WTPZ43 KNHC 071439 RRA

TCDEP3



HURRICANE BLAS DISCUSSION NUMBER  19

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032016

800 AM PDT THU JUL 07 2016



SATELLITE IMAGERY INDICATES THAT BLAS IS BEGINNING TO WEAKEN.  THE

EYE HAS BECOME A LITTLE LESS DISTINCT THIS MORNING, AND THE

SURROUNDING RING OF DEEP CONVECTION HAS WARMED OVER THE

NORTHWESTERN PORTION OF THE CIRCULATION.  A BLEND OF THE VARIOUS

DVORAK T- AND CI-NUMBERS FROM SAB, TAFB, AND UW-CIMSS YIELDS AN

INITIAL WIND SPEED OF 105 KT. BLAS IS CURRENTLY MOVING OVER

GRADUALLY DECREASING SSTS, WHICH SHOULD RESULT IN CONTINUED

WEAKENING, HOWEVER, GIVEN THE ANNULAR HURRICANE CHARACTERISTICS OF

BLAS THE RATE OF WEAKENING IS EXPECTED TO BE GRADUAL TODAY.  A MORE

RAPID SPIN DOWN SHOULD BEGIN TONIGHT OR FRIDAY WHEN BLAS MOVES OVER

EVEN COOLER WATER AND INTO A MORE STABLE ENVIRONMENT.  THE HURRICANE

IS FORECAST TO BECOME POST-TROPICAL IN ABOUT 72 HOURS, AND WEAKEN TO

A REMNANT LOW BY DAY 5.



BLAS IS MOVING WEST-NORTHWESTWARD OR 290/9.  THE HURRICANE IS

EXPECTED TO CONTINUE MOVING WEST-NORTHWESTWARD TODAY, BUT IS

FORECAST TO TURN NORTHWESTWARD ON FRIDAY BETWEEN A MID-LEVEL RIDGE

OVER NORTHERN MEXICO AND A MID-/UPPER-LEVEL LOW TO THE NORTHEAST OF

THE HAWAIIAN ISLANDS.  THE TRACK GUIDANCE HAS COME INTO BETTER

AGREEMENT THROUGH THIS TIME PERIOD, AND THE NHC FORECAST IS NEAR

THE MIDDLE OF THE GUIDANCE ENVELOPE THROUGH 72 HOURS.  AFTER BLAS

WEAKENS AND BECOMES A SHALLOWER SYSTEM, THE ECMWF TAKES THE CYCLONE

WEST-SOUTHWESTWARD WHILE THE REMAINDER OF THE GUIDANCE SHOWS A MORE

WESTWARD TRACK. THE NHC FORECAST FAVORS THE LATTER SCENARIO AND

REMAINS NORTH OF THE ECMWF SOLUTION AT DAYS 4 AND 5.=