WTPZ45 KNHC 130857 RRA

TCDEP5



TROPICAL STORM DARBY DISCUSSION NUMBER   7

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016

300 AM MDT WED JUL 13 2016



DARBY CONTINUES TO STRENGTHEN.  THE SATELLITE APPEARANCE HAS CHANGED

FROM A SHEAR PATTERN TO A CENTRAL DENSE OVERCAST, WITH A LARGER AND

DEEPER AREA OF CONVECTION THAN 6 HOURS AGO.  IN ADDITION, A WINDSAT

37 GHZ MICROWAVE PASS AT 0104 UTC SHOWED THE DEVELOPMENT OF A

LOW-LEVEL RING FEATURE.  THE INITIAL WIND SPEED IS RAISED TO 60

KT, A BIT ABOVE THE SATELLITE CLASSIFICATIONS IN DEFERENCE TO THE

IMPROVED INNER-CORE STRUCTURE.



SOMEWHAT SURPRISINGLY, DARBY HAS BEEN RAPIDLY INTENSIFYING DURING

THE PAST 24 HOURS, WITH A 30-KT WIND INCREASE DURING THAT TIME.

GIVEN THE RECENTLY OBSERVED MICROWAVE RING FEATURE AND A GENERALLY

CONDUCIVE ENVIRONMENT, IT MAKES SENSE TO BE ON THE HIGH SIDE OF THE

GUIDANCE IN THE NEAR-TERM.  AFTER 24 HOURS, SSTS SHOULD DROP TO

AROUND 27C, BUT THE SHEAR IS EXPECTED TO STAY LOW. THUS, THE

FORECAST INTENSITIES ARE LEVELED OFF FROM DAYS 1-3 IN AGREEMENT WITH

MUCH OF THE GUIDANCE.  A SLOW DECREASE IN WIND SPEED IS PREDICTED AT

LONG RANGE DUE TO GRADUALLY FALLING SSTS.   THE NHC INTENSITY

FORECAST IS MOST SIMILAR TO A CONSENSUS OF THE HWRF, SHIPS AND LGEM

MODELS.



THE STORM IS MOVING GENERALLY WESTWARD AT ABOUT 10 KT.  THIS

GENERAL MOTION IS EXPECTED FOR THE NEXT SEVERAL DAYS WHILE

DARBY REMAINS ON THE SOUTHERN SIDE OF A STRONG RIDGE OVER THE

EASTERN PACIFIC.  THE CYCLONE COULD TURN TOWARD THE WEST-NORTHWEST

BY THE END OF THE PERIOD WITH A WEAKER RIDGE POSSIBLE OVER THE

WESTERN PORTION OF THE BASIN. ONLY SMALL CHANGES WERE MADE TO THE=