Hurricane Isaac - Cat. 1

[CrazyC83]

Looks like TD9 around the corner...

[HURAKAN]

[curtadams]

Looks to have formed as a very sheared system during blackout. After blackout you can see a low-level circulation on shortwave SW of the convection: http://www.ssd.noaa.gov/goes/flt/t1/loop-ir2.html That matches the direction of shear there http://cimss.ssec.wisc.edu/tropic/real- ... g8shr.html Looks very close to being sheared apart and probably won't last long enough to get classified.

[Thunder44]

018
ABNT20 KNHC 240849
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT SUN SEP 24 2006

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
HELENE...LOCATED ABOUT 705 MILES WEST-NORTHWEST OF THE AZORES
ISLANDS.

A LARGE TROPICAL WAVE...ACCOMPANIED BY A BROAD SURFACE LOW PRESSURE
AREA...IS LOCATED ABOUT 1200 MILES EAST OF THE NORTHERN LEEWARD
ISLANDS. ALTHOUGH UPPER-LEVEL WINDS ARE CURRENTLY LIMITING THE
ORGANIZATION OF THIS SYSTEM...IT STILL HAS THE POTENTIAL TO DEVELOP
INTO A TROPICAL DEPRESSION OVER THE NEXT DAY OR TWO.

ELSEWHERE...TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH MONDAY.

$$
FORECASTER FRANKLIN

[Thunder44]

QS pass earlier this morning shows a closed surface circulation just SW of the convection near 19.0N 43.5W:

http://manati.orbit.nesdis.noaa.gov/sto ... _at_1.html

Higher resolution image shows the center maybe a little further south and some 40kt barbs that appear to be rain contaminated.

http://manati.orbit.nesdis.noaa.gov/dat ... Bas112.png

[cycloneye]

http://www.nrlmry.navy.mil/tc_pages/tc_home.html

NRL drops 96L,But maybe they are changing the header to say noname.If that is the case as always storm2k policy of waiting for the official word stands.

[Hyperstorm]

That's quite probable. The visible satellite images this morning reveal a well-defined and closed low-level circulation. This could be the trigger for an official upgrade. In any case, official or unofficial, this system meets already the characteristics of a tropical depression albeit a weak one (30 mph) due to the exposed nature of the swirl. I suppose they are trying to make a decision as we speak.

If it becomes a depression there should only be very slow development afterwards until that SW shear lets up, if at all. Wouldn't be surprised to see it as a depression for a couple of days before becoming a tropical storm.

Other than that, there should be no reason for a drop altogether as the system is looking the best it has during its lifetime.

[WindRunner]

Nothing saying it was deleted or, deactivated, or renumbered in the NHC's files, though the last position update was this morning at 06Z, while all other systems have 12Z positions on them. Probably an upgade, especially as the pressure is dropping:

BEGIN
NHC_ATCFSVR1
invest_al962006.invest
FSTDA
R
U
040
010
0000
200609240749
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 96, 2006, DB, O, 2006092006, 9999999999, , , , , , METWATCH, , AL962006
AL, 96, 2006091906, , BEST, 0, 88N, 235W, 20, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006091912, , BEST, 0, 86N, 245W, 20, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006091918, , BEST, 0, 85N, 256W, 20, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006092000, , BEST, 0, 89N, 269W, 20, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006092006, , BEST, 0, 98N, 279W, 20, 1010, DB, 0, , 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092012, , BEST, 0, 102N, 292W, 20, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006092018, , BEST, 0, 106N, 304W, 25, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006092100, , BEST, 0, 110N, 318W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 150, 70, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092106, , BEST, 0, 113N, 332W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092112, , BEST, 0, 115N, 345W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092118, , BEST, 0, 117N, 357W, 25, 1010, DB, 0, , 0, 0, 0, 0,
AL, 96, 2006092200, , BEST, 0, 118N, 369W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092206, , BEST, 0, 122N, 380W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1014, 200, 100, 0, 0, L, 0, , 0, 0, INVEST, D,
AL, 96, 2006092212, , BEST, 0, 129N, 388W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1014, 200, 75, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092218, , BEST, 0, 137N, 393W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 200, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092300, , BEST, 0, 142N, 398W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 200, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092306, , BEST, 0, 149N, 404W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1013, 200, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092312, , BEST, 0, 157N, 410W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1012, 250, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092318, , BEST, 0, 169N, 417W, 25, 1010, DB, 0, , 0, 0, 0, 0, 1012, 250, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092400, , BEST, 0, 182N, 425W, 25, 1009, DB, 0, , 0, 0, 0, 0, 1012, 250, 100, 0, 0, L, 0, , 0, 0, INVEST, M,
AL, 96, 2006092406, , BEST, 0, 190N, 433W, 25, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1012, 250, 100, 0, 0, L, 0, , 0, 0, INVEST, M,

