Subtropical Storm Joyce Advisory Number 1
NWS National Hurricane Center Miami FL AL102018
500 PM AST Wed Sep 12 2018
...JOYCE FORMS IN THE NORTH ATLANTIC...
SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...34.3N 41.9W
ABOUT 870 MI...1395 KM WSW OF THE AZORES
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...SW OR 220 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 500 PM AST (2100 UTC), the center of newly formed Subtropical
Storm Joyce was located near latitude 34.3 North, longitude 41.9
West. The storm is moving toward the southwest near 6 mph (9 km/h),
and this slow motion should continue during the next couple of days.
Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Joyce is forecast to transform into a tropical storm by Thursday
and strengthen some.
Winds of 40 mph extend outward up to 115 miles (185 km) from the
center.
The estimated minimum central pressure is 1006 mb (29.71 inches).
HAZARDS AFFECTING LAND
----------------------
None
NEXT ADVISORY
-------------
Next complete advisory at 1100 PM AST.
$$
Forecaster Avila
Subtropical Storm Joyce Discussion Number 1
NWS National Hurricane Center Miami FL AL102018
500 PM AST Wed Sep 12 2018
The strong low pressure system which the NHC has been monitoring in
the north Atlantic for a couple of days has developed a cyclonically
curved band of deep convection near the center, and scatterometer
data indicate that the winds are near 40 kt. Since the system is
still vertically stacked with an upper-low, it is then classified
as a subtropical cyclone at this time. However, the cyclone is
gaining organization while it is acquiring tropical characteristics.
The NHC forecast calls for Joyce to transform into a tropical system
in about 12 to 24 hours. Since the ocean is warm, some slight
strengthening is possible during the next 3 days. After that time,
Joyce will be over cooler waters and should then be absorbed by a
larger extratropical low.
Joyce has been moving southwestward or 225 degrees at 5 kt, steered
by the northerly flow around the subtropical high which has been
steering Florence and to west of the mid-latitude trough which
is forcing Helene to recurve. In a couple of days, global models
indicate that the steering pattern will change as the trough
amplifies, and Joyce should then turn toward the northeast with an
increase in forward speed.
FORECAST POSITIONS AND MAX WINDS
INIT 12/2100Z 34.3N 41.9W 40 KT 45 MPH
12H 13/0600Z 33.7N 42.6W 40 KT 45 MPH...TROPICAL STORM
24H 13/1800Z 33.0N 43.5W 40 KT 45 MPH
36H 14/0600Z 32.5N 43.5W 45 KT 50 MPH
48H 14/1800Z 32.5N 43.5W 50 KT 60 MPH
72H 15/1800Z 34.0N 41.0W 50 KT 60 MPH
96H 16/1800Z 37.0N 35.0W 40 KT 45 MPH
120H 17/1800Z...ABSORBED
$$
Forecaster Avila