Tropical Weather Update – October 17, 2019

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Tropical Weather Outlook

NWS National Hurricane Center Miami FL

800 AM EDT Thu Oct 17 2019

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

1. Showers and thunderstorms associated with a broad area of low

pressure located over the southwestern Gulf of Mexico continue to

show signs of organization.  Environmental conditions are expected

to be conducive for additional development, and a tropical or

subtropical storm is likely to form later today or tonight while the

system moves generally northeastward over the western Gulf of

Mexico.  The low is forecast to approach the northern or

northeastern Gulf Coast on Friday or Saturday and regardless of

development, the system is likely to produce gusty winds and rough

surf over those areas.  Locally heavy rainfall is also possible

across portions of the southeast U.S. late this week and this

weekend. Interests along the northern and northeastern Gulf coast

should monitor the progress of this system.  For more information

about marine hazards while the low moves across the Gulf of Mexico,

see products issued by the Tropical Analysis and Forecast Branch of

the National Hurricane Center. An Air Force Reserve reconnaissance

aircraft is scheduled to investigate the system this afternoon, if

necessary.

* Formation chance through 48 hours…high…80 percent.

* Formation chance through 5 days…high…80 percent.

High Seas Forecasts issued by the National Weather Service

can be found under AWIPS header NFDHSFAT1, WMO header FZNT01

KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

Offshore Waters Forecasts for the Gulf of Mexico issued by the

National Weather Service can be found under AWIPS header MIAOFFNT4,

WMO header FZNT24 KNHC, and online at

www.hurricanes.gov/text/MIAOFFNT4.shtml

Weather Outlook – Monday, October 7, 2019

Wind Fields Friday

 

Tropical Weather Outlook

NWS National Hurricane Center Miami FL

200 PM EDT Mon Oct 7 2019For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

1. A non-tropical low pressure system located over the central Atlantic

Ocean between Bermuda and the Azores is producing gale-force winds

to the north of its center.  Environmental conditions are forecast

to be generally conducive for the low to acquire some subtropical or

tropical characteristics during the next day or two, and this system

could become a tropical or subtropical storm on Tuesday or Wednesday

while it moves slowly westward.  Upper-level winds are expected to

become unfavorable for further development by Wednesday night.

Additional information on this system can be found in High Seas

Forecasts issued by the National Weather Service.

* Formation chance through 48 hours…medium…50 percent.

* Formation chance through 5 days…medium…50 percent.

2. Showers and thunderstorms located over the western Atlantic

between the southeastern coast of the United States and Bermuda

are associated with a trough of low pressure.  This system is

forecast to move northwestward and a non-tropical low pressure area

is expected to form when the system interacts with a frontal

boundary in a couple of days.  The low could acquire some

subtropical characteristics later in the week while it meanders

off the east coast of the United States.  Additional information on

this system can also be found in High Seas Forecasts issued by the

National Weather Service.

* Formation chance through 48 hours…low…near 0 percent.

* Formation chance through 5 days…low…30 percent.

3. A trough of low pressure extending from the Straits of Florida

northeastward across the southern Florida peninsula is producing

disorganized showers and thunderstorms.  Some slight development of

this system is possible on Tuesday when it moves over the far

western Atlantic.  The disturbance is forecast to merge with a

frontal boundary and developing low off the east coast of the

United States by Wednesday, and no further development is

anticipated after that time.  Regardless of development, this system

is expected to produce locally heavy rainfall over portions of the

the southern Florida peninsula during the next day or so.

* Formation chance through 48 hours…low…10 percent.

* Formation chance through 5 days…low…10 percent.

High Seas Forecasts issued by the National Weather Service

can be found under AWIPS header NFDHSFAT1, WMO header FZNT01

KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

Tropical Depression #10 – September 17, 2019

Weekly_Outlook (2)

 

Tropical Depression Ten Discussion Number   1

NWS National Hurricane Center Miami FL       AL102019

1100 AM AST Tue Sep 17 2019

Deep convection associated with the area of low pressure over the

central Atlantic has become more persistent and better organized

this morning.  Data T-numbers from both SAB and TAFB are 2.0 on the

Dvorak scale, therefore advisories are being initiated on a tropical

depression.  The initial intensity is set at 30 kt, in line with the

satellite estimates.  The depression is forecast to move over

gradually increasing sea surface temperatures within a favorable

upper-level environment.  The only negative factor for

intensification appears to be some nearby dry air, but with low

shear conditions expected, so steady strengthening is forecast

during the next several days.  The NHC forecast calls for the

depression to become a tropical storm later today, and attain

hurricane status within 72 hours. The NHC intensity forecast is in

good agreement with the SHIPS and LGEM statistical models.

