Atlantic Tropical Weather Outlook


113
ABNT20 KNHC 221111
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Sep 22 2018

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

The National Hurricane Center is issuing advisories on Tropical
Depression Eleven, located about 500 miles east of the Windward
Islands.

Shower and thunderstorm activity continues to become better
organized near the center of a low pressure system located about
500 miles south of the southern Cabo Verde Islands, and a tropical
depression appears to be forming. If these trends continue,
advisories will be initiated on this system later today while the
low moves westward at about 20 mph.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...80 percent.

A broad area of low pressure located about 200 miles south of
Bermuda is producing only minimal shower activity. Strong upper-
level winds are expected to diminish by Sunday or Monday, which
could allow for some slow development of this system while it moves
westward and then northwestward over the southwestern Atlantic
Ocean. By the middle of next week, upper-level winds are likely to
strengthen again, which would limit additional development as the
system moves closer to the southeastern coast of the United States.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...30 percent.

Satellite imagery indicates that a non-tropical low pressure system
is forming along a frontal boundary about 900 miles west-southwest
of the Azores. Conditions are expected to become conducive for the
low to acquire subtropical or tropical characteristics, and a
subtropical or tropical cyclone is likely to form by early next week
while the low meanders over the central Atlantic Ocean. For more
information on this system, see High Seas Forecasts issued by the
National Weather Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...70 percent.

&&
Public Advisories on Tropical Depression Eleven are issued under WMO
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories on Tropical Depression Eleven are issued under
WMO header WTNT21 KNHC and under AWIPS header MIATCMAT1.

High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
on the Web at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

$$
Forecaster Brennan

Summary for Tropical Depression Eleven (AT1/AL112018)

...TROPICAL DEPRESSION NOT MOVING VERY MUCH... ...EXPECTED TO DISSIPATE IN A DAY OR TWO...
 As of 5:00 AM AST Sat Sep 22
 the center of Eleven was located near 13.0, -53.5
 with movement W at 5 mph.
 The minimum central pressure was 1007 mb
 with maximum sustained winds of about 35 mph.

Tropical Depression Eleven Public Advisory Number 2

Issued at 500 AM AST Sat Sep 22 2018  

495 
WTNT31 KNHC 220835
TCPAT1

BULLETIN
Tropical Depression Eleven Advisory Number   2
NWS National Hurricane Center Miami FL       AL112018
500 AM AST Sat Sep 22 2018

...TROPICAL DEPRESSION NOT MOVING VERY MUCH...
...EXPECTED TO DISSIPATE IN A DAY OR TWO...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...13.0N 53.5W
ABOUT 505 MI...810 KM E OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 500 AM AST (0900 UTC), the center of Tropical Depression Eleven
was located near latitude 13.0 North, longitude 53.5 West.  The
depression is moving slowly toward the west near 5 mph (7 km/h).  A
slow westward or west-northwestward motion is expected during the
next couple of days.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Little change in strength is forecast during the next day or so,
and the depression is expected to dissipate east of the Lesser
Antilles by Sunday night.

The estimated minimum central pressure is 1007 mb (29.74 inches).


HAZARDS AFFECTING LAND
----------------------
None


NEXT ADVISORY
-------------
Next complete advisory at 1100 AM AST.

$$
Forecaster Berg


Tropical Depression Eleven Forecast Advisory Number 2

Issued at 0900 UTC SAT SEP 22 2018  

494 
WTNT21 KNHC 220835
TCMAT1
 
TROPICAL DEPRESSION ELEVEN FORECAST/ADVISORY NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112018
0900 UTC SAT SEP 22 2018
 
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
 
TROPICAL DEPRESSION CENTER LOCATED NEAR 13.0N  53.5W AT 22/0900Z
POSITION ACCURATE WITHIN  15 NM
 
PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT   4 KT
 
ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB
MAX SUSTAINED WINDS  30 KT WITH GUSTS TO  40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT.  RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.
 
REPEAT...CENTER LOCATED NEAR 13.0N  53.5W AT 22/0900Z
AT 22/0600Z CENTER WAS LOCATED NEAR 13.0N  53.5W
 
FORECAST VALID 22/1800Z 13.3N  54.3W
MAX WIND  30 KT...GUSTS  40 KT.
 
FORECAST VALID 23/0600Z 13.6N  55.4W
MAX WIND  25 KT...GUSTS  35 KT.
 
FORECAST VALID 23/1800Z 13.8N  56.8W...POST-TROP/REMNT LOW
MAX WIND  25 KT...GUSTS  35 KT.
 
