Wdpn31 Pgtw 030300 

msgid/genadmin/navpacmetoccen Pearl Harbor hi/jtwc// 

subj/prognostic reasoning for typhoon 01w warning nr 11//
rmks/
1. For meteorologists.
2. Prognostic reasoning for 030000z to 060000z Apr 2007
   a. Typhoon (TY) 01w (Kong-Rey), located approximately 55 nm north
of Saipan, has tracked northwestward at 14 knots over the past six
hours. Current Dvorak estimates range from 65 knots to 90 knots and
AMSU intensity estimates remain low near 50-55 knots. Current
intensity is based on an average of the more representative dvorak
intensity estimates of 65 to 77 knots. Animated multispectral
satellite imagery indicates that central convection has become
better organized over the past six hours with a ragged 16-nm eye
now evident in imagery. A 022254z ssmis image also shows the eye
as well as improved convective banding over all quadrants. 
   B. Track philosophy shows very little change from the previous
forecasts. TY 01w continues to track along the southwestern periphery
of the mid-level subtropical ridge toward a weakness in the ridge.
A strong midlatitude trough continues to deepen and shift eastward
and as of 02/12z was positively tilted from eastern China north-
eastward into Korea/northern Japan. Strong midlatitude westerlies
prevail across the northern Pacific. The system is expected to
track increasingly poleward through tau 24 and will turn sharply
northeastward and accelerate as the system tracks above the ridge
axis and encounters midlatitude westerlies. The available dynamic
aids are in relatively good agreement on the track with the
exception of NOGAPS which is excessively fast. Track speed is the
biggest challenge especially after tau 36 when the system begins
to weaken and track northeastward. This forecast is based on a
consensus of the dynamic aids and persistence through tau 36 but
is adjusted slower than conw after this time due to the excessive
speeds with the NOGAPS model.  
   C. TY 01w remains situated within a generally favorable environment
with good poleward outflow and fair divergence enhanced by midlatitude
westerlies. However, equatorward outflow remains restricted due to
convergence associated with an upper trough which is situated south
of the system. Animated water vapor imagery shows an upper low near
4n 133e with troughing and dry air extending northeastward to the
system. TY 01w is forecast to weaken quickly after tau 24 due
primarily to strong vertical wind shear, cooler SST (24-26c), and
significantly lower ocean heat content.  
   D. Current wind radii are based on Quikscat and microwave
imagery. Forecast wind radii are based on climatology for an 
average-sized system and persistence. 
Forecast team: alpha
//
bt
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