000
WTPZ41 KNHC 170834
TCDEP1
POST-TROPICAL CYCLONE ALVIN DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 AM PDT FRI MAY 17 2013
ASCAT AND OSCAT DATA SHOW THAT ALVIN LACKS A CLOSED CIRCULATION IN
ITS WESTERN SEMICIRCLE. THE LATEST SATELLITE IMAGES ALSO INDICATE
THAT THE SYSTEM HAS BECOME ELONGATED WITHOUT A WELL-DEFINED CENTER
AND FURTHER EMBEDDED WITHIN THE ITCZ. THEREFORE...ALVIN IS NO
LONGER A TROPICAL CYCLONE...AND THIS IS THE LAST ADVISORY.
ALTHOUGH THE REMNANTS WILL BE OVER WARM WATER FOR THE NEXT COUPLE
OF DAYS...THE GLOBAL MODELS GENERALLY SHOW PERSISTENT WESTERLY
SHEAR...WHICH WILL LIKELY INHIBIT ANY REGENERATION ATTEMPTS.
FOR ADDITIONAL INFORMATION ON THIS SYSTEM 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 17/0900Z 10.3N 112.0W 30 KT 35 MPH
12H 17/1800Z...DISSIPATED
$$
FORECASTER BLAKE
000
WTPZ41 KNHC 170834
TCDEP1
POST-TROPICAL CYCLONE ALVIN DISCUSSION NUMBER 8
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 AM PDT FRI MAY 17 2013
ASCAT AND OSCAT DATA SHOW THAT ALVIN LACKS A CLOSED CIRCULATION IN
ITS WESTERN SEMICIRCLE. THE LATEST SATELLITE IMAGES ALSO INDICATE
THAT THE SYSTEM HAS BECOME ELONGATED WITHOUT A WELL-DEFINED CENTER
AND FURTHER EMBEDDED WITHIN THE ITCZ. THEREFORE...ALVIN IS NO
LONGER A TROPICAL CYCLONE...AND THIS IS THE LAST ADVISORY.
ALTHOUGH THE REMNANTS WILL BE OVER WARM WATER FOR THE NEXT COUPLE
OF DAYS...THE GLOBAL MODELS GENERALLY SHOW PERSISTENT WESTERLY
SHEAR...WHICH WILL LIKELY INHIBIT ANY REGENERATION ATTEMPTS.
FOR ADDITIONAL INFORMATION ON THIS SYSTEM PLEASE SEE HIGH
SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFEPI AND WMO HEADER FZPN01 KWBC.
FORECAST POSITIONS AND MAX WINDS
INIT 17/0900Z 10.3N 112.0W 30 KT 35 MPH
12H 17/1800Z...DISSIPATED
$$
FORECASTER BLAKE
000
WTPZ41 KNHC 170241
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
800 PM PDT THU MAY 16 2013
ALVIN CONTINUES TO PRODUCE DISORGANIZED DEEP CONVECTION IN BROKEN
BANDS TO THE SOUTHEAST AND WEST OF THE CENTER. THE CENTER OF
CIRCULATION REMAINS EMBEDDED IN THE ITCZ AND COULD BE IN THE
PROCESS OF DEGENERATING INTO AN OPEN TROUGH. SATELLITE INTENSITY
ESTIMATES ARE 1.5 AND 2.5 FROM SAB AND TAFB...RESPECTIVELY. DESPITE
THE RAGGED APPEARANCE OF THE CYCLONE IN SATELLITE IMAGERY...THE
INITIAL INTENSITY ESTIMATE IS CONSERVATIVELY REDUCED TO 35 KT UNTIL
THERE IS MORE DEFINITIVE PROOF THAT ADDITIONAL WEAKENING HAS
OCCURRED.
ALVIN IS LOCATED ON THE SOUTHERN EDGE OF A BELT OF STRONG WESTERLY
FLOW ASSOCIATED WITH AN UPPER-LEVEL TROUGH LOCATED SEVERAL HUNDRED
MILES WEST OF THE BAJA CALIFORNIA PENINSULA. AS A RESULT...UW-CIMSS
SHEAR ANALYSES CONTINUE TO DIAGNOSE 20-25 KT OF WEST-SOUTHWESTERLY
SHEAR OVER THE CYCLONE. IT IS UNLIKELY THAT THE SHEAR WILL DECREASE
DURING THE FORECAST PERIOD...ACCORDING TO THE ECMWF/UKMET MODELS
WHICH HAVE MORE ACCURATELY FORECAST THE UPPER-AIR PATTERN NEAR
ALVIN THAN HAS THE GFS. IT IS THEREFORE DIFFICULT TO IMAGINE ALVIN
STAGING A COMEBACK IN WHAT IS FORECAST TO BE AN INCREASINGLY HOSTILE
ENVIRONMENT OVER THE NEXT FEW DAYS. THE NEW NHC INTENSITY FORECAST
IS SIMILAR TO OR SLIGHTLY LOWER THAN THE PREVIOUS ONE AND A BIT
LOWER THAN THE LATEST INTENSITY GUIDANCE. ALVIN IS EXPECTED TO
DEGENERATE INTO A REMNANT LOW OR AN OPEN TROUGH IN THREE DAYS...IF
NOT SOONER.
