WTPZ42 KNHC 230233 RRA

TCDEP2



TROPICAL STORM FRANK DISCUSSION NUMBER   6

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072016

900 PM MDT FRI JUL 22 2016



DEEP CONVECTION ASSOCIATED WITH FRANK HAS BECOME A LITTLE BETTER

ORGANIZED DURING THE PAST SEVERAL HOURS, WITH CONVENTIONAL AND

MICROWAVE SATELLITE IMAGERY SHOWING A BAND TRYING TO WRAP AROUND

THE EAST SIDE OF THE CENTER.  THE INITIAL INTENSITY IS INCREASED

TO 55 KT IN BEST AGREEMENT WITH THE INTENSITY ESTIMATE FROM SAB AND

THE CIMSS ADT.  AN APPARENT CENTER AT THE TOP OF THE CONVECTION IS

A LITTLE SOUTH OF THE LOW-LEVEL CENTER SEEN IN MICROWAVE IMAGERY,

WHICH MAY BE DUE TO ONGOING NORTHERLY SHEAR.



FRANK HAS TURNED WEST-NORTHWESTWARD WITH THE MOTION NOW 295/10.

THE STORM IS ON THE SOUTH SIDE OF A EAST-WEST ORIENTED DEEP-LAYER

RIDGE EXTENDING WESTWARD FROM THE SOUTHERN UNITED STATES INTO THE

EASTERN PACIFIC.  THE DYNAMICAL MODELS FORECAST THIS RIDGE TO

REMAIN IN PLACE WITH SLIGHT WEAKENING DURING THE NEXT SEVERAL DAYS.

THIS SHOULD ALLOW FRANK TO CONTINUE GENERALLY WEST-NORTHWESTWARD

WITH SOME DECREASE IN FORWARD SPEED THROUGH THE FORECAST PERIOD.

THE TRACK GUIDANCE HAS CHANGED LITTLE SINCE THE PREVIOUS ADVISORY,

AND THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS FORECAST

THAT LIES NEAR THE CONSENSUS OF THE GFS AND ECMWF MODELS.



FRANK SHOULD REMAIN IN A MODERATE SHEAR ENVIRONMENT AND OVER WARM

SEA SURFACE TEMPERATURES FOR THE NEXT 48 HOURS OR SO, WHICH SHOULD

ALLOW SLOW STRENGTHENING.  AFTER THAT TIME, DECREASING SEA SURFACE

TEMPERATURES ALONG THE FORECAST TRACK SHOULD CAUSE GRADUAL

WEAKENING.  THE NEW INTENSITY FORECAST HAS A SLIGHTLY HIGHER PEAK=