Since the depression is still in the development phase, the initial

motion is a somewhat uncertain 295/10 kt.  A strong deep-layer

ridge to the north of the cyclone should steer the depression

generally west-northwestward at a faster forward speed during the

next few days.  The track guidance is in relatively good agreement

through 72 hours, and brings the cyclone near the northern Leeward

Islands in about 3 days.  By late in the period, the cyclone is

expected to reach the western periphery of the ridge, and there is

increasing spread among the guidance.  The global model ensemble

means are along the right side of the envelope while the HWRF and

UKMET are along the left side.  The NHC track lies close the

consensus aids, which is also in good agreement with the latest

ECMWF.

Interests in the northern Leeward Islands should monitor the

progress of this system.

FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 12.9N 44.9W  30 KT  35 MPH

12H  18/0000Z 13.8N 46.1W  35 KT  40 MPH

24H  18/1200Z 14.7N 47.9W  40 KT  45 MPH

36H  19/0000Z 15.5N 50.2W  45 KT  50 MPH

48H  19/1200Z 16.3N 52.9W  55 KT  65 MPH

72H  20/1200Z 18.2N 59.2W  65 KT  75 MPH

96H  21/1200Z 20.2N 64.7W  75 KT  85 MPH

120H  22/1200Z 22.5N 69.0W  80 KT  90 MPH

Update Hurricane Dorian – September 6, 2019

Hurricane Dorian Discussion Number  52

NWS National Hurricane Center Miami FL       AL052019

500 AM EDT Fri Sep 06 2019

 

The center of the eye of Hurricane Dorian is located just off the

coast of North Carolina not far from Cape Lookout.  Based on data

from the Air Force Hurricane Hunters and Doppler radar velocities,

the initial intensity is set at 80 kt.  This estimate is a

compromise between the flight-level winds and SFMR values.  The

minimum pressure remains quite low, 956 mb, based on surface

observations and aircraft fixes.  There have been several reports in

eastern North Carolina of sustained tropical-storm-force winds and

hurricane-force gusts, with the strongest winds being reported in

the northern eyewall.

 

Dorian is moving northeastward at 12 kt.  A faster northeastward

motion is expected during the next few days as a mid- to upper-level

trough, currently over the U.S. Great Lakes, approaches the system

and accelerates the steering flow.  This track forecast takes the

hurricane along the coast of North Carolina during the next several

hours and near or over Atlantic Canada this weekend.  The models

are tightly clustered, and the NHC track forecast lies near the

middle of the guidance envelope.Hu

 

The hurricane is expected to gradually weaken during the next couple

of days due to an increase in wind shear and drier air. Dorian is

expected to cross the north wall of the Gulf Stream current in about

36 hours, and head over much colder waters after that.  These

atmospheric and oceanic conditions should cause the cyclone to

become a powerful hurricane-force extratropical in about 2 days.  As

the system gains latitude, the tropical-storm-force winds are

expected to expand significantly.  The NHC intensity forecast is

largely an update of the previous one and in line with the various

consensus aids.

 

Key Messages:

 

  1. Life-threatening storm surge and dangerous winds are expected

to continue along portions of the North Carolina coast, portions of

southeast Virginia and the southern Chesapeake Bay.  Water levels

could rise well in advance of the arrival of strong winds. Residents

in these areas should follow advice given by local emergency

officials.

 

  1. Flash flooding is occurring, and will continue to become more

widespread across the eastern Carolinas and far southeast Virginia

this morning. There is a high risk of flash flooding over these

areas, where significant, life-threatening flash flooding is

expected.

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  06/0900Z 34.6N 76.2W  80 KT  90 MPH

12H  06/1800Z 36.0N 74.1W  75 KT  85 MPH

24H  07/0600Z 38.8N 69.9W  75 KT  85 MPH

36H  07/1800Z 42.5N 65.4W  70 KT  80 MPH

48H  08/0600Z 46.7N 61.6W  60 KT  70 MPH…POST-TROP/EXTRATROP

72H  09/0600Z 53.0N 52.0W  45 KT  50 MPH…POST-TROP/EXTRATROP

96H  10/0600Z 58.0N 36.0W  40 KT  45 MPH…POST-TROP/EXTRATROP

120H  11/0600Z 0.0S 0.0W   0 KT   0 MPH…DISSIPATED

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