The Steering of Dorian

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

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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

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Quoting 1473. theyoungmet:
Thanks guys! I feel welcome already :)

Yes I agree with Bluestorm5, come to the chat :) it'd be nice to meet another teen on here
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Quoting 1473. theyoungmet:
Thanks guys! I feel welcome already :)


Most of us teens is on chat right now. Why don't you join us :) We can get to know each other quickly there and tell you about blog!

http://www.wunderground.com/community/chat.asp
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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)


Welcome!
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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)


Welcome to WU!
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I want to emphasize that, although Dorian is firing convection again, there are two important parameters to keep in mind:

It's doing so during the diurnal maximum. If it can do it during the diurnal minimum, the game will change.

The convection isn't very organized, and there is no evidence of banding features.
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Thanks guys! I feel welcome already :)
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Good night!!:)


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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)

Welcome to the blog.
Member Since: July 6, 2010 Posts: 113 Comments: 32043
Quoting 1341. AussieStorm:


Looks like it's going to go back to a T-wave very soon. has the classic V shape appearing.

Aussie, awesome! We all get better with age, don't we...really! Thanks, thyemsage
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Quoting 1455. RascalNag:
Link

While in all likelihood it's just a short-lived feature that doesn't have enough time to develop too much, it's shaping up pretty nicely - right now it's grabbing some convection as the dry air pocket to its northwest fades, and while the shear is 20 knots, it's decreasing. Ocean temps are enough to sustain it, too. Looks like it's trying to compete with Dorian for the best looking storm of the night before it dies...


East winds to the north

West winds to the south
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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)

Welcome to the blog :)Why don't you join some of us on the Weather Chat?
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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)


Welcome to the community, dude.
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Quoting 1459. TideWaterWeather:


Actually, DMAX is not "an intense flare up of convection" but rather a condition where the cooler night time air allows convection and conduction from the ocean water to the air above, thus aiding in thunderstorm development. During DMIN, The warmer air temps tend to create an atmospheric CAP that reduces the ability for deeper thunderstorms to develop.


Blogger does not have the correct definition of SAL either.
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Quoting 1460. theyoungmet:
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)
Nice to see another teen on here. There are lot of teens on here that love meteorology! Welcome to WU! You came to the right place for discussion and this is IMO the best place to discuss about weather!
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1464. scott39
Quoting 1458. KoritheMan:


If it's over the center, it could try to reinforce the westerly winds (which aren't there according to that ASCAT pass) and tighten up the low-level center again.
Is it a long shot...Hail Mary time?
Watch closely, how almost at the exact moment that dry air channel to the north of Dorian, closes, we see immediate strengthening.

Just my take ...

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Quoting 1457. NCHurricane2009:
Looks like my second intensity forecast I created at 6 AM yesterday morning on Dorian verifying spot-on tonight....

I explained in my blog post how at first it looked like Dorian was going to intensify quiet a bit...and then explain why instead he has weakened. Its all related to the upper wind pattern....


upper winds have nothing todo with Dorian weakening over the past 24hrs.. it's been the dry air
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1461. scott39
Notice Avila said Dorian has a vigorous low-to mid- level circulation. That means he is a fighter, and even if it becomes a remnant low....vigorous wont go away easily, especially with the better enviroment that he is headed into. Or he could die within 24 hours. Mother Nature is challenging all the time. My hat is off to all Mets.
Hey guys! Long time member of other weather forums, but I only realized WU had a blog this season. And I got to say, this is the sassiest and most funny weather forum I've ever read. The fights you guys have are beyond hilarious. Anyway, I'm a 16 year old weather enthusiast that's striving for a metrology degree in college. But don't worry I'm not gonna be posting ASCAT 24/7 or wish cast. I'm here to now cast. I hope you guys accept me into your community. This season promises to be one to remember.

