000
WTPZ45 KNHC 280846
TCDEP5
TROPICAL STORM DARBY DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 AM PDT MON JUN 28 2010
 
TROPICAL STORM DARBY IS FEELING THE EFFECTS OF STRONG EASTERLY
VERTICAL SHEAR. SSMIS MICROWAVE IMAGERY CLEARLY SHOWS THE LOW-LEVEL
CENTER DISPLACED ABOUT 45 NM NORTHEAST OF THE EDGE OF THE DEEP
CONVECTION.  DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB
SUGGEST 35 AND 45 KT RESPECTIVELY AT 06 UTC.  THE INITIAL INTENSITY
IS ANALYZED TO BE 35 KT BASED ON THE CONTINUED DETERIORATION IN THE
CONVECTIVE STRUCTURE SINCE THE SYNOPTIC TIME.

THE CYCLONES INITIAL MOTION IS 060/5.  THE SYSTEM IS PRIMARILY BEING
STEERED BY THE LOW-LEVEL SOUTHWESTERLY MONSOONAL FLOW SOUTH OF
CENTRAL AMERICA.  THIS STEERING PATTERN SHOULD CONTINUE FOR THE
NEXT TWO DAYS WHILE DARBY WEAKENS.  THE FORECAST TRACK IS SIMILAR
TO THE PREVIOUS ADVISORY AND IS BASED ON THE MODEL CONSENSUS.

WHILE DARBY REMAINS OVER VERY WARM SSTS AND IS EMBEDDED IN VERY
MOIST AIR...THE EFFECTS OF STRONG VERTICAL SHEAR ARE LIKELY TO
CONTINUE THE WEAKENING TREND DURING THE NEXT TWO DAYS.  ALL GLOBAL
MODELS SHOW STRONG EASTERLY SHEAR OF 20 TO 30 KT DUE TO THE
COMBINATION OF UPPER-LEVEL EASTERLIES OVERLYING LOW-LEVEL
SOUTHWESTERLY MONSOONAL FLOW.  THE INTENSITY FORECAST IS A BLEND OF
THE LGEM...DECAY SHIPS...AND HWRF MODELS AND IS UNCHANGED FROM THE
PREVIOUS ADVISORY.  DARBY IS LIKELY TO BECOME A REMNANT LOW BEFORE
REACHING SOUTHERN MEXICO IN ABOUT TWO DAYS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/0900Z 14.2N 101.4W    35 KT
 12HR VT     28/1800Z 14.5N 100.4W    30 KT
 24HR VT     29/0600Z 15.0N  98.9W    25 KT
 36HR VT     29/1800Z 15.4N  97.3W    20 KT...POST-TROP/REMNT LOW
 48HR VT     30/0600Z 15.7N  96.0W    20 KT...POST-TROP/REMNT LOW
 72HR VT     01/0600Z...DISSIPATED
 
$$
FORECASTER LANDSEA/STEWART