msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc//
subj/prognostic reasoning for tropical depression 17w warning nr 01//
rmks/
1. For meteorologists.
2. 12 hour summary and analysis.
   A. Tropical depression (td) 17w has rapidly consolidated in the
low levels over the past 12 to 18 hours. A strong band of westerlies
south of the low level circulation center (LLCC) likely contributed
to the spin-up of cyclonic vorticity. Upper level analysis indicates
that the 200 mb anticyclone has begun to develop over the LLCC,
lowering the vertical wind shear values.
   B. The initial intensity of 25 kts is based on Dvorak estimates 
of 1.5 from rjtd and pgtw, and 2.0 from knes. Additionally, a 010214z
ascat pass indicates a tight LLCC with winds near 35 kts in the
southeastern quadrant near the most intense convection, and winds
of 20 to 25 kts at the center of the storm. A 011324z AMSU microwave
image indicates that the LLCC is exposed at this time, with deep
convection over the southeastern quadrant. A small upper level
cyclone to the northwest of TD 17w may be temporarily inhibiting
convection over the LLCC. TD 17w is currently quasi-stationary in
an area of weak steering between a weak mid-level subtropical ridge
to the north over Okinawa and a near-equatorial ridge south of the
storm. 
3. Forecast reasoning.
   A. This is the initial forecast for TD 17w.
   B. TD 17w will remain quasi-stationary through tau 48, due to
the competing steering ridges to its north and south. The limited
objective aids and fields agree on the slow initial movement. After
tau 48, the model fields indicate a weakening of the near-equatorial
ridge, with the subtropical ridge to the north becoming the primary
steering influence. The fields then depict a westward to northwest-
Ward track through tau 72. As the 200 mb anticyclone builds over
the LLCC, TD 17w will deepen. The TUTT lies to the northeast of the
storm, and it is likely a developing TUTT cell will provide a pole-
Ward outflow channel that will allow for rapid intensification,
especially after tau 48.
4. Justification for correction: corrected spelling and grammar.
Forecast team: Bravo.//