Tropical Depression Dorian

[Snow_Miser]

00z ATCF has Dorian at 50 kt/60 mph and 1000 mb. Continues to gradually intensify it seems.

[Superstorm93]

Looks like we can expect the GFS to stop with the hurricane intensity garbage tomorrow @ 12z 

 

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD
1502Z WED JUL 24 2013


DUE TO THE THREAT OF CWD NEXT WEEK FOR THE TROPICAL SYSTEM IN THE
ATLANTIC, NCEP/NCO IS MOVING THE "GO LIVE" OF THE NEW WCOSS
SUPERCOMPUTERS UP TO TOMORROW, THURSDAY 7/25.

THE PRODUCTION SUITE ON WCOSS SYSTEM TIDE WILL BEGIN SENDING OUT
THE OFFICIAL OPERATIONAL PRODUCTS AT ROUGHLY 1230Z. DATA
DISSEMINATION FROM THE CURRENT CCS SUPERCOMPUTER WILL CEASE AT
THAT POINT, ALTHOUGH A FEW MODELS WILL CONTINUE TO COME FROM THE
CCS AS THEY BLEED OFF OVER THE FIRST FEW HOURS AFTER THE SWITCH
TO WCOSS SYSTEM TIDE.

 

AL, 04, 2013072500, , BEST, 0, 149N, 324W, 50, 1000, TS

 

[hurricaneman]

This is strengthening over cooler waters, that could be bad news in a few days as at that time it will have more octane to work with and no one should let their guard down after a week as if the ridge is stronger than modeled this could hit Florida or the eastern gulf or close to modeled it could hit the Carolinas to the Northeast or even the Canadian Maritimes

[Ed Lizard]

This is strengthening over cooler waters, that could be bad news in a few days as at that time it will have more octane to work with and no one should let their guard down after a week as if the ridge is stronger than modeled this could hit Florida or the eastern gulf or close to modeled it could hit the Carolinas to the Northeast or even the Canadian Maritimes

 

Gulf to the Canadian Maritimes.  Got it.

 

 

BTW, anybody NOAA-ish have the number to whoever does the SSD floaters?  They are still using the Euro satellite, and I want to see Dorian in frequently updating cold clouds topped glory.

[DopplerWx]

Let's just remember this thing has a long ways to go and a few more obstacles to overcome.  I'll be happy if she just keeps some semblance of a core over the next 7 days.

[TropicalAnalystwx13]

I'm surprised at how well Dorian is doing. It's currently passing over what should be the coldest waters of its existence, 25C, and still firing decent convection over its center. I would not be surprised at all to see this system become a bit stronger than forecast both in the short-term and in the longer term.

 

The GFS indicates there should be an upper-level trough in the Bahamas region in a few days, but if Dorian is a formidable tropical storm or minimal hurricane, it could bust through this and continue to intensify. It's a wait-and-see situation. 

 

EDIT: and by the way...the NHC changed their mind (back down to 45kt) -- 

 

AL, 04, 2013072500, , BEST, 0, 149N, 324W, 45, 1002, TS, 34, NEQ, 40, 0, 0, 30, 1014, 120, 20, 60, 0, L, 0, , 0, 0, DORIAN, D,

 

I'd assume it's based on a recent ASCAT pass. Not particularly suggestive of anything stronger yet:

 

[andyhb]

This is strengthening over cooler waters, that could be bad news in a few days as at that time it will have more octane to work with and no one should let their guard down after a week as if the ridge is stronger than modeled this could hit Florida or the eastern gulf or close to modeled it could hit the Carolinas to the Northeast or even the Canadian Maritimes

 

In other words, we don't know where it's going yet.

[Amped]

I'm surprised at how well Dorian is doing. It's currently passing over what should be the coldest waters of its existence, 25C, and still firing decent convection over its center. I would not be surprised at all to see this system become a bit stronger than forecast both in the short-term and in the longer term.

 

The GFS indicates there should be an upper-level trough in the Bahamas region in a few days, but if Dorian is a formidable tropical storm or minimal hurricane, it could bust through this and continue to intensify. It's a wait-and-see situation. 

 

 

Seems the last few years when there's a TD or TS over the Caribbean the warm water induced crapvection ends up producing outflow boundaries and secondary centers that do the storm more harm than good.  Maybe the slightly cooler less explosive environment is better before the system reaches hurricane strength.

[Ground Scouring]

In other words, we don't know where it's going yet.

I would say that a FL or E-Gulf hit is probably out of the question, given the stronger intensity of Dorian in the short term (=more northerly track through 24 hours before bending back just N of due west) and the relatively zonal pattern forecast for days five through seven. Even with a faster component to Dorian through the forecast period, the ridge does not look to be strong enough to force a strong TS Dorian into the FL coast. The real question is whether the timing and amplitude of the shortwave will interact with a more westerly Dorian on days six and seven, thereby forcing a path into the Carolinas or a close bypass to SNE.

[IsentropicLift]

The system has really good outflow right now thanks to the shear relaxing. The water vapor loop shows considerable expansion of moisture in all quadrants.

[Srain]

Captured a sunset image over Dorian. Interesting 'little spin' at 10N/35W at that time. Southern flack may provide enough inflow to at least maintain development.