THE INITIAL MOTION ESTIMATE IS 285/12. ALVIN SHOULD CONTINUE MOVING
WEST-NORTHWESTWARD FOR THE NEXT DAY OR TWO AROUND THE SOUTHWESTERN
PERIPHERY OF A MID-LEVEL RIDGE CENTERED OVER SOUTHERN MEXICO. THE
GLOBAL MODELS THEN SHOW THE MID-LEVEL CENTER OF ALVIN BEING CARRIED
NORTHWESTWARD AND NORTHWARD AHEAD OF A LARGE UPPER-LEVEL TROUGH
NEAR 120W...WITH THE LOW-LEVEL REMNANT VORTICITY CENTER LIKELY
SEPARATING FROM IT AND MOVING ON A MORE WESTERLY COURSE IN THE
TRADE WIND FLOW. THE TRACK GUIDANCE AGREES WELL ON THIS SCENARIO...
AND THE NHC TRACK FORECAST IS NEAR OR JUST LEFT OF THE PREVIOUS
ONE AND THE MULTI-MODEL CONSENSUS TVCE.
FORECAST POSITIONS AND MAX WINDS
INIT 17/0300Z 9.8N 110.8W 35 KT 40 MPH
12H 17/1200Z 10.2N 111.8W 35 KT 40 MPH
24H 18/0000Z 11.0N 113.2W 35 KT 40 MPH
36H 18/1200Z 11.7N 114.5W 30 KT 35 MPH
48H 19/0000Z 12.1N 115.9W 30 KT 35 MPH
72H 20/0000Z 12.5N 119.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 21/0000Z 12.3N 121.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 22/0000Z 12.0N 123.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
$$
FORECASTER KIMBERLAIN
000
WTPZ41 KNHC 162041
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 PM PDT THU MAY 16 2013
THERE IS SOME QUESTION WHETHER ALVIN STILL HAS A CLOSED LOW-LEVEL
CIRCULATION. THE STORM IS STILL FULLY EMBEDDED WITHIN THE ITCZ AND
IS SOMEWHAT DIFFICULT TO DISTINGUISH FROM ANOTHER CLUSTER OF DEEP
CONVECTION A FEW HUNDRED NAUTICAL MILES TO ITS SOUTHWEST. SINCE
THE SATELLITE APPEARANCE HAS WORSENED SINCE THIS MORNING...AND
DVORAK INTENSITY ESTIMATES ARE T3.0 FROM TAFB AND T2.5 FROM
SAB...THE INITIAL INTENSITY IS LOWERED TO 40 KT. THIS COULD BE
OVERLY GENEROUS.
ALVIN ACCELERATED A BIT THIS MORNING BUT HAS AN AVERAGE MOTION OF
285/10 KT. SINCE THE STORM HAS BEEN UNABLE TO DETACH ITSELF FROM
THE ITCZ...IT IS DOUBTFUL THAT ALVIN WILL MAKE MUCH NORTHWARD
PROGRESS. IN DIRECT CONTRAST TO YESTERDAY...THE TRACK GUIDANCE IS
NOW IN FULL AGREEMENT ON A GENERAL WEST-NORTHWESTWARD MOTION DURING
THE 5-DAY FORECAST PERIOD WITH VERY LITTLE SPREAD AMONG THE
INDIVIDUAL MODELS. THE UPDATED NHC TRACK FORECAST IS ESSENTIALLY
UNCHANGED FROM THE PREVIOUS ONE.
THE UW-CIMSS SHEAR ANALYSIS INDICATES THAT ALVIN IS BEING AFFECTED
BY 20-25 KT OF WESTERLY SHEAR...AND IT IS UNLIKELY THAT THE SHEAR
WILL ABATE DURING THE NEXT FEW DAYS. THE CURRENT STRUCTURE OF THE
STORM DOES NOT SUGGEST THAT STRENGTHENING IS LIKELY...AND THE NEW
NHC INTENSITY FORECAST HAS AGAIN BEEN LOWERED. THIS FORECAST
ESSENTIALLY FOLLOWS THE SHIPS...LGEM...AND FSU SUPERENSEMBLE MODELS.
ALVIN IS FORECAST TO DEGENERATE TO A REMNANT LOW IN ABOUT 4 DAYS.
