Hurricane Isaac, Part 3 - Analysis and Forecasting Thread

[thewxmann]

Dry air is clearly gotten back into the core, should stop further intensification for now.

One could argue that Isaac never really had a core, considering the "outer eyewall" has looked more like a broken rainband than a true eyewall.

[Nikolai]

Turtle, do you have a link to the cam showing Lake P from the angle you posted on your blog? Thanks!

Re: flood stage for Lake P (from Wikipedia):

In 2007, the United States Army Corps of Engineers published results from a year long study intended primarily to determine the canal's "safe water level" for the 2007 hurricane season. The Corps of Engineers divided the 4.8 miles (7.7 km) of walls and levee into 36 sections to analyze just how much storm surge each can withstand. It found that only two sections, those closest to Pump Station No. 6 and on the high ground of Metairie Ridge, can hold more than 13 feet (4.0 m) of water. Many other sections of walls and levees can't be counted on to contain more than 7 feet (2.1 m) of water.^[9]

The executives at the FOX station out of NOLA should be fired, and the Mayor should be kicked out. They've both made statements against the NWS, and have minimized the storm's potential. 'Dodged a bullet,'--maybe--but you never minimize even a tropical storm when your city is below sea level. Stupid, stupid, stupid.

[Ian]

NOAA DOPPLER RADAR INDICATES THAT HURRICANE ISAAC MADE LANDFALL

ALONG THE COAST OF SOUTHEAST LOUISIANA IN PLAQUEMINES PARISH JUST

SOUTHWEST OF THE MOUTH OF THE MISSISSIPPI RIVER AT 645 PM CDT...

2345 UTC...WITH MAXIMUM SUSTAINED WINDS OF 80 MPH...130 KM/H.

closest time scan of landfall 1

[turtlehurricane]

Turtle, do you have a link to the cam showing Lake P from the angle you posted on your blog? Thanks!

They show it from time to time here: http://www.fox8live.com/category/235642/watch-fox8live

[Derecho!]

Dry air is clearly gotten back into the core, should stop further intensification for now.

Nope.

Last pass just now had 970 extrap (the sondes have been running 2-3 mb below extrap pressures) so it's still intensifying.

Probably not a good idea to make grand judgements on a small part of a few minutes of a radar loop.

[heavy_wx]

Based on the latest radar from LIX, it appears that the outer eyewall band is being pulled towards the center, possibly becoming part of the inner eyewall. This is also suggested by the recent increase in outbound velocity on the west side of the center.

[Kaner587]

967 extrapolated

[Thundersnow12]

One of the DOW's is deployed south of Boothville, LA and reported a 93-mph wind gust

[lester]

235530 2856N 08930W 8428 01242 9701 +216 +197 224014 016 013 002 00

235600 2857N 08931W 8433 01232 9695 +216 +200 264013 014 014 002 03

235630 2858N 08932W 8431 01226 9682 +225 +203 278010 012 016 002 03

235700 2900N 08933W 8431 01220 9676 +228 +205 015002 007 009 002 03

235730 2902N 08933W 8434 01214 9673 +228 +208 066012 014 004 001 03

235800 2903N 08933W 8426 01223 9674 +223 +211 067020 023 004 002 03

235830 2904N 08935W 8429 01220 9679 +215 +213 047026 028 017 002 00

235900 2903N 08937W 8436 01217 9679 +223 +215 031028 029 031 003 00

235930 2902N 08939W 8427 01230 9688 +216 +216 018036 038 037 003 00

000000 2900N 08940W 8429 01239 9701 +210 +210 009041 042 039 003 05

[turtlehurricane]

235530 2856N 08930W 8428 01242 9701 +216 +197 224014 016 013 002 00

235600 2857N 08931W 8433 01232 9695 +216 +200 264013 014 014 002 03

235630 2858N 08932W 8431 01226 9682 +225 +203 278010 012 016 002 03

235700 2900N 08933W 8431 01220 9676 +228 +205 015002 007 009 002 03

235730 2902N 08933W 8434 01214 9673 +228 +208 066012 014 004 001 03

235800 2903N 08933W 8426 01223 9674 +223 +211 067020 023 004 002 03

235830 2904N 08935W 8429 01220 9679 +215 +213 047026 028 017 002 00

235900 2903N 08937W 8436 01217 9679 +223 +215 031028 029 031 003 00

235930 2902N 08939W 8427 01230 9688 +216 +216 018036 038 037 003 00

000000 2900N 08940W 8429 01239 9701 +210 +210 009041 042 039 003 05

Convection exploding over the center: http://www.ssec.wisc.edu/~rabin/goes14/band4/loop_srso.html

