Major Hurricane Katia

[knightrider]

http://www.ssd.noaa....lt/t2/rgb-l.jpg

Perfection. I would say that there is definite strengthening given its presentation.

In regards to track, as i suspected it is a 100% FISH baring a few isolated islands.

In regards to a hit on the UK, no chance. The problem with those models is that they show the track even when the storm is extratropical (i.e. as long as they have some tropical charectarisitics). Coming from anywhere near Newfoundland completely rules out the chance. The closest we get is when a storm approaches from near the Azores as is still undergoing transition near the UK. I would be extremely sceptical about the 1966 Scottish 'Hurricane' and there is no doubt in my mind that it was undergoing transition, so while it may have had gusts equivelant to a category 2, it certainly did not have a symetrical warm core.

The 1987 storm also developed in the Azores didn't it? I know it's main source of gaining power came when passing over the Bay of Biscay.

[Somerset Squall]

Agreed Iceberg, definitely a major now, latest from CIMSS

CI# /Pressure/ Vmax

5.9 / 950.2mb/112.4kt

How long will the RI last I wonder. Outflow is certainly superb, to the south especially. Katia has mulitiple vortices in her eye, similar to Isabel in 2003.

[Paranoid]

112kts would put Katia at the upper end of Cat 3 i think, T 6.0 also equates to a low end Cat 4. Certainly looks good on the visible images but the convection isn't quite as strong in the NE quadrant, seems skewed towards the SW.

Edited September 5, 2011 by Paranoid

[DAVID SNOW]

The 1987 storm also developed in the Azores didn't it? I know it's main source of gaining power came when passing over the Bay of Biscay.

Bay of Biscay i think.

[Iceberg]

Katia looks to have come to an end of the latest bout of intensification, I would say something like 110-115kts so a boarderline CAT 4 now, but NHC might her as a very high end CAT 3.

Still time for a bit more intensification so a mid CAT 4 is certainly still possible.

Katia is fantastic looking (the best looking storm of the season by far).

Path still looks to be just off the US coast so no real impact for the US.

For the UK ECM at 168 has it crossing northern England with still 60-70mph sustained winds and gusts to 80 which would be pretty dire. The below shows the paths and also shows what looks to be a path from the BAMM models across southern england, a very rare event for it to even be thought of and probably the first BAMM prediction like this for an ex CAT 4 Hurricane I can remember in 10 years.

Katia will still be a very potent beast if it gets anywhere near our shores, it will be travelling very quickly and so might still be extra tropical in nature.

Edited September 5, 2011 by Iceberg

[Paranoid]

Latest CIMSS estimates put Katia at T#6.2 with a pressure of 942mb and winds of 119.8kt. If that's accurate, Katia's currently on par with Irene at her peak. Katia looks better than Irene did on visible images so i think Katia may end up being the stronger of the two.

[summer blizzard]

the 1987 storm was indeed an ex hurricane which had undergone extra tropical transition. very strong hurricane is katia.

[Aaron]

Katia looks to have come to an end of the latest bout of intensification, I would say something like 110-115kts so a boarderline CAT 4 now, but NHC might her as a very high end CAT 3.

Still time for a bit more intensification so a mid CAT 4 is certainly still possible.

Katia is fantastic looking (the best looking storm of the season by far).

Path still looks to be just off the US coast so no real impact for the US.

For the UK ECM at 168 has it crossing northern England with still 60-70mph sustained winds and gusts to 80 which would be pretty dire. The below shows the paths and also shows what looks to be a path from the BAMM models across southern england, a very rare event for it to even be thought of and probably the first BAMM prediction like this for an ex CAT 4 Hurricane I can remember in 10 years.

Katia will still be a very potent beast if it gets anywhere near our shores, it will be travelling very quickly and so might still be extra tropical in nature.

She's a beast alright

[Paranoid]

Interested to see what the NHC set Katia's intensity at for the next advisory. CIMSS intensity estimates seem higher than other satellite estimates, but i would be surprised if Katia is at less than 120mph winds given the amount of structural change we've seen today.