HOWEVER...ADVISORIES COULD BE TERMINATED AT ANY TIME IF IT IS
DETERMINED THAT THERE IS NO LONGER A CLOSED CIRCULATION.
FORECAST POSITIONS AND MAX WINDS
INIT 16/2100Z 9.5N 109.1W 40 KT 45 MPH
12H 17/0600Z 9.8N 110.5W 40 KT 45 MPH
24H 17/1800Z 10.8N 112.0W 35 KT 40 MPH
36H 18/0600Z 11.5N 113.3W 35 KT 40 MPH
48H 18/1800Z 12.0N 114.7W 35 KT 40 MPH
72H 19/1800Z 13.0N 117.5W 30 KT 35 MPH
96H 20/1800Z 13.0N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 21/1800Z 13.0N 122.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
$$
FORECASTER BERG
000
WTPZ41 KNHC 162041
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 PM PDT THU MAY 16 2013
THERE IS SOME QUESTION WHETHER ALVIN STILL HAS A CLOSED LOW-LEVEL
CIRCULATION. THE STORM IS STILL FULLY EMBEDDED WITHIN THE ITCZ AND
IS SOMEWHAT DIFFICULT TO DISTINGUISH FROM ANOTHER CLUSTER OF DEEP
CONVECTION A FEW HUNDRED NAUTICAL MILES TO ITS SOUTHWEST. SINCE
THE SATELLITE APPEARANCE HAS WORSENED SINCE THIS MORNING...AND
DVORAK INTENSITY ESTIMATES ARE T3.0 FROM TAFB AND T2.5 FROM
SAB...THE INITIAL INTENSITY IS LOWERED TO 40 KT. THIS COULD BE
OVERLY GENEROUS.
ALVIN ACCELERATED A BIT THIS MORNING BUT HAS AN AVERAGE MOTION OF
285/10 KT. SINCE THE STORM HAS BEEN UNABLE TO DETACH ITSELF FROM
THE ITCZ...IT IS DOUBTFUL THAT ALVIN WILL MAKE MUCH NORTHWARD
PROGRESS. IN DIRECT CONTRAST TO YESTERDAY...THE TRACK GUIDANCE IS
NOW IN FULL AGREEMENT ON A GENERAL WEST-NORTHWESTWARD MOTION DURING
THE 5-DAY FORECAST PERIOD WITH VERY LITTLE SPREAD AMONG THE
INDIVIDUAL MODELS. THE UPDATED NHC TRACK FORECAST IS ESSENTIALLY
UNCHANGED FROM THE PREVIOUS ONE.
THE UW-CIMSS SHEAR ANALYSIS INDICATES THAT ALVIN IS BEING AFFECTED
BY 20-25 KT OF WESTERLY SHEAR...AND IT IS UNLIKELY THAT THE SHEAR
WILL ABATE DURING THE NEXT FEW DAYS. THE CURRENT STRUCTURE OF THE
STORM DOES NOT SUGGEST THAT STRENGTHENING IS LIKELY...AND THE NEW
NHC INTENSITY FORECAST HAS AGAIN BEEN LOWERED. THIS FORECAST
ESSENTIALLY FOLLOWS THE SHIPS...LGEM...AND FSU SUPERENSEMBLE MODELS.
ALVIN IS FORECAST TO DEGENERATE TO A REMNANT LOW IN ABOUT 4 DAYS.
HOWEVER...ADVISORIES COULD BE TERMINATED AT ANY TIME IF IT IS
DETERMINED THAT THERE IS NO LONGER A CLOSED CIRCULATION.
FORECAST POSITIONS AND MAX WINDS
INIT 16/2100Z 9.5N 109.1W 40 KT 45 MPH
12H 17/0600Z 9.8N 110.5W 40 KT 45 MPH
24H 17/1800Z 10.8N 112.0W 35 KT 40 MPH
36H 18/0600Z 11.5N 113.3W 35 KT 40 MPH
48H 18/1800Z 12.0N 114.7W 35 KT 40 MPH
72H 19/1800Z 13.0N 117.5W 30 KT 35 MPH
96H 20/1800Z 13.0N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 21/1800Z 13.0N 122.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
$$
FORECASTER BERG
000
WTPZ41 KNHC 161432
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
800 AM PDT THU MAY 16 2013
ALVIN APPEARS TO HAVE DEGRADED IN STRUCTURE OVERNIGHT. INFRARED
SATELLITE IMAGERY AND SCATTEROMETER DATA INDICATE THAT THE
CIRCULATION HAS HAD DIFFICULTY SEPARATING FROM THE ITCZ...AND THE
LOW-LEVEL CENTER IS LIKELY LOCATED ON THE WESTERN EDGE OF THE DEEP
CONVECTION. THE INTENSITY IS BEING HELD AT 45 KT BASED ON THE
EARLIER ASCAT DATA...BUT SATELLITE ESTIMATES SUGGEST THAT ALVIN
COULD BE A BIT WEAKER.
