EPAC: COSME - Post-Tropical

[cycloneye]

HURRICANE COSME DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
200 AM PDT WED JUN 26 2013

COSME LIKELY PEAKED WITH AN INTENSITY OF 75 KT AT 0000 AND 0600 UTC
BASED ON A BLEND OF VARIOUS SATELLITE INTENSITY ESTIMATES...AND THE
PRESENCE OF AN 18 NMI DIAMETER EYE IN WINDSAT...SSMIS...AND AMSU-B
MICROWAVE SATELLITE IMAGERY BETWEEN 0100 UTC AND 0430 UTC. OVER THE
PAST COUPLE OF HOURS SINCE THE 0600 UTC SATELLITE CURRENT INTENSITY
ESTIMATE OF T4.5/77 KT FROM BOTH TAFB AND SAB...THE CONVECTION ON
THE WEST SIDE OF THE CIRCULATION HAS ERODED SIGNIFICANTLY AS COSME
HAS BEGUN ITS TREK OVER COLDER WATERS. AS A RESULT...THE ADVISORY
INTENSITY HAS BEEN LOWERED SLIGHTLY TO 70 KT.

AFTER THE MULTIPLE JOGS AND WOBBLES IN THE TRACK OVER THE PAST TWO
DAYS...HURRICANE COSME APPEARS TO HAVE SETTLED INTO A NICE SMOOTH
MOTION OF 290/12 KT. THE CYCLONE IS EXPECTED TO CONTINUE TO MOVE
WEST-NORTHWESTWARD FOR THE NEXT 48 HOURS ALONG THE SOUTHERN
PERIPHERY OF A MASSIVE DEEP-LAYER RIDGE SITUATED TO ITS NORTH...
AND THEN TURN WESTWARD AFTER THAT FOR THE REMAINDER OF THE FORECAST
PERIOD. THE LATEST NHC MODEL GUIDANCE REMAINS TIGHTLY PACKED AND IN
EXCELLENT AGREEMENT...SO THE OFFICIAL FORECAST TRACK IS JUST AN
EXTENSION OF THE PREVIOUS ADVISORY TRACK.

COSME IS CURRENTLY PASSING OVER THE 26C SST ISOTHERM AND WILL
CONTINUE TO MOVE OVER COLDER WATER...REACHING SUB-22C SSTS BY 36
HOURS. THE VERTICAL SHEAR IS FORECAST TO BE LIGHT AND THE ROBUST
UPPER-LEVEL OUTFLOW PATTERN IS EXPECTED TO REMAIN INTACT FOR AT
LEAST THE NEXT 24 HOURS...FACTORS THAT COULD POSSIBLY HELP COSME
RETAIN HURRICANE STATUS FOR ANOTHER 6-12 HOURS. BY 18-24 HOURS...
HOWEVER...THE MUCH COLDER WATERS AND INCREASING COLD UPWELLING
BENEATH THE CYCLONE SHOULD INDUCE RAPID WEAKENING OF THE CYCLONE...
WITH DEGENERATION INTO A NON-CONVECTIVE REMNANT LOW BY 48 HOURS...
IF NOT SOONER. THE NHC INTENSITY FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND FOLLOWS THE DECAY-SHIPS MODEL...WHICH
INDICATES DISSIPATION OF THE CYCLONE BY 72 HOURS.

THE EXTENSIVE 12-FT SEAS RADII ARE THE RESULT OF LONG-FETCH
SOUTHERLY CROSS-EQUATORIAL FLOW GENERATING LARGE SWELLS...WHICH
WILL CONTINUE TO AFFECT MUCH OF THE SOUTHWESTERN PACIFIC COAST OF
MEXICO AND THE SOUTHERN BAJA CALIFORNIA PENINSULA DURING THE NEXT
COUPLE OF DAYS.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 18.4N 114.5W 70 KT 80 MPH
12H 26/1800Z 19.0N 116.3W 65 KT 75 MPH
24H 27/0600Z 19.9N 118.9W 50 KT 60 MPH
36H 27/1800Z 20.6N 121.6W 40 KT 45 MPH
48H 28/0600Z 21.1N 124.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 29/0600Z 21.7N 129.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 30/0600Z 21.7N 134.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 01/0600Z 21.7N 138.1W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER STEWART

[greenkat]

Down to TS.

