapolitan:
ATCF has Leslie back to 60 knots again, while pressure is down to 990mb for the first time:

AL, 12, 2012090512, , BEST, 0, 256N, 628W, 60, 990, TS, 50, NEQ, 60, 50, 20, 40, 1013, 250, 40, 0, 0,


No surprise. Leslie's got a well defined eye now.
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1067. VINNY04
Quoting WxLogic:


See Post 1043 (above).
Thanks. dont look like much potential out there.
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1066. WxLogic
Quoting VINNY04:
Any one got a picture of the gulf temps right now?


See Post 1043 (above).
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Judge (mom) is sending me to prison(school) as well gotta role
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1064. VINNY04
Any one got a picture of the gulf temps right now?
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I got to go to school/prison just as Leslie and Michael are getting better. Will be interesting to see what they look like when I get home, bye.
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1061. VR46L
Quoting TropicalAnalystwx13:
Invest 90L is going to be over Isaac's cool spot in the Gulf of Mexico as it emerges. Don't expect this to become anything more than a minimal tropical storm before making landfall in Florida.

And on that note, I'm off to prison..I mean school.



Have a good day at school

THE WATER IN THE WEST OF THE GULF IS ROCKET FUEL !!!

But not in the North East of the Gulf !!
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Quoting Neapolitan:
AL, 12, 2012090512, , BEST, 0, 256N, 628W, 60, 990, TS, 50, NEQ, 60, 50, 20, 40, 1013, 250, 40, 0, 0,

Not surpirsed as Leslie is finally looking better.

Quoting weatherh98:


I'm going there too.... Prison these days.

I know right, they do some crazy stuff these days.

Quoting CybrTeddy:
Looks like we might be in store for another CV storm in a few days. 00z UKMET.

06z GFS.

00z CMC.


If you are unsure of the next names on the list are Nadine, Oscar, Patty, Rafael, Sandy, Tony, Valerie, and William.

Assuming that Leslie does become a major hurricane, Michael becomes a hurricane, 90L develops into Nadine, and we get Oscar all by 5 days, I will be impressed. That's a lot of assumption, but certainly possible.

I think it is very possible for that to happen and we still got the other half of the season to go.

One more thing this is my 3000th comment!
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Quoting Neapolitan:
AL, 12, 2012090512, , BEST, 0, 256N, 628W, 60, 990, TS, 50, NEQ, 60, 50, 20, 40, 1013, 250, 40, 0, 0,


If anyone here is new to these.

AL = Atlantic.
12 = Leslie.
201290512 = current date.
BEST = best track.
256N, 628W = current location.
60 = current maximum sustained winds (in knots), would be 70mph.
990 = minimum pressure (down 4mb)
TS = tropical Storm.
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Here's my Daily Briefing video blog for Wednesday Link
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1057. yqt1001
This is Michael btw.





Generally these small storms pull some form of rapid intensification once the eyewall forms.
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Quoting TropicalAnalystwx13:
Invest 90L is going to be over Isaac's cool spot in the Gulf of Mexico as it emerges. Don't expect this to become anything more than a minimal tropical storm before making landfall in Florida.

And on that note, I'm off to prison..I mean school.



I'm going there too.... Prison these days.
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ATCF has Leslie back to 60 knots again, while pressure is down to 990mb for the first time:

AL, 12, 2012090512, , BEST, 0, 256N, 628W, 60, 990, TS, 50, NEQ, 60, 50, 20, 40, 1013, 250, 40, 0, 0,
Member Since: November 8, 2009 Posts: 4 Comments: 13604
1054. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 40960
Quoting allancalderini:
As Nadine if it gets name.


Oh thank God
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Member Since: Posts: Comments:
Leslie not looking bad. Organizing as shear appears to be finally dropping.

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Quoting TropicalAnalystwx13:
Invest 90L is going to be over Isaac's cool spot in the Gulf of Mexico as it emerges. Don't expect this to become anything more than a minimal tropical storm before making landfall in Florida.

And on that note, I'm off to prison..I mean school.


I don't think anything more than a weak TS from 90L as well. Good luck in prison, I mean school.
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Looks like we might be in store for another CV storm in a few days. 00z UKMET.

06z GFS.

00z CMC.


If you are unsure of the next names on the list are Nadine, Oscar, Patty, Rafael, Sandy, Tony, Valerie, and William.

Assuming that Leslie does become a major hurricane, Michael becomes a hurricane, 90L develops into Nadine, and we get Oscar all by 5 days, I will be impressed. That's a lot of assumption, but certainly possible.
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1048. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 40960
1047. yqt1001
Quoting washingtonian115:
If we get 6 this month that'll leave us with only two on the list.The models do show a active September.


Could you imagine how crazy it would be if we (unlikely) got Alpha this year? 2010 and 2011 had a better shot, being that both were neutral/la nina. Yet this year is pulling some kind of crazy El Nino madness.
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1046. LargoFl
ok got the model track......
Member Since: August 6, 2011 Posts: 4 Comments: 40960
Quoting weatherh98:




Isaac is coming back
As Nadine if it gets name.
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90l..steal.energy.from.leslie...
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Invest 90L is going to be over Isaac's cool spot in the Gulf of Mexico as it emerges. Don't expect this to become anything more than a minimal tropical storm before making landfall in Florida.

And on that note, I'm off to prison..I mean school.

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1042. LargoFl
CMC....................
Member Since: August 6, 2011 Posts: 4 Comments: 40960
Quoting TropicalAnalystwx13:
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
If we get 6 this month that'll leave us with only two on the list.The models do show a active September.
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Quoting RTSplayer:
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.


Did you look at my post before you posted this? I quickly corrected this and REMOVED YOUR NAME FROM MY POST, it was another member who posted the old NHC advisory from 1992.
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Quoting TropicalAnalystwx13:

It'll be pulled northeast towards Florida in a few days.




Isaac is coming back
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Quoting LargoFl:
boy we have to watch this one closely, does it still look like Tampa bound?


It would need unlikely RI to be of any worry. Debby was a much worse situation as it stalled as a TS for days. This blob will be ejected NE before long.
Member Since: May 31, 2007 Posts: 0 Comments: 1208
1037. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 40960

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

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