ALTHOUGH THE HISTORICALLY TWO BEST GLOBAL MODELS...THE GFS AND
ECMWF...HAVE HAD SOME DISAGREEMENT ON ALVIN...EACH APPEARS TO HAVE
BEEN RIGHT TO SOME DEGREE. THE GFS HAD A BETTER HANDLE ON
GENESIS...BUT THE ECMWF MAY HAVE BEEN RIGHT THAT ALVIN WOULD NOT
STRENGTHEN SIGNIFICANTLY. AS OPPOSED TO YESTERDAY...THE SHIPS
GUIDANCE NOW INDICATES THAT 15 TO 20 KT OF VERTICAL SHEAR WILL
AFFECT ALVIN DURING THE NEXT FIVE DAYS...AND NEITHER OF THE
STATISTICAL MODELS NOW SHOWS THE CYCLONE REACHING HURRICANE
STRENGTH. THE PROSPECTS FOR SIGNIFICANT INTENSIFICATION APPEAR TO
BE DWINDLING...AND THE OFFICIAL FORECAST ESSENTIALLY HOLDS THE
INTENSITY STEADY FOR THE NEXT 48 HOURS. A MORE PRONOUNCED INCREASE
IN WESTERLY SHEAR SHOULD BEGIN A DEFINITE WEAKENING TREND BY DAY
3...AND ALVIN COULD DEGENERATE TO A REMNANT LOW NEAR THE END OF THE
FORECAST PERIOD. NEEDLESS TO SAY...THERE IS STILL LOW CONFIDENCE IN
THE INTENSITY FORECAST.
SINCE THE OFFICIAL INTENSITY FORECAST HAS BEEN LOWERED...THE NHC
TRACK FORECAST HAS BEEN SHIFTED A BIT FARTHER SOUTH AND WEST WITH
THE ASSUMPTION THAT LOWER-LEVEL FLOW WILL HAVE A GREATER INFLUENCE
ON STEERING. THE TRACK MODELS ARE IN BETTER AGREEMENT ON THE
GENERAL DIRECTION TODAY ALTHOUGH THERE IS STILL A SPEED
DISCREPANCY...ESPECIALLY BETWEEN THE GFS AND ECMWF.
FORECAST POSITIONS AND MAX WINDS
INIT 16/1500Z 9.4N 107.7W 45 KT 50 MPH
12H 17/0000Z 9.9N 108.8W 50 KT 60 MPH
24H 17/1200Z 10.7N 110.5W 50 KT 60 MPH
36H 18/0000Z 11.2N 112.3W 50 KT 60 MPH
48H 18/1200Z 11.6N 113.6W 50 KT 60 MPH
72H 19/1200Z 13.0N 116.0W 45 KT 50 MPH
96H 20/1200Z 13.5N 118.5W 30 KT 35 MPH
120H 21/1200Z 13.5N 120.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
FORECASTER BERG
000
WTPZ41 KNHC 161432
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
800 AM PDT THU MAY 16 2013
ALVIN APPEARS TO HAVE DEGRADED IN STRUCTURE OVERNIGHT. INFRARED
SATELLITE IMAGERY AND SCATTEROMETER DATA INDICATE THAT THE
CIRCULATION HAS HAD DIFFICULTY SEPARATING FROM THE ITCZ...AND THE
LOW-LEVEL CENTER IS LIKELY LOCATED ON THE WESTERN EDGE OF THE DEEP
CONVECTION. THE INTENSITY IS BEING HELD AT 45 KT BASED ON THE
EARLIER ASCAT DATA...BUT SATELLITE ESTIMATES SUGGEST THAT ALVIN
COULD BE A BIT WEAKER.
ALTHOUGH THE HISTORICALLY TWO BEST GLOBAL MODELS...THE GFS AND
ECMWF...HAVE HAD SOME DISAGREEMENT ON ALVIN...EACH APPEARS TO HAVE
BEEN RIGHT TO SOME DEGREE. THE GFS HAD A BETTER HANDLE ON
GENESIS...BUT THE ECMWF MAY HAVE BEEN RIGHT THAT ALVIN WOULD NOT
STRENGTHEN SIGNIFICANTLY. AS OPPOSED TO YESTERDAY...THE SHIPS
GUIDANCE NOW INDICATES THAT 15 TO 20 KT OF VERTICAL SHEAR WILL
AFFECT ALVIN DURING THE NEXT FIVE DAYS...AND NEITHER OF THE
STATISTICAL MODELS NOW SHOWS THE CYCLONE REACHING HURRICANE
STRENGTH. THE PROSPECTS FOR SIGNIFICANT INTENSIFICATION APPEAR TO
BE DWINDLING...AND THE OFFICIAL FORECAST ESSENTIALLY HOLDS THE
INTENSITY STEADY FOR THE NEXT 48 HOURS. A MORE PRONOUNCED INCREASE
IN WESTERLY SHEAR SHOULD BEGIN A DEFINITE WEAKENING TREND BY DAY
3...AND ALVIN COULD DEGENERATE TO A REMNANT LOW NEAR THE END OF THE
FORECAST PERIOD. NEEDLESS TO SAY...THERE IS STILL LOW CONFIDENCE IN
THE INTENSITY FORECAST.