COSME HAS BEGUN ITS WEAKENING PHASE...AS MICROWAVE SATELLITE IMAGERY
INDICATE THAT THE EYE IS NO LONGER CLOSED. BASED UPON THE INFRARED
GEOSTATIONARY IMAGERY...THE TAFB AND DVORAK INTENSITY ESTIMATES
HAVE DROPPED TO 3.0/4.0...WHILE THE CIMSS ADVANCED DVORAK TECHNIQUE
INDICATES T3.7 OR 55-60 KT. THE INTENSITY IS ANALYZED TO BE 60
KT...JUST BELOW HURRICANE FORCE. A 0937Z AMSU SATELLITE PASS
PROVIDED GUIDANCE ON THE TROPICAL STORM WIND RADII...WHICH HAS BEEN
EXPANDED OUTWARD SLIGHTLY BASED UPON THE CIRA SIZE ANALYSIS.

THE AFOREMENTIONED AMSU PASS ALONG WITH AN 1106Z SSMI PASS ALLOW FOR
A FAIRLY CONFIDENT ASSESSMENT OF THE INITIAL POSITION OF COSME.
THE CYCLONE IS MOVING WEST-NORTHWEST AT 12 KT...DUE TO THE STEERING
INFLUENCE OF A DEEP-LAYER RIDGE TO ITS NORTH. COSME SHOULD
CONTINUE WEST-NORTHWESTWARD FOR THE NEXT 36-48 HOURS BEFORE BENDING
WESTWARD THEREAFTER. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED AND
HAS SHIFTED SLIGHTLY NORTHWARD...IN PART DUE TO A MORE NORTHERLY
INITIAL POSITION. THE TRACK PREDICTION IS LIKEWISE SLIGHTLY NORTH
OF THE PREVIOUS ADVISORY.

WHILE COSME SHOULD CONTINUE TO EXPERIENCE LOW VERTICAL WIND SHEAR
WITHIN A MOIST ENVIRONMENT...THE CYCLONE SHOULD QUICKLY DECAY DUE
TO TRAVERSING COLD WATER. EVEN THOUGH THE DEEP CONVECTION IS
CURRENTLY QUITE VIGOROUS...WHEN COSME REACHES 22C SSTS TOMORROW THE
CONVECTION IS LIKELY TO COLLAPSE...AND THE SYSTEM IS EXPECTED
BECOME A REMNANT LOW IN ABOUT 36 HOURS. THE INTENSITY PREDICTION IS
CLOSE TO THE VARIABLE CONSENSUS TECHNIQUE AND IS A BIT BELOW THE
PREVIOUS ADVISORY.

THE EXTENSIVE 12-FT SEAS RADII ARE THE RESULT OF LONG-FETCH
SOUTHERLY CROSS-EQUATORIAL FLOW GENERATING LARGE SWELLS...WHICH
WILL CONTINUE TO AFFECT MUCH OF THE SOUTHWESTERN PACIFIC COAST OF
MEXICO AND THE SOUTHERN BAJA CALIFORNIA PENINSULA DURING DAY OR SO.



FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 19.1N 115.6W 60 KT 70 MPH
12H 27/0000Z 19.9N 117.5W 50 KT 60 MPH
24H 27/1200Z 20.8N 120.3W 40 KT 45 MPH
36H 28/0000Z 21.8N 123.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 28/1200Z 22.3N 125.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 29/1200Z 22.5N 131.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 30/1200Z 22.5N 135.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/1200Z 22.5N 138.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER LANDSEA

[cycloneye]

TROPICAL STORM COSME DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
200 PM PDT WED JUN 26 2013

COSME CONTINUES TO WEAKEN. A COMBINATION OF CONVENTIONAL AND
MICROWAVE SATELLITE IMAGERY INDICATES THAT THE EYEWALL HAS
DISSIPATED...AND THAT THE LOW-LEVEL CENTER IS LOCATED JUST TO THE
EAST OF THE REMAINING CONVECTION. THE INITIAL INTENSITY IS REDUCED
TO 50 KT BASED ON THE PREVIOUS ADVISORY INTENSITY AND THE DECAY OF
THE CLOUD PATTERN SINCE THAT TIME. THIS IS A LITTLE BELOW THE
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB...WHICH ARE
CURRENTLY CONSTRAINED BY THE DECAY RULES OF THE DVORAK TECHNIQUE.

