Disorganized Leslie headed towards Bermuda

By: Dr. Jeff Masters , 4:18 PM GMT on September 03, 2012

Tropical Storm Leslie continues to struggle with 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. These thunderstorms are as far removed from the center as we've so far with Leslie, as seen on satellite loops. 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 Wednesday night. At that time, Leslie will be over warm ocean waters of 29°C, and the reduction in shear and warm waters should allow Leslie to intensify into at least a Category 1 hurricane by Friday, as predicted by most of the intensity forecast models. Intensification to a stronger storm may be hampered by its slow motion, which will cause Leslie to churn up cool water from the depths that will slow intensification. Once Leslie begins moving more quickly on Saturday, this effect will diminish, and Leslie could be at Category 2 strength on Saturday, as predicted by the HWRF and LGEM models. Steering currents for Leslie are expected to be weak on Tuesday - Friday, as Leslie gets stuck between two upper level lows. The latest guidance from our top computer continues to show Leslie making a very close pass by Bermuda on Saturday, and that island can expect a 3-day period of rough weather Friday through Sunday. 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 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 most likely long-term fate of Leslie will be for it to miss land entirely and brush by the coasts of Nova Scotia and Newfoundland, but any forecast of what a tropical cyclone might do a full seven days in advance is pretty speculative. Regardless, Leslie will bring an extended period of high waves to Bermuda, the U.S. East Coast, and Nova Scotia and Newfoundland this week. These waves will be capable of causing significant beach erosion and dangerous rip currents.


Figure 1. Morning satellite image of Tropical Storm Leslie. The low-level circulation center is fully exposed to view, thanks to strong northwest winds creating 15 - 20 knots of wind shear.

Invest 99L in the Central Atlantic
A small extratropical low pressure system that got cut off from the jet stream and is now spinning away in the Central Atlantic, near 26°N 42°W, (Invest 99L), is headed west at 10 mph, and has developed a small amount of heavy thunderstorm activity. This storm is not a threat to any land areas, and in their 8 am EDT Tropical Weather Outlook on Monday, NHC gave 99L a 30% chance of developing into a tropical cyclone by Wednesday morning.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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Looks like September will continue to be active per the GFS. 120 hrs out, tropical wave emerges and becomes "Michael" while Leslie approaches major hurricane status, this was also on the 06z and 00z runs.


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Quoting washingtonian115:
I see flat troughing.Of course things will change as we get closer in time.


Just tell me it's not heading west. My hiatus on hurricanes worked with Isaac, sending him north and not over me like was possible, but it was a close miss with many around here losing electric with the winds we did get. I don't want to test it again this year.
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Quoting GTcooliebai:
GFS 300 hrs.

I see flat troughing.Of course things will change as we get closer in time.
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GFS 300 hrs.

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General consensus is a Category 2 hurricane in 120 hours.

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Close huh....177 hours GFS
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Leslie's cone looks like an isometric of a morbidly obese dunce cap.
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ROPICAL STORM LESLIE DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
1100 AM AST MON SEP 03 2012

LESLIE CONTINUES TO BE AFFECTED BY ABOUT 15 KT OF NORTHWESTERLY
SHEAR...ACCORDING TO ANALYSIS FROM UW-CIMSS. THIS SHEAR HAS CAUSED
THE CONVECTIVE PATTERN TO BE QUITE ASYMMETRIC WITH NEARLY ALL OF
THE COLD CLOUD TOPS CONFINED TO THE SOUTHEASTERN PORTION OF THE
CIRCULATION. THERE HAS BEEN LITTLE CHANGE IN THE DVORAK
CLASSIFICATIONS THIS CYCLE...SO THE INITIAL INTENSITY IS HELD AT 50
KT. THE SHIPS MODEL SHOWS THE SHEAR INCREASING A LITTLE OVER THE
NEXT 24 HOURS...WHICH SHOULD LIMIT THE STORM FROM STRENGTHENING
DURING THAT TIME PERIOD. AFTER THAT...HOWEVER...THE SHEAR IS
EXPECTED TO RELAX AND GIVEN THAT THE OTHER ATMOSPHERIC AND OCEANIC
CONDITIONS APPEAR FAVORABLE...LESLIE WILL LIKELY HAVE AN
OPPORTUNITY TO GAIN STRENGTH. THE OFFICIAL FORECAST IS SIMILAR TO
THE PREVIOUS ONE AND BASICALLY A BLEND OF THE SHIPS AND LGEM
GUIDANCE.