EDIT: No upgrade:

AL, 96, 2006092412, , BEST, 0, 192N, 433W, 25, 1008, DB, 34, NEQ, 0, 0, 0, 0, 1012, 250, 75, 0, 0, L, 0, , 0, 0, INVEST, M,

[cycloneye]

24/1145 UTC 19.1N 43.1W T1.5/1.5 96L -- Atlantic Ocean


http://www.ssd.noaa.gov/PS/TROP/positions.html

[WindRunner]

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO TPC/NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONES.

NATIONAL HURRICANE CENTER NORTH ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL962006) ON 20060924 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
060924 1200 060925 0000 060925 1200 060926 0000

LAT LON LAT LON LAT LON LAT LON
BAMD 19.2N 43.3W 20.4N 43.8W 21.4N 44.4W 22.7N 45.8W
BAMM 19.2N 43.3W 19.7N 44.2W 20.2N 45.3W 21.0N 47.0W
A98E 19.2N 43.3W 20.5N 44.3W 21.3N 45.1W 22.8N 45.5W
LBAR 19.2N 43.3W 20.7N 43.9W 21.7N 44.7W 22.9N 45.7W
SHIP 25KTS 26KTS 28KTS 32KTS
DSHP 25KTS 26KTS 28KTS 32KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
060926 1200 060927 1200 060928 1200 060929 1200

LAT LON LAT LON LAT LON LAT LON
BAMD 24.0N 47.4W 26.7N 51.1W 29.6N 55.0W 33.1N 58.4W
BAMM 22.0N 49.0W 24.5N 53.2W 27.3N 57.4W 30.2N 60.7W
A98E 23.8N 46.7W 24.8N 49.3W 26.1N 52.2W 29.3N 55.8W
LBAR 24.1N 46.6W 25.6N 48.2W 26.1N 49.8W 25.7N 52.8W
SHIP 36KTS 45KTS 51KTS 57KTS
DSHP 36KTS 45KTS 51KTS 57KTS

...INITIAL CONDITIONS...
LATCUR = 19.2N LONCUR = 43.3W DIRCUR = 325DEG SPDCUR = 10KT
LATM12 = 18.2N LONM12 = 42.5W DIRM12 = 327DEG SPDM12 = 12KT
LATM24 = 15.7N LONM24 = 41.0W
WNDCUR = 25KT RMAXWD = 75NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 250NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$


And again - no upgrade.

[OURAGAN]

96L IS ON THE NRL AGAIN NOW, it's not a depression, it seems to me a sheared system.

[Thunder44]

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org For Official Information please refer to the NHC and NWS products.

Analysis:

This is how it looks to me now...

This system has become less organized this morning as upper-level SW shear has increased significantly over the center. The low-level center appears to be moving to the NW or WNW, while the thunderstorms are moving to the NE and diminishing. Tropical cyclone development is looking less likely this morning, and I no longer expect this system to develop. Although there is still the slight possibility that shear may decrease within the next 24hrs to allow development over the next few days.

The latest GFS and GFDL models have shifted to the west with this system and much weaker. I think this scenario is becoming more likely, as the LLC may continue moving more westward without developing.

[Sanibel]

Hmm, I can't believe this but Central Atlantic WV loop makes it look like a ridge is building above 96L that could take it (I can't believe I'm saying this) more west. We'll see if it is just illusion.

[Thunder44]

354
ABNT20 KNHC 241520
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1130 AM EDT SUN SEP 24 2006

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER HAS ISSUED ITS LAST ADVISORY ON
HELENE...WHICH HAS BECOME EXTRATROPICAL ABOUT 595 MILES
WEST-NORTHWEST OF THE AZORES.