THE INITIAL MOTION IS 295/11. A DEEP-LAYER RIDGE NORTH AND
NORTHEAST OF COSME SHOULD STEER THE CYCLONE GENERALLY WEST-
NORTHWESTWARD FOR THE NEXT 24-36 HR...WITH A TURN TOWARD THE WEST
EXPECTED AFTER THAT TIME. SOME DECELERATION MAY OCCUR AROUND
96-120 HOURS AS THE REMNANTS OF COSME APPROACH A WEAKNESS IN THE
RIDGE. THE TRACK MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
SCENARIO...AND THE NEW FORECAST TRACK LIES NEAR THE CENTER OF THE
GUIDANCE ENVELOPE.

COSME SHOULD CONTINUE TO QUICKLY WEAKEN OVER SEA SURFACE
TEMPERATURES OF 21C-24C. THE CYCLONE IS EXPECTED TO DECAY TO A
CONVECTIONLESS REMNANT LOW BY 36 HOURS...AND THIS COULD OCCUR
EARLIER THAN CURRENTLY FORECAST. THE GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT THE REMNANT LOW SHOULD REMAIN IDENTIFIABLE THROUGH
THE END OF THE FORECAST PERIOD.

THE EXTENSIVE 12-FT SEAS RADII ARE THE RESULT OF LONG-FETCH
SOUTHERLY CROSS-EQUATORIAL FLOW GENERATING LARGE SWELLS...WHICH
WILL CONTINUE TO AFFECT MUCH OF THE SOUTHWESTERN PACIFIC COAST OF
MEXICO AND THE SOUTHERN BAJA CALIFORNIA PENINSULA DURING THE NEXT
DAY OR SO.

FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 19.3N 116.5W 50 KT 60 MPH
12H 27/0600Z 19.9N 118.4W 45 KT 50 MPH
24H 27/1800Z 20.8N 121.2W 35 KT 40 MPH
36H 28/0600Z 21.6N 124.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 28/1800Z 21.9N 126.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 29/1800Z 22.0N 132.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 30/1800Z 22.0N 135.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/1800Z 22.0N 139.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER BEVEN

[cycloneye]

TROPICAL STORM COSME DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
800 PM PDT WED JUN 26 2013

DEEP CONVECTION ASSOCIATED WITH COSME HAS BEEN DECREASING IN
COVERAGE AND INTENSITY. AN EARLIER TRMM OVERPASS INDICATED THAT
THE LOW-LEVEL CENTER OF THE CYCLONE WAS LOCATED NEAR THE
EAST-SOUTHEASTERN EDGE OF THE MAIN AREA OF DEEP CONVECTION...
SUGGESTING THAT THE SYSTEM WAS BEGINNING TO BECOME DECOUPLED IN THE
VERTICAL. THE CURRENT INTENSITY IS ESTIMATED TO BE 45 KT IN
ACCORDANCE WITH A DVORAK ESTIMATE FROM SAB. COSME WILL SOON BE
MOVING OVER SUB-22C SEA SURFACE TEMPERATURES...SO CONTINUED STEADY
WEAKENING IS LIKELY. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF
THE DSHIPS AND LGEM GUIDANCE...AND SHOWS THE SYSTEM BECOMING A
REMNANT LOW IN 24 HOURS.

