ATL: DORIAN - Post-Tropical - Discussion

[gatorcane]

00Z Intensity Guidance. Still alot of disagreement:

[SFLcane]

Looking very impressive tonight going over those cooler sst's. As levi mentioned in his video water temps warm from here on out.

[MiamiensisWx]

There sure has been a good many EC troughs this summer. Hopefully the trend will continue and make Dorian a fish.....MGC

This is the perennial issue for us residents in FL. Since 1995 we have seen storms approach from near the islands: Erin 1995; Bertha and Fran 1996; Bonnie 1998; Dennis and Floyd 1999; Ivan 2004; Debbie 2000; TD #9 2003; Chris and Ernesto 2006; Dean 2007; Chantal, Hannah, and Ike 2008; Earl and Gaston 2010; Emily and Irene 2011; and Isaac 2012, among others. All the ones that I mentioned were once projected to approach or hit SE FL, my former residence until this year, and either recurved or were in a weakened state upon arrival. All these incidents were fortunate, but aside from Frances and Jeanne 2004--each of which, like Erin 1995, hit east-central rather than southeast FL--no storm since Katrina in 2005 has hit SE FL from an easterly component. Two of the three SE FL hurricane strikes, Irene 1999 and Wilma 2005, came from the south and southwest rather than from the east. Most of the Cape Verde menaces recurved offshore The timing of the troughs has been incredibly fortunate for SE FL, and though I now live in St. Petersburg, I am concerned about the beach erosion should a direct impact by a Cape Verde system affect SE FL. A large-sized system, even a direct Sandy-type event, would destroy structures which extend seaward from the high-tide line. Wilma and Irene came from the south and west and so did not produce the erosion that a direct strike from the Atlantic would. When will the "luck" run out? Hopefully not too soon!

[BigB0882]

New video by Levi Cowan.

http://www.tropicaltidbits.com/blog/201 ... -westward/

Thanks. I love his videos. I find it interesting that he only mentions two options, out to sea or into the East coast around the Carolinas. I find that interesting because it shows he seems pretty sure that it will eventually start recurving but the question is will it happen soon enough to miss the coast there? He doesn't seem to see any way for it to continue West into FL or into the Gulf. Not that it's impossible, but for now that doesn't seem to even be worth mentioning for him.

Florida into the GOM seems very very unlikely at this point. Its too big of a weakness for Dorian to miss on the East Coast.

Perhaps you are right. I just always hear about the ridging being stronger than expected or the trough to be weaker, etc. It always makes me wonder if there is a way for the ridge to build in and push this West into the Gulf. I never know if these weaknesses are a sure thing or not.

[BigB0882]

6 of them show the intensity decreasing after about 108 hours and 7 show intensity increasing or at least holding rather steady. Much disagreement, for sure.

[gatorcane]

Florida into the GOM seems very very unlikely at this point. Its too big of a weakness for Dorian to miss on the East Coast.

That also what I am leaning on, but it is still a bit early to make that call especially since that weakness that needs to pick this system up is still beyond about 168 hours in the model runs which are not always accurate this far out. Systems do come to mind that were supposed to recurve much sooner that did not plus the GFS is known to breakdown ridges too quickly in the long-range.

[Bocadude85]

Florida into the GOM seems very very unlikely at this point. Its too big of a weakness for Dorian to miss on the East Coast.

That also what I am leaning on, but it is still a bit early to make that call especially since that weakness that needs to pick this system up is still beyond about 168 hours in the model runs which are not always accurate this far out. Systems do come to mind that were supposed to recurve much sooner that did not plus the GFS is known to breakdown ridges too quickly in the long-range.

There is not much tropical cyclone history for Southeast Florida in the month of July so I would say most likely Dorian will miss us to the east but I would like to point out that the models were calling for a significant east coast trough a few days ago and are now backing off on the idea.. the ridge has been very persistent this year.

[cycloneye]

BULLETIN
TROPICAL STORM DORIAN ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST WED JUL 24 2013

...TRADE WINDS PUSHING DORIAN WEST-NORTHWESTWARD ACROSS THE
ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.1N 33.2W
ABOUT 615 MI...990 KM W OF THE CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 20 MPH...32 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 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 STORM DORIAN WAS
LOCATED NEAR LATITUDE 15.1 NORTH...LONGITUDE 33.2 WEST. DORIAN IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 20 MPH...32 KM/H. A WEST-
NORTHWESTWARD TO WESTWARD MOTION AT A SIMILAR FORWARD SPEED IS
EXPECTED TO CONTINUE THROUGH FRIDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.