Quick Dorian comment: he never really lost his low level vort. and he still has some sort of circulation (no mid level spin and it's a very small core). Dmax should be good to him as he makes his way past the 40 kt shear and dry air. Shear is letting up in front, but he is without an anticyclone and will take the full force of the shear the ULL is producing. He may die at some point soon, but the wave will continue to be steered towards the Bahamas. Keep am eye on him because Dorian is the storm that surprises us when you least expect it. Hopefully those cold tops grow on him tonight over the weak LLC (should be around 1010 mb relative to the heights over the Atlantic currently)
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Quoting 1441. sar2401:


"Dmax- is Diurnal Maximum is an intense flare up at convection just before sunrise and DMIN is the opposite. Dmax occurs just before sunrise when the differences in temperatures between the ocean and the air are the greatest; helps to create instability and convection"


This is from a very useful list of abbreviations and acronyms from one of our own bloggers. Very useful stuff.


Actually, DMAX is not "an intense flare up of convection" but rather a condition where the cooler night time air allows convection and conduction from the ocean water to the air above, thus aiding in thunderstorm development. During DMIN, The warmer air temps tend to create an atmospheric CAP that reduces the ability for deeper thunderstorms to develop.
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Quoting 1454. yankees440:


Of what significance, if any, is there of the convection covering the center? Is that a sign of possible strengthening, holding steady, or nothing in particular?


If it's over the center, it could try to reinforce the westerly winds (which aren't there according to that ASCAT pass) and tighten up the low-level center again.
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Looks like my second intensity forecast I created at 6 AM yesterday morning on Dorian verifying spot-on tonight....

I explained in my blog post how at first it looked like Dorian was going to intensify quiet a bit...and then explain why instead he has weakened. Its all related to the upper wind pattern....
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Dorian looks as if he has eaten the dry air and is jumping past it in this loop

Link
Member Since: August 18, 2011 Posts: 0 Comments: 622
Link

While in all likelihood it's just a short-lived feature that doesn't have enough time to develop too much, it's shaping up pretty nicely - right now it's grabbing some convection as the dry air pocket to its northwest fades, and while the shear is 20 knots, it's decreasing. Ocean temps are enough to sustain it, too. Looks like it's trying to compete with Dorian for the best looking storm of the night before it dies...
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Quoting 1452. KoritheMan:
Since this pass was at 0z, I wonder what the circulation looks like now? Recent satellite imagery suggests that the bursting convection is covering nearly the entire center, albeit lacking banding or significant organization.



Of what significance, if any, is there of the convection covering the center? Is that a sign of possible strengthening, holding steady, or nothing in particular?
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Quoting 1447. cchsweatherman:
Looks like some popcorn convection is building out ahead of the storm to the west. Definitely seeing an upward trend with Dorian tonight; enough to save it is the question.


Well, the convection saved Dorian at the last advisory that's for sure.
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Since this pass was at 0z, I wonder what the circulation looks like now? Recent satellite imagery suggests that the bursting convection is covering nearly the entire center, albeit lacking banding or significant organization.

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1451. scott39
Quoting 1448. CosmicEvents:
The NHC was apparently ready to cart off Dorian but he's feeling better at the moment. GN all.
.
Now that was funny!
1450. JLPR2
Quoting 1441. sar2401:


"Dmax- is Diurnal Maximum is an intense flare up at convection just before sunrise and DMIN is the opposite. Dmax occurs just before sunrise when the differences in temperatures between the ocean and the air are the greatest; helps to create instability and convection"


This is from a very useful list of abbreviations and acronyms from one of our own bloggers. Very useful stuff.


Actually I'm no expert but believe I know the basics, 6 years blogging here have not gone in vain. xD
Member Since: September 4, 2007 Posts: 7 Comments: 8697
Definitely appears new convection firing is over Dorian's center and is growing each frame -
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The NHC was apparently ready to cart off Dorian but he's feeling better at the moment. GN all.
.
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Looks like some popcorn convection is building out ahead of the storm to the west. Definitely seeing an upward trend with Dorian tonight; enough to save it is the question.
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Allstar17:
My bad, I didn't see this one! Been a long day. Excuse my lapse. I still don't think hoping a storm shows up in the Caribbean is 'down casting"


000
WTNT44 KNHC 270232
TCDAT4

TROPICAL STORM DORIAN DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST FRI JUL 26 2013

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. THE BEST OPTION IS TO KEEP
THE CYCLONE FOR A COUPLE OF MORE ADVISORY CYCLES AND MONITOR THE
EVOLUTION OF THE CONVECTION. SHIPS AND LGEM RE-INTENSIFY THE
CYCLONE A LITTLE BIT BY THE END OF THE FORECAST PERIOD.
HOWEVER...THE OFFICIAL FORECAST IS BIASED TOWARD THE GFS AND THE
ECMWF GLOBAL MODELS WHICH GRADUALLY WEAKEN DORIAN.

