Tropical Depression Dorian

[phil882]

000

WTNT44 KNHC 240841

TCDAT4

TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 1

NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013

500 AM EDT WED JUL 24 2013

GEOSTATIONARY SATELLITE IMAGES SHOW THAT THE DEEP CONVECTION

ASSOCIATED WITH THE LOW PRESSURE SYSTEM OVER THE EASTERN ATLANTIC

HAS INCREASED IN COVERAGE AND BECOME MORE CONCENTRATED NEAR THE

CENTER OVERNIGHT AND EARLY THIS MORNING. EARLIER SCATTEROMETER

DATA INDICATED THAT THE SYSTEM HAD A WELL-DEFINED CENTER AND

MAXIMUM WINDS OF AROUND 30 KT. BASED ON THESE DATA...THE SYSTEM IS

NOW BEING CLASSIFIED AS A TROPICAL DEPRESSION.

THE DEPRESSION IS MOVING WEST-NORTHWESTWARD OR 285 DEGREES AT

17 KT. THE CYCLONE IS EXPECTED TO BE STEERED WESTWARD OR WEST-

NORTHWESTWARD TO THE SOUTH OF A LARGE DEEP-LAYER RIDGE OVER

THE CENTRAL AND EASTERN ATLANTIC. THE DYNAMICAL MODEL GUIDANCE

IS IN VERY GOOD AGREEMENT ON THIS SCENARIO...ALTHOUGH THERE ARE

SOME DIFFERENCES IN HOW FAST THE CYCLONE MOVES WESTWARD. THE GFS

AND ECMWF SHOW A FASTER FORWARD MOTION THAN MOST OF THE OTHER

TRACK MODELS. AS A RESULT...THE NHC FORECAST LEANS TOWARD THESE

TYPICALLY RELIABLE MODELS AND SHOWS A FASTER WESTWARD MOTION THAN

THE MULTI-MODEL CONSENSUS.

THE INTENSITY FORECAST IS OF LOWER CONFIDENCE THAN THE TRACK

FORECAST. ALTHOUGH THE SHEAR IS EXPECTED TO REMAIN LOW DURING THE

NEXT FEW DAYS...THE CYCLONE WILL BE MOVING OVER SLIGHTLY COOLER

WATERS AND INTO A LITTLE DRIER ENVIRONMENT OVER THE NEXT

DAY OR TWO. THEREFORE...ONLY SLIGHT STRENGTHENING IS INDICATED

IN THE NHC FORECAST. LATER IN THE FORECAST PERIOD...THE CYCLONE

IS EXPECTED TO APPROACH AN UPPER-LEVEL TROUGH OVER THE WEST-CENTRAL

ATLANTIC WHICH COULD CAUSE AN INCREASE IN SOUTHWESTERLY SHEAR.

BECAUSE OF THIS...THE NHC FORECAST SHOWS LITTLE CHANGE IN STRENGTH

DURING THE 3 TO 5 DAY TIME PERIOD.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 13.9N 28.1W 30 KT 35 MPH

12H 24/1800Z 14.6N 30.8W 35 KT 40 MPH

24H 25/0600Z 15.5N 34.4W 40 KT 45 MPH

36H 25/1800Z 16.2N 37.8W 40 KT 45 MPH

48H 26/0600Z 16.8N 41.2W 40 KT 45 MPH

72H 27/0600Z 18.2N 49.0W 40 KT 45 MPH

96H 28/0600Z 19.3N 56.5W 40 KT 45 MPH

120H 29/0600Z 20.0N 62.0W 40 KT 45 MPH

$

FORECASTER BROWN

[Srain]

000

WTNT44 KNHC 240841

TCDAT4

TROPICAL DEPRESSION FOUR DISCUSSION NUMBER 1

NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013

500 AM EDT WED JUL 24 2013

GEOSTATIONARY SATELLITE IMAGES SHOW THAT THE DEEP CONVECTION

ASSOCIATED WITH THE LOW PRESSURE SYSTEM OVER THE EASTERN ATLANTIC

HAS INCREASED IN COVERAGE AND BECOME MORE CONCENTRATED NEAR THE

CENTER OVERNIGHT AND EARLY THIS MORNING. EARLIER SCATTEROMETER

DATA INDICATED THAT THE SYSTEM HAD A WELL-DEFINED CENTER AND

MAXIMUM WINDS OF AROUND 30 KT. BASED ON THESE DATA...THE SYSTEM IS

NOW BEING CLASSIFIED AS A TROPICAL DEPRESSION.

THE DEPRESSION IS MOVING WEST-NORTHWESTWARD OR 285 DEGREES AT

17 KT. THE CYCLONE IS EXPECTED TO BE STEERED WESTWARD OR WEST-

NORTHWESTWARD TO THE SOUTH OF A LARGE DEEP-LAYER RIDGE OVER

THE CENTRAL AND EASTERN ATLANTIC. THE DYNAMICAL MODEL GUIDANCE

IS IN VERY GOOD AGREEMENT ON THIS SCENARIO...ALTHOUGH THERE ARE

SOME DIFFERENCES IN HOW FAST THE CYCLONE MOVES WESTWARD. THE GFS

AND ECMWF SHOW A FASTER FORWARD MOTION THAN MOST OF THE OTHER

TRACK MODELS. AS A RESULT...THE NHC FORECAST LEANS TOWARD THESE

TYPICALLY RELIABLE MODELS AND SHOWS A FASTER WESTWARD MOTION THAN

THE MULTI-MODEL CONSENSUS.