SINCE THE OFFICIAL INTENSITY FORECAST HAS BEEN LOWERED...THE NHC
TRACK FORECAST HAS BEEN SHIFTED A BIT FARTHER SOUTH AND WEST WITH
THE ASSUMPTION THAT LOWER-LEVEL FLOW WILL HAVE A GREATER INFLUENCE
ON STEERING. THE TRACK MODELS ARE IN BETTER AGREEMENT ON THE
GENERAL DIRECTION TODAY ALTHOUGH THERE IS STILL A SPEED
DISCREPANCY...ESPECIALLY BETWEEN THE GFS AND ECMWF.
FORECAST POSITIONS AND MAX WINDS
INIT 16/1500Z 9.4N 107.7W 45 KT 50 MPH
12H 17/0000Z 9.9N 108.8W 50 KT 60 MPH
24H 17/1200Z 10.7N 110.5W 50 KT 60 MPH
36H 18/0000Z 11.2N 112.3W 50 KT 60 MPH
48H 18/1200Z 11.6N 113.6W 50 KT 60 MPH
72H 19/1200Z 13.0N 116.0W 45 KT 50 MPH
96H 20/1200Z 13.5N 118.5W 30 KT 35 MPH
120H 21/1200Z 13.5N 120.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
FORECASTER BERG
000
WTPZ41 KNHC 160856
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 AM PDT THU MAY 16 2013
ALVIN CONTINUES TO SLOWLY STRENGTHEN WITH SATELLITE IMAGES SHOWING
VERY DEEP CONVECTION RESEMBLING A CENTRAL DENSE OVERCAST. MICROWAVE
PASSES...HOWEVER...SHOW A LESS ORGANIZED SYSTEM THAN A QUICK GLANCE
WOULD SUGGEST...WITH THE LOW-LEVEL CENTER DISPLACED A FAIR DISTANCE
WEST OF THE STRONGEST BURST. ASCAT AND SATELLITE ESTIMATES SUGGEST
AN INTENSITY OF ABOUT 45 KT...SO THAT WILL BE THE INITIAL WIND
SPEED.
CURRENT WATER VAPOR IMAGES SHOW A LOT OF UPPER-LEVEL WESTERLY WINDS
HEADED TOWARD THE CYCLONE...WITH SOME EVIDENCE OF THE FLOW ALREADY
IMPINGING ON THE CENTER. THE FUTURE STRENGTH OF THE CYCLONE IS
NOT AN EASY FORECAST THIS MORNING WITH CONSIDERABLY MORE SHEAR IN
MOST OF THE MODEL FIELDS THAN YESTERDAY. ALTHOUGH ALL OF THE
GUIDANCE CONTINUE TO SHOW SOME INTENSIFICATION...ONLY THE GFDL
MODEL REALLY SHOWS ALVIN BECOMING ANY MORE THAN A LOW-END CATEGORY
ONE HURRICANE. THE NEW NHC FORECAST IS ABOUT THE SAME AS THE
PREVIOUS ONE FOR THE FIRST 24H...THEN IS REDUCED FOR THE REST OF
THE FORECAST PERIOD TO ACCOUNT FOR THE LATEST MODEL CONSENSUS
GUIDANCE. WEAKENING SHOULD COMMENCE IN ABOUT 3 DAYS DUE TO
INCREASING WESTERLY SHEAR AND GRADUALLY DECREASING SSTS.
