Tropical Storm Isaac, Part 2: Isaac Moving Into The Gulf Of Mexico-Hurricane Warnings For Morgan City, LA/MS/AL & FL Panhandle To Destin, FL

[Cheeznado]

Euro has shifted north a fair amount at 84 hours....has more of a weakness to the north than the previous runs.

[wxmeddler]

Well, from the new HDOB bit, it looks like we have a very broad area of low pressure... possibly we may have caught it in the act.

[Superstorm93]

Euro has shifted north a fair amount at 84 hours....has more of a weakness to the north than the previous runs.

Yeah.

Seems like it skirts it along the north coast of Cuba allowing some gradual intensification during that time. I find it very odd that it shoots this NNW in order to reach Hispaniola.

[deltadog03]

HR 96, this is W of tampa...and south of Destin moving NNW....looks pretty dang strong....

[Superstorm93]

Exploding south of the Panhandle by 108 hours and heading WNW with a hair more northerly component.

Fingers crossed that we could finally have a EURO/GFS consensus.

EDIT: Panhandle landfall by 120 hours.

[Cheeznado]

Landfall between Pensacola and Mobile Tuesday night

[atownwxwatcher]

Looks like we have a general consensus..

Now my only question is this..

If the center is not located where NHC has it located and it is further south west (as previous microwave image posted seemed to support) .Would this not throw the solutions off of what we are seeing now? What implications would IF it is further SW overall have?

[Superstorm93]

ECM and GFS are in agreement for this first time.

Now we just need a center fix and for the NHC to actually acknowledge it.

[deltadog03]

Nearly identical with euro and gfs now....I would expect a little nudge right/east for the 5am update....euro crawls this NNE onshore btw...

[deltadog03]

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[Superstorm93]

[Cheeznado]

If you look at the 06hr panel of the Euro, it has it down close to 15N, farther south than the NHC position. So a readjustment south would not really affect that model as much as you might think.

[valkhorn]

ECM and GFS are in agreement for this first time.

Now we just need a center fix and for the NHC to actually acknowledge it.

But where are they initializing Isaac? If the center turns out to be further south than what is there according to the NHC then there's no way it makes it through the FL Keys.

[HurricaneJosh]

Nearly identical with euro and gfs now....I would expect a little nudge right/east for the 5am update....euro crawls this NNE onshore btw...

Why would they nudge it E? The new runs actually match the currently forecast landfall point pretty well.

[atownwxwatcher]

But where are they initializing Isaac? If the center turns out to be further south than what is there according to the NHC then there's no way it makes it through the FL Keys.

This is why I am asking because this compared to the last frame also looks like it has taken a drop towards the SW as well....

And then these steering currents do not really seem like they are to supportive of a WNW heading either..

[tmagan]

06Z Observations

[Minnesota Meso]

Actually, I believe the the mission that was conducted today to sample the ridge to North and East of Issac was probably, to this point in time, the most important data set that we have seen. It wouldn't be a bad Idea to that tomorrow as well.

[gulfcane]

Strongest vorticity further south.

[Superstorm93]

Way down to 15.1 N @ 850mb

I'd like a VDM to confirm obviously.

[Ed Lizard]

This is why I am asking because this compared to the last frame also looks like it has taken a drop towards the SW as well....

And then these steering currents do not really seem like they are to supportive of a WNW heading either..

When the system in question is large enough and strong enough to clearly influence the flow around it, I don't see how the CIMSS mean level flow chart remains a useful tool in determining short term steering. I find it useful for weak or small systems, but Isaac has altered the low-mid level flow around it enough I don't know how one can say WNW movement isn't supported just from that diagram.

Now, assuming the center is reforming South, and doing short term extrapolation of movement might allow one to say W to WNW motion in the short term seems likely. But, and I am only an amateur, so I could be wrong, but the CIMSS layer steering chart in this case is of very limited use.

[dan88]

850mb windshift occured roughly at 15.1N, 69.7W. The surface center, while broad, appears to be North of this somewhere between 15.2N and 15.5N as this is where the SFMR drops to below 10kt over this range. However, the extrap pressure is between 1000mb and 1001mb for quite some distance, from here to up past 16N.

South of 15.1 however, the SFMR, after a very slow drop off going South from 16N to 15.2N, goes up very quickly to 30-35kt.

