Skip Navigation Links
NOAA NOAA United States Department of Commerce

Tropical Storm DARBY


ZCZC MIATCDEP5 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DARBY DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
800 AM PDT WED JUN 23 2010
 
THE CONVECTIVE ORGANIZATION OF DARBY HAS INCREASED SHARPLY DURING
THE PAST 6 HOURS AS STRONGLY CURVED BANDING FEATURES HAVE
DEVELOPED. IN FACT...RECENT VISIBLE SATELLITE IMAGES HINT THAT A
BANDING EYE FEATURE COULD BE FORMING...BUT THIS MAY JUST BE A SMALL
DRY SLOT THAT HAS DEVELOPED. INTENSITY ESTIMATES ARE T3.0 FROM TAFB
AND T2.5 FROM SAB. GIVEN THE IMPROVED SATELLITE APPEARANCE SINCE
THE 12Z FIXES...THE INITIAL INTENSITY IS SET AT 45 KT.
 
THE INITIAL MOTION ESTIMATE IS 285/08. THE FORECAST TRACK OF DARBY
HINGES HEAVILY UPON WHAT HAPPENS TO THE DISTURBANCE LOCATED OVER
THE CENTRAL CARIBBEAN SEA. THE GFDL AND HWRF MODELS...PLUS ALL OF
THE GLOBAL MODELS EXCEPT FOR THE GFS...DEVELOP THE CARIBBEAN
DISTURBANCE TO VARIOUS DEGREES OVER THE NEXT 5 DAYS...WHICH CAUSES
THE SUBTROPICAL RIDGE TO THE NORTH OF DARBY TO WEAKEN BY DAYS 3-4.
THIS RESULTS IN A WEAKENING OF THE STEERING FLOW...AND SOME OF THE
MODELS EVEN FORECAST SOME WEAK BINARY INTERACTION WITH THE
DEVELOPING CARIBBEAN DISTURBANCE AFTER THAT SYSTEM ENTERS THE
SOUTHERN GULF MEXICO. THE GFS DOES NOT SHOW ANY INTERACTION WITH
THE CARIBBEAN DISTURBANCE BECAUSE IT NEITHER DEVELOPS DARBY OR THE
OTHER SYSTEM. DUE TO THE POOR 06Z INITIALIZATION AND SHORT TERM
FORECAST TRENDS BY THE GFS MODEL...LESS WEIGHT HAS BEEN PLACED ON
THAT MODEL AND IT IS CONSIDERED AN OUTLIER. THE OFFICIAL FORECAST
MAINTAINS THE PREVIOUS FORECAST TREND OF SLOWING DOWN DARBY IN THE
72-120 HOUR TIME FRAME DUE TO EXPECTED INTERACTION WITH THE LARGE
CARIBBEAN SYSTEM...REGARDLESS OF WHETHER OR NOT THAT SYSTEM GOES ON
TO BECOME A TROPICAL CYCLONE.

THE RECENT SHARP INTENSIFICATION TREND WOULD SUGGEST THAT DARBY MAY
BE IN THE EARLY STAGES OF RAPID INTENSIFICATION. HOWEVER...DESPITE
THE IMPROVED BANDING FEATURES...CLOUD TOPS IN THE INNER CORE REGION
HAVE WARMED SUGGESTING THAT DRY AIR MAY BE ACTING TO ERODE THE
CENTRAL DEEP CONVECTION. THE GFS-BASED SHIPS MODEL INDICATES THAT
THE VERTICAL SHEAR WILL DECREASE TO LESS THAN 5 KNOTS OVER THE
COURSE OF THE NEXT 36 HOURS...WHICH WOULD STRONGLY FAVOR RAPID
INTENSIFICATION. THE OFFICIAL FORECAST TRACK IS A BLEND OF THE
SHIPS AND PREVIOUS FORECAST IN CASE THE EROSION OF THE INNER CORE
CONVECTION CONTINUES...AND ALSO TO MAINTAIN SOME CONTINUITY WITH
THE PREVIOUS ADVISORY. HOWEVER...THE SHIPS MODEL IS INDICATING A
GREATER THAN 40 PERCENT CHANCE OF RAPID INTENSIFICATION
OCCURRING...AND THIS SCENARIO WILL BE CLOSELY ASSESSED FOR THE NEXT
ADVISORY PACKAGE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/1500Z 11.8N  94.8W    45 KT
 12HR VT     24/0000Z 12.2N  95.9W    50 KT
 24HR VT     24/1200Z 12.6N  97.4W    60 KT
 36HR VT     25/0000Z 12.9N  98.8W    65 KT
 48HR VT     25/1200Z 13.2N  99.8W    70 KT
 72HR VT     26/1200Z 13.7N 101.1W    70 KT
 96HR VT     27/1200Z 14.2N 101.5W    70 KT
120HR VT     28/1200Z 14.7N 101.5W    65 KT
 
$$
FORECASTER STEWART
 
NNNN