A BEVY OF ASCAT AND OTHER MICROWAVE DATA SHOW THAT ALVIN IS
MOVING A BIT SLOWER...290/9. THIS GENERAL MOTION SEEMS PROBABLE
DURING THE NEXT COUPLE OF DAYS WHILE THE CYCLONE REMAINS SOUTH OF A
MID-LEVEL RIDGE OVER MEXICO. AFTER THAT TIME...GLOBAL MODELS ARE
GENERALLY SHOWING LESS OF AN INTERACTION BETWEEN A TROUGH OVER THE
SOUTHWESTERN UNITED STATES AND ALVIN...WHICH RESULTS IN LESS OF A
TURN TO THE NORTHWEST IN THE LONGER RANGE. THE OFFICIAL FORECAST
HAS BEEN SHIFTED TO THE LEFT OF THE PREVIOUS ONE...FOLLOWING THE
TREND OF THE GUIDANCE...BUT IS GENERALLY TO THE RIGHT OF THE MODEL
CONSENSUS AFTER 24H.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0900Z 9.1N 106.9W 45 KT 50 MPH
12H 16/1800Z 9.5N 108.2W 50 KT 60 MPH
24H 17/0600Z 10.2N 109.8W 60 KT 70 MPH
36H 17/1800Z 11.0N 111.5W 65 KT 75 MPH
48H 18/0600Z 11.6N 112.8W 65 KT 75 MPH
72H 19/0600Z 12.8N 115.2W 60 KT 70 MPH
96H 20/0600Z 14.0N 117.0W 40 KT 45 MPH
120H 21/0600Z 14.5N 118.5W 25 KT 30 MPH
$$
FORECASTER BLAKE
000
WTPZ41 KNHC 160856
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
200 AM PDT THU MAY 16 2013
ALVIN CONTINUES TO SLOWLY STRENGTHEN WITH SATELLITE IMAGES SHOWING
VERY DEEP CONVECTION RESEMBLING A CENTRAL DENSE OVERCAST. MICROWAVE
PASSES...HOWEVER...SHOW A LESS ORGANIZED SYSTEM THAN A QUICK GLANCE
WOULD SUGGEST...WITH THE LOW-LEVEL CENTER DISPLACED A FAIR DISTANCE
WEST OF THE STRONGEST BURST. ASCAT AND SATELLITE ESTIMATES SUGGEST
AN INTENSITY OF ABOUT 45 KT...SO THAT WILL BE THE INITIAL WIND
SPEED.
CURRENT WATER VAPOR IMAGES SHOW A LOT OF UPPER-LEVEL WESTERLY WINDS
HEADED TOWARD THE CYCLONE...WITH SOME EVIDENCE OF THE FLOW ALREADY
IMPINGING ON THE CENTER. THE FUTURE STRENGTH OF THE CYCLONE IS
NOT AN EASY FORECAST THIS MORNING WITH CONSIDERABLY MORE SHEAR IN
MOST OF THE MODEL FIELDS THAN YESTERDAY. ALTHOUGH ALL OF THE
GUIDANCE CONTINUE TO SHOW SOME INTENSIFICATION...ONLY THE GFDL
MODEL REALLY SHOWS ALVIN BECOMING ANY MORE THAN A LOW-END CATEGORY
ONE HURRICANE. THE NEW NHC FORECAST IS ABOUT THE SAME AS THE
PREVIOUS ONE FOR THE FIRST 24H...THEN IS REDUCED FOR THE REST OF
THE FORECAST PERIOD TO ACCOUNT FOR THE LATEST MODEL CONSENSUS
GUIDANCE. WEAKENING SHOULD COMMENCE IN ABOUT 3 DAYS DUE TO
INCREASING WESTERLY SHEAR AND GRADUALLY DECREASING SSTS.
A BEVY OF ASCAT AND OTHER MICROWAVE DATA SHOW THAT ALVIN IS
MOVING A BIT SLOWER...290/9. THIS GENERAL MOTION SEEMS PROBABLE
DURING THE NEXT COUPLE OF DAYS WHILE THE CYCLONE REMAINS SOUTH OF A
MID-LEVEL RIDGE OVER MEXICO. AFTER THAT TIME...GLOBAL MODELS ARE
GENERALLY SHOWING LESS OF AN INTERACTION BETWEEN A TROUGH OVER THE
SOUTHWESTERN UNITED STATES AND ALVIN...WHICH RESULTS IN LESS OF A
TURN TO THE NORTHWEST IN THE LONGER RANGE. THE OFFICIAL FORECAST
HAS BEEN SHIFTED TO THE LEFT OF THE PREVIOUS ONE...FOLLOWING THE
TREND OF THE GUIDANCE...BUT IS GENERALLY TO THE RIGHT OF THE MODEL
CONSENSUS AFTER 24H.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0900Z 9.1N 106.9W 45 KT 50 MPH
12H 16/1800Z 9.5N 108.2W 50 KT 60 MPH
24H 17/0600Z 10.2N 109.8W 60 KT 70 MPH
36H 17/1800Z 11.0N 111.5W 65 KT 75 MPH
48H 18/0600Z 11.6N 112.8W 65 KT 75 MPH
72H 19/0600Z 12.8N 115.2W 60 KT 70 MPH
96H 20/0600Z 14.0N 117.0W 40 KT 45 MPH
120H 21/0600Z 14.5N 118.5W 25 KT 30 MPH
$$
FORECASTER BLAKE
000
WTPZ41 KNHC 160247
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
800 PM PDT WED MAY 15 2013
ALVIN IS STRENGTHENING. SATELLITE DATA DURING THE LAST SEVERAL HOURS
SHOWS A WELL-DEFINED BAND WRAPPING A LITTLE MORE THAN HALFWAY
AROUND THE CIRCULATION. A BURST OF CONVECTION HAS ALSO RECENTLY
FORMED NEAR THE CENTER...POSSIBLY THE BEGINNINGS OF A CENTRAL DENSE
OVERCAST. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 2.5
AT 0000 UTC. SINCE THAT TIME...HOWEVER...THE CONVECTIVE
ORGANIZATION OF ALVIN HAS INCREASED FURTHER. ON THIS BASIS...THE
INITIAL INTENSITY IS RAISED TO 40 KT.
