ATL: KATIA - Post Tropical - Discussion

[CharlestonDoc]

Beach erosion is definitely a real issue. We actually had a fair amount of beach damage and erosion just from the bit of Irene that swiped us here in Charleston, SC.

Why is it a "recurve" rather than just a curve? I've been wondering this for years. When did it curve the first time? Is it that it curves north and then northeast?

Recurve indicates a bend back towards the origination point. In this case, any storm that curves back towards it's developed longitude in this case is said to have recurved. In the N. Hemisphere in the atlantic ocean that often means that for a storm to have recurved, it means it has to have gone East instead of West. That also means technically storms like Lenny or Vince which began moving east after developing did not recurve in it's true definition.

The bulk of storms all at some point recurve due to the fact that they detach from the easterly trade winds and head north due to the Coriolis effect and meet up with the mid-latitude westerlies. So, a storm develops in say the MDR for the atlantic at 10N 35W, then curves towards the north and ends up 20N 50W, then curves again this time NE-ENE-E after hitting the westerlies and ends up say at 40N and 35W at the end of a track. That motion is known as the recurve since it came back towards it original starting Longitude.

Thank you (and others) for this explanation! I could have looked up "recurve" in the dictionary, I guess, but I learned a lot more this way

And talk about a recurve--Katia looks like she will make a sharp u-turn lol
Thank goodness!

[AHS2011]

Anyone thinking Earl?

[7&COUNTING]

Hopefully she will not cause any flooding for the OBX. They are supposed to get some pretty decent swells from her. Only time will tell I suppose.

[wxman57]

95 kts now, according to the 12Z model initialization. On its way to Cat 3 today (or more).

[RL3AO]

Eye almost 60 miles wide.

As wxman said, should be a cat 3 soon, if its not already.

[cvalkan4]

why would the Weather Channel EVER want to hype a non-existent situation,

Ratings. People really need to stop watching that 'channel'. They stopped focusing on weather over two years ago.

In defense of TWC, I would point out that coastal NC is likely to see some significant wave action from Katia, so effects on our weather are not really "non-existent."

Also, I enjoyed the in-studio discussions between Cantore and Brian Norcross when Irene was approaching. They went into a lot more depth about the models than I expected. Seems like TWC is trying a little harder lately to get back to some meteorology. I hope so.

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 05 SEP 2011 Time : 121500 UTC
Lat : 24:13:53 N Lon : 62:37:42 W


CI# /Pressure/ Vmax
5.5 / 959.1mb/102.0kt


Final T# Adj T# Raw T#
5.5 5.6 5.6

Estimated radius of max. wind based on IR : 42 km

Center Temp : +9.9C Cloud Region Temp : -66.3C

Scene Type : LARGE EYE

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 131km
- Environmental MSLP : 1015mb

Satellite Viewing Angle : 31.5 degrees

[CrazyC83]

Large eye systems often tend to be a bit weaker than Dvorak suggests.

[CrazyC83]

If Katia turns early, could it stay strong in the north-central Atlantic and threaten the Azores post-recurve?

[cpdaman]

ive gotta hand it to the GFS on this one.....schooling euro. yup it did.euro was slow and sw and caved to gfs. gfs owned katia

[northtxboy]

i dont know about you guys but I dont trust katia or any of these models at this time. Remember Irene? she was supposed to nail florida, SC with a direct hit. It wasnt untill recon went in and got some fresh data for the models that we saw the hard shift to the east. Even the almighty eruo was wrong untill the fresh data.

[HurricaneWarning92]

The eye is huge...

[Boriken]

Eye starting to shrink? looks amazing.

[OuterBanker]

Thank God that Katia will be a fish. She will probably kick up some waves as she passes well off shore and maybe cause some beach erosion. But she will be far enough away that we probably won't even see the clouds from her. I really don't think anyone on the east coast could take a second strike right now. And with any luck, it will be the last threat of this year. Lee's rains do concern me, hopefully the areas that received excessive rains from Irene will not see much from Lee.

[bobbisboy]

Eye starting to shrink? looks amazing.

Yes, and it looks like there are mini vortices within the eye itself

[SouthDadeFish]

Yes, and it looks like there are mini vortices within the eye itself

Yes I noticed that as well. Kind of reminds me of Isabel with the large eye. I'm not saying she is a cat 5 though.

[cycloneye]

BULLETIN
HURRICANE KATIA ADVISORY NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 AM AST MON SEP 05 2011

...KATIA STRENGTHENS AND DEVELOPS A LARGE EYE...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.6N 63.3W
ABOUT 540 MI...870 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...110 MPH...175 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...965 MB...28.50 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 AM AST...1500 UTC...THE CENTER OF HURRICANE KATIA WAS
LOCATED NEAR LATITUDE 24.6 NORTH...LONGITUDE 63.3 WEST. KATIA
IS MOVING TOWARD THE NORTHWEST NEAR 13 MPH...20 KM/H...AND THIS
GENERAL MOTION WITH A SLIGHT DECREASE IN FORWARD SPEED IS EXPECTED
THROUGH WEDNESDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 110 MPH...175 KM/H...
WITH HIGHER GUSTS. KATIA IS A CATEGORY TWO HURRICANE ON THE
SAFFIR-SIMPSON HURRICANE WIND SCALE. ADDITIONAL STRENGTHENING IS
FORECAST...AND KATIA COULD BECOME A MAJOR HURRICANE LATER TODAY.

