Dr. Jeff Masters' WunderBlog

Tropical Depression Two forms from Invest 98L

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

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

Categories: Hurricane

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51. GeoffreyWPB 9:48 PM GMT on July 17, 2011
Member Since: September 10, 2007 Posts: 0 Comments: 9110

52. KEEPEROFTHEGATE (Mod) 9:48 PM GMT on July 17, 2011
T.C.F.W. 02L/TD/B/CX MARK 28.13N/78.11W Member Since: July 15, 2006 Posts: 143 Comments: 40425

53. RitaEvac 9:48 PM GMT on July 17, 2011
Got ridges from sea to shining sea this year, an no lil short wave is gonna yank this sucker out to sea, everything going westbound this year. Hell it might even go NE temporarily then go back west when new ridge comes back in. Member Since: July 14, 2008 Posts: 1 Comments: 8878

54. scCane 9:49 PM GMT on July 17, 2011
Quoting Tazmanian: nop no going out too sea i get my crows ready It better, I'm going to Myrtle Beach Tuesday. Member Since: May 9, 2007 Posts: 0 Comments: 152

55. ncstorm 9:49 PM GMT on July 17, 2011
I dont know why people are saying that the models didnt predict development..in fact the ECWMF, CMC, NOGAPS and NAM predicted development..they weren't consistent with their runs but they did see something with the set up..thats why I had a problem with Dr. Masters statement with it "none of the reliable models showing development" early this week.. Member Since: August 19, 2006 Posts: 7 Comments: 8369

56. Levi32 9:49 PM GMT on July 17, 2011
Good afternoon. Blog update: Special Tropical Tidbit for Sunday, July 17th, with Video Member Since: November 24, 2005 Posts: 586 Comments: 25441

57. Tazmanian 9:50 PM GMT on July 17, 2011
with TD 2 no shutted landing this week Member Since: May 21, 2006 Posts: 5088 Comments: 111327

58. MrstormX 9:50 PM GMT on July 17, 2011
So why no upgrade yet? Member Since: May 27, 2009 Posts: 0 Comments: 4224

59. SLU 9:50 PM GMT on July 17, 2011
Quoting CybrTeddy: Given the vortex message had 50 mph sustained.. I don't see why they can't give it 40 mph, I've seen worse looking TS before. Quoting Stormchaser2007: If recon is finding consistent 40-50mph winds, it's a TS regardless of what it looks like. True. But this now reopens the barrel of anacondas concerning strong tropical waves in the deep tropics which don't get the benefit of the recon but have an excellent satellite representation and evidence of tropical storm conditions but because there are no direct observations they don't get named. This creates lots of confusion about the naming of tropical storms. Member Since: July 13, 2006 Posts: 11 Comments: 2846

60. caneswatch 9:50 PM GMT on July 17, 2011
I do know the NHC has their "bad" moments, and I think this track is going to be one of them. There's absolutely no way that Bret is going NE with those very weak steering currents. It's going to continue to head south, and there will be TS Warnings for the Bahamas, and I won't be surprised if there's a TS Warning for some of Florida too. Member Since: October 8, 2008 Posts: 14 Comments: 4473

61. ackee 9:51 PM GMT on July 17, 2011
HOW WOULD U RATE THE NHC HANDLE OF TD#2/Bert SO FAR A GOOD B FAIR C AVERAGE D POOR Member Since: July 15, 2008 Posts: 0 Comments: 1194

62. CanesfanatUT 9:51 PM GMT on July 17, 2011
Interesting that the 0Z and 12Z ECWMF runs both have a strong vort heading into the central GOMex from the wave that just left Africa. 12Z looks stronger though with closed isobars. Have any other models developed this wave? Member Since: September 3, 2007 Posts: 0 Comments: 458

63. RitaEvac 9:51 PM GMT on July 17, 2011
And if it keeps going south that short wave is gonna have a less influence on it anyway. Member Since: July 14, 2008 Posts: 1 Comments: 8878

64. stormwatcherCI 9:51 PM GMT on July 17, 2011
Quoting ncstorm: I dont know why people are saying that the models didnt predict development..in fact the ECWMF, CMC, NOGAPS and NAM predicted development..they weren't consistent with their runs but they did see something with the set up..thats why I had a problem with Dr. Masters statement with it none of the reliable models showing development early this week.. They were showing development but seems like a little further north. Predictions cannot be an exact science as conditions are constantly changing. Member Since: October 9, 2008 Posts: 0 Comments: 8038

65. Tazmanian 9:51 PM GMT on July 17, 2011
Quoting MrstormX: So why no upgrade yet? upgrades will come out 8pm or 11pm tonight Member Since: May 21, 2006 Posts: 5088 Comments: 111327

