Tropical storm warnings issued for Potential Tropical Cyclone Two
Posted by
Chris in Tampa on 6/18/2017, 4:59 pm
Not yet a depression or tropical storm and for the first time advisories are written so a tropical storm warning can be issued.
Still waiting for graphical track.
"Potential Tropical Cyclone Two Discussion Number 1 NWS National Hurricane Center Miami FL AL022017 500 PM AST Sun Jun 18 2017
The disturbance over the deep tropical Atlantic has become better organized today, although a pair of ASCAT-A and B passes this morning indicated that the system does not have a closed low-level circulation, which isn't surprising given the fast translational speed of the system. The ASCAT passes showed peak winds of near 30 kt well north of the center, and given that the environment is expected to be conducive for some additional development before the shear increases in the eastern Caribbean Sea, strengthening is forecast, and the disturbance is expected to become a tropical storm before reaching the Windward Islands in 36 to 48 hours.
The National Hurricane Center now has the option to issue advisories on disturbances that are not yet tropical cyclones, but which pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours. Under previous policy this was not possible. These systems are known as Potential Tropical Cyclones in advisory products and are numbered from the same list as depressions. Because of the threat to the Windward Islands, advisories have been initiated on Potential Tropical Cyclone Two and the appropriate warnings have been issued by the respective governments in the Windward Islands. Advisory packages will continue until the threat of tropical-storm-force winds for land areas sufficiently diminishes, although if the system becomes a tropical cyclone, the normal rules for discontinuing advisories would apply. Users should be aware that forecast uncertainty for disturbances is generally larger than for tropical cyclones, especially beyond 48-72 hours.
The disturbance will be steered quickly westward to west- northwestward over the next several days to the south of a mid-level subtropical ridge over the central Atlantic. The NHC track forecast is close to a blend of the latest GFS and ECMWF tracks. There is a fair bit of across-track spread in the model guidance, which isn't surprising given the lack of a well-defined center. However, given that tropical storm conditions are expected to extend well north of the center, users should not focus on the exact track of the center, and the track forecast is of lower certainty than usual.
Most of the intensity guidance shows mostly modest strengthening during the next 36 hours, with the system moving over SSTs of 27-28C and the deep-layer shear at 10 kt or less. The NHC forecast shows the system peaking at 45 kt, in agreement with the intensity model consensus. Quick weakening is expected after that time as southerly shear increases dramatically while the system moves into the eastern Caribbean Sea. The system is forecast to become a remnant low by 72 hours and dissipate by day 4.
FORECAST POSITIONS AND MAX WINDS
INIT 18/2100Z 7.5N 50.4W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 19/0600Z 8.2N 53.3W 30 KT 35 MPH 24H 19/1800Z 9.5N 57.0W 35 KT 40 MPH...TROPICAL CYCLONE 36H 20/0600Z 10.6N 60.5W 45 KT 50 MPH 48H 20/1800Z 11.9N 64.0W 40 KT 45 MPH 72H 21/1800Z 13.5N 71.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 22/1800Z...DISSIPATED
$$ Forecaster Brennan"
"Potential Tropical Cyclone Two Advisory Number 1 NWS National Hurricane Center Miami FL AL022017 500 PM AST Sun Jun 18 2017
...TROPICAL STORM WARNING ISSUED FOR PORTIONS OF THE WINDWARD ISLANDS...
SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...7.5N 50.4W ABOUT 815 MI...1310 KM ESE OF THE WINDWARD ISLANDS MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...W OR 280 DEGREES AT 23 MPH...37 KM/H MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY:
The government of Barbados has issued a Tropical Storm Warning for Barbados, St. Vincent, and the Grenadines.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for... * Barbados * St. Vincent and the Grenadines
A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.
For storm information specific to your area, please monitor products issued by your national meteorological service.
DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 500 PM AST (2100 UTC), the disturbance was centered near latitude 7.5 North, longitude 50.4 West. The system is moving toward the west near 23 mph (37 km/h). A fast motion toward the west- northwest is expected to continue for the next 48 hours. On the forecast track, the disturbance is expected to move through the Windward Islands Monday night and Tuesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours, and the disturbance is expected to reach tropical storm intensity on Monday before it reaches the Windward Islands.
Shower and thunderstorm activity associated with the disturbance has become better organized since yesterday, and some additional development is possible during the next couple of days before conditions become less favorable for tropical cyclone formation over the Caribbean Sea. * Formation chance through 48 hours...high...70 percent * Formation chance through 5 days...high...70 percent
The estimated minimum central pressure is 1008 mb (29.77 inches).
HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected to first reach the warning area overnight Monday and Tuesday morning, making outside preparations difficult or dangerous.
RAINFALL: The disturbance is expected to produce total rain accumulations of 2 to 4 inches over the Windward Islands Monday through Tuesday.
NEXT ADVISORY ------------- Next intermediate advisory at 800 PM AST. Next complete advisory at 1100 PM AST.
$$ Forecaster Brennan"
http://www.nhc.noaa.gov/#Two |
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In this thread:
Potential Tropical Cyclone Two -
cypresstx,
6/18/2017, 4:29 pm- "Potential" ? (only one big problem with that) - tvsteve, 6/19/2017, 1:41 am
- TS force winds arrival - 8pm tonight - tvsteve, 6/19/2017, 1:13 am
- Tropical storm warnings issued for Potential Tropical Cyclone Two - Chris in Tampa, 6/18/2017, 4:59 pm
- Track - Chris in Tampa, 6/18/2017, 5:14 pm
- Re: Potential Tropical Cyclone Two - Chris in Tampa, 6/18/2017, 4:34 pm
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