Tropical Depression Two forms from Invest 98L

By: Dr. Jeff Masters , 9:33 PM GMT on July 17, 2011

Share this Blog
0
+

Tropical Depression Two (TD2) formed from Invest 98L this afternoon. Hurricane Hunters flew into the suspect area and found a surface circulation north of the Bahamas, with maximum sustained winds of 35 mph. They also determined the system had become warm core—a characteristic that must be present in order to declare a tropical cyclone. Satellite imagery continues to show the system is becoming more organized with a stronger circulation. Wind shear is forecast to remain favorable for the system until Tuesday or Wednesday when higher shear will slide in from the north. Sea surface temperatures are warm enough to sustain a tropical storm.


Figure 1. Satellite imagery of Tropical Depression Two in the Atlantic, east of Florida. This graphic will update to the current satellite imagery.


Figure 2. Official 5-day forecast for Tropical Depression Two. This graphic will remain current.

Forecast for TD2

The models are coming into better agreement as TD2 has become more organized. In terms of dynamical forecast models, the HWRF and GFS both forecast TD2 to max out just above tropical storm strenth. HWRF intensifies TD2 to around 47 mph in the next 24 hours, whereas GFS is a bit slower to bring the system up to tropical storm status. Two statistical models, the DSHP (SHIPS model that includes land interaction) and the LGEM (Logistical Growth Equation Model) both intensify TD2 to a moderate tropical storm over the next 2-3 days.

There tends to be a lot of uncertainty involved with tropical cyclones that form under these circumstances, but our forecast remains in line with the National Hurricane Center and the reliable forecast models. TD2 will move slowly to the northeast in weak steering currents over the next few days before eventually becoming an extratropical storm. There is minimal chance that this system will cross over Florida into the Gulf of Mexico. Timing and path depend heavily on how intense the cyclone gets, as Jeff mentioned in his blog earlier today. A weaker storm will tend to stay south, whereas a stronger storm will grow taller in the atmosphere and winds at higher levels will influence it and steer it northeast.

None of the reliable models predict tropical cyclone development over the remainder of the Atlantic through July 23.

Angela

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 875 - 825

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

Thank you Jesus for the NHC. Even they underestimated this one. 19N81W just radioed me and said it's a bumpy ride tonight. :)
Member Since: May 26, 2011 Posts: 0 Comments: 1193
Quoting wxhatt:
As quoted from the blog update:

"Timing and path depend heavily on how intense the cyclone gets, as Jeff mentioned in his blog earlier today. A weaker storm will tend to stay south, whereas a stronger storm will grow taller in the atmosphere and winds at higher levels will influence it and steer it northeast."
That is true, but in this case it depends on the perimeters present in the atmosphere. There is an upper-level ridge located over the United States that would influence the steering of Bret, should it intensify to the point that it can feel deep-layer steering.
Member Since: Posts: Comments:
Quoting crAAzyCane:
Link

IR Loop looks like shear is relaxing even more and he's starting to break free from that frontal boundary.
that would really help and is highly hopeful on my part
Member Since: Posts: Comments:
Time: 06:25:00Z
Coordinates: 27.5333N 77.5333W
Acft. Static Air Press: 848.4 mb (~ 25.05 inHg)
Acft. Geopotential Hgt: 1,526 meters (~ 5,007 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 108° at 25 knots (From the ESE at ~ 28.7 mph)
Air Temp: 12.6°C* (~ 54.7°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 34 knots (~ 39.1 mph)
SFMR Peak (10s) Sfc. Wind: 46 knots (~ 52.9 mph)
SFMR Rain Rate: 21 mm/hr (~ 0.83 in/hr)
(*) Denotes suspect data

Tons of these 50-60 mph surface readings, I wonder why they only went up to 45mph
Member Since: Posts: Comments:
Quoting TomTaylor:
it uses steering currents, so I don't know why it wouldn't be helpful.

And I believe he was just trying to point out that if it were a more intense storm, it would be steered by a deeper layer of the atmosphere, allowing it to take a westward track, as indicated by the BAM-Deep layer model.
It's not too helpful when the steering currents are very weak. And to be honest, a stronger storm wouldn't really take a more westward track as stated in Dr. Masters blog. It will be more likely to feel the weakness in the ridge...
Member Since: Posts: Comments:
As quoted from the blog update:

"Timing and path depend heavily on how intense the cyclone gets, as Jeff mentioned in his blog earlier today. A weaker storm will tend to stay south, whereas a stronger storm will grow taller in the atmosphere and winds at higher levels will influence it and steer it northeast."
Member Since: Posts: Comments:
Looks to have 'wobbled' towards the east in the last few frames. Just an observation, not saying that this is true movement.