THE CENTER OF CIRCULATION APPEARS TO BE MOVING WESTWARD AT 19 KNOTS.
THE SYSTEM IS EMBEDDED WITHIN THE DEEP EASTERLIES...AND AS TROPICAL
CYCLONE...REMNANT LOW OR TROUGH...IT WILL CONTINUE TO MOVE WESTWARD
UNTIL DISSIPATION IN ABOUT 4 DAYS...OR HOPEFULLY SOONER.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 17.9N 48.1W 35 KT 40 MPH
12H 27/1200Z 18.3N 51.2W 30 KT 35 MPH
24H 28/0000Z 18.8N 55.5W 30 KT 35 MPH
36H 28/1200Z 19.3N 59.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/0000Z 20.0N 63.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 30/0000Z 21.0N 70.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 31/0000Z...DISSIPATED

$$
FORECASTER AVILA

Member Since: August 18, 2011 Posts: 0 Comments: 622
Quoting 1439. DavidHOUTX:


Which specific advisory are you referring to? I don't see that on any of his latest advisories. If you didn't know, they make their advisories based off of the current situations. I would also hope anyone in the NHC hopes a Hurricane entering the Bahamas or Antilles islands is a bad thing.


000
WTNT34 KNHC 270232
TCPAT4

BULLETIN
TROPICAL STORM DORIAN ADVISORY NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST FRI JUL 26 2013

...DORIAN FORECAST TO BECOME A REMNANT LOW IN A DAY OR SO...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.9N 48.1W
ABOUT 985 MI...1585 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1010 MB...29.83 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

INTERESTS IN THE NORTHERN LEEWARD ISLANDS SHOULD MONITOR THE
PROGRESS OF DORIAN.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM DORIAN WAS
LOCATED NEAR LATITUDE 17.9 NORTH...LONGITUDE 48.1 WEST. DORIAN IS
MOVING TOWARD THE WEST NEAR 22 MPH...35 KM/H...AND THIS GENERAL
MOTION IS EXPECTED TO CONTINUE DURING THE NEXT DAY OR TWO.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 40 MPH...65 KM/H...
WITH HIGHER GUSTS. DORIAN IS EXPECTED TO WEAKEN AND BECOME A
REMNANT LOW IN A DAY OR SO.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM TO
THE NORTH OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB...29.83 INCHES.


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


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

$$
FORECASTER AVILA


It is in the forecast discussion. It was simply a joke anyway.
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Dorian may have a friend in high places.

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Quoting 1442. TideWaterWeather:


IMO.. DMIN/DMAX gets way to much credit here....while it is true that DMAX provides the best conditions for heat transfer, a storm that has a favorable environment can strengthen and even go RI no matter what time of day it is...These terms are simply over used and not understood by most here..


I disagree in the present circumstances. Dorian is a weak system on the edge. The diurnal convection cycle may be playing a critical role in Dorian's state.
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Quoting 1434. BaltimoreBrian:
The new convection looks like it is over the low level center. If it holds for the next few hours it will probably be enough to keep Dorian designated a tropical storm for the next advisory. But will it survive D-min?


IMO.. DMIN/DMAX gets way to much credit here....while it is true that DMAX provides the best conditions for heat transfer, a storm that has a favorable environment can strengthen and even go RI no matter what time of day it is...These terms are simply over used and not understood by most here..
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1441. sar2401
Quoting JLPR2:
I'm no expert but I'm gonna guess that the warmer waters are now making a better contrast to the falling air temperatures rendering D-max more efficient or beneficial for Dorian?

Any experts out there care to confirm, explain or deny? :)


"Dmax- is Diurnal Maximum is an intense flare up at convection just before sunrise and DMIN is the opposite. Dmax occurs just before sunrise when the differences in temperatures between the ocean and the air are the greatest; helps to create instability and convection"


This is from a very useful list of abbreviations and acronyms from one of our own bloggers. Very useful stuff.
Member Since: October 2, 2004 Posts: 0 Comments: 15190
1440. scott39
Looks like Dorian is taking advantage of Avilas stay of execution. "Should have pulled the switch on me while you could Avila," says Dorian....ahahaha...aahahaha.aaaahahahaha........I love bed time stories:)
Quoting 1433. AllStar17:


Avila is a downcaster! LOL.

