cieldumort
(Moderator)
Wed Jul 24 2013 03:55 AM
Dorian Forecast Lounge

A healthy tropical wave and associated surface low that rolled into the far eastern Atlantic a few days ago has acquired sufficient organized convection tonight to be classified a tropical depression.

FOUR is expected to become Tropical Storm Dorian, and it is likely to continue moving in a general west-northwest motion for the next few days. After that, models begin diverging some more, but not altogether significantly.

This is where to put mid to long range forecasts on TD4's potential for further development and forecast track. TD4-related longer range model output discussions are also appropriate here.


ftlaudbob
(Storm Chaser)
Wed Jul 24 2013 06:38 AM
Re: Tropical Depression Four Forecast Lounge

I see the NHC keeps it as TS through the forecast period.Their thinking must has changed about the conditions ahead of the system.
It is looking very healthy right now: http://www.ssd.noaa.gov/PS/TROP/floaters/98L/imagery/rbtop-animated.gif


MikeCAdministrator
(Admin)
Wed Jul 24 2013 09:51 AM
Re: Tropical Depression Four Forecast Lounge

TD#4 is pretty small area wise, so it's more susceptible to intensity swings, but right now it seems to be strengthening quite a bit more rapidly than normal, but I doubt it can hold this look for long.

Very interesting day for this storm, regardless.


danielwAdministrator
(Moderator)
Wed Jul 24 2013 09:58 AM
Re: Tropical Depression Four Forecast Lounge

I'm seeing model output for TS Dorian on Clark's website. No update on NHC page, yet.
System looks well organized on visible sats.


MikeCAdministrator
(Admin)
Wed Jul 24 2013 10:21 AM
Re: Tropical Depression Four Forecast Lounge

It's true, the models initialized the system as a 45MPH tropical storm, so it's more than a little likely it'll be at least that at 11AM. The satellite photos also go along with that.

MichaelA
(Weather Analyst)
Wed Jul 24 2013 11:56 AM
Re: Tropical Depression Four Forecast Lounge

Another one with a relatively high translational speed. I wonder if this will be the trend throughout this season, or will it relax some in August/September? At any rate, doesn't that high speed hinder development somewhat?

LoisCane
(Veteran Storm Chaser)
Wed Jul 24 2013 12:56 PM
Re: Tropical Depression Four Forecast Lounge

Because of the low water temperatures and poor presentation ...until last night... of the system they went conservative with their forecast intensity. Must remember that many of the models yesterday didn't recognize it and few kept it alive more than a very short period.

When you looked at her yesterday visually w/o relying on the models you could see the structure setting up and the long tail dipping down into the ITZ which is a classic Cape Verde signature.

If you looked at the WV loop you could see that darkest, driest air was moving to the West.

Sometimes we rely too much on models. Then again the models insisted she was forming back when we couldnt' even see her and ... continuity in modeling means a lot even though they dropped it yesterday.

He is going into dry air and lower water temperatures. And, he is small. The stronger he gets now before he hits the worst of the negative conditions will help it down the road.

Now the models are intensifying it near PR into a Hurricane.

With models it's best to watch the patterns vs anyone model run.

Compelling storm to watch ... and yes I would say it's a sign of things to come.


MikeCAdministrator
(Admin)
Wed Jul 24 2013 01:50 PM
Re: Dorian Forecast Lounge

The models with Dorian this afternoon suggest more chance of a recurve before the US than earlier, and with how far north this system is already I'd probably lean toward that ultimately at this point.

It'll be close, and may go back and forth, but climatology and the currently globals *slightly* lean toward a recurve before getting to the US coast, although the NE islands and Bahamas are still to close to call.

