Post-tropical Cyclone Leslie

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Public Advisory:

Post-Tropical Cyclone Leslie Advisory Number   9...Corrected
NWS National Hurricane Center Miami FL       AL132018
1100 AM AST Tue Sep 25 2018

Corrected Discussion and Outlook section

...LESLIE BECOMES A POST-TROPICAL CYCLONE...
...THIS IS THE LAST ADVISORY...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...31.6N 44.4W
ABOUT 1080 MI...1735 KM WSW OF THE AZORES
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...E OR 100 DEGREES AT 12 MPH...19 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 1100 AM AST (1500 UTC), the center of Post-Tropical Cyclone
Leslie was located near latitude 31.6 North, longitude 44.4 West.
The post-tropical cyclone is moving toward the east near 12 mph (19
km/h).  A faster northeastward motion is expected on Wednesday,
followed by a northward turn Wednesday night.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Strengthening as an extratropical cyclone is expected, and Leslie is
forecast to become a large and powerful post-tropical cyclone by
Wednesday with winds increasing to hurricane force on Thursday.

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


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


NEXT ADVISORY
-------------
This is the last public advisory issued by the National Hurricane
Center on Leslie.  Additional information can be found in High Seas
Forecasts issued by the National Weather Service, under AWIPS header
NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web at
https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

$$
Forecaster Roberts



Discussion:
TCDAT3  
  
Post-Tropical Cyclone Leslie Discussion Number   9  
NWS National Hurricane Center Miami FL       AL132018  
1100 AM AST Tue Sep 25 2018  
  
Leslie has become a post-tropical cyclone.  Conventional and  
microwave satellite imagery show that Leslie's surface circulation  
has become elongated along an intruding baroclinic zone indicated  
by a recent 1158 UTC ASCAT-A pass.  Any deep convection appears to  
be developing due to dynamic forcing.  A rather large stratocumulus  
cloud shield and associated cooler, stable air is quickly advecting  
into the area as well. The initial intensity is maintained at 30 kt  
for this last advisory.  
  
Leslie is forecast to strengthen during the next couple of days due  
to baroclinic processes. The official forecast, based on the GFS and  
European global models, and the SHIPS statistical intensity  
guidance, shows an increase of the sustained winds to hurricane  
force in 2 days, around the same period that the shear drops below  
10 kt.  The non-tropical low is then forecast to move south of the  
strong upper-level westerlies and detach from the frontal boundary.  
According to the global models and the Florida State Cyclone Phase  
forecast, Leslie should make a transition from a frontal system to  
an asymmetric shallow warm-core seclusion.  Beyond day 3, guidance  
suggests that Leslie will acquire subtropical characteristics and a  
more symmetric, deepening warm-core low while meandering in weaker  
steering currents.  The intensity forecast follows this scenario and  
is based on the aforementioned global and statistical models.  
  
Leslie is now moving eastward at a slightly faster forward motion,  
about 10 kt.  A turn to the north is expected in 36 hours followed  
by a slower westward motion as Leslie slips south of the  
mid-latitude westerlies.  Through the remaining portion of the  
forecast, Leslie should move at a slower speed generally westward  
as a ridge builds to the north. NHC forecast is nudged toward the  
TVCN consensus through 48 hours, then follows more closely to the  
GFEX (GFS/ECMWF) consensus model.  
  
This is the last advisory issued by the National Hurricane Center on  
Leslie.  Additional information on this system can be found in High  
Seas Forecasts issued by the National Weather Service, under AWIPS  
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web  
at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.  
  
