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The Steering of Dorian

By: Lee Grenci 3:54 PM GMT on July 26, 2013

The 5 A.M. discussion from the National Hurricane Center indicated that Tropical Storm Dorian "lost organization" as it encountered southwesterly wind shear and middle- to upper-tropospheric dry air (one of the traditions I learned from the late John Hope was to never use "he" or "she" to describe a named tropical cyclone). NHC's discussion also focused on low- to middle-tropospheric winds associated with the the Atlantic subtropical high-pressure system (06Z GFS model analysis of 700-mb heights early this morning) as the primary steering currents for Tropical Storm Dorian (see the 06Z GFS model analysis of 700-mb heights and 700-mb streamlines below (larger image). At the time, Dorian was moving to the west-northwest at 17 knots.



The 06Z GFS model analysis of 700-mb heights and 700-mb streamlines on July 26, 2013. 700-mb wind speeds are color-coded in knots. Larger image. Courtesy of Penn State.

When I was a young forecaster (a long, long time ago), I typically looked at mid-tropospheric winds as a proxy for the general movement of tropical cyclones. That's because mid-tropospheric winds serve as a rough approximation for the mean airflow in the troposphere. More specifically, old timers like me looked at the winds between 700 mb and 500 mb at a radius of approximately five to seven degrees latitude from the center of the storm (one degree latitude equals 60 nautical miles). As it turns out, winds in the layer from 700 mb to 500 mb often tend to correlate best with the movement of tropical cyclones (at these radii, environmental winds are essentially unaltered by the circulation associated with the tropical cyclone).

Obviously, my approach as a young forecaster was old school. Nonetheless, my simple method had some merit. Indeed, research has shown that a deep-layer mean flow (between 1000 mb to 100 mb, for example) can be used as a tool to assess steering currents (this technique captures the spirit of my old-school approach).

Subtropical highs are not the only features that steer tropical cyclones. Indeed, mid-latitude systems (500-mb troughs, for example) can also steer tropical cyclones as they move poleward from the Tropics. At times, two tropical cyclones can steer each other, assuming that they're close enough for their circulations to interact (the Fujiwhara effect...a topic for a future blog). Finally, tropical cyclones contribute to their own steering, especially when steering currents are rather weak (the Beta effect, which is fodder for another future blog).


The variation of the steering layers for tropical cyclones with minimum central pressure. Larger image. Courtesy of CIMSS and Dr. Chris Velden.

That's all well and good, Grenci, but why did NHC specifically reference "low- to mid-tropospheric winds in their 5 A.M. discussion today? Experience gained from the careful observations of operational forecasters eventually prompted further research aimed at establishing the connection between the minimum pressure of a tropical cyclone and the corresponding depth of the steering layer. The bar graph above (larger image), which displays the minimum pressure of tropical cyclones versus the depth of their steering layers in the Atlantic basin, supports the notion that the steering layer for a tropical depression is shallower and resides lower in the troposphere. In contrast, the steering layer for strong hurricanes is much deeper. The simple physical connection for you to take away after reading my blog is that a weak tropical cyclone (like Dorian) is usually associated with a shallow vortex. Thus, the mean wind in a correspondingly shallow and low-level layer serves as the steering current. As a general rule, the deeper the vortex, the deeper the layer mean that steers the tropical cyclone.


The 09Z analysis of the streamlines designating the mean wind in the layer from 850 mb to 700 mb on July 26, 2013. Larger image. Courtesy of CIMSS.

To get a better sense for the movement of Dorian, focus your attention on the first layer on the left of the bar graph above (central pressure between 1000 mb and 1010 mb). The steering current for Dorian and other similarly weak tropical storms boils down to the mean wind between 850 mb (roughly 5000 feet) and 700 mb (10000 feet). The 09Z analysis from CIMSS (above; larger image) indicates the streamlines of the mean wind in the layer between 850 mb and 700 mb. Wind speeds are color-coded in knots.

At the other end of the spectrum, note the deep steering layers for strong tropical cyclones whose central pressures are lower than 940 mb or range from 940 mb to 949 mb.