The other storm, 99L, will be something for Bermuda to watch, but it will likely stay well east of the island.


ftlaudbob
(Storm Chaser)
Wed Jul 24 2013 02:04 PM
Re: Dorian Forecast Lounge

If she can survive the next three days or so,we COULD have our first hurricane of the season.Right now she is starting to feel the effects of lower sst's and higher wind shear.You can see that here: http://www.ssd.noaa.gov/PS/TROP/floaters/04L/imagery/rbtop-animated.gif

And she will also have to survive a lot of dry air just ahead of her.You can see that here: http://www.ssd.noaa.gov/goes/east/tatl/wv-animated.gif


MikeCAdministrator
(Admin)
Wed Jul 24 2013 03:25 PM
Re: Dorian Forecast Lounge

12Z GFS curves it to the north just after approaching the Northeastern Caribbean islands (but never crossing the islands) and then turns it to the north no US landfall, EURO doesn't keep it together, The Canadian Gem is the most interesting has it going through keys, then back over Ft. Myers and up the I-4 corridor around August 1st . (ala Charley), but this is one of the weaker models as far as accuracy go,.

doug
(Weather Analyst)
Wed Jul 24 2013 03:51 PM
Re: Dorian Forecast Lounge

Trying to recall, but I think the Euro out performed the GFS in the last storm. Still early on the models.

panhandler
(Registered User)
Wed Jul 24 2013 06:00 PM
Re: Dorian Forecast Lounge

It looks like it get get much larger considering what it is pulling up from the south and the clouds that appear to curve back into it from the north west. That is a hellish looking swath of drier air just ahead, not to mention windshear currently coming from the SW across the Caribean.

Ed DunhamAdministrator
(Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017))
Thu Jul 25 2013 01:31 AM
Re: Dorian Forecast Lounge

The 25/00Z run of the GFS does ramp up the intensity after the five day point and the extended run brings Dorian well into the Bahamas before the turn to the north begins. Models are likely to bounce east or west from run to run on how far to the west Dorian will get. It looks like the upper level low near 23N 66W could become a major player in determining the eventual track of Dorian. It could pull up what might remain of the dry air to the north while fortifying a firm narrow ridge between the upper low and the tropical cyclone. At the 5-day point the GFS puts the upper low near Bermuda at 300MB.
ED


MikeCAdministrator
(Admin)
Thu Jul 25 2013 07:19 AM
Re: Dorian Forecast Lounge

The 6Z GFS animation) weakens Dorian a bit as it gets halfway to the Caribbean islands, but then regains as it goes just north of the Caribbean islands, through the southern Bahamas, and keeps it moving west, eventually into Southeast Florida and then turns it up the spine of Florida. Main feature causing this is the ridge north and misses a trough that would turn it more north early. This is a long time to keep it going west like that, possible, but I'm sure this will change over the next few days.

The euro loses dorian, around the same time the GFS weakens it. As small and "healthy" as this storm is now, the Euro may not be a good indicator currently.

Climatology still suggests Dorian will curve before making it to the US, but currently there is enough evidence to support that it may not, so it will need to be watched this week and next. That said, odds are, that it will recurve before getting that far west. That said, those in the cone, Florida, and Southeast up through North Carolina will want to check back in next week.



ftlaudbob
(Storm Chaser)
Thu Jul 25 2013 11:09 AM
Re: Dorian Forecast Lounge

I hope the GFS is wrong on that one Mike.That would bring it right into my beach here.Looks like this storm will get a lot of attention in a few days.It certainly has my attention now. Looks like it will make it through to just north of PR,where it will have nice and warm SST's and low shear.Still a lot of time to watch this.

MikeCAdministrator
(Admin)
Thu Jul 25 2013 12:22 PM
Re: Dorian Forecast Lounge

12Z run of GFS today keeps Dorian further south, and moves it over Puerto rico and Plows itself into Hispaniola and dies.