[Iceberg]

Nhc have her at 100kts and admit they are probably being a little conservative. Soon find out tomorrow

[knocker]

WTNT32 KNHC 052037

TCPAT2

BULLETIN

HURRICANE KATIA ADVISORY NUMBER 31

NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011

500 PM AST MON SEP 05 2011

...KATIA BECOMES A MAJOR HURRICANE...BIGGEST THREAT CONTINUES TO BE

DANGEROUS RIP CURRENTS ALONG THE U.S. EAST COAST AND BERMUDA...

SUMMARY OF 500 PM AST...2100 UTC...INFORMATION

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

LOCATION...25.2N 63.9W

ABOUT 495 MI...795 KM S OF BERMUDA

MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H

PRESENT MOVEMENT...NW OR 310 DEGREES AT 12 MPH...19 KM/H

MINIMUM CENTRAL PRESSURE...959 MB...28.32 INCHES

WATCHES AND WARNINGS

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

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

INTERESTS IN BERMUDA SHOULD MONITOR THE PROGRESS OF KATIA.

DISCUSSION AND 48-HOUR OUTLOOK

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

AT 500 PM AST...2100 UTC...THE CENTER OF HURRICANE KATIA WAS LOCATED

NEAR LATITUDE 25.2 NORTH...LONGITUDE 63.9 WEST. KATIA IS MOVING

TOWARD THE NORTHWEST NEAR 12 MPH...19 KM/H...AND THIS GENERAL MOTION

WITH A SLIGHT DECREASE IN FORWARD SPEED IS EXPECTED THROUGH

WEDNESDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 115 MPH...185 KM/H...

WITH HIGHER GUSTS. KATIA IS A CATEGORY THREE HURRICANE ON THE

SAFFIR-SIMPSON HURRICANE WIND SCALE. SOME ADDITIONAL STRENGTHENING

IS FORECAST THROUGH TUESDAY...FOLLOWED BY LITTLE CHANGE IN STRENGTH

ON WEDNESDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM

THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205

MILES...335 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 959 MB...28.32 INCHES.

HAZARDS AFFECTING LAND

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

SURF...LARGE SWELLS GENERATED BY KATIA ARE EXPECTED TO AFFECT MOST

OF THE EAST COAST OF THE UNITED STATES...BERMUDA...THE GREATER

ANTILLES...AND EAST-FACING BEACHES OF THE BAHAMAS DURING THE NEXT

FEW DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF

AND RIP CURRENT CONDITIONS. SWELLS AFFECTING THE NORTHERN LEEWARD

ISLANDS SHOULD CONTINUE TO SUBSIDE TODAY. PLEASE CONSULT PRODUCTS

FROM YOUR LOCAL WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION.

NEXT ADVISORY

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

NEXT COMPLETE ADVISORY...1100 PM AST.

$$

FORECASTER BERG

[Paranoid]

All the satellite estimates now estimate Katia's pressure is sub 950. Is it me or has Katia become a little bit more ragged in the past few hours?

[Iceberg]

Katia struggled a bit in the early hours, but only after NHC upgraded her to a CAT 4 Hurricane.

However since this morning some deep convection has almost circled the eye cloud tops are -90C and some serious upward and downward movement of air will be happening in the core, given this and the strinking eye I would still keep her as a CAT 4. IF the -90 cloud tops encircle the eye completely and the CDO expands a little then recon *might* find some CAT 5 flight winds in the eye which are very restricted (140-150kts) and some very deep pressure i.e sub 930. This does depend though on the structure over the next few hrs but Katia does have a chance of achieiving this.

ECM has Katia on quite a bizarre northwards course, which has no model agreement, however it still has semi tropical style winds off greenland with sustained speeds of 80+mph.

A more realistic track is the GFS.

HWRF track is interesting to say the least and still has 100kt+ winds during the extra tropical phase as it gets into SST's of 18C in the NW atlantic.

[Coast]

Katia, which was named the second hurricane of the season in the Atlantic Ocean last week, became a major hurricane by Monday night, increasing its intensity to a Category 4 storm. The U.S. National Hurricane Center (NHC) has said that large swells of surf generated by Katia are expected to affect most of the U.S. East Coast, Bermuda, the Greater Antilles and east-facing beaches of the Bahamas as it moves north-west during the next few days. NHC warned that these swells are likely to cause life-threatening surf and rip current conditions.