FORECAST VALID 24/0600Z...DISSIPATED
 
REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 13.0N  53.5W
 
NEXT ADVISORY AT 22/1500Z
 
$$
FORECASTER BERG
 
 

Tropical Depression Eleven Forecast Discussion Number 2

Issued at 500 AM AST Sat Sep 22 2018  

624 
WTNT41 KNHC 220836
TCDAT1

Tropical Depression Eleven Discussion Number   2
NWS National Hurricane Center Miami FL       AL112018
500 AM AST Sat Sep 22 2018

Deep convection remains displaced to the east of the depression's
center due to 30-40 kt of westerly shear.  Although Dvorak final-T
numbers from TAFB and SAB have decreased since yesterday--now a
consensus T1.0--the initial intensity is held, perhaps generously,
at 30 kt.  Strong westerly shear is expected to persist for several
days, which at the very least will prevent the depression from
getting any better organized.  Since the global models show the
depression opening up into a trough in about 24 hours, the new NHC
intensity forecast brings down the winds a little faster, shows the
system becoming a remnant low by 36 hours, and dissipates the low
entirely by 48 hours well east of the Windward Islands.  This
evolution could certainly occur more quickly than indicated by the
official forecast.

The center of the depression has not been moving much, and it's
possible the sheared convection is trying to pull it back toward
the east.  However, the average motion over the past 12 hours is
westward, or 270/4 kt.  The track guidance insists that the
depression should move slowly west-northwestward over the next
couple of days, but given that the system has not made any
northward progress, I elected to skirt the southern edge of the
guidance envelope.  This new forecast is a little south of the
previous NHC track prediction.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0900Z 13.0N  53.5W   30 KT  35 MPH
 12H  22/1800Z 13.3N  54.3W   30 KT  35 MPH
 24H  23/0600Z 13.6N  55.4W   25 KT  30 MPH
 36H  23/1800Z 13.8N  56.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  24/0600Z...DISSIPATED

$$
Forecaster Berg


Tropical Depression Eleven Wind Speed Probabilities Number 2

Issued at 0900 UTC SAT SEP 22 2018


441 
FONT11 KNHC 220835
PWSAT1
                                                                    
TROPICAL DEPRESSION ELEVEN WIND SPEED PROBABILITIES NUMBER   2      
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112018               
0900 UTC SAT SEP 22 2018                                            
                                                                    
AT 0900Z THE CENTER OF TROPICAL DEPRESSION ELEVEN WAS LOCATED NEAR  
LATITUDE 13.0 NORTH...LONGITUDE 53.5 WEST WITH MAXIMUM SUSTAINED    
WINDS NEAR 30 KTS...35 MPH...55 KM/H.                               
                                                                    
Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH)                  
   ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME      
   EASTERN  DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME      
   CENTRAL  DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME      
                                                                    
WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS                 
                                                                    
CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST     
   ...34 KT (39 MPH... 63 KM/H)...                                  
   ...50 KT (58 MPH... 93 KM/H)...                                  
   ...64 KT (74 MPH...119 KM/H)...                                  
FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS               
                                                                    
PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE               
    OP  IS THE PROBABILITY OF THE EVENT BEGINNING DURING            
        AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY)               
   (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN           
        06Z SAT AND THE FORECAST HOUR (CUMULATIVE PROBABILITY)      
                                                                    
PROBABILITIES ARE GIVEN IN PERCENT                                  
X INDICATES PROBABILITIES LESS THAN 1 PERCENT                       
PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN
THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT.             
PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY              
64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT.                 
                                                                    
                                                                    
  - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - -   
                                                                    
               FROM    FROM    FROM    FROM    FROM    FROM    FROM 
  TIME       06Z SAT 18Z SAT 06Z SUN 18Z SUN 06Z MON 06Z TUE 06Z WED
PERIODS         TO      TO      TO      TO      TO      TO      TO  
             18Z SAT 06Z SUN 18Z SUN 06Z MON 06Z TUE 06Z WED 06Z THU
                                                                    
FORECAST HOUR    (12)   (24)    (36)    (48)    (72)    (96)   (120)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
LOCATION       KT                                                   
                                                                    
$$                                                                  
FORECASTER BERG                                                     

Tropical Depression Eleven Graphics


Tropical Depression Eleven 5-Day Uncertainty Track Image
5-Day Uncertainty Track last updated Sat, 22 Sep 2018 08:37:38 GMT

Tropical Depression Eleven 34-Knot Wind Speed Probabilities
Wind Speed Probabilities last updated Sat, 22 Sep 2018 09:21:54 GMT