THE INITIAL MOTION ESTIMATE IS 290/11. ALVIN SHOULD CONTINUE MOVING
WEST-NORTHWESTWARD AROUND THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL
RIDGE CENTERED OVER SOUTHERN MEXICO DURING THE NEXT COUPLE OF DAYS.
AFTER THAT TIME...THE MODEL GUIDANCE DIVERGES RATHER SIGNIFICANTLY
AS A RESULT OF DIFFERING MODEL SOLUTIONS REGARDING THE STRENGTH OF
THE VORTEX AND THEIR HANDLING OF A MID- TO UPPER-LEVEL TROUGH
PASSING THROUGH THE SOUTHWESTERN UNITED STATES. THE GFS DEPICTS A
STRONGER SYSTEM THAT FEELS THE EFFECT OF A MORE AMPLIFIED EXTENSION
OF THE ABOVE TROUGH TO THE NORTHWEST OF ALVIN. ON THE OTHER HAND...
THE UKMET AND ECMWF MAINTAIN A WEAKER SYSTEM AND A LESS AMPLIFIED
TROUGH NORTHWEST OF THE CYCLONE...AND HENCE HAVE A MORE WESTERLY
COURSE. ALTHOUGH THE OFFICIAL FORECAST GENERALLY SPLITS THE
DIFFERENCE BETWEEN THE GUIDANCE...IT CONTINUES TO LEAN SOMEWHAT
MORE ON THE STRONGER GFS SOLUTION...PLACING THE TRACK FORECAST
SLIGHTLY RIGHT OF THE PREVIOUS ONE AND NEAR THE MULTI-MODEL
CONSENSUS TVCE. GIVEN THE DISPARATE TRACK GUIDANCE...HOWEVER...THE
CONFIDENCE IN THE TRACK FORECAST IS LOWER THAN NORMAL.
ALVIN IS FORECAST TO REMAIN IN A FAVORABLE LOCATION TO THE SOUTH OF
AN UPPER-LEVEL RIDGE AXIS DURING THE NEXT DAY OR TWO. THIS SHOULD
PROVIDE A LOW-SHEAR ENVIRONMENT AS THE CYCLONE MOVES OVER VERY WARM
WATERS...LIKELY RESULTING IN ADDITIONAL INTENSIFICATION. IN FACT...
THE SHIPS RAPID INTENSIFICATION INDICATES A NEARLY 1 IN 2 CHANCE OF
A 30-KT INCREASE IN INTENSITY DURING THE NEXT 24 HOURS. AFTER
THAT...THE GFS KEEPS ALVIN IN A LOW SHEAR ENVIRONMENT OVER SLOWLY
DECREASING SEA SURFACE TEMPERATURES UNTIL DAYS 4-5...WHEN THE SHEAR
INCREASES ABRUPTLY. THE ECMWF/UKMET SHOW ALVIN ENCOUNTERING
WESTERLY SHEAR MUCH SOONER...WHICH WOULD STIFLE ANY SIGNIFICANT
INTENSIFICATION. THE NHC INTENSITY FORECAST PLACES MORE WEIGHT ON
THE STRONGER GFS SOLUTION AND REPRESENTS A BLEND OF THE LATEST
SHIPS...DYNAMICAL...AND FSSE GUIDANCE.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0300Z 9.0N 105.9W 40 KT 45 MPH
12H 16/1200Z 9.5N 107.3W 50 KT 60 MPH
24H 17/0000Z 10.2N 109.0W 60 KT 70 MPH
36H 17/1200Z 10.9N 110.5W 70 KT 80 MPH
48H 18/0000Z 11.6N 111.9W 80 KT 90 MPH
72H 19/0000Z 13.0N 114.0W 75 KT 85 MPH
96H 20/0000Z 14.7N 116.0W 55 KT 65 MPH
120H 21/0000Z 16.0N 117.3W 35 KT 40 MPH
$$
FORECASTER KIMBERLAIN
000
WTPZ41 KNHC 160247
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013
800 PM PDT WED MAY 15 2013
ALVIN IS STRENGTHENING. SATELLITE DATA DURING THE LAST SEVERAL HOURS
SHOWS A WELL-DEFINED BAND WRAPPING A LITTLE MORE THAN HALFWAY
AROUND THE CIRCULATION. A BURST OF CONVECTION HAS ALSO RECENTLY
FORMED NEAR THE CENTER...POSSIBLY THE BEGINNINGS OF A CENTRAL DENSE
OVERCAST. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 2.5
AT 0000 UTC. SINCE THAT TIME...HOWEVER...THE CONVECTIVE
ORGANIZATION OF ALVIN HAS INCREASED FURTHER. ON THIS BASIS...THE
INITIAL INTENSITY IS RAISED TO 40 KT.