A LARGE TROPICAL WAVE...ACCOMPANIED BY A BROAD SURFACE LOW PRESSURE
AREA...IS LOCATED ABOUT 1200 MILES EAST OF THE NORTHERN LEEWARD
ISLANDS. UPPER-LEVEL WINDS ARE ONLY MARGINALLY FAVORABLE FOR
TROPICAL CYCLONE FORMATION IN THIS AREA. HOWEVER...ONLY A SLIGHT
INCREASE IN THE ORGANIZATION OF THIS SYSTEM WOULD RESULT IN THE
FORMATION OF A TROPICAL DEPRESSION LATER TODAY OR ON MONDAY AS IT
DRIFTS GENERALLY NORTHWESTWARD.

ELSEWHERE...TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH MONDAY.

$$
FORECASTER PASCH

[HURAKAN]

The convection is very shallow and the system is completely exposed.

[Bgator]

IF this system were to get caught under a High and move westerly now, would caonditions become more favorable?

[caribepr]

What happened to using smaller images??? Some of ARE still dial up users and do want to see the images before the next run

[WindRunner]

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO TPC/NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONES.

NATIONAL HURRICANE CENTER NORTH ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL962006) ON 20060924 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
060924 1800 060925 0600 060925 1800 060926 0600

LAT LON LAT LON LAT LON LAT LON
BAMD 18.9N 43.9W 19.8N 44.9W 20.9N 46.2W 22.3N 48.1W
BAMM 18.9N 43.9W 19.3N 45.1W 19.9N 46.6W 20.9N 48.4W
A98E 18.9N 43.9W 19.3N 45.7W 20.2N 47.3W 21.6N 49.2W
LBAR 18.9N 43.9W 19.5N 45.0W 20.5N 46.6W 21.8N 48.4W
SHIP 25KTS 27KTS 30KTS 34KTS
DSHP 25KTS 27KTS 30KTS 34KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
060926 1800 060927 1800 060928 1800 060929 1800

LAT LON LAT LON LAT LON LAT LON
BAMD 23.9N 50.3W 27.4N 54.5W 30.5N 57.8W 34.4N 59.0W
BAMM 22.1N 50.6W 24.8N 54.8W 27.2N 58.0W 29.5N 60.1W
A98E 23.7N 51.3W 27.4N 55.9W 30.4N 58.5W 33.8N 57.0W
LBAR 23.5N 50.2W 26.7N 53.1W 29.2N 55.2W 32.1N 56.8W
SHIP 39KTS 48KTS 55KTS 59KTS
DSHP 39KTS 48KTS 55KTS 59KTS

...INITIAL CONDITIONS...
LATCUR = 18.9N LONCUR = 43.9W DIRCUR = 290DEG SPDCUR = 8KT
LATM12 = 18.4N LONM12 = 42.9W DIRM12 = 338DEG SPDM12 = 6KT
LATM24 = 16.5N LONM24 = 42.2W
WNDCUR = 25KT RMAXWD = 75NM WNDM12 = 25KT
CENPRS = 1009MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$


SHIPS is very slow when it comes to developing this system.

[Thunder44]

365
ABNT20 KNHC 242113
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 PM EDT SUN SEP 24 2006

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE EXTRATROPICAL STORM...REMNANTS OF HELENE ARE LOCATED ABOUT 350
MILES NORTHWEST OF THE AZORES.

A LARGE TROPICAL WAVE...ACCOMPANIED BY A BROAD SURFACE LOW PRESSURE
AREA...LOCATED ABOUT 1150 MILES EAST OF THE NORTHERN LEEWARD
ISLANDS HAS BECOME LESS ORGANIZED DURING THE DAY. UPPER-LEVEL WINDS
ARE ONLY MARGINALLY FAVORABLE FOR TROPICAL CYCLONE FORMATION AND
THE POTENTIAL FOR A TROPICAL DEPRESSION TO FORM HAS DIMINISHED.

ELSEWHERE...TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH MONDAY.

$$
FORECASTER AVILA

[MGC]

There is a well defined surface circulation. Currently it is being sheared and there is quite a bit of dry air to the NW of the circulation center. Little if any convection near the center, convection is well displaced to the NE. I don't see the shear letting up for the next couple days. I doubt we have a TD any time soon.....MGC