THE INTENSITY FORECAST IS OF LOWER CONFIDENCE THAN THE TRACK

FORECAST. ALTHOUGH THE SHEAR IS EXPECTED TO REMAIN LOW DURING THE

NEXT FEW DAYS...THE CYCLONE WILL BE MOVING OVER SLIGHTLY COOLER

WATERS AND INTO A LITTLE DRIER ENVIRONMENT OVER THE NEXT

DAY OR TWO. THEREFORE...ONLY SLIGHT STRENGTHENING IS INDICATED

IN THE NHC FORECAST. LATER IN THE FORECAST PERIOD...THE CYCLONE

IS EXPECTED TO APPROACH AN UPPER-LEVEL TROUGH OVER THE WEST-CENTRAL

ATLANTIC WHICH COULD CAUSE AN INCREASE IN SOUTHWESTERLY SHEAR.

BECAUSE OF THIS...THE NHC FORECAST SHOWS LITTLE CHANGE IN STRENGTH

DURING THE 3 TO 5 DAY TIME PERIOD.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 13.9N 28.1W 30 KT 35 MPH

12H 24/1800Z 14.6N 30.8W 35 KT 40 MPH

24H 25/0600Z 15.5N 34.4W 40 KT 45 MPH

36H 25/1800Z 16.2N 37.8W 40 KT 45 MPH

48H 26/0600Z 16.8N 41.2W 40 KT 45 MPH

72H 27/0600Z 18.2N 49.0W 40 KT 45 MPH

96H 28/0600Z 19.3N 56.5W 40 KT 45 MPH

120H 29/0600Z 20.0N 62.0W 40 KT 45 MPH

$

FORECASTER BROWN

[wxmeddler]

First morning light and shadows from the center is always a good thing.

[Mike.Ventrice]

I know this has been discussed on the other thread but this case is a nice example of  strong atmospheric convectively-coupled Kelvin wave passing the Atlantic and resulting in a tropical cyclone ~ 2 days after the passage over the eastern MDR.

 

This CCKW was clearly observable in upper-level circulation and hit 3 standard deviations in VP200. Below is a time-lon plot of U200 anoms with Kelvin filtered U200 ontop. Note the strong upper-level zonal wind divergence that propagated from the west across the MDR this past week. This is the strongest signal in the tropics, and it certaintly overpowered the weak-suppressed MJO state over the Atlantic.

 

[thewxmann]

Man, what if we had CCKW during a favorable MJO state..

[Mike.Ventrice]

Man, what if we had CCKW during a favorable MJO state..

It'd be like late Aug-1995 all over again  

[Ed Lizard]

Never gets all that strong, and is weakening somewhat as it enters the Bahamas per FIM9

 

[Srain]

[Srain]

We may see Dorian before too much longer.

 

 

[phil882]

We may see Dorian before too much longer.

 

07242013_1145_goes13_x_vis1km_high_04LFOUR_30kts-1008mb-136N-272W_100pc.jpg

 

07242013 12Z TS Dorian aal04_2013072412_track_early.png

 

Yep

 

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 35, 1006, TS, 34, NEQ, 30, 0, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D, 

 

The whole formative banding eyewall isn't bad either.

 

[IsentropicLift]

DVORAK estimates are 1012mb and 30kts

 

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.4
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 24 JUL 2013 Time : 124500 UTC
Lat : 14:12:46 N Lon : 29:13:25 W

CI# /Pressure/ Vmax 2.0 /1012.0mb/ 30.0kt
Final T# Adj T# Raw T#
1.8 2.0 3.4

Center Temp : -43.3C Cloud Region Temp : -47.3C

Scene Type : SHEAR (0.04^ TO DG)

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 33km
- Environmental MSLP : 1014mb

Satellite Name : MSG3
Satellite Viewing Angle : 37.4 degrees

[Eskimo Joe]

Latest satellite imagery shows some nice, robust convection wrapping around the center.

[wxmx]

It has been upgraded to TS Dorian.

[wxmx]

Well, it was renamed TS Dorian in the NHC site, then it went back to TD4

[Srain]

TROPICAL STORM DORIAN FORECAST/ADVISORY NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042013
1500 UTC WED JUL 24 2013

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 14.3N  29.9W AT 24/1500Z
POSITION ACCURATE WITHIN  20 NM

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT  18 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1002 MB
MAX SUSTAINED WINDS  45 KT WITH GUSTS TO  55 KT.
34 KT....... 40NE  30SE   0SW  30NW.
12 FT SEAS.. 45NE  30SE   0SW  30NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT.  RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 14.3N  29.9W AT 24/1500Z
AT 24/1200Z CENTER WAS LOCATED NEAR 14.0N  29.0W

FORECAST VALID 25/0000Z 15.0N  32.6W
MAX WIND  50 KT...GUSTS  60 KT.
50 KT... 20NE   0SE   0SW  20NW.
34 KT... 50NE  40SE  30SW  40NW.