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


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

$$
FORECASTER BERG



TROPICAL STORM DORIAN DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST WED JUL 24 2013

INFRARED SATELLITE IMAGERY INDICATES THAT THE LOW-LEVEL CENTER OF
DORIAN HAS BECOME MORE EMBEDDED BENEATH THE COLD CONVECTIVE TOPS.
DVORAK ESTIMATES FROM TAFB AND SAB ARE NOW A CONSENSUS T3.0/45 KT
WHILE UW-CIMSS OBJECTIVE ESTIMATES HAVE INCREASED TO 50-55 KT.
BASED ON RECENT ASCAT DATA...HOWEVER...DORIAN MAY NOT BE PRODUCING
SURFACE WINDS ANY HIGHER THAN ABOUT 40 KT. THIS COULD BE DUE TO
THE RESOLUTION OF ASCAT SINCE DORIAN IS A SMALL CYCLONE...SO THE
INTENSITY IS BEING HELD AT 45 KT ON THIS ADVISORY.

THE MOTION REMAINS 285/17 KT WITH DORIAN LYING ON THE WESTERN
PERIPHERY OF A NORTHWEST-TO-SOUTHEAST ORIENTED MID-LEVEL RIDGE. A
MID-LEVEL ANTICYCLONE IS EXPECTED TO DETACH FROM THE RIDGE AND MOVE
WESTWARD TO THE NORTH OF DORIAN FOR THE ENTIRE FORECAST PERIOD...
KEEPING THE TROPICAL CYCLONE ON A QUICK WEST-NORTHWESTWARD TO
WESTWARD TRAJECTORY. THERE IS VERY LITTLE SPREAD AMONG THE TRACK
MODELS ON THIS CYCLE...AND THE NEW NHC TRACK FORECAST IS VERY
SIMILAR TO THE PREVIOUS TRACK.

AN ANIMATION OF SEA SURFACE TEMPERATURE FIELDS INDICATES THAT THE
WATERS AHEAD OF DORIAN HAVE BEEN WARMING OVER THE PAST FEW
DAYS...AND IT APPEARS THAT THE CYCLONE WILL LIKELY REMAIN OVER
WATERS A LITTLE WARMER THAN PREVIOUSLY ANTICIPATED. IN
ADDITION...DORIAN SHOULD BE MOVING FAST ENOUGH THAT UPWELLING OF
COOLER WATER SHOULD NOT BE MUCH OF A FACTOR. THEREFORE...THE NEW
NHC INTENSITY FORECAST NO LONGER SHOWS SHORT-TERM WEAKENING AND
INSTEAD INDICATES SLIGHT STRENGTHENING THROUGH DAY 5. THIS
FORECAST IS JUST A LITTLE HIGHER THAN THE FLORIDA STATE
SUPERENSEMBLE AND THE INTENSITY CONSENSUS...BUT NOT NEARLY AS HIGH
AS THE STATISTICAL-DYNAMICAL SHIPS AND LGEM MODELS. CONFIDENCE IN
THE INTENSITY FORECAST IS RATHER LOW AT THIS POINT UNTIL WE KNOW
HOW DORIAN FARES OVER THE NEXT DAY OR TWO.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 15.1N 33.2W 45 KT 50 MPH
12H 25/1200Z 15.7N 35.7W 50 KT 60 MPH
24H 26/0000Z 16.5N 39.0W 50 KT 60 MPH
36H 26/1200Z 17.2N 42.5W 50 KT 60 MPH
48H 27/0000Z 17.9N 46.3W 50 KT 60 MPH
72H 28/0000Z 19.0N 54.0W 55 KT 65 MPH
96H 29/0000Z 20.0N 60.5W 55 KT 65 MPH
120H 30/0000Z 20.5N 65.5W 55 KT 65 MPH

$$
FORECASTER BERG

[gatorcane]

000
WTNT34 KNHC 250246
TCPAT4

BULLETIN
TROPICAL STORM DORIAN ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST WED JUL 24 2013

...TRADE WINDS PUSHING DORIAN WEST-NORTHWESTWARD ACROSS THE
ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...15.1N 33.2W
ABOUT 615 MI...990 KM W OF THE CAPE VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 20 MPH...32 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 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 STORM DORIAN WAS
LOCATED NEAR LATITUDE 15.1 NORTH...LONGITUDE 33.2 WEST. DORIAN IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 20 MPH...32 KM/H. A WEST-
NORTHWESTWARD TO WESTWARD MOTION AT A SIMILAR FORWARD SPEED IS
EXPECTED TO CONTINUE THROUGH FRIDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.