THE INITIAL MOTION ESTIMATE IS 290/11. ALVIN SHOULD CONTINUE MOVING
WEST-NORTHWESTWARD AROUND THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL
RIDGE CENTERED OVER SOUTHERN MEXICO DURING THE NEXT COUPLE OF DAYS.
AFTER THAT TIME...THE MODEL GUIDANCE DIVERGES RATHER SIGNIFICANTLY
AS A RESULT OF DIFFERING MODEL SOLUTIONS REGARDING THE STRENGTH OF
THE VORTEX AND THEIR HANDLING OF A MID- TO UPPER-LEVEL TROUGH
PASSING THROUGH THE SOUTHWESTERN UNITED STATES. THE GFS DEPICTS A
STRONGER SYSTEM THAT FEELS THE EFFECT OF A MORE AMPLIFIED EXTENSION
OF THE ABOVE TROUGH TO THE NORTHWEST OF ALVIN. ON THE OTHER HAND...
THE UKMET AND ECMWF MAINTAIN A WEAKER SYSTEM AND A LESS AMPLIFIED
TROUGH NORTHWEST OF THE CYCLONE...AND HENCE HAVE A MORE WESTERLY
COURSE. ALTHOUGH THE OFFICIAL FORECAST GENERALLY SPLITS THE
DIFFERENCE BETWEEN THE GUIDANCE...IT CONTINUES TO LEAN SOMEWHAT
MORE ON THE STRONGER GFS SOLUTION...PLACING THE TRACK FORECAST
SLIGHTLY RIGHT OF THE PREVIOUS ONE AND NEAR THE MULTI-MODEL
CONSENSUS TVCE. GIVEN THE DISPARATE TRACK GUIDANCE...HOWEVER...THE
CONFIDENCE IN THE TRACK FORECAST IS LOWER THAN NORMAL.
ALVIN IS FORECAST TO REMAIN IN A FAVORABLE LOCATION TO THE SOUTH OF
AN UPPER-LEVEL RIDGE AXIS DURING THE NEXT DAY OR TWO. THIS SHOULD
PROVIDE A LOW-SHEAR ENVIRONMENT AS THE CYCLONE MOVES OVER VERY WARM
WATERS...LIKELY RESULTING IN ADDITIONAL INTENSIFICATION. IN FACT...
THE SHIPS RAPID INTENSIFICATION INDICATES A NEARLY 1 IN 2 CHANCE OF
A 30-KT INCREASE IN INTENSITY DURING THE NEXT 24 HOURS. AFTER
THAT...THE GFS KEEPS ALVIN IN A LOW SHEAR ENVIRONMENT OVER SLOWLY
DECREASING SEA SURFACE TEMPERATURES UNTIL DAYS 4-5...WHEN THE SHEAR
INCREASES ABRUPTLY. THE ECMWF/UKMET SHOW ALVIN ENCOUNTERING
WESTERLY SHEAR MUCH SOONER...WHICH WOULD STIFLE ANY SIGNIFICANT
INTENSIFICATION. THE NHC INTENSITY FORECAST PLACES MORE WEIGHT ON
THE STRONGER GFS SOLUTION AND REPRESENTS A BLEND OF THE LATEST
SHIPS...DYNAMICAL...AND FSSE GUIDANCE.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0300Z 9.0N 105.9W 40 KT 45 MPH
12H 16/1200Z 9.5N 107.3W 50 KT 60 MPH
24H 17/0000Z 10.2N 109.0W 60 KT 70 MPH
36H 17/1200Z 10.9N 110.5W 70 KT 80 MPH
48H 18/0000Z 11.6N 111.9W 80 KT 90 MPH
72H 19/0000Z 13.0N 114.0W 75 KT 85 MPH
96H 20/0000Z 14.7N 116.0W 55 KT 65 MPH
120H 21/0000Z 16.0N 117.3W 35 KT 40 MPH
$$
FORECASTER KIMBERLAIN
| 
