1. A large low pressure system located several hundred miles south of
the Gulf of Tehuantepec is moving west-northwestward at about 10
mph. Shower and thunderstorm activity has increased in coverage and
organization during the past several hours, and environmental
conditions are becoming more conducive for a tropical depression to
form during the next couple of days.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...80 percent.
AN AREA OF CONVECTION IS LOCATED NEAR 9.5N 94.6W,
APPROXIMATELY 400 NM SOUTH OF SALINA CRUZ, MEXICO. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING YET BROAD
LOW-LEVEL CIRCULATION CENTER (LLCC). A 202240Z SSMIS IMAGE INDICATES
FRAGMENTED BANDING OVER THE NORTHERN SEMI-CIRCLE AND CURVED
CONVECTIVE BANDING OVER THE SOUTHERN SEMI-CIRCLE WRAPPING INTO A
MORE DEFINED LLCC. RECENT SCATTEROMETER DATA DEPICTS AN ELONGATED
CIRCULATION WITH 20 TO 25 KNOT WINDS CONFINED TO THE NORTHEAST
PERIPHERY OF THE SYSTEM. THE SYSTEM IS LOCATED SOUTH OF THE UPPER-
LEVEL SUBTROPICAL RIDGE AXIS WITH LOW TO MODERATE (10 TO 20 KNOTS)
EASTERLY VERTICAL WIND SHEAR AND STRONG DIFFLUENT FLOW. THE DYNAMIC
MODELS INDICATE DEVELOPMENT INTO A TROPICAL DEPRESSION WITHIN THE
NEXT 24 TO 36 HOURS AS THE SYSTEM TRACKS GENERALLY NORTHWESTWARD.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.
ASCAT passes at 0338 UTC and 0430 UTC indicated that the cyclone
was producing winds of 35 kt in a small area to the north of the
center. Since that time, the convective pattern has become
significantly better organized, and it is estimated that the system
is now a 40-kt tropical storm. Earlier microwave data indicated
that Marie has a well-defined low-level ring, which can often be a
precursor to rapid intensification if environmental conditions are
favorable. With waters near 30 degrees Celsius, high levels of
atmospheric moisture, and favorable upper-level diffluence, it
appears that RI is a definite possibility, and Marie could become a
hurricane in about 24 hours. Environmental conditions are
expected to remain conducive for strengthening for much of the
forecast period, and in fact, the global models indicate significant
deepening of the cyclone through about day 4 before Marie reaches
cooler waters. The statistical-dynamical models are also
incredibly aggressive, with the SHIPS model making Marie a category
4 hurricane in 4 days. The NHC intensity forecast is roughly
between the SHIPS and LGEM models, which are the highest of the
guidance. This is higher than the previous forecast, and it now
explicitly shows Marie becoming a major hurricane later in the