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


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

$$
FORECASTER BERG

[gatorcane]

000
WTNT44 KNHC 250247
TCDAT4

TROPICAL STORM DORIAN DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST WED JUL 24 2013

INFRARED SATELLITE IMAGERY INDICATES THAT THE LOW-LEVEL CENTER OF
DORIAN HAS BECOME MORE EMBEDDED BENEATH THE COLD CONVECTIVE TOPS.
DVORAK ESTIMATES FROM TAFB AND SAB ARE NOW A CONSENSUS T3.0/45 KT
WHILE UW-CIMSS OBJECTIVE ESTIMATES HAVE INCREASED TO 50-55 KT.
BASED ON RECENT ASCAT DATA...HOWEVER...DORIAN MAY NOT BE PRODUCING
SURFACE WINDS ANY HIGHER THAN ABOUT 40 KT. THIS COULD BE DUE TO
THE RESOLUTION OF ASCAT SINCE DORIAN IS A SMALL CYCLONE...SO THE
INTENSITY IS BEING HELD AT 45 KT ON THIS ADVISORY.

THE MOTION REMAINS 285/17 KT WITH DORIAN LYING ON THE WESTERN
PERIPHERY OF A NORTHWEST-TO-SOUTHEAST ORIENTED MID-LEVEL RIDGE. A
MID-LEVEL ANTICYCLONE IS EXPECTED TO DETACH FROM THE RIDGE AND MOVE
WESTWARD TO THE NORTH OF DORIAN FOR THE ENTIRE FORECAST PERIOD...
KEEPING THE TROPICAL CYCLONE ON A QUICK WEST-NORTHWESTWARD TO
WESTWARD TRAJECTORY. THERE IS VERY LITTLE SPREAD AMONG THE TRACK
MODELS ON THIS CYCLE...AND THE NEW NHC TRACK FORECAST IS VERY
SIMILAR TO THE PREVIOUS TRACK.

AN ANIMATION OF SEA SURFACE TEMPERATURE FIELDS INDICATES THAT THE
WATERS AHEAD OF DORIAN HAVE BEEN WARMING OVER THE PAST FEW
DAYS...AND IT APPEARS THAT THE CYCLONE WILL LIKELY REMAIN OVER
WATERS A LITTLE WARMER THAN PREVIOUSLY ANTICIPATED. IN
ADDITION...DORIAN SHOULD BE MOVING FAST ENOUGH THAT UPWELLING OF
COOLER WATER SHOULD NOT BE MUCH OF A FACTOR. THEREFORE...THE NEW
NHC INTENSITY FORECAST NO LONGER SHOWS SHORT-TERM WEAKENING AND
INSTEAD INDICATES SLIGHT STRENGTHENING THROUGH DAY 5. THIS
FORECAST IS JUST A LITTLE HIGHER THAN THE FLORIDA STATE
SUPERENSEMBLE AND THE INTENSITY CONSENSUS...BUT NOT NEARLY AS HIGH
AS THE STATISTICAL-DYNAMICAL SHIPS AND LGEM MODELS. CONFIDENCE IN
THE INTENSITY FORECAST IS RATHER LOW AT THIS POINT UNTIL WE KNOW
HOW DORIAN FARES OVER THE NEXT DAY OR TWO.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 15.1N 33.2W 45 KT 50 MPH
12H 25/1200Z 15.7N 35.7W 50 KT 60 MPH
24H 26/0000Z 16.5N 39.0W 50 KT 60 MPH
36H 26/1200Z 17.2N 42.5W 50 KT 60 MPH
48H 27/0000Z 17.9N 46.3W 50 KT 60 MPH
72H 28/0000Z 19.0N 54.0W 55 KT 65 MPH
96H 29/0000Z 20.0N 60.5W 55 KT 65 MPH
120H 30/0000Z 20.5N 65.5W 55 KT 65 MPH

$$
FORECASTER BERG

[gatorcane]

[cycloneye]

Interesting excerpt of 11 PM discussion about the sst's.