Katia became a category four hurricane on the Saffir-Simpson scale when its maximum sustained winds increased to 135 mph with higher gusts. Katia is located about 450 miles south of Bermuda, and is moving toward the northwest across the North Atlantic Ocean at a speed of 10 mph, NHC said in its latest public advisory. A general motion toward the west-northwest and a decrease in forward speed are expected during the next couple of days. This general motion is expected to continue through Wednesday before the storm slowly weakens.

There are no coastal watches or warnings in effect.

http://www.rttnews.c...Id=1707031&SM=1

Hopefully she will miss most of the landmass.

[weatherobsuk]

Been keeping my eye on the sea swell heights, and no doubt the +20ft heights forecasted out in the Atlantic coming close to Ireland from +160hr is from Katia.

[Gray-Wolf]

I hope we do not see a failure to turn as forecast? After the damp sqab (for N.Y.C.) that Irene proved We can do without any near misses from a major 'cane in that area?

As for us and the remnant? Any thoughts? is summer dragged back with it or do we see a heavy system pass over us?

[Coast]

Totally hypothetical of course, but just extrapolating the current directional movement and path onwards, does this seem reasonable?

[knocker]

WTNT32 KNHC 060833

TCPAT2

BULLETIN

HURRICANE KATIA ADVISORY NUMBER 33

NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011

500 AM AST TUE SEP 06 2011

...MAJOR HURRICANE KATIA MOVING STEADILY NORTHWESTWARD...DANGEROUS

RIP CURRENTS REMAIN THE MAIN HAZARD ALONG THE U.S. EAST COAST AND

BERMUDA...

SUMMARY OF 500 AM AST...0900 UTC...INFORMATION

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

LOCATION...26.5N 65.1W

ABOUT 400 MI...645 KM S OF BERMUDA

MAXIMUM SUSTAINED WINDS...125 MPH...205 KM/H

PRESENT MOVEMENT...NW OR 315 DEGREES AT 10 MPH...17 KM/H

MINIMUM CENTRAL PRESSURE...950 MB...28.05 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 HURRICANE KATIA WAS LOCATED

NEAR LATITUDE 26.5 NORTH...LONGITUDE 65.1 WEST. KATIA IS MOVING

TOWARD THE NORTHWEST NEAR 10 MPH...17 KM/H. THIS GENERAL MOTION

IS EXPECTED TO CONTINUE THROUGH WEDNESDAY...FOLLOWED BY A TURN

TOWARD THE NORTH-NORTHWEST BY THURSDAY.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 125 MPH...205

KM/H...WITH HIGHER GUSTS. KATIA IS A CATEGORY THREE HURRICANE ON

THE SAFFIR-SIMPSON WIND SCALE. SOME FLUCTUATIONS IN STRENGTH ARE

POSSIBLE DURING THE NEXT 24 HOURS...FOLLOWED BY SLOW WEAKENING.

HURRICANE-FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM

THE CENTER...AND TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 205

MILES...335 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB...28.05 INCHES.

HAZARDS AFFECTING LAND

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

SURF...LARGE SWELLS GENERATED BY KATIA WILL CONTINUE TO AFFECT MOST

OF THE EAST COAST OF THE UNITED STATES...BERMUDA...THE GREATER

ANTILLES...AND EAST-FACING BEACHES OF THE BAHAMAS DURING THE NEXT

FEW DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF

AND RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL

WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION.

NEXT ADVISORY

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

NEXT COMPLETE ADVISORY...1100 AM AST.

$$

FORECASTER KIMBERLAIN

[Iceberg]

Katia is doing her best to prove everyone wrong by ingesting a bit dollop of dry air into the centre. TBH she is lacking an eyewall currently in places so will be losing any chance of high wind speeds.

Looking at Dvorak estimates she is probably 90-95kts now so maybe low end CAT 3.

[AderynCoch]

Another EWRC taking place surely, but once Katia reorganises I doubt there'll be much time left to strengthen further.

[Iceberg]

I must confess myself to be impressed with the speed that Katia recovers talk about a yo-yo storm.