I should point out that these results do not include the impact of the Beta effect on the movement of a tropical cyclone. Moreover, other factors such as season, latitude, easterly versus westerly environmental flow, the rates at which the intensity of tropical cyclones changes with time, etc., probably can skew these results a bit, but, as a general rule, the bar graph above will get you in the ballpark in all the ocean basins.

We've come a long way since I was a young forecaster.

Lee

Hurricane Tropical Meteorology

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.

looks like we are going to keep Dorian a TS at 11:00
2003. pottery
Quoting mikatnight:
Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.



Striated Heron, I think.
Quoting 1913. washingtonian115:
Let's see what shear has to say about Dorian..Still not optimistic..I wanted it to be like Danielle from 2010.That's all I asked!.

You do realize Danielle was almost a month further into the season then Dorian. The Cape Verde hurricanes don't really ramp up until the meat of the season. The fact that Dorian did form out near the Cape Verdes in July is something that is still a likely harbinger for an active Cape Verde season.
Quoting 1976. Hurricanes305:
Sea surface temperature increase to 28C along with moisture around 55W. So its bulking up till it gets there by 2pm. After that it has a chance of strengthening just in time for the 5pm advisory. If this happens Tropical storm watches may be issued for the Northern Hispaniola and/or SE Bahamas (Turks and Caicos) by 11pm tonight granted it survive today. Next 24-48 hours is crucial!
Quoting 1976. Hurricanes305:
Sea surface temperature increase to 28C along with moisture around 55W. So its bulking up till it gets there by 2pm. After that it has a chance of strengthening just in time for the 5pm advisory. If this happens Tropical storm watches may be issued for the Northern Hispaniola and/or SE Bahamas (Turks and Caicos) by 11pm tonight granted it survive today. Next 24-48 hours is crucial!
NHC is killing him in 36 hours, saying is his last breath'....lets see what happens...
Quoting 1962. wunderkidcayman:

yeah I know how you feel I use to be like that until 01 when the M storm passed here the waves where massive like waves you would only see in movies anyway my mother was outside when this this was passin us and the sea came up and took my mother dragged her up our lawn slapped her on the concrete wall surrounding our Front and sides and dragged her towards the sea luckily for her me and a few other jumped in to save her and then more so in 04 with Ivan and well that was self-explanatory what Ivan done to Cayman


That's a terrible picture, thanks God you guys managed to save her.. Hope it'll never happen again.

We did experience severe hurricanes as well... and I would fear a strong Cat 2 and higher... but minimal hurricanes and TS are fun and very exciting.
2007. LargoFl
Quoting 2001. mikatnight:
Good Morning!


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?




The spotted bird is a Sandhill Crane, if memory serves. Beautiful photos you take, by the way!

No, I take that back, a poster above was right, Striated Heron. Google image comparisons show I misremembered.
Good morning

I just looked at the ASCAT pass from yesterday evening and it shows that Dorian no longer had a closed low at that time.

I wonder why the NHC didn't declassify it as an open wave ?. Was there any discussion about this last night ?
Quoting 2005. HuracanTaino:
NHC is killing him in 36 hours, saying is his last breath'....lets see what happens...


I see a greater chance of him surviving today than I saw last night...last night looked like its last hurrah
Quoting 2009. kmanislander:
Good morning

I just looked at the ASCAT pass from yesterday evening and it shows that Dorian no longer had a closed low at that time.

I wonder why the NHC didnt declassify it as an open wave ?. Was there any discussion about this last night ?


If I remember, most acknowledged ASCAT but noted visible satellite still showed a robust LLC. OSCAT has had issues as well.
Quoting 2003. pottery:


Striated Heron, I think.


Thanks Pottery. Search results come up with all kinds of images for that name, no wonder I had such a hard time finding it!
Quoting 2009. kmanislander:
Good morning

I just looked at the ASCAT pass from yesterday evening and it shows that Dorian no longer had a closed low at that time.

I wonder why the NHC didnt declassify it as an open wave ?. Was there any discussion about this last night ?
HI Kman , I am asking myself the same question , on their discussion they think the same way but I believe they are waiting for another pass to confirm and I also believe recon is going to investigate also
2014. LargoFl
Quoting 2008. StormsWanted:



The spotted bird is a Sandhill Crane, if memory serves. Beautiful photos you take, by the way!