AN ANIMATION OF SEA SURFACE TEMPERATURE FIELDS INDICATES THAT THE
WATERS AHEAD OF DORIAN HAVE BEEN WARMING OVER THE PAST FEW
DAYS...AND IT APPEARS THAT THE CYCLONE WILL LIKELY REMAIN OVER
WATERS A LITTLE WARMER THAN PREVIOUSLY ANTICIPATED. IN
ADDITION...DORIAN SHOULD BE MOVING FAST ENOUGH THAT UPWELLING OF
COOLER WATER SHOULD NOT BE MUCH OF A FACTOR. THEREFORE...THE NEW
NHC INTENSITY FORECAST NO LONGER SHOWS SHORT-TERM WEAKENING AND
INSTEAD INDICATES SLIGHT STRENGTHENING THROUGH DAY 5.

[Blown Away]

Florida into the GOM seems very very unlikely at this point. Its too big of a weakness for Dorian to miss on the East Coast.

That also what I am leaning on, but it is still a bit early to make that call especially since that weakness that needs to pick this system up is still beyond about 168 hours in the model runs which are not always accurate this far out. Systems do come to mind that were supposed to recurve much sooner that did not plus the GFS is known to breakdown ridges too quickly in the long-range.

There is not much tropical cyclone history for Southeast Florida in the month of July so I would say most likely Dorian will miss us to the east but I would like to point out that the models were calling for a significant east coast trough a few days ago and are now backing off on the idea.. the ridge has been very persistent this year.

IF Dorian were to visit SFL it will happen in August, so using July climatology doesn't apply...

NHC track still almost due west day 4/5, but at 20/65 is when GFS started pulling NW...

[bzukajo]

Sorry if I am ignorant, but what is the UKM picking up on?

[meriland23]

Uploaded with ImageShack.us

Apparently NHC found waters to be warmer than they expected them to be.

[floridasun78]

i dont see nhc talking about shear vat 11pm avd plus their say DORIAN may stay longer warmer water that big change at 11pm

[ozonepete]

Interesting excerpt of 11 PM discussion about the sst's.

AN ANIMATION OF SEA SURFACE TEMPERATURE FIELDS INDICATES THAT THE WATERS AHEAD OF DORIAN HAVE BEEN WARMING OVER THE PAST FEW
DAYS...AND IT APPEARS THAT THE CYCLONE WILL LIKELY REMAIN OVER WATERS A LITTLE WARMER THAN PREVIOUSLY ANTICIPATED. IN
ADDITION...DORIAN SHOULD BE MOVING FAST ENOUGH THAT UPWELLING OF COOLER WATER SHOULD NOT BE MUCH OF A FACTOR. THEREFORE...THE NEW
NHC INTENSITY FORECAST NO LONGER SHOWS SHORT-TERM WEAKENING AND INSTEAD INDICATES SLIGHT STRENGTHENING THROUGH DAY 5.

Hmmm. A few of us have been saying since yesterday that SSTs were not going to be a factor. Maybe a lucky guess? Anyway each new forecast shows shear to be less of a problem than originally thought and there are also indications that mid-levels will be pretty moist all the way to the islands now. This is making it a lot more likely that Dorian can make hurricane status in the next few days. Let's hope that it stays north of the islands. Luckily all of the models are still in really tight agreement that it will.

[meriland23]

i dont see nhc talking about shear vat 11pm avd plus their say DORIAN may stay longer warmer water that big change at 11pm

I agree, I noticed that too. In fact, they didn't mention really any negative effects towards it.. not even dry air.. which is unusual, they usually mention that on updates.. but if it is strengthening at 120 hrs, obviously the warmer waters and other factors working to help strengthen it are overpowering the shear/dry air.. that or the things working against it are not as potent as once forecasted.... just a opinion..

[gatorcane]

Here is the 12Z GFS 500MB steering at 180 hours which is the steering that generally steers hurricanes. You can see Dorian there just north of Puerto Rico.

There is a weakness there along the East Coast of the United States caused by a shortwave moving eastward north of the Great Lakes but I wouldn't call this the "all clear" weakness by any means. For one thing this is 180 hours out. For another, it wouldn't take much for the Atlantic ridge to build a bit more westward as others have pointed out or for that weakness to not end up developing causing the cyclone to be steered further west.

Something to watch for sure in subsequent GFS runs...

[bzukajo]

There is no such thing as bad data. Even if totally wrong in a predictive sense, I really want to know the variables and the path of resolution for the UMK model.