ATL: LESLIE - Post-Tropical - Discussion

[ozonepete]

100% sure we will have less storms in Sept than August? did I hear that right?

Yep, 100% sure. We had 8 form in August. Odds of 8 forming in September are remote.

Btw, wxman, how ya doin' in your office pool?

[Ken711]

BULLETIN
TROPICAL STORM LESLIE ADVISORY NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
1100 PM AST SAT SEP 01 2012

...LESLIE TURNS NORTHWESTWARD WITH LITTLE CHANGE IN STRENGTH...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.2N 58.4W
ABOUT 310 MI...495 KM NE OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM LESLIE WAS
LOCATED NEAR LATITUDE 20.2 NORTH...LONGITUDE 58.4 WEST. LESLIE IS
MOVING TOWARD THE NORTHWEST NEAR 18 MPH...30 KM/H. A GRADUAL TURN
TOWARD THE NORTH-NORTHWEST AND NORTH...ALONG WITH A DECREASE IN
FORWARD SPEED...IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON THE
FORECAST TRACK...THE CENTER OF LESLIE SHOULD MOVE AWAY FROM THE
LEEWARD ISLANDS TONIGHT AND SUNDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 65 MPH...100 KM/H...WITH HIGHER
GUSTS. LESLIE IS CURRENTLY IN AN AREA OF UNFAVORABLE UPPER-LEVEL
WINDS...AND SOME WEAKENING IS POSSIBLE DURING THE NEXT 48 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 160 MILES...260 KM
FROM THE CENTER. NOAA BUOY 41044...LOCATED NORTHWEST OF THE
CENTER...RECENTLY REPORTED 1-MINUTE MEAN WINDS OF 45 MPH...
72 KM/HR...AND A WIND GUST OF 54 MPH...86 KM/HR.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 998 MB...29.47 INCHES.

[floridasun78]

ok turn have started

[floridasun78]

i see models want make LESLIE do loop

[ozonepete]

i see models want make LESLIE do loop

Wouldn't surprise me at all. Looks like shear will eventually drop off a lot and steering winds will become very light. If that happens Leslie could be around a long time.

[EDR1222]

some of us who enjoy tropical weather eagerly look forward to aug/sept. say anything you want, but 2004/05 were 2 years tropical enthuiasts will never forget. and before anyone blasts me, nothing i want or dont want has anything to do with what the weather does, so no guilt trips. in tornado season tornado chasers hope and pray for tornados to chase, but i dont get mad at them. in winter, many people want bitter cold and snow, which can also cause extreme hardship for many, but again, i dont get upset over it. i chase tropical weather the only way i can, over the computer.

back to leslie, looking sick poor girl.

I agree with you completely Rainstorm. Most of us on here are weather enthusiasts and get excited this time of year..........and there is absolutely nothing wrong with that.

Also agree that Leslie is not looking so good this evening.

[ozonepete]

Improving again, at least temporarily...

[cheezyWXguy]

Improving again, at least temporarily...

http://i189.photobucket.com/albums/z174 ... 020545.jpg

yeah, shes been holding some fairly deep convection for sometime now, but it still appears the low level center is pretty significantly displaced.

[ozonepete]

Improving again, at least temporarily...

http://i189.photobucket.com/albums/z174 ... 020545.jpg

yeah, shes been holding some fairly deep convection for sometime now, but it still appears the low level center is pretty significantly displaced.

It's all about the shear. Such a hard thing to forecast, and sometimes we can't even figure out why that shear is there in the first place! Still, it looks like that worst shear zone is moving away to the northwest at nearly the same speed as Leslie does. I think one of the main reasons that this particular storm is surviving the whole nasty environment is its size. It's big enough that it has a pretty big environment of its own (its circulation envelope) and that disrupts the shear before it gets overpowering. Just an educated guess as to why this storm is still going. To see what I mean just watch the rgb or avn tropical satellite loops. This is a pretty big system. If it ever gets into a good environment it could intensify pretty big time, just like Isaac finally did. I mean it may get really beaten up but it can't get killed until it runs into land or cold water.

http://www.ssd.noaa.gov/goes/east/tatl/flash-avn.html

[ozonepete]

Temporarily still getting better...