Thanks! I also looked at the sandhill crane...never thought he'd be this hard to ID.
Quoting 2009. kmanislander:
Good morning

I just looked at the ASCAT pass from yesterday evening and it shows that Dorian no longer had a closed low at that time.

I wonder why the NHC didnt declassify it as an open wave ?. Was there any discussion about this last night ?

yeah but then it closed up and started to pop some convection

I said it would reorganise and well it did do that
Quoting 2009. kmanislander:
Good morning

I just looked at the ASCAT pass from yesterday evening and it shows that Dorian no longer had a closed low at that time.

I wonder why the NHC didnt declassify it as an open wave ?. Was there any discussion about this last night ?

The 5AM discussion mentioned that ASCAT and OSCAT passes suggested that the circulation may no longer be closed, but they resisted declassifying because they wanted to monitor it further before classifying it as a remnant low.
2018. 7544
looking at where d is now and the high it looks like what ever is left of dorian will wind up in south fla but the ? is will it be strong or weak ?



Dorians party about to end
Sure is a beautiful mornin. WAVE SPL looks decent...xD
2021. 62901IL
I bet you guys anything that dorian will be an open wave at the next advisory.
2022. Grothar
Coordinates: 18.3N 51.1W 12Z
Coordinates: 18.0N 49.0W 06Z
Coordinates: 17.8N 47.1W 00Z

Wow. Seems to still be moving WNW. Interesting to see what the 18Z will be.
Quoting 2020. SPLbeater:
Sure is a beautiful mornin. WAVE SPL looks decent...xD


Could try to organize
2024. LargoFl
GFS has him back in 72 hours
2025. DDR
Good morning pottery did you get rain last night and this morning?
Quoting 2019. chrisdscane:



Dorians party about to end

umm not its not
2027. WWPR
Quoting 2001. mikatnight:
Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.



Loos like a Juvenile Yellow Crowned Night Heron...but a juvenile for sure.
Quoting 2021. 62901IL:
I bet you guys anything that dorian will be an open wave at the next advisory.


No, It will still be at 40 with pressure of 1011 mb
Quoting 2004. TylerStanfield:

You do realize Danielle was almost a month further into the season then Dorian. The Cape Verde hurricanes don't really ramp up until the meat of the season. The fact that Dorian did form out near the Cape Verdes in July is something that is still a likely harbinger for an active Cape Verde season.
Be funny after all this foreshadowing you all are doing nothing significant came from this cape verde season.And what I meant was that a more deserving storm should come down the line and get the name not this weakling..
2030. Grothar
Quoting 2001. mikatnight:
Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.



The middle one looks like a striated crane. The top one looks like regular crane and the bottom picture looks like little Dexter.
2011. Stoopid1

2013. Seflhurricane

I have reviewed the 11 PM Discussion in the NHC storm archive and they mention that Dorian still had a vigorous low and mid level circulation so it would appear they did not want to declassify too soon in the event the low closed off again later last night.

To my eye Dorian looks like an open wave again this morning but hopefully ASCAT will give us a good look soon.
Quoting 2022. Grothar:
Coordinates: 18.3N 51.1W 12Z
Coordinates: 18.0N 49.0W 06Z
Coordinates: 17.8N 47.1W 00Z

Wow. Seems to still be moving WNW. Interesting to see what the 18Z will be.

actually its W but just a tad N of W but still moving W
Visible images indicate that Dorian is very likely degenerating into an open wave, i see no LLC and if there is one its super weak
Quoting 2029. washingtonian115:
Be funny after all this foreshadowing you all are doing nothing significant came from this cape verde season.And what I meant was that a more deserving storm should come down the line and get the name not this weakling..

Oh washi, you and your hurricane names...
Quoting 2021. 62901IL:
I bet you guys anything that dorian will be an open wave at the next advisory.

nah 40mph TS
2036. 62901IL
Quoting 2033. Seflhurricane:
Visible images indicate that Dorian is very likely degenerating into an open wave, i see no LLC and if there is one its super weak

Bye bye dorian...nice knowing ya...
Quoting 2016. wunderkidcayman:

yeah but then it closed up and started to pop some convection

I said it would reorganise and well it did do that


How do you know it closed up again ??
So, Dorian finally got thunderstorms but lost its center... What a shame :p
2039. 62901IL
Quoting 2038. Doppler22:
So, Dorian finally got thunderstorms but lost its center... What a shame :p

I know.
07/27/2013 Daily Update - GOES East Infrared Hurricane Sector Animation

Finally...TS Dorian arrives into the Hurricane Sector imagery today!