FORECAST POSITIONS AND MAX WINDS  
  
INIT  25/1500Z 31.6N  44.4W   30 KT  35 MPH  TD...POST-TROPICAL
 12H  26/0000Z 32.1N  42.5W   40 KT  45 MPH  TS...POST-TROP/EXTRATROP
 24H  26/1200Z 33.6N  40.1W   50 KT  60 MPH  TS...POST-TROP/EXTRATROP
 36H  27/0000Z 35.6N  39.9W   60 KT  70 MPH  TS...POST-TROP/EXTRATROP
 48H  27/1200Z 36.1N  41.7W   65 KT  75 MPH  CAT-1...POST-TROP/EXTRATROP
 72H  28/1200Z 35.5N  45.3W   60 KT  70 MPH  TS...SUBTROPICAL STORM
 96H  29/1200Z 34.6N  48.1W   55 KT  65 MPH  TS...SUBTROPICAL STORM
120H  30/1200Z 34.4N  49.6W   50 KT  60 MPH  TS...SUBTROPICAL STORM
  
$$  
Forecaster Roberts
Note: Storm classification added by stormcarib.com
TD=TROPICAL DEPRESSION; TS=TROPICAL STORM; CAT-1=CATEGORY-1 HURRICANE...


Wind Speed:
PWSAT3
                                                                    
POST-TROPICAL CYCLONE LESLIE WIND SPEED PROBABILITIES NUMBER   9    
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132018               
1500 UTC TUE SEP 25 2018                                            
                                                                    
AT 1500Z THE CENTER OF POST-TROPICAL CYCLONE LESLIE WAS LOCATED NEAR
LATITUDE 31.6 NORTH...LONGITUDE 44.4 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           
        12Z TUE 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       12Z TUE 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT
PERIODS         TO      TO      TO      TO      TO      TO      TO  
             00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT 12Z SUN
                                                                    
FORECAST HOUR    (12)   (24)    (36)    (48)    (72)    (96)   (120)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
LOCATION       KT                                                   
                                                                    
$$                                                                  
FORECASTER ROBERTS                                                  


Forecast/Advisory:

POST-TROPICAL CYCLONE LESLIE FORECAST/ADVISORY NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132018
1500 UTC TUE SEP 25 2018

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

POST-TROPICAL CYCLONE CENTER LOCATED NEAR 31.6N  44.4W AT 25/1500Z
POSITION ACCURATE WITHIN  30 NM

PRESENT MOVEMENT TOWARD THE EAST OR 100 DEGREES AT  10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1007 MB
MAX SUSTAINED WINDS  30 KT WITH GUSTS TO  40 KT.
12 FT SEAS..270NE 150SE 150SW   0NW.
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 31.6N  44.4W AT 25/1500Z
AT 25/1200Z CENTER WAS LOCATED NEAR 31.7N  45.2W

FORECAST VALID 26/0000Z 32.1N  42.5W...POST-TROP/EXTRATROP
MAX WIND  40 KT...GUSTS  50 KT.
34 KT...  0NE   0SE   0SW 240NW.

FORECAST VALID 26/1200Z 33.6N  40.1W...POST-TROP/EXTRATROP
MAX WIND  50 KT...GUSTS  60 KT.
50 KT...  0NE   0SE   0SW 120NW.
34 KT...  0NE 150SE 210SW 300NW.

FORECAST VALID 27/0000Z 35.6N  39.9W...POST-TROP/EXTRATROP
MAX WIND  60 KT...GUSTS  75 KT.
50 KT...  0NE   0SE  50SW 130NW.
34 KT...270NE 200SE 280SW 350NW.

FORECAST VALID 27/1200Z 36.1N  41.7W...POST-TROP/EXTRATROP
MAX WIND  65 KT...GUSTS  80 KT.
50 KT...150NE 100SE 180SW 240NW.
34 KT...290NE 210SE 300SW 420NW.

FORECAST VALID 28/1200Z 35.5N  45.3W...SUBTROPICAL STORM
MAX WIND  60 KT...GUSTS  75 KT.
50 KT...120NE  90SE  90SW 150NW.
34 KT...200NE 150SE 250SW 350NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY

OUTLOOK VALID 29/1200Z 34.6N  48.1W...SUBTROPICAL STORM
MAX WIND  55 KT...GUSTS  65 KT.

OUTLOOK VALID 30/1200Z 34.4N  49.6W...SUBTROPICAL STORM
MAX WIND  50 KT...GUSTS  60 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 31.6N  44.4W

THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE
CENTER ON THIS SYSTEM.  ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE
FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER
SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

$$
FORECASTER ROBERTS


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