WTNT42 KNHC 250233 RRA

TCDAT2



TROPICAL STORM GASTON DISCUSSION NUMBER  10

NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072016

1100 PM AST WED AUG 24 2016



SATELLITE INTENSITY ESTIMATES FROM ALL AGENCIES, RECENT ASCAT

MEASUREMENTS, AND NUMEROUS DROPSONDES FROM THE UNMANNED NASA

GLOBAL HAWK AIRCRAFT INDICATE THAT THE INITIAL INTENSITY OF GASTON

REMAINS AT 60 KT. STRONG UPPER-LEVEL WESTERLIES BLOWING AROUND THE

BASE OF AN UPPER LOW TO THE NORTHWEST OF GASTON ARE ALREADY

AFFECTING THE SYMMETRY OF THE CYCLONE, AND THE LOW-LEVEL CENTER IS

ON THE WESTERN EDGE OF THE CONVECTION. THIS STRONG WESTERLY SHEAR IS

EXPECTED TO LAST FOR ABOUT 36 HOURS, RESULTING IN SOME WEAKENING.

MOST OF THE GLOBAL MODELS MOVE THE UPPER LOW TOWARD THE SOUTHWEST,

AND IN ABOUT 2 DAYS, GASTON WILL AGAIN BE IN A FAVORABLE ENVIRONMENT

FOR INTENSIFICATION.  ON THIS BASIN, THE NHC FORECAST WEAKENS THE

CYCLONE DURING THE NEXT 24 TO 36 HOURS, AND THEN CALLS FOR GASTON TO

INTENSIFY AND REACH HURRICANE STRENGTH OVER THE WARM WATERS OF THE

CENTRAL ATLANTIC. THE FORECAST FOLLOWS CLOSELY THE SHIPS MODEL AND

THE INTENSITY CONSENSUS.



GASTON IS MOVING TOWARD THE NORTHWEST OR 310 DEGREES AT 15 KT

STEERED BY THE FLOW BETWEEN THE SUBTROPICAL HIGH AND THE SAME

LOW THAT IS CAUSING THE SHEAR. AS THE LOW MOVES SOUTHWESTWARD AND

THE RIDGE TO THE NORTH OF THE CYCLONE AMPLIFIES, GASTON SHOULD TURN

A LITTLE MORE TOWARD THE WEST-NORTHWEST WITH A DECREASE IN FORWARD

SPEED. THE NHC FORECAST IS THE MIDDLE OF THE GUIDANCE ENVELOPE AND

IS BASICALLY ON TOP OF THE LATEST MULTI-MODEL CONSENSUS. NO

SIGNIFICANT CHANGES WERE MADE TO THE PREVIOUS TRACK FORECAST.





FORECAST POSITIONS AND MAX WINDS=