This is a long loop animation from the GOES East Infrared Hurricane Sector imagery. Featured the death of TS Chantal and the track conditions ahead of TS Dorian, including tracking forecasts by the NHC for 7/25/2013 thru 7/27/2013.

2041. LargoFl
1. Tampa-St. Petersburg, Fla.

The Tampa-St. Petersburg area, on the west coast of Florida, is extremely vulnerable to storm surge flooding, and has been fortunate to escape a direct hit from a strong hurricane for many years. Climate Central calculates the 100-year flood height in this area is 6.5 feet above the high tide line. Using Climate Central’s Surging Seas sea level rise mapping tool — it becomes clear that there are about 125,000 people currently living below this flood level. In St. Petersburg alone, there are more than 45,000 homes that lie below 6 feet in elevation, and would likely be vulnerable to a storm surge of that magnitude or greater.

Click image to enlarge. Radar image of Hurricane Charley as it swept ashore south of Tampa in 2004. Credit: National Hurricane Center.

According to Climate Central’s research, sea level rise is escalating the threat of damaging storm surge flooding in the Tampa area. The odds that a flood exceeding 6.5 feet would occur in Tampa before 2030 are about 14 percent without global warming, but these odds increase to 20 percent with the effects of global warming-related sea level rise factored in.

Tampa is no stranger to hurricanes, including storms that came very close to the city but avoided a worst-case scenario track during the past decade. According to the Hurricane City website, tropical storms and hurricanes have passed within 60 miles of Tampa on 68 occasions since 1871. These included Hurricanes Frances and Jeanne, both of which struck during 2004. However, Tampa has not suffered a direct hit by a strong hurricane since way back in 1921, when a storm surge of 10.5 feet occurred in Tampa Bay.

Hurricane Charley in 2004 was initially forecasted to strike Tampa-St. Petersburg as a Category 2 storm, but shortly before landfall it intensified rapidly into a Category 4 storm, and turned eastward sooner than expected, inflicting its worst damage on the Port Charlotte area, south of Tampa. Charley caused $16 billion in damage.
2042. 7544
Quoting 2033. Seflhurricane:
Visible images indicate that Dorian is very likely degenerating into an open wave, i see no LLC and if there is one its super weak


thats a good looking open wave may be can just call it a blob for now groo
Quoting 2027. WWPR:


Looks like a Juvenile Yellow Crowned Night Heron...but a juvenile for sure.

Interesting, I also looked at those. I agree, definitely a juvenile...something. Thanks for your input! Where's IndianRivGuy? he'd know fer sure.
1.93" of rain over night at my house in S. Ft. Myers. 3"-5" of rain reported in the area from Ft. Myers down to Naples Fl.
2045. Grothar
Quoting 2042. 7544:


thats a good looking open wave may be can just call it a blob for now groo


It looks like it is on its way out. Really putrid and weak.

Quoting 2017. TylerStanfield:

The 5AM discussion mentioned that ASCAT and OSCAT passes suggested that the circulation may no longer be closed, but they resisted declassifying because they wanted to monitor it further before classifying it as a remnant low.


Quite clear from ASCAT that there were no West winds at all with Dorian last night. Wide open circulation on the South side.

Very interested to see what the NHC says in 30 MIN
Quoting 2004. TylerStanfield:

You do realize Danielle was almost a month further into the season then Dorian. The Cape Verde hurricanes don't really ramp up until the meat of the season. The fact that Dorian did form out near the Cape Verdes in July is something that is still a likely harbinger for an active Cape Verde season.


Also the 3rd one to form in the deep tropics this year (see Masters' post for July 8).
2049. baulas
Quoting 2027. WWPR:


Loos like a Juvenile Yellow Crowned Night Heron...but a juvenile for sure.


Yes, this is correct.