This run may be a bit too far south, but at the same time Dorian appears to be weakening today. With,based on visible satellite photos, the low level center possibly decoupling from the mid levels, which would allow for a further south track.


doug
(Weather Analyst)
Thu Jul 25 2013 12:36 PM
Re: Dorian Forecast Lounge

Agreed, the RGB seems to represent the effects of shear. All convection now is being generated on the east half only. I bleieve the effects of this shear were part of the anticipated forecast for Dorian.

ftlaudbob
(Storm Chaser)
Thu Jul 25 2013 12:55 PM
Re: Dorian Forecast Lounge

Yes,this was expected.Really just have to wait a few days to when it gets around PR and see what happens then.

Ed DunhamAdministrator
(Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017))
Thu Jul 25 2013 01:32 PM
Re: Dorian Forecast Lounge

Actually I think that its suffering a little from some self-induced shear created by its rapid movement to the west. The low-level center has picked up some speed and is more or less racing ahead of the convection that is building through the mid and upper levels. Because of that separation from the primary convection and the strong ridge that continues to build to the north of the cyclone, the movement has become due west or more in line with the low-level easterlies. The outer feeder band to the west has actually become better formed in the past few hours and that would probably not happen if increasing westerly shear was hitting the system. With the rapid movement likely to continue for awhile, I suspect that Dorian will stay rather weak for a few days with its primary convection displaced just east of the low-level center.
ED


ftlaudbob
(Storm Chaser)
Thu Jul 25 2013 05:06 PM
Re: Dorian Forecast Lounge

She now has completely recovered,and is looking very good.She has survived the cool SST'S and the shear.She will now be entering warmer SST'S and low shear.I think we will have our first Hurricane of the season in a few days.The 5PM NHC forecast track remains the same.By the middle of next week SE Florida COULD be under the gun.This is still 3,000 miles away so there is plenty that can happen and plenty of time to watch her.

ftlaudbob
(Storm Chaser)
Thu Jul 25 2013 08:51 PM
Re: Dorian Forecast Lounge

Our girl got cut off from that moisture she was sucking in from the south.We now will see what effect it will have on her.See the last frame.

http://www.ssd.noaa.gov/PS/TROP/floaters/04L/imagery/rbtop-animated.gif


OrlandoDan
(Weather Master)
Fri Jul 26 2013 06:57 AM
Re: Dorian Forecast Lounge

Dorian is still holding on. Whagt are the chances of heer turning polar after the end of the forecast period? If she gets stronger and the steering current to the west weaken, she will turn poleward.

MikeCAdministrator
(Admin)
Fri Jul 26 2013 07:12 AM
Re: Dorian Forecast Lounge

It's going through a rough area today and may not make it (as a storm). It's small enough to possibly hang on though, but there still isn't much to suggest it moving poleward anytime soon. Especially if it stays weak across most of the Atlantic, in fact the GFS plows it into or skirts just north of Hispaniola and then into Cuba, still going westward the entire time. The ridging forecast remains strong, but it's well into forecast crazy land that far out (talking about Aug 1st-2nd)

Euro still has it falling apart, but that model has more trouble with tiny systems.

Right now the forecast "cone" is about is good as a forecast you can get, and immediately beyond I don't see anything turning it poleward immediately after it, but if a weakness in the ridge does form it may be possible. Probably will have a better idea on Tuesday once it gets just north of the eastern Caribbean.


ftlaudbob
(Storm Chaser)
Fri Jul 26 2013 10:34 AM
Re: Dorian Forecast Lounge

I am really hoping this thing falls apart because from everything I can see it should turn a little north once it reaches the southern Bahamas.That would bring what ever is left into SE Florida.If I were to bet right now I would say she will be just a wave in a day or 2.

ftlaudbob
(Storm Chaser)
Fri Jul 26 2013 12:25 PM
Re: Dorian Forecast Lounge

And now the end is near...........I think she is toast.

doug
(Weather Analyst)
Fri Jul 26 2013 03:46 PM
Re: Dorian Forecast Lounge

there is still a low level circulation, but virtually no convection...cannot see how that can continue at storm strength,,,

