Major Hurricane Felix

[kold weather]

Well that 132kts flight level wind probably will force the hand of the NHc, given the deep convection the NCH will almost certainly use the 90% ratio I'd have thought Steve, i can only remember Wilma and Dean having deeper convection then Felix has right now. Expect upgrade very shortly. It'll be 135mph with central pressure of 954mbs i suspect.

Edited September 2, 2007 by kold weather

[summer blizzard]

954mb, 128KT (147mph)...

I hope the 128 in the recon data was in mph, because 147mph is a strong category 4.

[SnowBear]

Pit, here ya go!

http://www.nhc.noaa.gov/abouthdobs_2007.shtml

[Paranoid]

Even though they seem to be at similar strengths, Felix currently has a much higher pressure than his 1995 counterpart. 1995's Hurricane Felix was around the same strength with a 929mbar central pressure, whereas 2007's Felix is closer to 950mbar.

I think it's time for me to break out the avatars again

Edited September 2, 2007 by Paranoid

[SnowBear]

I thought they used a 30 second average for the strength of the hurricane though?

185730 1335N 07117W 6966 02903 9794 +072 +072 150130 132 999 999 05

The 132 is a 10 second average

Not that it makes much difference, its gonna go Cat5 almost without doubt lol

Edited September 2, 2007 by SnowBear

[Iceberg]

Felix is a very small hurricane, core wise so will intensify very quickly with relatively higher pressure. Equally he needs to expand to survive the Yucatan.

[summer blizzard]

954mb is the lowest pressure found yet, surface windspeeds however are 132KT (137mph), that is a moderate category 4, i would'nt be suprised if this is a category 5 by midnight.

[Iceberg]

Atlantic use 10 Sec, Pacific use 30 sec, don't ask me why !.

Those are flight level winds SB, you need to take 10% off to get a rough surface estimate.

[SnowBear]

Okies! will go by the 10 second, I have always gone for the longer period, gives a more true reflection on the constant wind speed.

132knts it is!

[SMU]

Last 2 or 3 frames of the infrared loop has what appears to be a northerly Jog-

My friend goes to jamaica Mon-... I wonder how badly this will be effected-

S

[SnowBear]

Ya, I know about the fl to sfc calculation, which can vary and is a pain in the a$$, havent looked to see what they should be using for the reduction ratio on this one, but probably 10%, more likely 15%

301

URNT12 KNHC 021917

VORTEX DATA MESSAGE

A. 02/18:54:20Z

B. 13 deg 29 min N

071 deg 25 min W

C. 700 mb 2703 m

D. 95 kt

E. 268 deg 008 nm

F. 356 deg 114 kt

G. 268 deg 007 nm

H. 957 mb

I. 8 C/ 3060 m

J. 16 C/ 3050 m

K. 13 C/ NA

L. CLOSED WALL

M. C12

N. 12345/ 7

O. 0.02 / 01 nm

P. AF305 0806A FELIX OB 12

MAX FL WIND 122 KT NE QUAD 17:21:10 Z

MAX OUTBOUND FL WIND 132 KT NE QUAD 18:57:10 Z

SFC CNTR WITHIN 5NM OF FL CNTR

STADIUM EFFECT

AL06 2007

[kold weather]

The ob was in the eyewall and with very deep convection the reduction factor will be 90% of the flight level wind I'd expect, I'd be very surprised if its lower then that to be honest. I think given Dvorak also supports cat-4 I'll be very surprised if the NHC holds back from upgrading Felix shortly.

Recon vortex also notes the Stadium effect that is present with Felix right now.

By the way yes ther eis a slight northerly jog, currently taking it appears a motion around 282 degrees which willtake it a otuch tothe north of the NHC guidence plots, every bit of latitude means a Honduras hit becomes a little less likely. it should be noted that Felix is stair-stepping, it went close to WNW before backing a touch to the west again a sit heads around the southern side of a fairly strong upper high.