IT WILL CONTINUE TO MOVE WESTWARD
UNTIL DISSIPATION IN ABOUT 4 DAYS...OR HOPEFULLY SOONER.




Have a great night.


Which specific advisory are you referring to? I don't see that on any of his latest advisories. If you didn't know, they make their advisories based off of the current situations. I would also hope anyone in the NHC hopes a Hurricane entering the Bahamas or Antilles islands is a bad thing.


000
WTNT34 KNHC 270232
TCPAT4

BULLETIN
TROPICAL STORM DORIAN ADVISORY NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
1100 PM AST FRI JUL 26 2013

...DORIAN FORECAST TO BECOME A REMNANT LOW IN A DAY OR SO...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.9N 48.1W
ABOUT 985 MI...1585 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...1010 MB...29.83 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

INTERESTS IN THE NORTHERN LEEWARD ISLANDS SHOULD MONITOR THE
PROGRESS OF DORIAN.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM DORIAN WAS
LOCATED NEAR LATITUDE 17.9 NORTH...LONGITUDE 48.1 WEST. DORIAN IS
MOVING TOWARD THE WEST NEAR 22 MPH...35 KM/H...AND THIS GENERAL
MOTION IS EXPECTED TO CONTINUE DURING THE NEXT DAY OR TWO.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 40 MPH...65 KM/H...
WITH HIGHER GUSTS. DORIAN IS EXPECTED TO WEAKEN AND BECOME A
REMNANT LOW IN A DAY OR SO.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM TO
THE NORTH OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB...29.83 INCHES.


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


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

$$
FORECASTER AVILA
Member Since: August 18, 2011 Posts: 0 Comments: 622
Off topic: I know this is off topic, but I'm excited about it. Today I was asked to put in the paperwork to help train service dogs for active duty and veterans who have PTSD and TBI. I'd be training them to train their dog, and best of all, there is no cost to the soldier or vet, unlike most programs. It's volunteer and I'm really looking forward to it.

To try to keep on topic, all that rain north of me? Well, I think Pat will see it and it's going to slide right to the east of me. I'll need my hose tomorrow morning to water the garden again.
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GoM system if indeed it survives the dry air and sheer.
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1436. Patrap
Member Since: July 3, 2005 Posts: 424 Comments: 128284
1435. Patrap
Member Since: July 3, 2005 Posts: 424 Comments: 128284
The new convection looks like it is over the low level center. If it holds for the next few hours it will probably be enough to keep Dorian designated a tropical storm for the next advisory. But will it survive D-min?
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Quoting 1424. DavidHOUTX:


Avila knows his stuff



Avila is a downcaster! LOL.

IT WILL CONTINUE TO MOVE WESTWARD
UNTIL DISSIPATION IN ABOUT 4 DAYS...OR HOPEFULLY SOONER.


Quoting 1426. Grothar:


Aw, don't make me cry now. You all have fun and keep your eye on that blo...

I hear a little voice in the back that is getting very angry.

Nite everyone.


Have a great night.
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1432. Patrap
I'll close the Pyramid door,

Gro, rest tonight.
Member Since: July 3, 2005 Posts: 424 Comments: 128284
Having this convection form is good and all, and it'll keep the system a tropical cyclone, but we need to see if it persists into tomorrow and organizes. It's probably only happening because of DMAX.

Member Since: July 6, 2010 Posts: 113 Comments: 32043
Quoting 1426. Grothar:


Aw, don't make me cry now. You all have fun and keep your eye on that blo...

I hear a little voice in the back that is getting very angry.

Nite everyone.


Nite Gro
Member Since: August 18, 2011 Posts: 0 Comments: 622
1429. Patrap
I met Avila here in NOLA the day after QUIKScat failed.

Was a cool conversation.
Member Since: July 3, 2005 Posts: 424 Comments: 128284
1428. Grothar
Quoting 1419. AllStar17:


Who knows.


The Shadow knows.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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