[gulfcane]

URNT15 KNHC 240655

AF300 1009A ISAAC HDOB 15 20120824

064700 1503N 06937W 8429 01493 //// +162 //// 238012 015 029 003 01

064730 1504N 06936W 8433 01488 0007 +170 +170 213008 010 031 002 01

064800 1504N 06934W 8434 01487 0005 +170 +170 169008 009 032 002 01

064830 1504N 06932W 8438 01483 0004 +170 +170 168007 009 034 001 01

064900 1504N 06931W 8426 01499 //// +162 //// 227014 017 029 005 01

064930 1504N 06929W 8431 01497 //// +168 //// 206015 017 029 004 01

065000 1504N 06927W 8432 01495 0010 +170 +170 191015 016 022 003 01

065030 1505N 06925W 8434 01493 0009 +170 +170 185015 016 019 003 01

065100 1505N 06924W 8433 01493 0017 +170 +170 176015 017 021 002 05

065130 1507N 06923W 8436 01493 0018 +160 +160 170015 016 /// /// 05

065200 1507N 06925W 8429 01498 0014 +170 +170 168013 014 /// /// 05

065230 1507N 06926W 8436 01490 0009 +173 +169 171013 014 022 001 00

065300 1507N 06928W 8432 01494 0009 +170 +170 177012 013 020 001 05

065330 1506N 06929W 8430 01494 0010 +170 +170 178009 012 026 001 01

065400 1506N 06931W 8434 01488 0005 +170 +170 159007 012 030 003 01

065430 1506N 06933W 8434 01486 0002 +170 +170 110006 007 033 002 05

065500 1505N 06934W 8439 01481 0001 +177 +175 115005 006 032 002 03

065530 1504N 06935W 8429 01490 0000 +179 +170 137003 006 035 000 00

065600 1502N 06936W 8440 01483 0007 +170 +170 259006 007 034 000 01

065630 1501N 06937W 8425 01496 0007 +170 +170 277007 008 033 003 01

Center is at 15.1N 69.6W in my opinion.

[wxmeddler]

Still sheared... the gap is closing. My guess for the surface center would be somewhere around 15.35N 69.90W

Time: 06:55:30Z
Coordinates: 15.0667N 69.5833W
Acft. Static Air Press: 842.9 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,490 meters (~ 4,888 feet)
Extrap. Sfc. Press: 1000.0 mb (~ 29.53 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 137° at 3 knots (From the SE at ~ 3.4 mph)
Air Temp: 17.9°C (~ 64.2°F)
Dew Pt: 17.0°C (~ 62.6°F)
Peak (10s) Flt. Lvl. Wind: 6 knots (~ 6.9 mph)
SFMR Peak (10s) Sfc. Wind: 35 knots (~ 40.2 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)

[HurricaneJosh]

Lolz, is a consolidated center too much to ask after three days? I mean, really.

[Superstorm93]

Lolz, is a consolidated center too much to ask after three days? I mean, really.

It's like Dolly 2008 all over again except 300% longer duration.

I guess this is the 850 center

[kbbballkid37]

Even a few hours ago, when overlayed w/ the last nhc official track, it's clear that Isaac reformed to the SW

[wxsniss]

1 hr late but not posted yet...

NHC sticking with significantly farther north surface center, hard to appreciate with the Recon and Obs shown below:

summary of 200 am AST...0600 UTC...information

----------------------------------------------

location...16.9n 69.4w

about 115 mi...185 km SSE of Santo Domingo Dominican Republic

about 225 mi...360 km ESE of Port au Prince Haiti

maximum sustained winds...45 mph...75 km/h

present movement...WNW or 290 degrees at 17 mph...28 km/h

minimum central pressure...1001 mb...29.56 inches

AF recon investigating 850 center at around 15.1n 69.5w:

No obvious surface center, let alone a vertically stacked one:

[gulfcane]

Game Change

000

URNT12 KNHC 240720

VORTEX DATA MESSAGE AL092012

A. 24/06:55:40Z

B. 15 deg 03 min N

069 deg 35 min W

C. 850 mb 1420 m

D. 37 kt

E. 211 deg 6 nm

F. 116 deg 38 kt

G. 011 deg 168 nm

H. 1000 mb

I. 17 C / 1524 m

J. 18 C / 1513 m

K. 17 C / NA

L. NA

M. NA

N. 1345 / 8

O. 0.02 / 10 nm

P. AF300 1009A ISAAC OB 03

MAX FL WIND 38 KT N QUAD 05:27:30Z

MAX FL TEMP 20 C 332 / 71 NM FROM FL CNTR

[Superstorm93]

120 NM south west of the last VDM

A. Time of Center Fix: 24th day of the month at 6:55:40Z

B. Center Fix Coordinates: 15°03'N 69°35'W (15.05N 69.5833W)

B. Center Fix Location: 238 miles (383 km) to the S (175°) from Santo Domingo, Dominican Republic.

[dan88]

Pressure likely in the upper 990's now, drop 1000mb, but with 26kt winds at the surface