Katia now has a solid ring of deep convection around the eye, but the eye is/hasn't cleared.

I am not sure whether there has been an ERC or just a collapse of the eye due to dry air, it's difficult to judge.

Recon should have taken off at midday and should be reporting back soon on it's flight towards katia.

1. HURRICANE KATIA FLIGHT ONE -- TEAL 70 A. 06/17Z B. AFXXX 0112A KATIA C. 06/1415Z D. 27.5N 66.5W E. 06/1615Z-06/1830Z F. SFC TO 10,000 FT 2. OUTLOOK FOR SUCCEEDING DAY: PSBL 07/17Z FIX 3. REMARK: NOAA G-IV RESEARCH MISSIONS FOR HURRICANE KATIA TAKING OFF 06/11Z AND 07/11Z.

[knocker]

Latest enhanced WV.

[knocker]

WTNT32 KNHC 061445

TCPAT2

BULLETIN

HURRICANE KATIA ADVISORY NUMBER 34

NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011

1100 AM AST TUE SEP 06 2011

...KATIA WEAKENS A LITTLE...TROPICAL STORM WATCH ISSUED FOR

BERMUDA...

SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION

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

LOCATION...27.0N 65.9W

ABOUT 370 MI...600 KM S OF BERMUDA

MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H

PRESENT MOVEMENT...NW OR 310 DEGREES AT 9 MPH...15 KM/H

MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

WATCHES AND WARNINGS

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

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

THE BERMUDA WEATHER SERVICE HAS ISSUED A TROPICAL STORM WATCH FOR

BERMUDA.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...

* BERMUDA

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE

POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR ADDITIONAL STORM INFORMATION...PLEASE MONITOR PRODUCTS ISSUED BY

THE BERMUDA WEATHER SERVICE.

DISCUSSION AND 48-HOUR OUTLOOK

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

AT 1100 AM AST...1500 UTC...THE CENTER OF HURRICANE KATIA WAS

LOCATED NEAR LATITUDE 27.0 NORTH...LONGITUDE 65.9 WEST. KATIA IS

MOVING TOWARD THE NORTHWEST NEAR 9 MPH...15 KM/H...AND THIS MOTION

IS EXPECTED TO CONTINUE THROUGH WEDNESDAY...FOLLOWED BY A TURN

TOWARD THE NORTH-NORTHWEST AND NORTH BY THURSDAY. ON THE FORECAST

TRACK...THE CORE OF KATIA IS EXPECTED TO MOVE OVER THE WESTERN

ATLANTIC BETWEEN BERMUDA AND THE EAST COAST OF THE UNITED STATES.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 120 MPH...195

KM/H...WITH HIGHER GUSTS. KATIA IS A CATEGORY THREE HURRICANE ON

THE SAFFIR-SIMPSON HURRICANE WIND SCALE. FLUCTUATIONS IN INTENSITY

ARE POSSIBLE THROUGH WEDNESDAY...AND WEAKENING IS EXPECTED BY

WEDNESDAY NIGHT AND THURSDAY. A HURRICANE HUNTER AIRCRAFT WILL

CHECK THE INTENSITY OF KATIA THIS AFTERNOON.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 65 MILES...100 KM...FROM

THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205

MILES...335 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 954 MB...28.17 INCHES.

HAZARDS AFFECTING LAND

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

SURF...LARGE SWELLS GENERATED BY KATIA WILL CONTINUE TO AFFECT MOST

OF THE EAST COAST OF THE UNITED STATES...BERMUDA...THE GREATER

ANTILLES...AND EAST-FACING BEACHES OF THE BAHAMAS DURING THE NEXT

FEW DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF

AND RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL

WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION.

WIND...TROPICAL-STORM-FORCE WINDS...ESPECIALLY IN GUSTS...ARE

POSSIBLE ON BERMUDA THROUGH THURSDAY.

RAINFALL...KATIA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF

1 TO 2 INCHES ACROSS BERMUDA.

NEXT ADVISORY

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

NEXT INTERMEDIATE ADVISORY...200 PM AST.

NEXT COMPLETE ADVISORY...500 PM AST.

$$

FORECASTER BERG/AVILA

[AderynCoch]

I am not sure whether there has been an ERC or just a collapse of the eye due to dry air, it's difficult to judge.