And hoping that Dorian dissipates. No one needs a hurricane.
2050. centex
I think they didn't want to declassify and maybe need to reclassify in short time frame. Anyway they much more pessimistic and now pegged when it will be gone for good. If it keeps firing convection and maintains LLC they may have a tough time declassifying until when forecasted. But if it drops convection this afternoon, would not be surprised if they pull the plug.
Quoting 2045. Grothar:


It looks like it is on its way out. Really putrid and weak.



What does that graphic have to do with how I feel. ... Give me a chance to get some coffee before making those comments.
2052. Grothar
Quoting 2032. wunderkidcayman:

actually its W but just a tad N of W but still moving W


That is what WNW usually indicates within a certain parameter.
Well, I had higher expectations for Dorian. Whatever, I predicted that Erin would be the first significant storm anyway. Maybe that wave out by Africa?
2054. Grothar
Quoting 2051. Some1Has2BtheRookie:


What does that graphic have to do with how I feel. ... Give me a chance to get some coffee before making those comments.



I could have said, ragged and cranky, but I didn't. I still have modicum of kindness. (Although it has been running thin lately)
Quoting 2030. Grothar:


The middle one looks like a striated crane. The top one looks like regular crane and the bottom picture looks like little Dexter.


You got all three!
"Don, what do we have for our contestant today?"
I might go out on a limb now but I'll say TD Dorian at the next TWO :o)

Taco :o)
2057. hydrus
Quoting 2052. Grothar:


That is what WNW usually indicates within a certain parameter.
I,m from the west side of south eastern North Carolina...:)
Quoting 2047. Seflhurricane:
Very interested to see what the NHC says in 30 MIN


I would be surprised if they didn't declassify it.
Hi kman.

This is what Lixon Avila said at 11 PM about why he didn't pull the plug on Dorian at that time.

DORIAN APPEARS TO STILL HAVE A VIGOROUS LOW- TO MID-LEVEL
CIRCULATION IN CONVENTIONAL SATELLITE IMAGERY WITH 30 TO 35 KNOTS
MEASURED BY A RECENT ASCAT PASS...BUT IT HAS BEEN DEVOID OF DEEP
CONVECTION FOR SEVERAL HOURS. I WAS TEMPTED TO DECLARE DORIAN A
REMNANT LOW IN THIS ADVISORY...BUT GIVEN THE FACT THAT THE
CIRCULATION IS MOVING OVER WARMER WATERS AND SHEAR IS FORECAST TO
LESSEN...NEW CONVECTION COULD REDEVELOP
Morning all

What is left of Dorian is going to get eaten alive once it gets just N of the Antilles.

Windsat from about an hour ago shows that very weak S side. There is a little banding indicating there may be some light W winds down there, but again; it's not a system that can handle the shear it is headed for.

2061. tc1120
Quoting 2001. mikatnight:
Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.



Looks like a Straited or a juvenile Tri-Colored Heron.
Quoting 2037. kmanislander:


How do you know it closed up again ??

late yesterday when the LLCOC became visible if you examined it closer you could see that the S side was open and you an then see it closing off then it became very clear as it was clearly naked and devoid on convection and then night fell and wasn't fully visible however it could have been seen on the RGB night and Shortwave ir as very faint clouds due to its low level and night time but watching it it eventually got higher and the convection started to pop and the it got covered and is still covered yeah the scat showed it open but that was before all what I just said
2063. hydrus
Quoting 2056. taco2me61:
I might go out on a limb now but I'll say TD Dorian at the next TWO :o)

Taco :o)
Do you always climb a tree when making a tropical forecast.?...jk....really:)
Quoting 2001. mikatnight:
Good Morning!

Am I the only one getting bored with these sunrise pics and the Lantana bridge?


I looked forever trying to find what kind of bird this is, but I'm still not sure. Some type of heron maybe? Perhaps a juvenile, dunno. Anybody know?


Dexter's other passion is chasing balls - little action shot here!

Collected 0.6" of rain yesterday in a brief, but intense little downpour, and ended our rainless streak at 4 days. NWS calling for a 60% chance today mostly between 5 & 8 pm. Maybe I'll find a 4x4 and mount that rain gauge today. There's always hope.



