San Juan, PR Morning AFD excerpt could explain the reason for the track anomalies.

.PREV DISCUSSION... /ISSUED 613 AM AST MON AUG 30 2010/

SYNOPSIS...HURRICANE EARL LOCATED OVER THE NORTHERN LEEWARD
ISLANDS WILL CONTINUE TO MOVE WEST AND ACROSS THE LOCAL FORECAST
AREA. THEN ON TUESDAY NIGHT HIGH PRESSURE IN THE WEST CENTRAL
ATLANTIC WILL RIDGE TO THE SOUTHWEST AND INTO THE NORTHEAST
CARIBBEAN...AND CONTINUE UNTIL THURSDAY EVENING. A LOW PRESSURE
SYSTEM WILL MOVE INTO THE EASTERN CARIBBEAN THURSDAY THROUGH
SATURDAY.

http://www.srh.noaa.gov/productview.php?pil=AFDSJU&max=61

PUERTO RICO/U.S. VIRGIN ISLANDS HOURLY WEATHER ROUNDUP
NATIONAL WEATHER SERVICE SAN JUAN PR
200 PM AST MON AUG 30 2010

PRZ001-004-301900-
PUERTO RICO

CITY SKY/WX TMP DP RH WIND PRES REMARKS
SAN JUAN LMM LGT RAIN 81 77 89 NW20G33 29.64F FOG
AGUADILLA PTSUNNY 86 79 79 N20G30 29.78F HX 99
$$

PRZ006-007-301900-
U.S. VIRGIN ISLANDS

CITY SKY/WX TMP DP RH WIND PRES REMARKS
CHARLOTTE AMA LGT RAIN 82 75 78 NW33G59 29.41F