WTPA43 PHFO 220851 RRA

TCDCP3



TROPICAL STORM DARBY DISCUSSION NUMBER  43

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP052016

1100 PM HST THU JUL 21 2016



CLOUD TOPS ASSOCIATED WITH DARBY HAVE WARMED SIGNIFICANTLY OVER THE

PAST SIX HOURS, WHILE OVERALL ORGANIZATION HAS DECREASED. OUTFLOW

REMAINS BEST TO THE NORTH AND NORTHEAST, BUT HAS BECOME HINDERED TO

THE SOUTHEAST. OBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES

REMAIN 3.0/45 KNOTS FROM ALL THREE ANALYSIS CENTERS (HFO, JTWC,

SAB), BUT AN 0324 UTC WINDSAT PASS SHOWED A SWATH OF 55 KT WINDS

ACROSS THE NORTHEAST SEMICIRCLE CLOSE TO THE LLCC, PROMPTING A

CONTINUED INITIAL INTENSITY OF 55 KT FOR THIS ADVISORY. INITIAL

RECONNAISSANCE INTO DARBY BY THE 53RD WEATHER RECONNAISSANCE

SQUADRON IS SCHEDULED FOR FRIDAY MORNING, AND THEIR DATA WILL GIVE

US A MUCH BETTER IDEA AS TO DARBY'S INTENSITY AND SIZE.



INITIAL MOTION IS 265/09 KT, REPRESENTING A BIT OF SLOWING SINCE

THE LAST ADVISORY. WINDSAT AND SSMIS FROM EARLIER THIS EVENING

HINTED THAT DARBY WAS TILTED SLIGHTLY TO THE NORTHEAST WITH HEIGHT,

CONSISTENT WITH SHIPS SHOWING SOUTHWESTERLY SHEAR BETWEEN 10 AND 15

KNOTS. THE INITIAL MOTION SLIGHTLY SOUTH OF DUE WEST MAY BE DUE TO

EARLIER ADVISORY POSITIONS PLACED SLIGHTLY TOO FAR NORTH. AT ANY

RATE, DARBY CONTINUES TO MOVE ALONG THE SOUTHERN FLANK OF A RIDGE

CENTERED NORTH OF HAWAII AND WILL CONTINUE TO DO SO THROUGH 36

HOURS. AFTERWARDS, A DEEP LOW WILL DIG SOUTH AND WEAKEN THE RIDGE,

SLOWING THIS SYSTEM DOWN AND ALLOWING DARBY TO CURVE GENTLY

NORTHWESTWARD FROM 36 TO 72 HOURS, THEN NORTHWARD BEYOND 72 HOURS.

TRACK GUIDANCE SHIFTED SLIGHTLY TO THE RIGHT, PLACING THE CURRENT=