[dtk]

FWIW, the WCOSS GFS is the same as the Old "CSS" GFS. No changes have been made to the actual "code" except for a very small number of things they had to fix because the new WCOSS super computer didn't support those processes. Apparently, it runs 4 min faster on the WCOSS though. Maybe dtk can shed some more light on why it looks slightly different.

We are actually going live with the new supercomputer tomorrow instead of next week because of this system. The model has only been changed in terms of portability.....for the new hardware, os, compiler, etc. This means the codes are not bit reproducible. Having been cycled for a while, you expect to see differences. However, in a time mean sense, the differences should be random and not systematic.

[AutoPenalti]

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

[Snow_Miser]

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

 

I think the bolded is pretty important. The Marginal SSTs may not be as much of a limiting factor as previously thought.

[Superstorm93]

Cyclone remains completely shielded from  any dry air so far. 

 

It'll be interesting to see what the system looks like once it's at 60W and we have recon visiting it periodically. 

 

[DopplerWx]

Would be awesome to have a nice healthy cape verde cyclone to track over the next week.  looks like there will be limiting factors in dorian's way as it approaches the antilles.

[AutoPenalti]

I'll be preparing in Ft.Lauderdale just incase.

This is getting exciting by the day.

[Floydbuster]

Anyone else surprised that Dorian has held so good? Nice moisture pocket, good outflow and inflow, lack of significant SAL, not too much easterly shear, warming waters ahead. For a late July Cape Verde we could do worse.

[HurricaneFrances04]

I'll be preparing in Ft.Lauderdale just incase.

This is getting exciting by the day.

 

You just jinxed it. Thanks.

 

 

 

[Snow_Miser]

 

Not too shabby...

[phil882]

Anyone else surprised that Dorian has held so good? Nice moisture pocket, good outflow and inflow, lack of significant SAL, not too much easterly shear, warming waters ahead. For a late July Cape Verde we could do worse.

 

The lack of SAL was a real wildcard. As others have stated previously, you simply don't see this little SAL in the Atlantic basin in late July. It potentially also may explain why the SSTs the storm is traversing currently have warmed up significantly (since more sensible heating is making it to the ocean surface, rather than being absorbed by the dust). 

 

Just take a look at previous years compared to currently.

 

[Floydbuster]

The lack of SAL was a real wildcard. As others have stated previously, you simply don't see this little SAL in the Atlantic basin in late July. It potentially also may explain why the SSTs the storm is traversing currently have warmed up significantly (since more sensible heating is making it to the ocean surface, rather than being absorbed by the dust). 

 

Just take a look at previous years compared to currently.

 

 

 

Dorian is a tightly coiled tropical storm as well, unlike many previous Cape Verde systems in the last three or four years. Any chance Dorian could pop out a donut eye and become a 65 kt hurricane in the next 48-72 hrs and then weaken and wax and wane through 120 hrs?

[Ed Lizard]

Bed time, but through 5 days, it should be approaching an area that has 500 mb winds from the South, but if you look at the animation, the center of the 500 mb ridge is moving along with it, such that it hasn't started to really recurve yet.

 

Work tomorrow, the ridge keeps travelling with it, and that East Coast trough starts to dampens out as model is suggesting through 120 hours, well, not the most likely scenario, but glass 5/64th optimistic on a Florida-Carolina's hit.

 

Even if it is a fish storm, I predict random model runs, or at least ensemble members, that keep SE, MA, PHL, NYC and SNE forums interesting for at least the next five days.  Maybe closer to 10 if we're lucky.

[DopplerWx]

 

 

Not too shabby...

Wow, looking great tonight during d-max.  

[It's Always Sunny]

 Given that high pressure stays intact and the progged trough over the CONUS deepens enough and moves east to bring it up the coast. 

[Amped]

A big vortex looks to be puching through eastern canada at the time. WIll probably recurve unless it weakens substantially on future runs and another trough digs in MS Valley.  If the ridge is a little further southwest it maybe able to hit florida but I'm just guessing at this point, and assuming it hasn't been ripped apart.

[phil882]

Dorian is a tightly coiled tropical storm as well, unlike many previous Cape Verde systems in the last three or four years. Any chance Dorian could pop out a donut eye and become a 65 kt hurricane in the next 48-72 hrs and then weaken and wax and wane through 120 hrs?

 

We'll have to see that the latest microwave passes show... it could be anywhere from a minimal hurricane with a microwave eye to a partially exposed circulation on the edge of the cirrus canopy. Really no way to know unless we get a good overnight TRMM pass or SSMI. The lower resolution microwave imagers don't help a bunch. 

[yoda]

Very tight 850 vort at 165 entering Eastern Bahamas

 

http://mag.ncep.noaa.gov/Image.php?model=gfs&area=wnatl&param=850_vort_ht&cycle=00ℑ=gfs%2F00%2Fgfs_wnatl_165_850_vort_ht.gif

[Floydbuster]

Very well could be. Given that high pressure stays intact and the progged trough over the CONUS deepens enough and moves east to bring it up the coast. 

 

Yeah I suppose that'd be true. I guess I just was anticipating this to be dominated in the low level flow much more than it appears to be doing thus far.

 

Yowza...

 

[yoda]

Looks like 00z GFS is going to be a SE coast hit by the looks/pos of Dorian at 192 unless there is a hard recurve starting right there

 

Of course, we could always then buy that from 192-240 Dorian sits around off SE coast and meanders... prob due to poor steering currents