THE INITIAL MOTION ESTIMATE IS THE SAME AS IN THE PREVIOUS
ADVISORY...295/12. COSME IS EMBEDDED IN THE STEERING FLOW ON THE
SOUTH SIDE OF A LARGE MID-LEVEL HIGH PRESSURE AREA. A LOW- TO
MID-LEVEL RIDGE IS FORECAST BY THE GLOBAL MODELS TO PERSIST TO THE
NORTH OF COSME...OR ITS REMNANTS...FOR THE NEXT SEVERAL DAYS. THE
TRACK MODELS ARE IN GOOD AGREEMENT ON A TURN TOWARD THE WEST IN 24
TO 48 HOURS. IN THE LATTER PART OF THE FORECAST PERIOD...THE RIDGE
IS PREDICTED TO WEAKEN SOMEWHAT...AND THIS SHOULD LEAD TO A
DECREASE IN THE FORWARD SPEED OF THE CYCLONE. THE OFFICIAL TRACK
FORECAST REMAINS ROUGHLY IN THE MIDDLE OF THE GUIDANCE...AND IS
VERY SIMILAR TO THE PREVIOUS NHC TRACK.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 19.6N 117.6W 45 KT 50 MPH
12H 27/1200Z 20.4N 119.7W 35 KT 40 MPH
24H 28/0000Z 21.3N 122.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 28/1200Z 21.7N 125.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/0000Z 22.0N 128.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/0000Z 22.0N 133.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0000Z 22.0N 137.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0000Z 22.0N 140.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER PASCH

[Yellow Evan]

It has the classic EPAC dying TS look.

[cycloneye]

TROPICAL STORM COSME DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
200 AM PDT THU JUN 27 2013

ALL ORGANIZED DEEP CONVECTION ASSOCIATED WITH COSME HAS DISAPPEARED
DURING THE PAST FEW HOURS. MICROWAVE DATA SHOW THAT THE LOW AND
MID-LEVEL CENTERS OF COSME HAVE DECOUPLED...WITH THE LOW-LEVEL
CIRCULATION WELL SOUTHEAST OF THE MID-LEVEL CENTER. THE INTENSITY
IS LOWERED TO 40 KT...NEAR AN AVERAGE OF A PAIR OF ASCAT PASSES
FROM 0445 AND 0530 UTC. WITH THE CYCLONE FORECAST TO MOVE OVER
PROGRESSIVELY COOLER WATERS FOR THE NEXT 24H...COSME IS PROBABLY
FINISHED AS A TROPICAL CYCLONE WITH ORGANIZED CONVECTION UNLIKELY
TO REDEVELOP. REMNANT LOW STATUS IS LIKELY LATE TODAY ALONG WITH A
SLOW WEAKENING OF THE WINDS...IN AGREEMENT WITH THE GLOBAL MODELS
AND THE INTENSITY CONSENSUS.

THE INITIAL MOTION ESTIMATE IS A BIT FASTER AND TO THE LEFT OF THE
PREVIOUS ONE...290/14. THE CYCLONE CONTINUES ON TRACK AS IT REMAINS
SOUTH OF A RIDGE OVER THE EASTERN PACIFIC. THE REMNANTS OF COSME
WILL PROBABLY TURN WESTWARD UNDER THE INFLUENCE OF THE LOW-LEVEL
RIDGE...AND SLOW SOMEWHAT IN A COUPLE DAYS. THE OFFICIAL FORECAST
IS BASICALLY AN UPDATE OF THE PREVIOUS ONE AND IS VERY CLOSE TO THE
EASTERN PACIFIC TRACK CONSENSUS GUIDANCE.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 20.1N 119.3W 40 KT 45 MPH
12H 27/1800Z 20.7N 121.4W 35 KT 40 MPH...POST-TROPICAL
24H 28/0600Z 21.4N 124.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 28/1800Z 21.8N 127.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/0600Z 21.8N 130.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/0600Z 21.8N 134.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0600Z 22.0N 139.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z...DISSIPATED

$$
FORECASTER BLAKE

[cycloneye]

TROPICAL STORM COSME DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
800 AM PDT THU JUN 27 2013

