subj/prognostic reasoning for typhoon 02w warning nr 11//
rmks/
1. For meteorologists.
2. Prognostic reasoning for 190000z may to 220000z may 2007.
   A. Typhoon (TY) 02w (Yutu), located approximately 765 nm
southwest of Iwo Jima, has tracked north-northwestward at 12
knots over the past six hours. Recent microwave imagery depict
a distinct eye feature, lending high confidence to the analyzed
storm position.
   B. TY 02w is tracking toward a weakness in the subtropical
ridge (str) induced by a mid-latitude trough extending across the
korean peninsula and northeastern China. The system has tracked
along the periphery of the primary steering ridge anchored north
of the Mariana islands and will continue to do so throughout the
forecast period. TY 02w has begun to move more poleward and will
crest the ridge axis near tau 12. The track speed will slow as
the system approaches the ridge axis. After this time, tc 02w
will gradually accelerate toward the northeast as it begins to
interact with the midlatitude westerlies north of the str. TY 02w
will begin interacting with the baroclinic zone by tau 48 and
become imbedded within the approaching mid-latitude trough as it
completes extratropical transition by tau 72. 
   C. TY 02w has intensified over the past six hours and will
continue to intensify through tau 12 as poleward outflow is
enhanced by the mid-latitude flow to the north. The upper
tropospheric trough east of TY 02w continues to provide favorable
outflow, but this eastward outflow has decreased as the storm
moves north-northwestward. Low vertical wind shear and increasingly
favorable diffluence aloft will allow the storm to reach peak
intensity as it reaches the ridge axis near tau 12. Vertical wind
shear will increase after tau 24 and begin to slowly weaken the
system. TY 02w will begin extratropical transition by tau 48 and
become fully extratropical by tau 72.
   D. Current wind radii are based upon Quikscat and microwave
imagery. Forecast wind radii are based on climatology for an
average-sized system and analysis of wind field distortions
typically associated with extratropical transition.
Forecast team: Bravo//

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