JimB
(Registered User)
Fri Jul 26 2013 03:59 PM
Re: Dorian Forecast Lounge

You have to love dry air, what a difference from earlier to now:





ftlaudbob
(Storm Chaser)
Fri Jul 26 2013 05:56 PM
Re: Dorian Forecast Lounge

Dorian maybe dying,but from what I have seen so far this season,I am not looking forward to August and September.

ftlaudbob
(Storm Chaser)
Sat Jul 27 2013 12:23 AM
Re: Dorian Forecast Lounge

She is not going down easy.Look at this:

http://www.ssd.noaa.gov/PS/TROP/floaters/04L/imagery/rbtop-animated.gif



OrlandoDan
(Weather Master)
Sat Jul 27 2013 05:17 AM
Re: Dorian Forecast Lounge

She is defintley undergoing a burst of convection and I do not understand why. Looks like a fairly hostile environ for her.

Random Chaos
(Weather Analyst)
Sat Jul 27 2013 12:31 PM
Re: Dorian Forecast Lounge

Looks to me like there are two CoC's now, widely separated, with the western one firing some deep convection and the eastern one dissipating.

Ed DunhamAdministrator
(Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017))
Sat Jul 27 2013 12:55 PM
Re: Dorian Forecast Lounge

Dorian is an interesting system. The eastern circulation is probably the upper circulation that is getting wiped out by the dry air. The dry layer exists at the mid and upper levels of the atmosphere (mostly upper) whereas moist air is still in place at the lower levels so that moisture keeps firing bursts of convection near the low level circulation. We are also at the convective minimum for the day so the system is in its diurnally weakest timeframe. Dorian looks to be more like a TD - and barely that, but it will probably ramp up again later this evening. If not, its history.
ED


Random Chaos
(Weather Analyst)
Sat Jul 27 2013 03:39 PM
Re: Dorian Forecast Lounge

And now the entire system seems to be collapsing, looking more and more like a wave and less a tropical cyclone.

panhandler
(Registered User)
Sun Jul 28 2013 10:59 AM
Re: Dorian Forecast Lounge

Looks a lot better this morning on all satellite views. Can't find an ASCAT pass that properly captures the newly developing circulation, but apparently it looks healthy enough that recon is going to check it out at some point today.

ftlaudbob
(Storm Chaser)
Sun Jul 28 2013 04:30 PM
Re: Dorian Forecast Lounge

Because of my location and the fact that Dorian seems to be getting her act together a little(yes I know it is not technically still Dorian)I am back to watching this system very closely.She has pretty good outflow now and the overall structure has improved.

JMII
(Weather Master)
Sun Jul 28 2013 05:12 PM
Re: Dorian Forecast Lounge

Quote:

She has pretty good outflow now and the overall structure has improved.




Sure has. I had pretty much written her off: surrounded by dry air, lots of shear but then during the middle part of today she looked much better especially in terms of outflow. However now she looks like she rained herself out, almost all the moisture is gone.


ftlaudbob
(Storm Chaser)
Sun Jul 28 2013 05:25 PM
Re: Dorian Forecast Lounge

Quote:

Quote:

She has pretty good outflow now and the overall structure has improved.




Sure has. I had pretty much written her off: surrounded by dry air, lots of shear but then during the middle part of today she looked much better especially in terms of outflow. However now she looks like she rained herself out, almost all the moisture is gone.




Yea,was just looking at that.She will need to hang on for about 24-48 hours,then she will be under much better surroundings.Another crazy system.


ftlaudbob
(Storm Chaser)
Sun Jul 28 2013 08:09 PM
Re: Dorian Forecast Lounge

NHC has it up to a 50% chance now.Convection keeps coming and going.This is getting very interesting.The system as a whole has really grown in size.Stay tuned.

ftlaudbob
(Storm Chaser)
Sun Jul 28 2013 11:06 PM
Re: Dorian Forecast Lounge

Most of the models that are used to determine intensification,are calling for this system to become a hurricane.

