ATL: KATIA - Post Tropical - Discussion

[gatorcane]

00z tropical models:

[TYNI]

00z tropical models:

Gonna be a close call...

[TYNI]

It looks to me a bit west and possibly south of the position given, but admittedly quite hard to tell. Does seem to be moving rather rapidly.

Not sure how the dry air ahead will affect it, as it moves WNW...



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[SouthFloridawx]

The models are pretty close together on this one looking at the models.

[hurricaneCW]

Wow great model agreement with this one but yeah and more west shifts and the E.C could be in danger once again although right now I'm thinking a 20% curve between 55-60W (fish), 30% 60-65W (Bermuda?), 30% 65-70W (E. Canada), 10% 70-75W (New England, Eastern Canada), and 10% EC hit 75-80W (Carolinas north).

[TheBurn]

01:00Z MPE Katia

[CrazyC83]

Gaining latitude, interesting...

[Hybridstorm_November2001]

*sigh* NOT again, now I know how people in other parts of the basin felt during past seasons.

[cycloneye]

Gaining latitude, interesting...

Why you say is interesting?

[CrazyC83]

I would be STUNNED if I go from 27 years and 11 months of no hurricanes to 2 weeks with 2 hurricanes.

[Hybridstorm_November2001]

I would be STUNNED if I go from 27 years and 11 months of no hurricanes to 2 weeks with 2 hurricanes.

It has happened, at least, twice before (two storms hitting the NE, within a month or less of each other). Check out the storm dates in the below two links:

http://weather.unisys.com/hurricane/atlantic/1869/index.html

http://weather.unisys.com/hurricane/atlantic/1954/index.html

[CrazyC83]

I would be STUNNED if I go from 27 years and 11 months of no hurricanes to 2 weeks with 2 hurricanes.

It has happened, at least, twice before (two storms hitting the NE, within a month or less of each other). Check out the storm dates in the below two links:

http://weather.unisys.com/hurricane/atlantic/1869/index.html

http://weather.unisys.com/hurricane/atlantic/1954/index.html

It would have to be west of about 73W to reach me. But that just might happen?

[gatorcane]

Gaining latitude, interesting...

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Yes it looks like is now. Models seem to be in excellent agreement on a west-northwest track which would take this system north of the Leewards.

The global models did shift some to the west today and it will be prudent to look at a few more cycles, but it does appear right now there is a decent chance it misses the Leewards to the north.

In this case, unlike Irene, the center is well-defined, and the cyclone is moving in the direction it should be right now as shown by the XTRAP, so my confidence is higher.

I still will want to look at a few more model run cycles before being certain.

[Patrick99]

Anyone think these models are too north too soon? Has this really detached itself from the ITCZ yet?

[cycloneye]

DATE/TIME LAT LON CLASSIFICATION STORM
30/0000 UTC 10.8N 29.1W T2.5/2.5 12L

Perhaps more importantly:

DATE/TIME LAT LON CLASSIFICATION STORM
30/0000 UTC 10.8N 29.1W T2.5/2.5 12L

Looks like it's gaining latitude, peeps.

The most important thing is that we dont need a hurricane making landfall in the islands,especially,if it is gong to be strong as forecast. And in my case in PR,already in 2011 it has been very bad with Emily and Irene.

[HurricaneMaster_PR]

Not Katia yet

BULLETIN
TROPICAL DEPRESSION TWELVE ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST MON AUG 29 2011

...DEPRESSION COULD BECOME A TROPICAL STORM LATER TONIGHT OVER THE
FAR EASTERN TROPICAL ATLANTIC...

[SouthDadeFish]

Convection is increasing over the center:

[cycloneye]

BULLETIN
TROPICAL DEPRESSION TWELVE ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST MON AUG 29 2011

...DEPRESSION COULD BECOME A TROPICAL STORM LATER TONIGHT OVER THE
FAR EASTERN TROPICAL ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...11.0N 30.0W
ABOUT 460 MI...740 KM SW OF THE SOUTHERNMOST CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL DEPRESSION TWELVE
WAS LOCATED NEAR LATITUDE 11.0 NORTH...LONGITUDE 30.0 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 15 MPH...24
KM/H. THIS GENERAL MOTION ACCOMPANIED BY A GRADUAL INCREASE IN
FORWARD SPEED IS EXPECTED OVER THE NEXT 48 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. STRENGTHENING IS FORECAST DURING THE NEXT COUPLE OF
DAYS...AND THE DEPRESSION COULD BECOME A TROPICAL STORM EARLY
TUESDAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM AST.

$$
FORECASTER STEWART



TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122011
1100 PM AST MON AUG 29 2011

AT THE TIME OF THE SATELLITE FIXES AT 00Z...A LARGE CURVED
CONVECTIVE BAND WRAPPED ABOUT HALF WAY AROUND THE CIRCULATION...
WHICH RESULTED IN SATELLITE INTENSITY ESTIMATES OF T2.5/35 KT FROM
SAB AND T2.0/30 KT WITH A DATA-T NUMBER OF 2.5/35 KT FROM TAFB.
HOWEVER...SINCE THAT TIME THE CURVED BAND HAS DISSIPATED...AND THE
CONVECTIVE PATTERN HAS DEVOLVED INTO MORE OF A SHEAR PATTERN. A
SMALL BURST OF DEEP CONVECTION HAS DEVELOPED OVER AND JUST WEST OF
THE CENTER...BUT ONE THUNDERSTORM DOES NOT MAKE A TROPICAL STORM.
THEREFORE...THE INTENSITY IS BEING HELD AT 30 KT FOR THIS ADVISORY.