Member Since: Posts: Comments:
867. Skyepony (Mod)
I agree with cchsweatherman.. the stronger this gets the more weight BAMD gets.
Member Since: Posts: Comments:
Quoting TomTaylor:
it uses steering currents, so I don't know why it wouldn't be helpful.

And I believe he was just trying to point out that if it were a more intense storm, it would be steered by a deeper layer of the atmosphere, allowing it to take a westward track, as indicated by the BAM-Deep layer model.


Its more of an analysis of a model really, just an equation of a storm with certain parameters and what it would do if it was placed in the current location of the storm.
Member Since: Posts: Comments:
Quoting wxhatt:


Sorry, but there is no current westward component to it's movement currently.


I never suggested that. All that I stated is that the BAMD model shows what the general path would be for a stronger system given the atmospheric steering patterns.
Member Since: Posts: Comments:
Quoting SouthDadeFish:
The BAM suite isn't a dynamical model... It's a simple statistical model that uses the beta effect in its forecasting. Not too helpful here.
it uses steering currents, so I don't know why it wouldn't be helpful.

And I believe he was just trying to point out that if it were a more intense storm, it would be steered by a deeper layer of the atmosphere, allowing it to take a westward track, as indicated by the BAM-Deep layer model.
Member Since: Posts: Comments:
Quoting cchsweatherman:
By the way, the more this storm intensifies, the more influence it will feel from the ridge and want to head westward as suggested by the BAMD which shows the path a stronger system would take.


Sorry, but there is no current westward component to it's movement currently.
Member Since: Posts: Comments:
Quoting cchsweatherman:


I know its a statistical model, but it helps show the general steering pattern for a stronger system.
To an extent yes. From what I've heard and know, the stronger this thing gets the more likely it is to feel the weakness in the ridge and get pulled NE. Then again if it keeps drifting south who knows what will happen.
Member Since: Posts: Comments:
Bret is making the loop as Dr. Masters described. Then a break in the ridge to the north will develop, and then storm will move in a general north-northeast direction.

NHC quote: "BRET IS MOVING TOWARD
THE SOUTH-SOUTHEAST NEAR 4 MPH...6 KM/H...HOWEVER A TURN TOWARD THE
NORTH-NORTHEAST IS EXPECTED ON MONDAY."

There remains a possibility that Cape Hatteras will be affected by this storm.




Member Since: Posts: Comments:
Quoting SouthDadeFish:
The BAM suite isn't a dynamical model... It's a simple statistical model that uses the beta effect in its forecasting. Not too helpful here.


I know its a statistical model, but it helps show the general steering pattern for a stronger system.
Member Since: Posts: Comments:
Time: 06:15:00Z
Coordinates: 27.9333N 77.0667W
Acft. Static Air Press: 851.4 mb (~ 25.14 inHg)
Acft. Geopotential Hgt: 1,518 meters (~ 4,980 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 110° at 27 knots (From the ESE at ~ 31.0 mph)
Air Temp: 13.6°C* (~ 56.5°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 27 knots (~ 31.0 mph)
SFMR Peak (10s) Sfc. Wind: 41 knots* (~ 47.1 mph*)
SFMR Rain Rate: 19 mm/hr* (~ 0.75 in/hr*)
(*) Denotes suspect data

Going in on center.
Member Since: Posts: Comments:
Quoting cchsweatherman:
By the way, the more this storm intensifies, the more influence it will feel from the ridge and want to head westward as suggested by the BAMD which shows the path a stronger system would take.
The BAM suite isn't a dynamical model... It's a simple statistical model that uses the beta effect in its forecasting. Not too helpful here.
Member Since: Posts: Comments:
Quoting 7544:
throw the models out wait on the new runs


The next model runs will look like a spider with different colored legs...:^)
Member Since: Posts: Comments:
By the way, the more this storm intensifies, the more influence it will feel from the ridge and want to head westward as suggested by the BAMD which shows the path a stronger system would take.
Member Since: Posts: Comments:
Link

IR Loop looks like shear is relaxing even more and he's starting to break free from that frontal boundary.
Member Since: Posts: Comments:
I'm guessing next center fix will be 1001mb and then I'm going to sleep ;~)
Member Since: Posts: Comments:
funny that no model predicts a southeastward movement but that continues to happen.
Member Since: Posts: Comments:
851. 7544
throw the models out wait on the new runs
Member Since: Posts: Comments:
Quoting PrivateIdaho:


