319
WTPZ41 KNHC 300234
TCDEP1
TROPICAL STORM ALVIN DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012025
800 PM MST THU MAY 29 2025
INFRARED CLOUD TOP TEMPERATURES HAVE GRADUALLY WARMED OVER THE
CENTER OF ALVIN THIS EVENING. EARLIER AMSR-2 PASSIVE MICROWAVE
IMAGES SHOWED A RAGGED CONVECTIVE STRUCTURE ON THE WEST SIDE OF THE
STORM, AND RECENT SATELLITE TRENDS INDICATE THE SYSTEM MAY ALREADY
BE CONTENDING WITH SOME SHEAR AND INTRUSIONS OF DRIER AIR. THE
SUBJECTIVE DVORAK CLASSIFICATIONS AND OBJECTIVE INTENSITY ESTIMATES
RANGE FROM 45-55 KT, SO THE INITIAL INTENSITY IS HELD AT 50 KT.
ALVIN IS STILL MOVING TO THE NORTHWEST (325/10 KT) BUT SHOULD TURN
NORTH-NORTHWESTWARD AND NORTHWARD ON FRIDAY AND SATURDAY TOWARD A
WEAKNESS IN THE RIDGE CREATED BY A CUTOFF LOW OFFSHORE OF BAJA
CALIFORNIA. THE TRACK GUIDANCE REMAINS IN GOOD AGREEMENT, AND NO
MAJOR CHANGES WERE MADE TO THE UPDATED NHC TRACK FORECAST.
RECENT MICROWAVE DATA INDICATE THE STORM LACKS AN INNER CORE, SO
ALVIN WILL BE SUSCEPTIBLE TO THE NEGATIVE EFFECTS OF INCREASING
SHEAR AND DRIER MID-LEVEL AIR DURING THE NEXT COUPLE OF DAYS. IN
ADDITION, THE TRACK FORECAST BRINGS ALVIN OVER COOLER WATERS AS IT
NEARS THE BAJA CALIFORNIA PENINSULA. SO, GRADUAL WEAKENING IS
FORECAST AS THE ASSOCIATED CONVECTION IS LIKELY TO BECOME DISPLACED
FROM THE STORM CENTER BEGINNING ON FRIDAY. THIS FORECAST SHOWS
ALVIN BECOMING POST-TROPICAL IN 36 H AND SPINNING DOWN OVER THE
WEEKEND, IN AGREEMENT WITH THE GLOBAL MODEL FIELDS AND SIMULATED
SATELLITE IMAGERY.
FORECAST POSITIONS AND MAX WINDS
INIT 30/0300Z 16.0N 107.9W 50 KT 60 MPH
12H 30/1200Z 17.2N 108.5W 45 KT 50 MPH
24H 31/0000Z 18.7N 109.0W 40 KT 45 MPH
36H 31/1200Z 20.3N 109.3W 35 KT 40 MPH...POST-TROPICAL
48H 01/0000Z 21.9N 109.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 01/1200Z 23.7N 109.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 02/0000Z...DISSIPATED
FORECASTER REINHART
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