Edited September 2, 2007 by kold weather

[Iceberg]

Sorry SnowBear I was helping Summer...Too many SB's

Slight jog to the north from the NHC path

[SnowBear]

Ahh ha! Okies Iceberg, no worries

[summer blizzard]

Sorry SnowBear I was helping Summer...Too many SB's

Slight jog to the north from the NHC path

Lol, thnx however the 137mph was taking into account the 10% reduction, i just never wrote the equivelant in knots.

[January Snowstorm]

http://www.ssd.noaa.gov/goes/flt/t1/vis.jpg

Really does look something

[The PIT]

Pit, here ya go!

http://www.nhc.noaa.gov/abouthdobs_2007.shtml

Cheerz

[SMU]

New dvorak message just in-

UW - CIMSS

ADVANCED OBJECTIVE DVORAK TECHNIQUE

AODT - Version 6.4.2

Tropical Cyclone Intensity Algorithm

----- Current Analysis -----

Date : 02 SEP 2007 Time : 191500 UTC

Lat : 13:36:01 N Lon : 71:31:28 W

CI# /Pressure/ Vmax

6.7 / 929.4mb/132.2kt

Latitude bias adjustment to MSLP : +0.0mb

Estimated radius of max. wind based on IR : 17.5km

6hr-Avg T# 3hr-Avg T# Adj T# Raw T#

6.7 6.7 6.7 6.7

Eye Temp : +7.3C Cloud Region Temp : -71.3C

Scene Type : CLEAR EYE

Positioning Method : MANUAL

S

Ocean Basin : ATLANTIC

Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT

Weakening Flag : OFF

[Paranoid]

929.4? Surely that can't be Felix's pressure reading.

[Iceberg]

Stadium effect is certainly evident.

Edited September 2, 2007 by Iceberg

[SnowBear]

Wonder how long this thing will go before we get an ERC.

[kold weather]

The pressure won't be as low as that with Felix simply because the core is tighter then in a typical hurricane of this strength, that Dvorak pressure estimate is just that, an estimate based on the Sat.imagery but given pressure around the system are above average and its a tight system pressur ewil lbe higher then that...however I could well believe the wind speed estimates, its looking textbook and Felix almost certainly in my mind is a mid-storng cat-4 right now and the winds are gonig to keep on increasing as long as the Sat.imagery continues to show really good levels of organisation.

By the way what stunning images Iceberg, Felix looks utterly amazing right now with some really deep convection present around that eye, IMO looks better then Dean did at its max now and so when the winds do catch up to better represent the current levels of organisation there is a high chance itll be a cat-5. amazing really!

Edited September 2, 2007 by kold weather

[SMU]

The pressure won't be as low as that with Felix simply because the core is tighter then in a typical hurricane of this strength, that Dvorak pressure estimate is just that, an estimate based on the Sat.imagery but given pressure around the system are above average and its a tight system pressur ewil lbe higher then that...however I could well believe the wind speed estimates, its looking textbook and Felix almost certainly in my mind is a mid-storng cat-4 right now and the winds are gonig to keep on increasing as long as the Sat.imagery continues to show really good levels of organisation.

Indeed- Out of the 964 Recon earlier & the dvorak 929 I would go close to sub 940 CURRENT

S

[Jan 87]

Stadium effect is certainly evident.

Sorry if this has already been mentioned, but what is the stadium effect?

thanks

[SMU]

Sorry if this has already been mentioned, but what is the stadium effect?

thanks

Its when John motson assists with the commentary......

Stadium effect

.The stadium effect is a phenomenon observed in strong tropical cyclones. It is a fairly common event, where the clouds of the eyewall curve outward from the surface with height. This gives the eye an appearance resembling an open dome from the air, akin to a sports stadium. An eye is always larger at the top of the storm, and smallest at the bottom of the storm because the rising air in the eyewall follows isolines of equal angular momentum, which also slope outward with height.[19][20][21] This phenomenon refers to the characteristics of tropical cyclones with very small eyes, where the sloping phenomenon is much more pronounced

http://en.wikipedia.org/wiki/Eyewall

S

Edited September 2, 2007 by Steve Murr