[Snow_Miser]

235530 2856N 08930W 8428 01242 9701 +216 +197 224014 016 013 002 00

235600 2857N 08931W 8433 01232 9695 +216 +200 264013 014 014 002 03

235630 2858N 08932W 8431 01226 9682 +225 +203 278010 012 016 002 03

235700 2900N 08933W 8431 01220 9676 +228 +205 015002 007 009 002 03

235730 2902N 08933W 8434 01214 9673 +228 +208 066012 014 004 001 03

235800 2903N 08933W 8426 01223 9674 +223 +211 067020 023 004 002 03

235830 2904N 08935W 8429 01220 9679 +215 +213 047026 028 017 002 00

235900 2903N 08937W 8436 01217 9679 +223 +215 031028 029 031 003 00

235930 2902N 08939W 8427 01230 9688 +216 +216 018036 038 037 003 00

000000 2900N 08940W 8429 01239 9701 +210 +210 009041 042 039 003 05

967 mb is the lowest pressure I can read from that chart.

[SACRUS]

Closing images

[Derecho!]

For what it's worth GFDL and HWRF have less of a stall now - it's still slow movement though, slower than NHC I believe.

[David Reimer]

Radar velocities on the west side of Isaac have increased over the past 20 minutes. Now seeing multiple 90-95 knot readings at 6,500 feet.

[Scuddz]

CoC looks to have gone right back out over that little bay between the mainland and the delta

[Scott747]

The wind gust report from the landfall position report out of Galliano is where Josh is currently located....

A SUSTAINED WIND OF 45 MPH WITH A GUST TO 62 MPH WAS OBSERVED WITHIN

THE PAST HOUR AT LAKEFRONT AIRPORT IN NEW ORLEANS. A WIND GUST TO

56 MPH WAS RECENTLY REPORTED AT GALLIANO LOUISIANA.

*edit*

Wind gust report was out of Galliano, not landfall. My wording was probably confusing.

[MAG5035]

Should be seeing some classic Cantore footage here very shortly.

Base velocities a bit further south near Grand Isle, LA spiking to 90-95kts at about 6k feet.

[turtlehurricane]

CoC looks to have gone right back out over that little bay between the mainland and the delta

The center is between 50 and 80 miles from the true coastline, pressure probably wouldn't be dropping this fast otherwise.

[dan88]

000

URNT12 KNHC 290010

VORTEX DATA MESSAGE AL092012

A. 28/23:57:00Z

B. 29 deg 00 min N

089 deg 33 min W

C. 850 mb 1151 m

D. 57 kt

E. 093 deg 38 nm

F. 174 deg 82 kt

G. 093 deg 51 nm

H. 968 mb

I. 18 C / 1521 m

J. 23 C / 1524 m

K. 21 C / NA

L. OPEN SE

M. CO12-21

N. 12345 / 8

O. 0.02 / 1 nm

P. AF308 3209A ISAAC OB 06

MAX FL WIND 96 KT NE QUAD 22:49:30Z

MAX OUTBOUND FL WIND 94 KT W QUAD 00:03:50Z

;

[Snow_Miser]

For what it's worth GFDL and HWRF have less of a stall now - it's still slow movement though, slower than NHC I believe.

They bring Isaac inland between 6-12z tomorrow morning. That's still a considerable stall off of the Louisianna coast.

[CoastalWx]

The water both freshwater and salt water will be the biggest attention grabbers from here on out I think. I imagine this won't weaken anytime soon, thanks to its movement.