My best guess is a juvenile bittern
LLC is ill-defined but is still there. I would say wait till its official before saying it dead. Still wonder if that ULL may merge with Dorian like some tried to do earlier in the season. Dorian still has a low level circulation so it has the potential to merge seemingly.
Mikatnight,

That is a juvenille Yellow Crowned Night Heron. I have a pair that have been nesting over my car for the last 4 years. Fun to watch grow up, not so far to clean the crab parts off the roof, driveway, and car.
Quoting 2063. hydrus:
Do you always climb a tree when making a tropical forecast.?...jk....really:)

Yes I do just to see what is "Really" going own LOL

Taco :o)
Quoting 2059. Tropicsweatherpr:
Hi kman.

This is what Lixon Avila said at 11 PM about why he didn't pull the plug on Dirian at that time.

DORIAN APPEARS TO STILL HAVE A VIGOROUS LOW- TO MID-LEVEL
CIRCULATION IN CONVENTIONAL SATELLITE IMAGERY WITH 30 TO 35 KNOTS
MEASURED BY A RECENT ASCAT PASS...BUT IT HAS BEEN DEVOID OF DEEP
CONVECTION FOR SEVERAL HOURS. I WAS TEMPTED TO DECLARE DORIAN A
REMNANT LOW IN THIS ADVISORY...BUT GIVEN THE FACT THAT THE
CIRCULATION IS MOVING OVER WARMER WATERS AND SHEAR IS FORECAST TO
LESSEN...NEW CONVECTION COULD REDEVELOP


Yeah, read that in the archive. Reminds me of Dolly many years ago that opened up into a wave in the Caribbean but still had TS force winds and tons of convection. They kept it as a TS and the circulation closed off again near the Yucatan. With Dorian though the same reasoning would not apply save for the winds.

Anyway, the discussion coming up will sort this out.
Quoting 2052. Grothar:


That is what WNW usually indicates within a certain parameter.

Not really

Quoting 2058. kmanislander:


I would be surprised if they didn't declassify it.


I wouldn't be surprised if NHC keeps it 40mph TS
2070. hydrus
Quoting 2067. taco2me61:

Yes I do just to see what is "Really" going own LOL

Taco :o)
and i thought redwoods were tall....hhhaaa..
Good morning..I see that Dorian is barely hanging on..We shall see..
Quoting 2061. tc1120:


Looks like a Straited or a juvenile Tri-Colored Heron.


I'm going with straited. Seems to be the most popular pick. Thanks.
Quoting 2060. StormJunkie:
Morning all

What is left of Dorian is going to get eaten alive once it gets just N of the Antilles.

Windsat from about an hour ago shows that very weak S side. There is a little banding indicating there may be some light W winds down there, but again; it's not a system that can handle the shear it is headed for.



Wait before pulling the plug on it as it manage to stay alive overnight so that why the NHC is the experts. Cant wait to see what they at 11am
2074. 62901IL
Our time of judgement is approaching.
Quoting 2066. DaytonaBill:
Mikatnight,

That is a juvenille Yellow Crowned Night Heron. I have a pair that have been nesting over my car for the last 4 years. Fun to watch grow up, not so far to clean the crab parts off the roof, driveway, and car.


Great! Just when I was sure...
Quoting 2064. yonzabam:


My best guess is a juvenile bittern


Oh nooooooo...
2077. 7544
stays the same at 11 am imo next
nice tropical wave here
Quoting 2069. wunderkidcayman:



I wouldn't be surprised if NHC keeps it 40mph TS


This should be the case.
2080. SLU
Dorian is toast.

Should open up officially at 11am.
Quoting 2070. hydrus:
and i thought redwoods were tall....hhhaaa..


