Tropical Update: Tropical Storm Dorian – 7/26/2013

11 PM Update – Dorian on Life Support

Tropical Storm Dorian is on life support this evening and is expected to dissipate in the next day or so to a remnant low.  Dorian is presently located about 985 miles east of the Northern Leeward Island with maximum sustained winds of 40 mph with an estimated central pressure of 1010 mb.

The NHC almost declared Dorian a remnant low tonight, but decided to hold off given the fact that the circulation is moving over warmer waters and the shear is expected to lessen giving the system one last hurrah.  The decision was made to continue to monitor Dorian for a couple more advisory cycles (5AM & 11AM).

NHC Cone TS Dorian 11PM 2013 Jul 26

 

There is new tropical wave that has emerged off the coast of Africa that has about an ~7% chance of becoming a tropical cyclone in the next 48 hrs.

5 PM Update – Dorian Weakens

Tropical Storm Dorian continues to weaken and become disorganized as a result of westerly shear and a drier air mass.  Dorian is now moving West at a brisk 22 mph with maximum sustained winds dropping to 45 mph. Although weakening, Dorian’s tropical storm force winds are now reaching outwards of 70 miles. Presently, Dorian is located 1135 miles east of the Northern Leeward Islands. The latest estimated central pressure has risen to 1010 mb (another sign of weakening).

NHC Cone TS Dorian 5PM 2013 Jul 26

The forecast now shows TS Dorian slowing to a tropical depression on Sunday and completely disapating by day 5!   However, the system could degenerate into a tropical wave sooner.  The forecast track has shifted south from earlier today as a result of the high pressure system north of Dorian in the central Atlantic.  This high is moving west and will continue to keep what is currently TS Dorian on a western track.

11 AM Update – Dorian Remains Disorganized

Tropical Storm Dorian remains disorganized based on visual satellite images and appears to be weakening a bit. Dorian’s west-northwest movement sped up to 21 mph with a considerable increase in the estimated minimum central pressure which has risen to 1006 mb. Maximum sustained winds are still around 50 mph with a reach of 60 miles. TS Dorian is expected to track to the west at a slightly faster forward speed over the next couple of days.

An area of dry air in conjunction with moderate west-southwesterly shear should cause some further weakening of the system. This is the second update in a row in which the NHC has suggested Tropical Storm Dorian could degenerate into a tropical wave sometime this weekend. As of this morning, the Hurricane Hunter are scheduled to begin their 6-hour fixes on TS Dorian on Sunday afternoon.

NHC Cone TS Dorian 11AM 2013 Jul 26

5 AM Update – Dorian Becomes Slightly Disorganized Overnight

Tropical Storm Dorian remains approximately 1425 miles east of the Northern Leeward Islands on a west-northwest course moving at 20 mph. Dorian’s winds continue to max out at 50 mph and are extending outward some 60 miles. A turn towards the west is expected over the next couple days in conjunction with an increase in forward speed. The latest satellite data shows Dorian becoming less organized due to the southwesterly shear mentioned during last night’s llPM update which may lead to continued weakening period today.

The high pressure system in the Central Atlantic continues to drive TS Dorian on a west-northwest track. You can see in the surface analysis below that Dorian is interacting with the high essentially being pushed to the west.WSI Surface 12Z 2013 Jul 26

The forecast track from the National Hurricane Center remains in agreement with the models. There is an area of dry air directly to the west of Dorian that in will help weaken the system over the next day or so, but the forecast shows some re-intensificaiton in about 4 days. As of now, the intensity forecast shows winds topping out at 50 mph early next week.NHC Cone TS Dorian 5AM 2013 Jul 26

Below is a look at the various models tracks which are mostly in agreement.

SFWMD Spaghetti Model TS Dorian 5AM 2013 Jul 26

 

Based on what we know now, the NHC has proposed an alternative scenario where Tropical Storm Dorian could dissipate due to landfall in Hispaniola, or due to the the current hostile environment that is already weakening the system.

System History

Date Time Classification Max Winds (mph) Movement/Speed Pressure (mb)
July 24 5AM EST Tropical Depression 35 WNW at 20 mph 1008
11AM EST Tropical Storm 50 WNW at 21 mph 1002
5PM EST 50 WNW at 20 mph 1002
11PM EST 50 WNW at 20 mph 1002
July 25 5AM EST Tropical Storm 60 WNW at 17 mph 999
11AM EST 60 WNW at 17 mph 999
5PM EST 60 WNW at 18 mph 999
11PM EST 50 WNW at 20 mph 1001
July 26 5AM EST Tropical Storm 50 WNW at 20 mph 1001
11AM EST 50 WNW at 21 mph 1006
5PM EST 45 W at 22 mph 1010
11PM EST 40 W at 22 mph 1010

Current GOES-Floater Visible Satellite Image

GOES-Floater Visible

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