The latest NHC discussion confirms the eyewall replacement and subsequent expansion of wind radii (this in turn making gradual changes in intensity more likely):

"MICROWAVE IMAGERY FROM OVERNIGHT INDICATES THAT KATIA HAS GONE

THROUGH A CLASSIC EYEWALL REPLACEMENT WITH A WIDE RING OF DEEP

CONVECTION ENCLOSING A SMALLER AND ERODING INNER EYEWALL. AS WOULD

BE EXPECTED IN A CASE LIKE THIS...DVORAK FINAL T-NUMBERS HAVE

DECREASED TO BETWEEN 5.0 AND 5.5...AND CI NUMBERS REMAIN AT 6.0.

THE INITIAL INTENSITY IS BEING SET AT 105 KT BASED ON A BLEND OF

THESE NUMBERS. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS

SCHEDULED TO INVESTIGATE KATIA THIS AFTERNOON.

ALTHOUGH THE CENTER OF KATIA CONTINUES TO WOBBLE...THE SMOOTHED

INITIAL MOTION IS 310/9 KT. THERE HAS BEEN LITTLE CHANGE IN THE

TRACK FORECAST OR THE REASONING BEHIND IT. THE HURRICANE IS STILL

EXPECTED TO MAKE A TURN TOWARD THE NORTH-NORTHWEST AND NORTH OVER

THE NEXT 2 DAYS AS IT IS STEERED BETWEEN THE BERMUDA HIGH AND A

CLOSED MID- TO UPPER-LEVEL LOW OVER THE TENNESSEE AND OHIO VALLEYS.

THE GUIDANCE HAS SHIFTED SOMEWHAT TO THE NORTHWEST AT 72 HOURS...

SUGGESTING THAT THE RE-CURVATURE MAY NOT BE QUITE AS SHARP AS

PREVIOUSLY SHOWN. THE OFFICIAL FORECAST HAS BEEN NUDGED IN THAT

DIRECTION BUT LIES TO THE SOUTHEAST OF THE TVCA AND EXPERIMENTAL

TV15 CONSENSUS MODELS. AFTER 72 HOURS...KATIA IS EXPECTED TO

BECOME EMBEDDED IN THE MID-LATITUDE WESTERLIES. THE MODELS ARE

STILL SHOWING SOME DIVERGENCE IN SPEED AT 96 AND 120 HOURS...BUT

THE SPREAD IS NOT AS LARGE AS IT HAS BEEN IN PREVIOUS DAYS. ONLY A

SLIGHT NORTHWARD ADJUSTMENT WAS REQUIRED AT DAY 5.

SINCE KATIA IS GOING THROUGH AN EYEWALL REPLACEMENT AND WILL BE LEFT

WITH A LARGE RADIUS OF MAXIMUM WINDS...THE MOST LIKELY SCENARIO

WOULD BE FOR THE HURRICANE TO CHANGE LITTLE IN STRENGTH IN THE

SHORT TERM. GRADUAL WEAKENING SHOULD COMMENCE BY 36 HOURS AS KATIA

IS EXPECTED TO BE MOVING OVER WATERS OF LOWER OCEANIC HEAT CONTENT

OVER THE WESTERN ATLANTIC...AND POSSIBLY BE AFFECTED BY STRONGER

SHEAR. BY DAYS 4 AND 5...BAROCLINIC FORCING SHOULD PREVENT KATIA

FROM WEAKENING TOO MUCH...EVEN OVER COLDER WATERS...AND THE CYCLONE

IS FORECAST TO BE A POWERFUL EXTRATROPICAL STORM OVER THE NORTH

ATLANTIC. THE INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT...AND

THE OFFICIAL FORECAST IS MAINLY JUST AN UPDATE OF THE PREVIOUS

FORECAST."

http://www.nhc.noaa....l/061445.shtml?

[Iceberg]

Recon are in and have pressure around 958mb

Re etc I would like to see evidence before committing to it, the nhc are probably right but I have a feeling that the eye wall just collapsed due to dry air and as yet no new eye wall has replaced it recon should be able to confirm soon