We have "Really" Tall Pine Trees :o) LOL

Taco :o)
I wonder if Dexter has looked at the low pressure system by Cape Verde this morning.
2083. centex
I'm thinking last one more six hour period than dropped at 5. But hate when post something like this and proved wrong minutes later.
2084. hydrus
Quoting 2080. SLU:
Dorian is toast.
Where is the butter.?....all toast should have somethin on it..:)
The next step in google searching will be to put in a photo of something and click on search...
Quoting 2078. hurricanes2018:
nice tropical wave here


I expect a 70% red circle with pre-Erin in a few minutes.
Sunset at Puerto Barrios, Guatemala


Riverine boats onboard the USS Oak Hill. Note the beautiful blue waters of the Southern Caribbean
according to SST Dorian is about to step into hot waters 27 degrees and higher
The 925 mb vorticity ( 2500 feet ) shows the rotation with Dorian is located away from where the low center is supposed to be, suggestion that whatever circulation remains is either not due to a closed surface low or that Dorian is not vertically aligned.

2090. SLU
Quoting 2084. hydrus:
Where is the butter.?....all toast should have somethin on it..:)


hehe
2091. LargoFl
2092. hydrus
Quoting 2081. taco2me61:


We have "Really" Tall Pine Trees :o) LOL

Taco :o)
I " had " some pines..They died when Charley reconfigured them horizontally.
Many of you are using the ASCAT to assume Dorian has no circulation, but Dorian's core might be so small, the satellite pass may not be able to pick up any west winds. If only we had a recon...
Quoting 2083. centex:
I'm thinking last one more six hour period than dropped at 5. But hate when post something like this and proved wrong minutes later.


Really does not matter who turns out to be right or wrong. We all have an opinion and often there is an element of subjectivity in deciding whether to declassify or not. Indeed, we saw that last night when on a purely technical basis Dorian was no longer closed.
Quoting 2089. kmanislander:
The 925 mb vorticity ( 2500 feet ) shows the rotation with Dorian is located away from where the low center is supposed to be, suggestion that whatever circulation remains is either not due to a closed surface low or that Dorian is not vertically aligned.


if this is correct and I know its not correct all the time I don't know why but I have noticed it
Back in a few minutes
2097. LargoFl
2098. hydrus
Quoting 2087. Stoopid1:
Sunset at Puerto Barrios, Guatemala


Riverine boats onboard the USS Oak Hill. Note the beautiful blue waters of the Southern Caribbean
Blue and warm..A hurricane would slurp it up quick.
2099. JRRP
water temp getting warmer
Quoting 2093. theyoungmet:
Many of you are using the ASCAT to assume Dorian has no circulation, but Dorian's core might be so small, the satellite pass may not be able to pick up any west winds. If only we had a recon...


I'm not sure they would even go Because of the Sequester..... They are saying they will not fly into many of the Storms that are small and no threat to CONUS....

Taco :o)
Quoting 2089. kmanislander:
The 925 mb vorticity ( 2500 feet ) shows the rotation with Dorian is located away from where the low center is supposed to be, suggestion that whatever circulation remains is either not due to a closed surface low or that Dorian is not vertically aligned.


Dorian is not vertically aligned I think. The center is dislocated from the main convective structure. It's not gonna help when the TUTT introduces 40 knot shear once again. I wouldn't expect him to maintain a stacked center until he gets to the Bahamas or near Cuba.
well it is beginning of the period to look towards the African coast for the E storm. right now, there are no other threat areas, except the pathetically looking Dorian. The tropical wave se of the cape verdes have a little spin .but nothing that looks like an organizing system.
Epac TS no longer issuing Advisorys
Still 40mph TS 11:00 advisory
At least we have TS Flossie to watch. It is still expected to hit the Hawaiian Islands as a TS. The latest advisory was just issued and Flossie has 65mph, down from 70mph on the last advisory.
JeffMasters has created a new entry.
New
Last NHC advisory issued on FLOSSIE
Quoting 2103. stoormfury:
well it is beginning of the period to look towards the African coast for the E storm. right now, there are no other threat areas, except the pathetically looking Dorian. The tropical wave se of the cape verdes have a little spin .but nothing that looks like an organizing system.


There are two solid surface lows off the East Coast of the US. There are developing nice spin to them, and low level convergence is strengthening with developing cumulus cloud field, with low level banding trying to get going soth of the center east of NC, it's a closed circulation
Quoting 2089. kmanislander:
The 925 mb vorticity ( 2500 feet ) shows the rotation with Dorian is located away from where the low center is supposed to be, suggestion that whatever circulation remains is either not due to a closed surface low or that Dorian is not vertically aligned.