doug
(Weather Analyst)
Mon Jul 29 2013 07:42 AM
Re: Dorian Forecast Lounge

A quick run through the floater loops suggests to me that it is still a trough. The outflow looks less impressive this morning. The influence of the ULL to its NW is pronounced on the west side preventing any evacuation along its western edge. It has completely separated from the tropical convergence zone and will have to generate its energy internally for the most part. In that regard pressures are relatively high in the immediate surroundings 1016-1018, and it will have to sustain convective development in order to do so. Right now I think most of the convection is of diffluent origin, i.e. interaction with the ULL, particularly to the west of the base of the trough, which may spell the end of the system if it cannot develop a consistent convective core near the base of the trough. I think the NHC has correctly called this a toss up and I have no sense that further development in the sense of cyclone regeneration will occur.

ftlaudbob
(Storm Chaser)
Mon Jul 29 2013 11:03 AM
Re: Dorian Forecast Lounge

I agree that it is a toss up at this point,but given it's most likely path,people in S. Florida need to pay attention to see what happens with this system.

doug
(Weather Analyst)
Mon Jul 29 2013 12:04 PM
Re: Dorian Forecast Lounge

There does seem to be some broad, and I guess mid-level cyclonic circulation that is focused around a point near 22 N (actually just south of 22N) and 65 W. The effect of the ULL is playing havoc with the system right now, however.
Finally, the system is a non-factor in the two main models, which indicates this system will follow the fate of its immediate predecessor.


JMII
(Weather Master)
Mon Jul 29 2013 05:51 PM
Re: Dorian Forecast Lounge

Someone on the main thread already said what I was thinking: for a non-storm (IE: open wave) xDorian is really looking good atleast in terms of outflow and overall rotation (mid to upper levels). However the shear is keeping it from stacking vertically and there is no low at the bottom to focus the energy. Something is there, but all the moisture has been blown away throughout the day. Maybe this is finally the end? Or will it drift west for 3 days then refire as a Cat 1 in the GOM by week's end?

ftlaudbob
(Storm Chaser)
Mon Jul 29 2013 10:12 PM
Re: Dorian Forecast Lounge

The system really looks bad now,should be dead soon,but then again I have thought that before.Shear is our friend!

Random Chaos
(Weather Analyst)
Thu Aug 01 2013 09:36 PM
Re: Dorian Forecast Lounge

And then it fires again. Invest 91L up for the remnants of Dorian now off the Florida tip. Nothing major expected - 30% chance of any development - conditions aren't great.

doug
(Weather Analyst)
Fri Aug 02 2013 09:50 AM
Re: Dorian Forecast Lounge

And so it continues: latest visible shows some form of llc east of Vero with little vertical development near by, and most convection well south. This is the Gulf Stream, it is early August , and the environment is moist...the Outlook did not emphasize unfavorable conditions...and I suggest this be taken seriously.
If memory serves me correctly Katrina was born under a similar circumstance: a persistent vortex had meandered across the Atlantic and had been classified and then declassified in its crossing. One August day it wandered into the coastal waters of SE Florida and caught a breath and rapidly intensified. Not saying that will happen here but the possibility for rapid close in intensification is always something to consider.

Update: 10:15 base reflectivity suggests a weak surface rotation east of the coast between Ft. Pierce and Port St Lucie. Only scattered showers ...


ftlaudbob
(Storm Chaser)
Fri Aug 02 2013 10:10 AM
Re: Dorian Forecast Lounge

I can see the dark clouds over the ocean from this system.Very beautiful to be honest.

JMII
(Weather Master)
Fri Aug 02 2013 10:20 AM
Re: Dorian Forecast Lounge

Dorian (or its remnants) have tracked pretty much as forecast regarding time and location, its just the intensity that has been off. I've been telling my wife all week that its going be a washout this weekend. The front pushing in from the north seems pretty strong so xDorian is about to hit a wall that should stop any development.


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