FORECAST VALID 25/1200Z 15.8N  36.1W
MAX WIND  50 KT...GUSTS  60 KT.
50 KT... 20NE   0SE   0SW  20NW.
34 KT... 50NE  40SE  30SW  50NW.

FORECAST VALID 26/0000Z 16.4N  39.8W
MAX WIND  45 KT...GUSTS  55 KT.
34 KT... 50NE  40SE  30SW  50NW.

FORECAST VALID 26/1200Z 17.1N  43.4W
MAX WIND  40 KT...GUSTS  50 KT.
34 KT... 50NE  40SE  30SW  50NW.

FORECAST VALID 27/1200Z 18.3N  51.2W
MAX WIND  40 KT...GUSTS  50 KT.
34 KT... 50NE  40SE  30SW  50NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 28/1200Z 19.3N  58.2W
MAX WIND  40 KT...GUSTS  50 KT.

OUTLOOK VALID 29/1200Z 20.1N  64.0W
MAX WIND  40 KT...GUSTS  50 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 14.3N  29.9W

NEXT ADVISORY AT 24/2100Z

$$
FORECASTER STEWART


 

[Eyewall2005]

Some intensity guidance now bring Dorian to Cat2 12z

[Eskimo Joe]

Some intensity guidance now bring Dorian to Cat2 12z

Will be interesting to see if Dorian can slip far enough south of the low.

[icebreaker5221]

New GFS coming in much stronger in the 2-4 day range.

 

Edit: There appears to be less wind shear, as well as overall weaker mean flow resulting in a slower forward speed. 

[Superstorm93]

Convection is much more impressive than I was expecting to find

 

[Superstorm93]

12z guidance suggests the possibility of a clear run into the Bahamas. 

 

 

[hurricaneman]

All I can say is if the models keep upping the strength in the long run Florida needs to monitor this for next week

[eurojosh]

All I can say is if the models keep upping the strength in the long run Florida needs to monitor this for next week

 

It's quite early for that...  Does anyone know how many storms that have formed this far east have ended up impacting CONUS?  Few, I would imagine.

[Superstorm93]

GFS is finally showing something more than a wave for once. 

 

Somewhat close to the SHIPS/LGEM

 

[Amped]

Gfs back to its solution from 8 days ago.

[GaWx]

Per 7/24 12Z GFS fwiw, sighs of relief for the US as Dorian recurves east of the SE US at ~75W on 8/3-4 and misses a direct hit on Cape Cod on 8/6.

[eurojosh]

Per 7/24 12Z GFS fwiw, sighs of relief for the US as Dorian recurves east of the SE US at ~75W on 8/3-4 and misses a direct hit on Cape Cod on 8/6.

 

East Coast Surfer's Paradise...

[Eskimo Joe]

Per 7/24 12Z GFS fwiw, sighs of fail for the US as Dorian recurves east of the SE US at ~75W on 8/3-4 and misses a direct hit on Cape Cod on 8/6.

Fixed

[Ed Lizard]

Per 7/24 12Z GFS fwiw, sighs of relief for the US as Dorian recurves east of the SE US at ~75W on 8/3-4 and misses a direct hit on Cape Cod on 8/6.

 

 

I think back when he was at AccuWeather, Joe Bastardi would always say there was something wrong with the GFS model physics that would make apparent fish storms recurve to early.  Weenie baiting, maybe, but I always wanted to believe.

 

But last night, looked like Hispaniola might kill 98L/Dorian, now a near miss Cape Cod fish, splitting the difference, Daytona Beach area?  I did buy a t-shirt at RonJon's once.

 

 

Glass 5/32nd full optimistic

 

[boulderrr]

It's quite early for that...  Does anyone know how many storms that have formed this far east have ended up impacting CONUS?  Few, I would imagine.

 

I do know that, since record keeping began, there has not been a storm within 400 miles of Dorian's current position to make landfall on the U.S. prior to mid-August.

 

http://www.icatdamageestimator.com/radius-search?ActiveStorm=radius&Distance=400&x=16&y=9&ActiveStormName=Dorian

[GaWx]

Fixed

 

 When I said sighs of relief. I was thinking from the standpoint of the avg. property owner on/near the east coast (I'm one) and not from the standpoint  of the typical weenie on this BB.

 

- There have been 8 CONUS H hits from July geneses since 1995. Of these, 5 were phase 2 geneses. The other three were phase 3, phase 4, and within the circle. Like Dorian, Alex of 2004 formed when the MJO was within the circle.

 

Since 1995, 4 TC's of TS+ intensity have formed within the MDR like Dorian (east of 60W and south of 20N):

 - Bertha of '08

 - Emily of '05 (gave S TX TS winds)

 - Alex of '98

 - Bertha of '96 (direct H hit on NC)