66. KEEPEROFTHEGATE (Mod) 9:52 PM GMT on July 17, 2011
Member Since: July 15, 2006 Posts: 143 Comments: 40425

67. Tazmanian 9:52 PM GMT on July 17, 2011
Quoting ackee: HOW WOULD U RATE THE NHC HANDLE OF TD#2/Bert SO FAR A GOOD B FAIR C AVERAGE D POOR E vary poor Member Since: May 21, 2006 Posts: 5088 Comments: 111327

68. MrstormX 9:52 PM GMT on July 17, 2011
Quoting Tazmanian: upgrades will come out 8pm or 11pm tonight Special Upgrades Member Since:* May 27, 2009 Posts: 0 Comments: 4224

69. RitaEvac 9:53 PM GMT on July 17, 2011
So Wunderground blog gets a D too?! Member Since: July 14, 2008 Posts: 1 Comments: 8878

70. SLU 9:53 PM GMT on July 17, 2011
Quoting ackee: HOW WOULD U RATE THE NHC HANDLE OF TD#2/Bert SO FAR A GOOD B FAIR C AVERAGE D POOR C From only 40% at 2pm when the system was looking in great shape to a TD at 5pm and possibly a TS at 8pm Member Since: July 13, 2006 Posts: 11 Comments: 2846

71. Tazmanian 9:53 PM GMT on July 17, 2011
Quoting MrstormX: Special Upgrades oh Member Since:* May 21, 2006 Posts: 5088 Comments: 111327

72. RitaEvac 9:54 PM GMT on July 17, 2011
TAZ does Masters get a poor rating too for this? Member Since: July 14, 2008 Posts: 1 Comments: 8878

73. scCane 9:54 PM GMT on July 17, 2011
I'd give them an A. Right now this thing doesn't really look that great on the visible due to shear and D-min, it needs far more deep convection before it can be upgraded to a TS. Member Since: May 9, 2007 Posts: 0 Comments: 152

74. CybrTeddy 9:54 PM GMT on July 17, 2011
1008.9 mb (~ 29.79 inHg) Member Since: July 8, 2005 Posts: 253 Comments: 20202

75. MrstormX 9:54 PM GMT on July 17, 2011
I'd give them above average marks, I only question the track. Member Since: May 27, 2009 Posts: 0 Comments: 4224

78. GeoffreyWPB 9:55 PM GMT on July 17, 2011
Quoting ackee: HOW WOULD U RATE THE NHC HANDLE OF TD#2/Bert SO FAR A GOOD B FAIR C AVERAGE D POOR A. But possible TS Bert...not so good. :) Member Since: September 10, 2007 Posts: 0 Comments: 9110

79. Tazmanian 9:55 PM GMT on July 17, 2011
Quoting RitaEvac: TAZ does Masters get a poor rating too for this? nop he gets a C Member Since: May 21, 2006 Posts: 5088 Comments: 111327

80. ncstorm 9:56 PM GMT on July 17, 2011
Quoting stormwatcherCI: They were showing development but seems like a little further north. Predictions cannot be an exact science as conditions are constantly changing. yeah, thats why I'm not bashing the models because I posted those model runs in the blog..the low did set up more south but that was to be expected with the front and the trickery of these types of set ups Member Since: August 19, 2006 Posts: 7 Comments: 8369

81. KEEPEROFTHEGATE (Mod) 9:56 PM GMT on July 17, 2011
Quoting RitaEvac: So Wunderground blog gets a D too?! i want a rating as well how did i do forecasting the system Member Since: July 15, 2006 Posts: 143 Comments: 40425

82. TaylorSelseth 9:57 PM GMT on July 17, 2011
Quoting Stormchaser2007: Shortwave will move across the US and drag this to the NE in about 48-72 hours. How can the shortwave affect the storm with the ridge in the way? Member Since: August 29, 2008 Posts: 0 Comments: 324

83. RitaEvac 9:57 PM GMT on July 17, 2011
KOTG, don't remember you saying anything about it Member Since: July 14, 2008 Posts: 1 Comments: 8878

84. masonsnana 9:58 PM GMT on July 17, 2011
Quoting TxHurricanedude11: Its best to stop asking questions please,it gets annoying sometimes. A discussion includes questions and answers. Some of us do not have all the answers. Member Since: February 14, 2004 Posts: 2 Comments: 513

85. RitaEvac 9:59 PM GMT on July 17, 2011
Anytime I see storms over water hanging around during hurricane season, I dont give a damn what models or experts say. Especially when they say "nothing expected thru the next 5+days" Member Since: July 14, 2008 Posts: 1 Comments: 8878

86. stormwatcherCI 9:59 PM GMT on July 17, 2011
Quoting masonsnana: A discussion includes questions and answers. Some of us do not have all the answers. +1 LOL. Member Since: October 9, 2008 Posts: 0 Comments: 8038

87. GeoffreyWPB 9:59 PM GMT on July 17, 2011
Quoting KEEPEROFTHEGATE: i want a rating as well how did i do forecasting the system A+ Member Since: September 10, 2007 Posts: 0 Comments: 9110