[expat2carib]

TROPICAL STORM LESLIE ADVISORY NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012
500 AM AST SUN SEP 02 2012

...LESLIE STRENGTHENS SLIGHTLY AS IT CONTINUES TO MOVE NORTHWESTWARD
AWAY FROM THE LEEWARD ISLANDS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...20.8N 59.5W
ABOUT 295 MI...475 KM NNE OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.35 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 AM AST...0900 UTC...THE CENTER OF TROPICAL STORM LESLIE WAS
LOCATED NEAR LATITUDE 20.8 NORTH...LONGITUDE 59.5 WEST. LESLIE IS
MOVING TOWARD THE NORTHWEST NEAR 15 MPH...24 KM/H...AND THIS
GENERAL MOTION IS FORECAST TO CONTINUE TODAY. A GRADUAL TURN TOWARD
THE NORTH-NORTHWEST AND NORTH...ALONG WITH A DECREASE IN FORWARD
SPEED...IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK...THE CENTER OF LESLIE WILL CONTINUE TO MOVE AWAY FROM THE
LEEWARD ISLANDS.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. LESLIE IS CURRENTLY IN AN AREA OF UNFAVORABLE UPPER-LEVEL
WINDS...AND SOME FLUCTUATIONS IN STRENGTH WILL BE POSSIBLE DURING
THE NEXT 48 HOURS.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM
FROM THE CENTER. NOAA BUOY 41044...LOCATED NORTH OF THE CENTER...
HAS BEEN REPORTING 1-MINUTE MEAN WINDS OF 50 MPH...80 KM/HR...WITH
GUSTS TO NEAR 60 MPH...92 KM/HR...OVER THE PAST FEW HOURS.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB...29.35 INCHES.


HAZARDS AFFECTING LAND
----------------------
SURF...SWELLS GENERATED BY LESLIE COULD AFFECT PORTIONS OF THE
LEEWARD ISLANDS THROUGH THE WEEKEND...AND BEGIN TO AFFECT PUERTO
RICO AND THE VIRGIN ISLANDS LATER TODAY. THESE SWELLS COULD
CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE
CONSULT PRODUCTS FROM YOUR LOCAL WEATHER OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 AM AST.

$$
FORECASTER STEWART

[jinftl]

From 5am Discussion:

THE VERTICAL WIND SHEAR AFFECTING LESLIE IS EXPECTED TO BE MODERATE
FOR THE NEXT 24 HOURS OR SO...WHICH SHOULD CAP ANY SIGNIFICANT
INTENSIFICATION. AT 36 AND 48 HOURS...THE SHEAR IS FORECAST TO
INCREASE TO NEAR 30 KT...WHICH IS EXPECTED TO CAUSE THE CYCLONE TO
WEAKEN SOME.

ASSUMING LESLIE SURVIVES THE DAY 2 HOSTILE SHEAR
CONDITIONS...THE UPPER-LEVEL WIND ENVIRONMENT IS FORECAST TO
IMPROVE AND BECOME CONDUCIVE FOR SIGNIFICANT STRENGTHENING TO
OCCUR. THE INTENSITY FORECAST REMAINS ON THE CONSERVATIVE SIDE AT
DAYS 4 AND 5 DUE TO THE UNCERTAINTY IN JUST HOW MUCH LESLIE WILL
WEAKEN OVER THE DAY 2-3 TIME PERIOD.

[cycloneye]

12z Best Track is down to 55kts.

AL, 12, 2012090212, , BEST, 0, 214N, 609W, 55, 997, TS

ftp://ftp.nhc.noaa.gov/atcf/tcweb/inves ... 012.invest

[wxman57]

100% sure we will have less storms in Sept than August? did I hear that right?

Yep, 100% sure. We had 8 form in August. Odds of 8 forming in September are remote.

Btw, wxman, how ya doin' in your office pool?

I think I misunderstood the contest when I picked 9 storms. I thought it was for August, not the whole season.

Prior to the season, all the indicators were there that the Main Development Region (MDR) between Africa and the eastern Caribbean would be quite hostile, and that certainly is true. However, the region wasn't hostile enough for a few struggling tropical storms to briefly develop (Florence/Joyce). Ernesto and Helene struggled for much of their paths, though Ernesto briefly found favorable conditions in the west Caribbean. And then there were the three storms of subtropical origin (Alberto, Beryl and Chris). Clearly, the pre-season predictions of a hostile environment panned out. Everything continues to struggle (Leslie), and the northern latitudes seem more favorable than the tropics, as the longest-lived hurricanes formed out of the tropics (Kirk/Gordon). We now have Invest 99L way up at 28N/37W.