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 965 MB...28.50 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...500 PM AST.

$$
FORECASTER BERG


HURRICANE KATIA DISCUSSION NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 AM AST MON SEP 05 2011

KATIA APPEARS TO HAVE GONE THROUGH AN EYEWALL REPLACEMENT AND NOW
HAS A 30 N MI WIDE EYE SURROUNDED BY A RELATIVELY NARROW BAND OF
THE COLDEST CLOUD TOPS. DVORAK INTENSITY ESTIMATES HAVE RISEN TO
T5.0 FROM TAFB AND SAB...AND THE OBJECTIVE NUMBERS ARE AT T5.5.
THE INITIAL INTENSITY IS THEREFORE BEING RAISED TO 95 KT.

THE EYE HAS BEEN WOBBLING A BIT...BUT THE 12-HOUR SMOOTHED MOTION IS
310/11 KT. KATIA IS MOVING AROUND THE SOUTHWESTERN PERIPHERY OF A
CENTRAL ATLANTIC MID-LEVEL ANTICYCLONE AND TOWARDS DEEP-LAYER
TROUGHING OVER THE EASTERN UNITED STATES AND WESTERN ATLANTIC. THE
TRACK GUIDANCE IS IN GOOD AGREEMENT IN MAINTAINING A NORTHWESTWARD
HEADING WITH SOME DECREASE IN FORWARD SPEED DURING THE FIRST 48
HOURS. ALTHOUGH ALL THE GUIDANCE SHOWS SHARP RE-CURVATURE BETWEEN
BERMUDA AND THE U.S. EAST COAST IN ABOUT 3 DAYS...THERE IS STILL A
LARGE DIVERGENCE IN FORWARD SPEED WITH GREATER-THAN-NORMAL SPREAD
AT DAYS 4 AND 5. FOR THIS CYCLE...THE GUIDANCE IS BOUNDED BY THE
SLOWER-MOVING ECMWF AND UKMET...AND THE FASTER-MOVING GFS. IF
TRENDS FROM THE PAST FEW DAYS CONTINUE TODAY...I WOULD EXPECT
THE 12Z GUIDANCE TO SHOW LESS SPREAD AND FOR NOW WILL MAINTAIN THE
OFFICIAL FORECAST AS BEING SLOWER THAN THE CONSENSUS MODELS.

THE UPPER-LEVEL ENVIRONMENT NEAR KATIA APPEARS CONDUCIVE FOR FURTHER
STRENGTHENING OVER THE NEXT SEVERAL DAYS. HOWEVER...WITHIN THE NEXT
24 HOURS OR SO...THE HURRICANE WILL BE MOVING OVER OCEAN HEAT
CONTENT VALUES THAT DO NOT NORMALLY SUPPORT SIGNIFICANT
INTENSIFICATION. THE OFFICIAL FORECAST THEREFORE INDICATES GRADUAL
STRENGTHENING OVER THE NEXT 24 HOURS AND THEN MAINTAINS THE
INTENSITY THROUGH DAYS 2 AND 3. WEAKENING IS FORECAST ON DAYS 4
AND 5 AS VERTICAL SHEAR INCREASES...AND AS KATIA MOVES OVER EVEN
LESS CONDUCIVE OCEAN WATERS. THE OFFICIAL INTENSITY FORECAST IS AT
THE UPPER END OF THE GUIDANCE FOR MOST OF THE FORECAST PERIOD.

DUE TO THE EYEWALL REPLACEMENT...IT APPEARS THAT THE WIND FIELD HAS
EXPANDED A BIT...AND THIS IS REFLECTED IN THE ANALYSIS AND FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT 05/1500Z 24.6N 63.3W 95 KT 110 MPH
12H 06/0000Z 25.6N 64.2W 100 KT 115 MPH
24H 06/1200Z 26.9N 65.7W 105 KT 120 MPH
36H 07/0000Z 28.1N 67.3W 105 KT 120 MPH
48H 07/1200Z 29.2N 68.7W 100 KT 115 MPH
72H 08/1200Z 32.5N 70.5W 95 KT 110 MPH
96H 09/1200Z 37.0N 67.5W 80 KT 90 MPH
120H 10/1200Z 40.0N 60.0W 70 KT 80 MPH

$$
FORECASTER BERG

[cycloneye]

...KATIA STRENGTHENS AND DEVELOPS A LARGE EYE...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.6N 63.3W
ABOUT 540 MI...870 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...110 MPH...175 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...965 MB...28.50 INCHES

[Time_Zone]

.....You cant honestly convince me that Katia isnt a major hurricane right now, she looks beautiful.

[bobbisboy]

.....You cant honestly convince me that Katia isnt a major hurricane right now, she looks beautiful.

Agreed, the eye is already tightening and the highest cloud tops are nearly surrounding the eye...

the very best she's looked... No shock here if she busts the NHC intensity forecast....(CAT 4) imo

not a professional but this is what my eyes are seeing as relates to current presentation