[wxsniss]

Confirms concentric eyes we've been seeing on radar

delta T 6˚C, no reason should increase with such a disorganized eye

968mb, Euro's sub960 is probably less than 6 hours away if this stays over water

Product: Air Force Vortex Message (URNT12 KNHC)

Transmitted: 29th day of the month at 00:10Z

Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 308)

Storm Number & Year: 09L in 2012

Storm Name: Isaac (flight in the North Atlantic basin)

Mission Number: 32

Observation Number: 06

A. Time of Center Fix: 28th day of the month at 23:57:00Z

B. Center Fix Coordinates: 29°00'N 89°33'W (29.N 89.55W) (View map)

B. Center Fix Location: 74 miles (119 km) to the SSE (156°) from New Orleans, LA, USA.

C. Minimum Height at Standard Level: 1,151m (3,776ft) at 850mb

D. Estimated (by SFMR or visually) Maximum Surface Wind: 57kts (~ 65.6mph)

E. Location of the Estimated Maximum Surface Wind: 38 nautical miles (44 statute miles) to the E (93°) of center fix

F. Maximum Flight Level Wind Inbound: From 174° at 82kts (From the S at ~ 94.4mph)

G. Location of Maximum Flight Level Wind Inbound: 51 nautical miles (59 statute miles) to the E (93°) of center fix

H. Minimum Sea Level Pressure: 968mb (28.59 inHg)

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,521m (4,990ft)

J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 1,524m (5,000ft)

K. Dewpoint Temp (collected at same location as temp inside eye): 21°C (70°F)

K. Sea Surface Temp (collected at same location as temp inside eye): Not Available

L. Eye Character: Open in the southeast

M. Eye Shape: Concentric (has an inner and outer eye)

M. Inner Eye Diameter: 12 nautical miles (14 statute miles)

M. Outer Eye Diameter: 21 nautical miles (24 statute miles)

N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature

N. Fix Level: 850mb

O. Navigation Fix Accuracy: 0.02 nautical miles

O. Meteorological Accuracy: 1 nautical mile

Remarks Section:

Maximum Flight Level Wind: 96kts (~ 110.5mph) in the northeast quadrant at 22:49:30Z

Maximum Flight Level Wind Outbound: 94kts (~ 108.2mph) in the west quadrant at 0:03:50Z

[SunnyFL]

I just heard on WWL Radio, the newscaster said "the Tornado Watch for the area has expired. Most of the area in SE Louisana is under a Hurricane WATCH." Wow, I'd expect more from the mighty WWL.

[turtlehurricane]

I wonder if the SFMR is even working right, it's seemed way too low this whole storm and 110 mph flight level would suggest 95-100 mph in convection, not 65 mph! Winds sustained at 82 mph at mississippi canyon oil platform near where they're doing SFMR measurements (though it is fairly elevated).

I don't like how the NHC is giving SFMR precedent over all our other obs.

[CoastalWx]

The water both freshwater and salt water will be the biggest attention grabbers from here on out I think. I imagine this won't weaken anytime soon, thanks to its movement.

In fact still could tick up a bit thanks to the west movement?

[andyhb]

I just heard on WWL Radio, the newscaster said "the Tornado Watch for the area has expired. Most of the area in SE Louisana is under a Hurricane WATCH." Wow, I'd expect more from the mighty WWL.

It was just being reissued, the new watch is up now.

[CoastalWx]

I wonder if the SFMR is even working right, it's seemed way too low this whole storm and 110 mph flight level would suggest 95-100 mph in convection. Winds sustained at 82 mph at mississippi canyon oil platform.

I don't like how the NHC is giving SFMR precedent over all our other obs.

Well I think when you look at satellite, the convection is probably the best it's looked in a while, so the obs may be more telling...if you know what I mean. When the convection was disorganized earlier..that may have been the only thing to rely on (the SFMR) since perhaps winds weren't mixed well at the time.

[wxmx]

No recent recon fix yet, but radar suggests its wobbling to the W or SW.

[Derecho!]

I wonder if the SFMR is even working right, it's seemed way too low this whole storm and 110 mph flight level would suggest 95-100 mph in convection, not 65 mph! Winds sustained at 82 mph at mississippi canyon oil platform near where they're doing SFMR measurements (though it is fairly elevated).

I don't like how the NHC is giving SFMR precedent over all our other obs.

It's been multiple AC, both WC-130 and P-3, so it can't be a single SFMR unit.

[phil882]

Hi guys... remember that we have a separate thread for storm reports and observations. This thread is for analysis / forecasting only. I'll be moving any posts that have to do with storm reports and damage to the relevant thread.