Tropical Storm Karen Advisory Number 11
NWS National Hurricane Center Miami FL AL122019
500 PM AST Tue Sep 24 2019
...CENTER OF KAREN NOW NEAR SOUTHEASTERN PUERTO RICO...
SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...18.0N 65.8W
ABOUT 35 MI...55 KM SE OF SAN JUAN PUERTO RICO
ABOUT 70 MI...110 KM WNW OF ST. CROIX
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 0 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
None.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
* U.S. Virgin Islands
* Puerto Rico, including Vieques and Culebra
* British Virgin Islands
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
Interests elsewhere in the Lesser Antilles should monitor the
progress of Karen.
For storm information specific to your area in the United States,
including possible inland watches and warnings, please monitor
products issued by your local National Weather Service forecast
office. For storm information specific to your area outside of the
United States, please monitor products issued by your national
meteorological service.
DISCUSSION AND OUTLOOK
----------------------
At 500 PM AST (2100 UTC), the center of Tropical Storm Karen was
located near latitude 18.0 North, longitude 65.8 West. Karen is
moving toward the north near 8 mph (13 km/h). A turn toward the
north-northeast with some increase in forward speed is forecast
tonight, with this motion continuing through Wednesday night. On
the forecast track, the center of Karen will pass near or over
Puerto Rico and the Virgin Islands during the next few hours and
then move over the western Atlantic tonight and Wednesday.
Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Slow strengthening is forecast during the next couple of days.
Tropical-storm-force winds extend outward up to 80 miles (130 km)
mainly to the southeast of the center. During the past few hours,
wind gusts of tropical-storm force have been reported in portions
of the Virgin Islands.
The estimated minimum central pressure is 1005 mb (29.68 inches).
HAZARDS AFFECTING LAND
----------------------
Rainfall: Karen is expected to produce the following rainfall
accumulations through Wednesday:
Puerto Rico and the Virgin Islands...3 to 6 inches, isolated 10
inches.
Leeward Islands...1 to 3 inches, isolated 5 inches.
These rains may cause flash flooding and mudslides, especially in
mountainous areas.
WIND: Tropical-storm-force winds, especially in gusts, are
currently spreading across the warning area. Winds could be higher
on the windward sides of hills and mountains, and also in elevated
terrain.
NEXT ADVISORY
-------------
Next intermediate advisory at 800 PM AST.
Next complete advisory at 1100 PM AST.
$$
Forecaster Beven
NWS National Hurricane Center Miami FL AL122019
500 PM AST Tue Sep 24 2019
The satellite appearance of Karen has improved over the past
several hours, with a large convective band wrapped about halfway
around the center in the western semicircle and an outer band in
the southeastern semicircle. However, surface observations,
Doppler radar data, and reports from an Air Force Reserve Hurricane
Hunter aircraft indicate that the low-level circulation is elongated
from south to north and that multiple vorticity centers are present.
The lowest pressures and the strongest winds are at the southern
end of the elongation near the eastern end of the convective band,
and this is the center used for this advisory. The Hurricane Hunter
aircraft reported 53 kt flight-level winds at 850 mb and data
suggesting a central pressure near 1005 mb, so the initial intensity
is increased to 40 kt.
The initial motion is again 360/7, with some uncertainty due to the
multiple vorticity centers and an apparent re-formation of the
center closer to the convection between 15Z-18Z. Karen remains in a
complex steering environment that includes a low- to mid-level ridge
to the east and northeast, Tropical Storm Jerry to the north-
northwest, and a large mid- to upper-level trough extending from
near Jerry to eastern Cuba. These weather systems should steer
Karen generally north-northeastward for the next couple of days.
This motion should bring the center of Karen near or over Puerto
Rico and the Virgin Islands during the next few hours and then into
the open Atlantic tonight. During the 72-120 h period, the
large-scale models forecast a low- to mid-level ridge to build near
Karen, which will significantly slow its forward motion. The track
guidance is in somewhat better agreement that this ridge will cause
Karen to turn westward near the end of the forecast period,
although there remains a lot of uncertainty about when and how
fast. The new forecast track keeps Karen a little farther south
before this turn occurs, and thus the 120-h position is a little to
the south of the previous forecast.
Karen is moving into an area of weaker shear, and should remain in
that environment for the next 2-3 days. Thus, strengthening is
expected, with the main limiting factor being the current poor
organization of the circulation. From 72-120 h, the storm is
expected to start entraining dry air, which could limit
intensification despite the otherwise favorable shear and sea
surface temperature environment. In addition, several of the
global models suggest that another round of shear could affect
Karen near the 120 h point. If this occurs, the cyclone could end
up weaker than forecast in this advisory. The new intensity
forecast has minor changes from the previous forecast, and it again
lies between the weaker dynamical models and the stronger
statistical-dynamical models.
Key Messages:
1. Karen is expected to bring heavy rainfall, flash floods and
mudslides to Puerto Rico and the U.S. and British Virgin Islands
today, where a tropical storm warning is in effect. The rainfall
and potential flooding will likely continue on Wednesday even as the
center of Karen moves away from Puerto Rico and the Virgin Islands.
FORECAST POSITIONS AND MAX WINDS
INIT 24/2100Z 18.0N 65.8W 40 KT 45 MPH
12H 25/0600Z 19.6N 65.5W 40 KT 45 MPH
24H 25/1800Z 21.9N 64.9W 45 KT 50 MPH
36H 26/0600Z 24.2N 64.2W 50 KT 60 MPH
48H 26/1800Z 25.9N 63.5W 50 KT 60 MPH
72H 27/1800Z 27.2N 61.9W 55 KT 65 MPH
96H 28/1800Z 27.0N 62.5W 60 KT 70 MPH
120H 29/1800Z 26.5N 65.5W 60 KT 70 MPH
$$
Forecaster Beven