This situation reminds EARL 3 years ago while approaching the Leeward Islands
Quoting 2101. taco2me61:


I'm not sure they would even go Because of the Sequester..... They are saying they will not fly into many of the Storms that are small and no threat to CONUS....

Taco :o)

Dang sequester! But I want to knowwww (sorry my weather weenie side is coming out)
2112. Grothar
Quoting 2086. redwagon:


I expect a 70% red circle with pre-Erin in a few minutes.



I wouldn't expect to see more than 10-20%. It takes a while for these, although this is the one I have been worried about since last week.





Dorian look bad

Quoting 2073. Hurricanes305:


Wait before pulling the plug on it as it manage to stay alive overnight so that why the NHC is the experts. Cant wait to see what they at 11am


Wait, don't wait; it doesn't really matter at this point. It is headed for a very detrimental environment and that isn't going to change quick enough. Even if the ULL were moving or dissipating, it is not doing it at nearly the speed Dorian is headed for it. I would put it at under a less than 10% chance that it survives that shear. And if it does, I would put it at about a 1% chance that it does it with a closed circulation.
I wonder whats taking so long for the 11:00 update ?
2115. VR46L
New Blog LOL !!!!!!!
11am advisory is not out early, so probably a lot of
thought going into it.
People..
Shear is decreasing.
Dorian is entering warmer waters.
It looks better convective wise than last night.
Dry air isn't extremely bad.
Dorian should hang on a while...unless it don't have a closed circulation..
guys NEW BLOG!!!!!!
Quoting 2054. Grothar:



I could have said, ragged and cranky, but I didn't. I still have modicum of kindness. (Although it has been running thin lately)


Cranky?!?! What makes you think I am cranky??? lol

Just to show that I am not cranky, I will admit to the "ragged" comment. Sadly, coffee will resolve the cranky, but I will still be ragged. I have yet to find the drink that solves the ragged look. Wild Turkey doesn't do it, but then again it does get me to where I no longer care about my ragged look. :)
Link

While Dorian chugs along straddling the line between life and death, these two surface lows continue to churn off the East Coast. The NC one has a beautiful circulation and is really trying hard to get some convection going along with it, but its western side is dropping the ball there. The FL one is still busy improving its circulation, and seems to be doing a good job so far. The former of the two may not have enough time left in warm waters to do much, but if shear continues to decrease across the coast then perhaps the surface low currently off of Florida can make progress. Both are moving NNE.
2121. SLU
Poor CaribBoy. He's having another bad season.

GIVEN THE TRACK AND INTENSITY FORECAST...ALONG WITH THE WEAK WIND
FIELD OVER THE SOUTHERN SEMICIRCLE OF THE CYCLONE...WATCHES OR
WARNINGS ARE NOT NEEDED FOR THE ISLANDS OF THE NORTHEAST CARIBBEAN.
could see a yellow circle on the new african wave at 2:00.....but likely to suffer the same fate as Dorian down the road.
2123. hydrus
A long way out, but interesting.. CMC, GFS at 240..



I am fairly new to this blog and I have learnt a lot about the weather. I see many bloggers have written off this season already and we haven't finished July yet. So far this season is on par with some of the most active seasons ever eg 2011,2010,2008 or 1969!!
Quoting 2112. Grothar:



I wouldn't expect to see more than 10-20%. It takes a while for these, although this is the one I have been worried about since last week.





Dorian look bad

img src="http://www.ssd.noaa.gov/PS/TROP/floaters/04L/ imagery/rb-animated.gif" style=b"max-width:e Look bads but way bettter than yesterday
Dorian is a exposed LLC...We are thinking of dropping her on the next adv at 5pm. MLC is just south off the LLC. Dry air, shear ahead will give this a 20% chance of redevelopment in the next 48hrs (as of 5pm). Still discussing the exact details.
Quoting 2124. eddiedollar:
I am fairly new to this blog and I have learnt a lot about the weather. I see many bloggers have written off this season already and we haven't finished July yet. So far this season is on par with some of the most active seasons ever eg 2011,2010,2008 or 1969!!


And it only takes 1 storm. Andrew, the 1st storm of the season, wasn't until Aug.24th.

I bet people really thought that year was a bust at this time with no named storms.