One other thing we (I) predicted was that with the conditions so hostile in the MDR we'd see more near-shore (western Caribbean/Gulf) development/threats. That was true of Ernesto and Isaac. In fact, back in late July when I looked at wet Julys of the past it was clear that there was a significant correlation to wet Julys and hurricane hits in TX/LA in August/September. My prediction was for a hurricane hit in TX or LA over the next 2 months, and that certainly happened (Isaac).

It's just hard to predict subtropical development and weak, short-lived storm numbers. You almost have to add 2-4 to your predictions each season to account for them.

As for Leslie this morning, I find it extremely hard to believe it's a 65-70 mph TS. It doesn't even look like a TS. Without significant organized convection, how is it bringing any stronger winds aloft down to the surface?

[SFLcane]

So wxman what's your take on the rest of the season? You are absolutely correct on Everything being a struggle thus far this season we are yet to see a formidable hurricane across the main development region. Plenty of sts development with systems forming in far north Atlantic. If i were in Bermuda I'd keep tabs on Leslie.

[jconsor]

As for Leslie this morning, I find it extremely hard to believe it's a 65-70 mph TS. It doesn't even look like a TS. Without significant organized convection, how is it bringing any stronger winds aloft down to the surface?

I agree. Just looking at IR loop Leslie looks like barely a TS, probably a TD. However, looks can be deceiving. First few morning visible images reveal a vigorous circulation, though it is racing WNW at 17 kt away from the convection.

Also, buoy 41044 on the NE side of Leslie (where the strongest winds are) reported a 1-minute peak wind of 47 kt (for 3 consecutive hours, between 10-12), with a peak gust of 57 kt. The buoy has seen sustained tropical storm force winds for 12 consecutive hours. The lowest pressure of 1004.5 mb was reported around 6z, when the center of Leslie was about 90 miles to the south.

The peak 1-minute winds are the 2nd-to-last value reported in the raw buoy data - example from buoy 41044 here:

BBXX 41044 02121 99216 70586 46/// /1719 10276 20220 40095 53034 91150 22200 00286 11113 20808 300// 41110 70065 333 91224 555 11208 22222 31138 41628 50083 61149 165196 164217 162212 164202 167204 167199 71053 81624 91138

The 81624 is the peak one-minute wind group. 16 means the peak one-minute wind was from 160 degrees. 24 means the peak one-minute wind was 24 m/s, or 47 kt.

http://www.wunderground.com/MAR/buoy/41044.html
http://coolwx.com/cgi-bin/findbuoy.cgi?id=41044

Also, satellite estimates from OSCAT and Colorado State-CIRA suggest top sustained winds are around 55 kt:

http://manati.star.nesdis.noaa.gov/data ... TData.php/

[Incident_MET]

The 12z BAM guidance initialization showed a current course of 305 degrees. That doesn't look to be the case to me based on morning VIS imagery. Looks close to west. Withour planned recon, forecast tracks will remain subject to quality of the global guid without any aircraft input.

[SFLcane]

The 12z BAM guidance initialization showed a current course of 305 degrees. That doesn't look to be the case to me based on morning VIS imagery. Looks close to west. Withour planned recon, forecast tracks will remain subject to quality of the global guid without any aircraft input.

Indeed there it goes heading westward...

[Aric Dunn]

If we are wondering if this system is to threaten anyone. Then its current shallow state would be the best chance. The shallow bam and a couple models a few runs ago and multiple GFS members showed the system missing both trof if it remained weak or sheared and shallow. This is the case now even the bam shallow essentially is stalled for 3 to 4 days just about where it is now. however the low to mid level ridge that is pushing that cut off low to the west near the bahamas may have a chance to build nw of this system possibly like earlier runs impart a slow continued wnw motion.

[ROCK]

looks like she slowed wayyy down...or what some have said a WNW jog....not sure its temporary or not....msybe this is the start of the loop...any case, the LLC decoupled like it is she is not going to ramp up anytime soon unless the shear decreases..