About Jeff Masters
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
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.
Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather
472. superpete
Hi Stormpetrol
I was wondering the same thing until I read todays NHC 2 pm discussion,they mention 'no cyclonic signature associated with the wave, embedded in the monsoon trough' to this effect......
471. beell
It may mingle with the eastern FL ULL at some point.
Current RAP 700mb
And the SPC mentioned a cast-off remnant circulation from Issac earlier this afternoon. It was visible on Atlanta radar for a while. Not much left to it now.
This afternoon's convection is a result of westerly/southwesterly flow around the Isaac-trough and southeasterlies/seabreeze. Confluent/convergent flow.
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT MON SEP 03 2012
...FARTHER NORTH...SEVERAL BANDS OF BROKEN CONVECTION HAVE EVOLVED FROM GA INTO THE CAROLINAS. RADAR DATA SUGGESTS A WEAK MCV MAY BE EMBEDDED OVER NCNTRL GA AND THIS MAY ENCOURAGE UPWARD GROWTH OF BROKEN LINE SEGMENTS DOWNSTREAM AS THIS FEATURE LIFTS NEWD INTO NRN SC...
470. mitthbevnuruodo
I have to admit, I'd be a bit...ok, alot...surprised if Leslie ended up cat5, or even a cat4. I really have a hard time seeing it bomb out THAT much. IMO, it just doesn't look like the conditions are set good enough for all that.
469. ncstorm
this looks like the Atlantic Ocean blew up
468. RTSplayer
Map says sub-880 is possible, but highly, highly unlikely.
It would be incredibly explosive intensification to pull that one off.
467. windshear1993
466. GeoffreyWPB
Tropics are heating up...Interesting to see if the remnants of Isaac make it back to the GOM..
465. GTcooliebai
464. TampaWeatherBuff
Indeed. I doubt the data is quite that high in octane. Methinks that model better lay off the Red Bull for the next run.
463. CybrTeddy
00z.
21z
462. TropicalAnalystwx13
I fixed it, Taz. We get busy trying to update the ACE page, timeline, timeline page, current storm information section, and even articles (when one is warranted). Just bare with us...any mistakes you guys see will be corrected promptly.
461. RTSplayer
Look at that...
The 1004mb pressure extends half way into N. Carolina and Virginia.
Still a category 4 passing New Jersey, with 1008mb (stronger than TD13) pressure still extending into Georgia...
If this verifies, it would like double the year's ACE value in one storm, because this isn't just a "little" cat 5, it's a monster...
460. ncstorm
how close you think this can get to the CONUS from the midatlantic northwards...I dont like the Euro having the center passing west of Bermuda now..
459. wxchaser97
Lets all hope so because if the Euro is right then, bye bye Bermuda.
458. Tazmanian
from wikipedia
what you guys see here
Tropical Depression Thirteen
Current storm information
As of 5 p.m. EDT (2100 UTC) September 2, Tropical Storm Leslie is located within 30 nautical miles of 25.6°N 42.2°W, about 1350 mi (2170 km) WNW of the Cape Verde Islands. Maximum sustained winds are 30 knots (35 mph, 55 km/h), with stronger gusts. Minimum central pressure is 1012 mbar (hPa; 29.88 InHg), and the system is moving northwest at 3 kt (3 mph, 6 km/h)
457. aspectre
Cuz they're cheap. If they hit the beaches during the day, they'd hafta buy sun tan lotion.
456. HurricaneHunterJoe
Any blatant implications from that Most Wise One?
455. stormchaser19
Especially with the European for me is one of the most conservative model in intensity
454. CaicosRetiredSailor
453. windshear1993
452. GTcooliebai
451. Grothar
23.5N 62.0W - 006z
24.1N 62.8W - 012z
23.8N 63.1W - 018z
450. TropicalAnalystwx13
449. WeatherNerdPR
448. stormpetrol
447. Tazmanian
poor New England.
446. RTSplayer
That's peak intensity, not closest approach.
Still, with the 5mb initialization error adjustment that's down to 909mb, potentially.
I have 911mb adjusted intensity for closest approach now on the Euro...
445. stormpetrol
444. CybrTeddy
Good lord though, this is one of those times the Euro can way overbomb intensity forecasts. Brings Leslie all the way down to 914mb approaching New England. That would be nuts.
443. yqt1001
Yeah, you don't see those often, if ever. Especially on the more reliable models.
442. barbamz
Right, Gro. Next week I'll check the situation at the Med personally when I go to Italy for vacation (Toscana). But before that of course I dare to see what will happen with Leslie.
441. KEEPEROFTHEGATE (Mod)
all buildings made of stone cat 4 or greater to destroy stone
440. trHUrrIXC5MMX
what??????
can Leslie go so extremely far??
439. TropicalAnalystwx13
438. RTSplayer
Crap..
What the heck? How did I miss that?
I clearly mis-read the map when I was doing my adjusted intensity forecast.
You gotta be kidding me?!
That has 916mb right on Bermuda, and it needs a -5mb adjustment to account for the bad initialization.
The water temps cleary support it since it's going to be passing over a broad 30C to 31C SST region.
Conditions south of Bermuda easily favor that in terms of water temps and upper atmosphere temps.
Even if you adjusted the potential intensity map UP by 20mb, it would still be well within possibility.
The max wind predictor is 2 color scales above the "borderline/low end cat 5" zone as well.
I don't know what I was doing above, but I need to fix my numbers.
437. wxmod
This stuff doesn't matter. Fact is: Arctic ice VOLUME has been decimated. Your calculations only obscure that fact.
436. trHUrrIXC5MMX
WOW!!!!!!!!!! 917MB!!!!!!!!!!??
HOLLY COW!!!!!!
That's a major Cat 5!!!! I think that model is malfunctioning... lol
Nice Med storm... these are becoming more frequent lately...
It would be cool for an organization to track these storm like our NHC...
435. GTcooliebai
434. Tazmanian
if we get Michael from TD 13
that would mean we get Nadine,Oscar,Patty ,Rafael,Sandy
if i did it right
433. ncstorm
432. Hurricanes101
looks can be deceiving, dont be fooled by the convection
431. wxchaser97
Holy bleep bleep, cat5. That would be crazy, well it is peak season. Bermuda would have a bad time if the Euro came true.
430. WeatherNerdPR
Sorry for sounding like a jerk, it's just the way you wrote it made it look like you still were denying it (read:"sad clump of thunderstorms"). Of course you are entitled to your own opinion, but I still disagree with you on your remark regarding Helene. ;)
Interesting perspective. I guess you could say that tropical cyclones are a tier above other atmospheric disturbances. If that was you were trying to portray, you're right.
Yeah, I wouldn't regard the NHC as infallible (Igor not a Cat 5 grr), but you must recognize that they know more than you. Sometimes your comments make it sound like you have the "NHC is wrong and I'm right" mentality, but I digress.
Good to see that this discussion didn't end with us screaming "POOF!" at each other. :P
429. TropicalAnalystwx13
914 millibars.
428. stormpetrol
427. MahFL
A Cat2 won't do much to Bermuda, they have very strict building codes.
426. HurricaneDean07
Also.
5 Named storms in that image.
425. GTcooliebai
424. HurricaneDean07
917 MB?!
423. Grothar
I was reading up on this earlier. It doesn't seem to be as bad as they thought, but still very strong.
422. stormchaser19
Cat 5