THE INITIAL MOTION IS NOW 290/13 KT BASED ON A BLEND OF VISIBLE AND
MICROWAVE SATELLITE FIXES. THE GLOBAL AND REGIONAL MODELS ARE IN
EXCELLENT AGREEMENT ON A GENERAL WEST-NORTHWESTWARD MOTION OVER THE
NEXT 5 DAYS...BUT THERE ARE SPEED DIFFERENCES IN THE MODELS. THE
GFDL...UKMET...CANADIAN AND ECMWF MOVE THE DEPRESSION THE
FASTEST...WHEREAS THE GFS...HWRF...AND NOGAPS ARE SLOWER.
HOWEVER...THE TREND IN THE MOST RECENT MODEL RUNS HAS BEEN TO
WEAKEN THE MID/UPPER-LEVEL LOW NEAR 30N55W AND LIFT IT OUT TO THE
NORTHEAST SOONER THAN IN PREVIOUS RUNS. THIS RESULTS IN LESS OF A
WEAKNESS IN THE SUBTROPICAL RIDGE...WHICH IS ALSO FORECAST TO
CHANGE ITS CURRENT NORTH-SOUTH CONFIGURATION TO AN EAST-WEST
ORIENTATION BY 72 HOURS. THIS CHANGE IN THE STEERING FLOW SHOULD
KEEP THE CYCLONE MOVING ON A WEST-NORTHWESTWARD TRACK FOR THE NEXT
4 DAYS...AND THEN SLOW DOWN AND POSSIBLY TURN MORE WESTWARD BY DAY
5 AS A NARROW RIDGE DEVELOPS TO THE NORTH AND WEST OF THE SYSTEM.
SINCE THE DEPRESSION IS BASICALLY ON TRACK...THE NEW NHC FORECAST
IS JUST AN UPDATE AND EXTENSION OF THE PREVIOUS ADVISORY TRACK.

THE EROSION OF CONVECTIVE BANDING FEATURES HAS LIKELY BEEN DUE A
NARROW INTRUSION OF DRY AIR COMING IN THE FROM THE NORTHEAST.
HOWEVER...ALL AVAILABLE DIAGNOSTIC AND MODEL FORECAST DATA INDICATE
THAT THE CYCLONE IS SURROUNDED BY VERY MOIST MID-LEVEL AIR WITH
HUMIDITY VALUES OF 70 PERCENT OR HIGHER...WHICH SHOULD ALLOW FOR
DEEP CONVECTION TO RECOVER LATER TONIGHT AND FOR THE SYSTEM TO
REACH TROPICAL STORM STATUS WITHIN THE NEXT 6-12 HOURS. MODERATE
NORTHEASTERLY SHEAR IS ALSO FORECAST TO AFFECT THE CYCLONE FOR THE
NEXT 24 HOURS OR SO...WHICH SHOULD INHIBIT ANY RAPID DEVELOPMENT.
AFTER THAT...HOWEVER...THE SHEAR IS EXPECTED TO SHARPLY DECREASE...
AND AN UPPER-LEVEL ANTICYCLONE IS FORECAST TO DEVELOP OVER THE
SURFACE CIRCULATION. THIS IMPROVEMENT IN THE VENTILATION PROCESS
SHOULD ALLOW FOR THE CYCLONE TO AT LEAST STEADILY INTENSIFY AND
BECOME A HURRICANE IN 48-72 HOURS AS SUGGESTED BY THE SHIPS...
LGEM...HWRF...AND GFDL MODELS.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0300Z 11.0N 30.0W 30 KT 35 MPH
12H 30/1200Z 11.8N 32.0W 35 KT 40 MPH
24H 31/0000Z 12.8N 34.7W 45 KT 50 MPH
36H 31/1200Z 13.9N 37.8W 50 KT 60 MPH
48H 01/0000Z 14.8N 41.5W 60 KT 70 MPH
72H 02/0000Z 16.4N 47.5W 70 KT 80 MPH
96H 03/0000Z 18.3N 52.9W 80 KT 90 MPH
120H 04/0000Z 20.0N 57.0W 90 KT 105 MPH

$$
FORECASTER STEWART

[SouthDadeFish]

For all the heat Stewart takes about being aggressive on intensity, he decided to not upgrade this storm yet.

[SouthDadeFish]

I found this passage from the discussion particularly interesting...

THIS CHANGE IN THE STEERING FLOW SHOULD
KEEP THE CYCLONE MOVING ON A WEST-NORTHWESTWARD TRACK FOR THE NEXT
4 DAYS...AND THEN SLOW DOWN AND POSSIBLY TURN MORE WESTWARD BY DAY
5 AS A NARROW RIDGE DEVELOPS TO THE NORTH AND WEST OF THE SYSTEM.