Anybody want to bet on how close the next model runs are to the current forecast?


not even close...
Member Since: Posts: Comments:
Quoting VAbeachhurricanes:


still diving SE


Anybody want to bet on how close the next model runs are to the current forecast?
Member Since: Posts: Comments:
Pretty impressive numbers from the Hurricane Hunters. Definitely a strengthening Tropical Storm Bret.
Member Since: Posts: Comments:
Quoting SouthDadeFish:
If the next fix has a pressure at 1000mb or lower look out.


yeah, and if its moved more south...
Member Since: Posts: Comments:
845. Skyepony (Mod)
The three eye region scene types and five cloud region scene types are described
below:

Eye Region Scene Type Description
EYE Any eye type (clear, ragged, and obscured)
PINHOLE Very small eye/pronounced warm spot
LARGE Clear, well-defined eye with radius >= 38 km
Cloud Region Scene Type Description
UNIFORM CDO Overcast cloud region with uniform temperature structure
EMBEDDED CENTER Arc of convection within central overcast cloud region
IRREGULAR CDO Cloud region over storm center, but large shift in coverage
CURVED BAND Curved cloud region surrounding circulation center
SHEAR Displaced convection and exposed circulation center
Member Since: Posts: Comments:
51kt surface winds.

060130 2731N 07653W 8500 01537 //// +126 //// 140043 047 051 025 01
Member Since: Posts: Comments:
If the next fix has a pressure at 1000mb or lower look out.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
LOL, it's happened to me too. You have to purchase Parallels for $79.95 to be able to run Windows on your Mac.
So much money for everything.... ugh. Thanks for the heads up though.
Member Since: Posts: Comments:


still diving SE
Member Since: Posts: Comments:
840. Skyepony (Mod)
That's the Central Dense Overcast (CDO) coming together. Curved band like we are seeing with ADT & that last vortex message is the step before CDO which looks like an eye on radar that isn't on satellite.

Member Since: Posts: Comments:
Should be making a NE quad pass...

Could prove interesting.
Member Since: Posts: Comments:
Quoting SouthDadeFish:
Thanks! Looks amazing, not sure if I have the money to drop though lol. Maybe my next investment!


We will have to wait until things are REALLY happening and get the free trial....lol!
Member Since: Posts: Comments:
Quoting SouthDadeFish:
Aww boooo just noticed its Windows only. Oh well...
LOL, it's happened to me too. You have to purchase Parallels for $79.95 to be able to run Windows on your Mac.
Member Since: Posts: Comments:
Aww boooo just noticed its Windows only. Oh well...
Member Since: Posts: Comments:
Quoting Stormchaser2007:


GRLevel2AE

$250

Highly recommend it.
Thanks! Looks amazing, not sure if I have the money to drop though lol. Maybe my next investment!
Member Since: Posts: Comments:
Quoting MississippiWx:


Think they just had to update quickly. If they find evidence of anything higher, I'm sure they'll update. The main thing is that they issued the proper tropical storm warnings. Probably a little late, though. LOL.
LOL, I agree. Warnings should've been posted since the first advisory IMO.
Member Since: Posts: Comments:
832. 7544
hmm he just might miss the weakness
Member Since: Posts: Comments:
831. JRRP

Member Since: Posts: Comments:
Quoting SouthDadeFish:
Chaser, what radar products are you using?


GRLevel2AE

$250

Highly recommend it.

There's a free-trial as well.
Member Since: Posts: Comments:
Chaser, what radar products are you using?
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
45mph? Not sure if serious...LOL.


Think they just had to update quickly. If they find evidence of anything higher, I'm sure they'll update. The main thing is that they issued the proper tropical storm warnings. Probably a little late, though. LOL.
Member Since: July 15, 2006 Posts: 17 Comments: 10247
Quoting MississippiWx:
If Bret's pressure continues to fall like this, we should see an explosion of convection. I'd have a hard time believing that the pressure could keep falling so fast, though. He's over the warmest waters in the Atlantic, so we'll see.


Recon almost to center again, we shall see if it as dropped anymore as well as exact movement.
Member Since: Posts: Comments:
If Bret's pressure continues to fall like this, we should see an explosion of convection. I'd have a hard time believing that the pressure could keep falling so fast, though. He's over the warmest waters in the Atlantic, so we'll see.
Member Since: July 15, 2006 Posts: 17 Comments: 10247

Viewing: 875 - 825

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

Top of Page

About

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