89. stormpetrol 9:59 PM GMT on July 17, 2011
Time: 20:46:30Z Coordinates: 27.7833N 77.85W Acft. Static Air Press: 991.8 mb (~ 29.29 inHg) Acft. Geopotential Hgt: 185 meters (~ 607 feet) Extrap. Sfc. Press: 1013.6 mb (~ 29.93 inHg) D-value: - Flt. Lvl. Wind (30s): From 60° at 36 knots (From the ENE at ~ 41.4 mph) Air Temp: 18.0°C (~ 64.4°F) Dew Pt: 17.3°C (~ 63.1°F) Peak (10s) Flt. Lvl. Wind: 41 knots (~ 47.1 mph) SFMR Peak (10s) Sfc. Wind: 54 knots (~ 62.1 mph) SFMR Rain Rate: 51 mm/hr (~ 2.01 in/hr) () Denotes suspect data WOW!! no suspect data in this reading Member Since:* April 29, 2007 Posts: 0 Comments: 6394

90. cchsweatherman 10:00 PM GMT on July 17, 2011
Some very intense thunderstorms building over the Northern Bahamas. Definitely trying to strengthen further and will help in lowering pressures. Member Since: April 14, 2007 Posts: 8 Comments: 4926

91. scooster67 10:00 PM GMT on July 17, 2011
Quoting Levi32: Good afternoon. Blog update: Special Tropical Tidbit for Sunday, July 17th, with Video Excellent explanation, as always. Thanks Levi Member Since: September 26, 2010 Posts: 0 Comments: 637

92. MiamiHurricanes09 10:00 PM GMT on July 17, 2011
02L has moved towards the ENE in between the vortex message released at 21:08 UTC and the latest center fix that took place around 8 minutes ago. Member Since: September 2, 2009 Posts: 129 Comments: 19976

93. GeoffreyWPB 10:01 PM GMT on July 17, 2011
Member Since: September 10, 2007 Posts: 0 Comments: 9110

94. KEEPEROFTHEGATE (Mod) 10:01 PM GMT on July 17, 2011
Quoting RitaEvac: KOTG, don't remember you saying anything about it thats right cause iam a tracker been tracking it since yesterday first to issue T.C.F.A. this am as well and first to declared td right after and now i will be first to declare TS bret as well but nope i did not say nothing AT ALL Member Since: July 15, 2006 Posts: 143 Comments: 40425

95. stormpetrol 10:01 PM GMT on July 17, 2011
personally from the data I've seen, I think this a 45-50mph TS, but I'm not an an expert so I don't know, it's just my layman opinion Member Since: April 29, 2007 Posts: 0 Comments: 6394

96. Levi32 10:01 PM GMT on July 17, 2011
Quoting cchsweatherman: Some very intense thunderstorms building over the Northern Bahamas. Definitely trying to strengthen further and will help in lowering pressures. Thunderstorm activity remains quite weak for the moment. Intense would be -70C or colder cloud tops (red colors) Member Since: November 24, 2005 Posts: 586 Comments: 25441

97. MiamiHurricanes09 10:01 PM GMT on July 17, 2011
Quoting scCane: I'd give them an A. Right now this thing doesn't really look that great on the visible due to shear and D-min, it needs far more deep convection before it can be upgraded to a TS. Shear? Member Since: September 2, 2009 Posts: 129 Comments: 19976

99. PcolaDan 10:02 PM GMT on July 17, 2011
Quoting masonsnana: A discussion includes questions and answers. Some of us do not have all the answers. I have all the answers! (99% incorrect though when it comes to weather) Member Since: August 22, 2008 Posts: 12 Comments: 6008

100. Stormchaser2007 10:02 PM GMT on July 17, 2011
Quoting stormpetrol: Time: 20:46:30Z Coordinates: 27.7833N 77.85W Acft. Static Air Press: 991.8 mb (~ 29.29 inHg) Acft. Geopotential Hgt: 185 meters (~ 607 feet) Extrap. Sfc. Press: 1013.6 mb (~ 29.93 inHg) D-value: - Flt. Lvl. Wind (30s): From 60° at 36 knots (From the ENE at ~ 41.4 mph) Air Temp: 18.0°C (~ 64.4°F) Dew Pt: 17.3°C (~ 63.1°F) Peak (10s) Flt. Lvl. Wind: 41 knots (~ 47.1 mph) SFMR Peak (10s) Sfc. Wind: 54 knots (~ 62.1 mph) SFMR Rain Rate: 51 mm/hr (~ 2.01 in/hr) () Denotes suspect data WOW!! no suspect data in this reading Except for the RR's of 2"/hr Member Since:* June 9, 2007 Posts: 4 Comments: 15243

101. caneswatch 10:03 PM GMT on July 17, 2011
Quoting GeoffreyWPB: What's your opinion on Bret, Geoff? Member Since: October 8, 2008 Posts: 14 Comments: 4473

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