RECENT MICROWAVE DATA AND VISIBLE SATELLITE IMAGES INDICATE THAT THE
CENTER OF LESLIE WAS LOCATED A LITTLE TO THE WEST OF THE PREVIOUS
TRACK. BLENDING THE MICROWAVE DATA WITH EARLIER SATELLITE FIXES
YIELDS AN INITIAL MOTION ESTIMATE OF 330/7. LESLIE IS CURRENTLY
MOVING TOWARD A DEEP-LAYER TROUGH TO ITS NORTH. THIS TROUGH IS
EXPECTED TO SHIFT TO THE EAST...CAUSING THE STEERING CURRENTS TO
WEAKEN DURING THE NEXT DAY OR SO. THEREFORE...LESLIE IS ONLY
EXPECTED TO DRIFT NORTHWARD DURING THE 24 TO 72 HOUR TIME PERIOD.
LATE IN THE WEEK...THE COMBINED INFLUENCES OF A MID- TO UPPER-LEVEL
LOW OFF THE SOUTHEAST U.S. COAST AND A RIDGE TO THE EAST OF LESLIE
SHOULD CAUSE THE CYCLONE TO MOVE NORTH-NORTHWESTWARD OR NORTHWARD
AT A FASTER PACE. THE OFFICIAL FORECAST IS ADJUSTED ABOUT 30 N MI
TO THE WEST OF THE PREVIOUS TRACK DUE TO THE MORE WESTWARD INITIAL
POSITION.

DUE TO THE LARGE SIZE OF THE CYCLONE AND EXPECTED SLOW MOTION...
LARGE SWELLS PROPAGATING AWAY FROM THE TROPICAL CYCLONE WILL AFFECT
BERMUDA AND NEARLY ALL OF THE U.S. EAST COAST FOR MUCH OF THE WEEK.

FORECAST POSITIONS AND MAX WINDS

INIT 03/1500Z 24.4N 63.1W 50 KT 60 MPH
12H 04/0000Z 25.2N 63.2W 50 KT 60 MPH
24H 04/1200Z 25.8N 63.3W 50 KT 60 MPH
36H 05/0000Z 26.3N 63.4W 55 KT 65 MPH
48H 05/1200Z 26.8N 63.5W 55 KT 65 MPH
72H 06/1200Z 27.7N 63.6W 65 KT 75 MPH
96H 07/1200Z 29.0N 64.0W 75 KT 85 MPH
120H 08/1200Z 31.5N 64.5W 80 KT 90 MPH

$$
Member Since: December 31, 1969 Posts: Comments:
Quoting K8eCane:


HA Press in a dress LOVEIT. He did it for Portlight. Thats a good man


That pic of Presslord in a dress was 1st posted by Presslord several years ago and has been re-posted many times since. I think it had something to do with a fund raiser for PORTLIGHT but I'm a bit hazy on that. Point is, no one was offended and it was never removed, untill today. So a big thankyou goes out to all of the blog cops and Wunder admins for being such killjoys. I speak only for myself.
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FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOBILE, AL
908 AM CDT MON SEP 3 2012


...THE FLOOD WARNING CONTINUES FOR THE FOLLOWING RIVER IN MISSISSIPPI...

LEAF NEAR MCLAIN AFFECTING GEORGE...GREENE AND PERRY COUNTIES.

.RECENT HEAVY RAINS HAVE CAUSED SIGNIFICANT RISES ALONG THE RIVER.

SAFETY MESSAGE...
STAY TUNED TO DEVELOPMENTS BY LISTENING TO NOAA WEATHER RADIO.

&&

MSC039-041-111-041408-
/O.CON.KMOB.FL.W.0030.000000T0000Z-000000T0000Z/
/MCLM6.2.ER.120830T1924Z.120904T0000Z.000000T0000 Z.NO/
908 AM CDT MON SEP 3 2012

THE FLOOD WARNING CONTINUES FOR
THE LEAF NEAR MCLAIN
* UNTIL FURTHER NOTICE
* AT 8AM MONDAY THE STAGE WAS 24.1 FEET
* MODERATE FLOODING IS OCCURRING AND MODERATE FLOODING IS FORECAST
* FLOOD STAGE IS 18 FEET
* THE RIVER WILL CONTINUE RISING TO NEAR 24.2 FEET BY THIS EVENING THEN BEGIN
TO SLOWLY FALL. THE RIVER WILL REMAIN ABOVE FLOOD STAGE FOR SEVERAL DAYS.
* AT 24 FEET...COUNTY ROADS IMPASSIBLE BY HIGH WATER.
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Doc, if Leslie were to veer to Canada and hit there, would she still be a possible Cat 2?
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FLOOD STATEMENT
NATIONAL WEATHER SERVICE MOBILE, AL
928 AM CDT MON SEP 3 2012


...THE FLOOD WARNING CONTINUES FOR THE FOLLOWING RIVER IN MISSISSIPPI...

