msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc//
subj/prognostic reasoning for tropical depression 04w warning nr 04//
rmks/
1. For meteorologists.
2. 12 hour summary and analysis.
   A. During the past 12 hours tropical depression (td) 04w has 
moved generally northward and remained a weak tropical
system. More recently convection has become less organized
around the low level circulation center (LLCC) in response to a 
near-stationary frontal boundary to the northwest.
   B. TD 04w continues to slowly track northward, along the 
western periphery of a low to mid-level ridge located to the 
east of the storm, towards a break in the ridge. Convection 
continues to be sheared off into the midlatitudes disrupting 
the overall organization of the system and leaving the LLCC 
partially exposed. Preliminary evidence of extratropical trans-
ition is evident with model fields and satellite imagery
showing a frontal boundary just north of the system with
stratocumulus (indicative of drier and cooler air) beginning
to wrap around the western outer periphery of the system. In
addition an under-developed warm core structure exists accord-
ing to the AMSU temperature anomaly product. The current
intensity estimate is based on Dvorak values of 2.0 from pgtw,
rjtd and knes.
3. Forecast reasoning
   a. TD 04w is no longer expected to intensify beyond 40 knots 
due to a shortened timeframe for intensification prior to 
interacting with the baroclinic zone. Therefore, the current 
intensity trend reflects this change in forecast reasoning.
   B. The system will begin to track more northeastward
throughout the forecast period as the system begins to round
the subtropical ridge axis between tau 24 and 36. The system
will marginally intensify through tau 24, then begin to weaken
due to cooler SST and high vertical wind shear as it encounters
the baroclinic zone to the north. The system is expected to 
continue to weaken then complete extratropical transition by 
tau 48. 
Forecast team: Delta//