COSME HAS BEEN REDUCED TO A SWIRL OF LOW/MID-LEVEL CLOUDS WITH NO
ORGANIZED CONVECTION AS IT MOVES OVER SEA SURFACE TEMPERATURES OF
22-23C. THE INITIAL INTENSITY IS REDUCED TO 35 KT BASED ON
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB...AND THIS COULD BE
GENEROUS. BARRING AN UNEXPECTED RETURN OF THE CONVECTION...THE
CYCLONE SHOULD DEGENERATE TO A REMNANT LOW LATER TODAY. THE GLOBAL
MODELS SUGGEST THAT THE LOW IS LIKELY TO PERSIST FOR SEVERAL
DAYS...WITH THE SYSTEM FINALLY DECAYS TO A TROUGH IN ABOUT
120 HOURS.

THE INITIAL MOTION IS NOW 285/14. THE SYSTEM SHOULD GRADUALLY TURN
TOWARD THE WEST DURING THE NEXT 24-48 HOURS AS IT IS STEERED BY A
DEEP-LAYER RIDGE TO ITS NORTH. THE REMNANTS ARE LIKELY TO SLOW
THEIR FORWARD SPEED BY 72-96 HR AS THEY APPROACH A WEAKNESS IN THE
RIDGE. THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS
FORECAST AND IS IN THE MIDDLE OF THE GUIDANCE ENVELOPE.


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 20.4N 120.9W 35 KT 40 MPH
12H 28/0000Z 20.9N 123.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 28/1200Z 21.4N 125.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 29/0000Z 21.5N 128.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/1200Z 21.5N 131.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/1200Z 21.5N 135.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/1200Z 22.0N 139.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/1200Z...DISSIPATED

$$
FORECASTER BEVEN

[cycloneye]

Last Advisory Written


POST-TROPICAL CYCLONE COSME DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP032013
200 PM PDT THU JUN 27 2013

COSME CONSISTS OF A LARGE SWIRL OF LOW/MID-LEVEL CLOUDS WITH
ISOLATED SHOWERS IN THE WESTERN SEMICIRCLE. PASSIVE WIND DATA FROM
A SERIES OF SSM/IS OVERPASSES SUGGESTS THAT THE MAXIMUM WINDS HAVE
DROPPED BELOW TROPICAL-STORM FORCE. BASED ON THIS AND THE LACK OF
DEEP CONVECTION...IT IS ESTIMATED THAT COSME HAS DEGENERATED TO A
REMNANT LOW PRESSURE AREA.

THE INITIAL MOTION IS NOW 285/15. THE SYSTEM SHOULD GRADUALLY TURN
TOWARD THE WEST DURING THE NEXT 24-48 HOURS AS IT IS STEERED BY A
LOW/MID-LEVEL RIDGE TO ITS NORTH. THE REMNANTS ARE LIKELY TO SLOW
THEIR FORWARD SPEED BY 72-96 HR AS THEY APPROACH A WEAKNESS IN THE
RIDGE. THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS FORECAST
AND REMAINS IN THE MIDDLE OF THE GUIDANCE ENVELOPE.

THIS IS THE LAST ADVISORY ON COSME BY THE NATIONAL HURRICANE CENTER.
FOR ADDITIONAL INFORMATION ON THE REMNANT LOW PLEASE SEE HIGH
SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFEPI AND WMO HEADER FZPN01 KWBC.

FORECAST POSITIONS AND MAX WINDS

INIT 27/2100Z 20.9N 122.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
12H 28/0600Z 21.3N 124.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 28/1800Z 21.5N 127.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 29/0600Z 21.5N 130.1W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/1800Z 21.5N 132.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/1800Z 21.5N 137.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/1800Z 22.0N 140.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/1800Z...DISSIPATED

$$
FORECASTER BEVEN

[greenkat]

Poor Cosme... If only it were a bit smaller. Then we wouldn't have had the problems in Mexico, and it would be much stronger.

[Yellow Evan]

Poor Cosme... If only it were a bit smaller. Then we wouldn't have had the problems in Mexico, and it would be much stronger.

It would have weakened faster though.