PASCAGOULA AT MERRILL AFFECTING GEORGE...GREENE AND JACKSON COUNTIES.

.RECENT HEAVY RAINS HAVE CAUSED SIGNIFICANT RISES ALONG THE RIVER.

SAFETY MESSAGE...
STAY TUNED TO DEVELOPMENTS BY LISTENING TO NOAA WEATHER RADIO.

&&

MSC039-041-059-041428-
/O.CON.KMOB.FL.W.0033.000000T0000Z-000000T0000Z/
/MRRM6.2.ER.120831T1221Z.120905T1200Z.000000T0000 Z.NO/
928 AM CDT MON SEP 3 2012

THE FLOOD WARNING CONTINUES FOR
THE PASCAGOULA AT MERRILL
* UNTIL FURTHER NOTICE
* AT 8AM MONDAY THE STAGE WAS 24.7 FEET
* MINOR FLOODING IS OCCURRING AND MODERATE FLOODING IS FORECAST
* FLOOD STAGE IS 22 FEET
* THE RIVER WILL CONTINUE RISING TO NEAR 25 FEET BY WEDNESDAY AFTERNOON THEN
SLOWLY FALL. THE RIVER IS FORECAST TO FALL BELOW FLOOD STAGE ON SATUDAY.
* AT 23 FEET...STREETS AND OLD BUISNESS SECTION OF MERRILL FLOOD.
* AT 24 FEET...BRIDGE INACCESSIBLE BY CAR.

$$
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Thanks, Doc.
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Jeff, any thoughts on the potential ST Cyclone S of Nova Scotia?

Cheers,
Progster
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Leslie is moving at 8mph right now. in 1 day at it's present movement it center will travel 192miles. It's tropical wind field is 205miles, which mean's it will be in the shadow of it's previous 24hr. Wind over water for 24hrs to 36hrs will cause up-welling.

In 5 days the NHC is forecasting Leslie to travel 7°, which equates to 345.55miles (1°
Lat = 69.11miles)



Even the NHC says A TURN
TOWARD THE NORTH AND A SLOWER FORWARD SPEED IS EXPECTED OVER THE
NEXT 48 HOURS. Which would mean Leslie would be going slower than her current 8mph. Which Dr Maters mentions in his blog.

My prediction for Leslie, Strong Tropical Storm or Mid Cat 1 max.
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lets not forget our friends here,still suffering.....
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Leslie die all ready...
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2Sept.06pm's 21.8n61.3w has been re-evaluated&altered to
3Sept.12am's 22.1n61.4w-23.0n61.5w which have been re-evaluated&altered to
3Sept.06am's 22.1n61.4w-22.8n61.6w-23.5n62.0w which have been re-evaluated&altered
3Sept.12pm's 22.1n61.4w-22.8n61.6w-23.5n62.2w - 24.1n62.8w are now the most recent positions
(The previous vectors and straightline projections have been corrected for this mapping)
All times in GMT
Derived from NHC_ATCF data for TropicalStormLeslie at 3Sept.12pm
SVN-Savannah :: 09J-JekyllIsland :: BDA-Bermuda :: RSD-Eleuthera :: PWN-CrookedIsland

The easternmost dot on the longest line is TS.Leslie's most recently reported position

The longest line is a straightline projection through TS.Leslie's 2 most recent positions to it's closest approach to Bermuda
2Sept.12pm: TS.Leslie had been headed for passage over JekyllIsland (top,09Jblob)
2Sept.06pm: TS.Leslie had been headed for passage 178miles(286kilometres)WSWest of Bermuda
3Sept.12am: TS.Leslie had been headed for passage 3.4miles(5.4kilometres)ENEast of Bermuda (right,BDAblob)
3Sept.06am: TS.Leslie had been headed for a passage 253miles(408kilometres)SWest of Bermuda
3Sept.12pm: TS.Leslie was heading for passage 292miles(470kilometres)SWest of Bermuda

Copy&paste pwn-23.101n74.271w, ghb-25.152n76.135w, svn-31.72n81.138w, 09j-30.873n81.418w, 09j-31.1n81.403w, 30.896n67.435w, 32.382n64.592w, 29.898n68.143w, 32.281n64.887w-bda-32.368n64.647w, 20.4n59.4w-21.3n60.9w, 21.3n60.9w- 22.1n61.4w, 22.1n61.4w-22.8n61.6w, 22.8n61.6w-23.5n62.2w, 23.5n62.2w-24.1n62.8w, 23.5n62.2w-29.315n68.4w, 32.281n64.887w-29.315n68.4w into the GreatCircleMapper for a larger map and other information
The previous mapping for comparison
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Thanks Doc.
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ty
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Thanks Doc.

150 hours 12z GFS:

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather