Tropical Depression Irene Advisory 18
8:00 PM PDT Aug 8 2005 (11:00 PM EDT or 3Z Aug 9 2005)
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For official forecasts...please refer to the NHC. This is an independent product.
Please remember...tropical cyclones can be very unpredictable and can make sudden changes and/or shifts in both track and intensity.
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Convection has continued to fire just to the east of the center today. Based on trends and the fact that Irene is moving over warmer SSTs...I am inclined to be more generous this evening rather than conservative like I was over the last day...showing gradual strengthening to hurricane status in 120 hours. The shear is also forecast to weaken in about 36 hours as the upper level low to the northeast lifts to the north.
The track forecast is simple at the beginnign of the period. Low level easterly flow will steer the shallow system for the next two days. Later in the period...however...a weakness should develop in the subtropical ridge in response to a trough digging down from eastern Canada. Now it gets tricky. Many of the models...including the GFS...GFDL...MM5...NOGAPS...and the UKMET...have Irene stalling around Bermuda as a trough bypasses it...and then recurving it back toward the United States. The CMC continues to be the outlier with a stronger ridge. The location of the trough and Irene will be critical...and it will determine whether Irene recurves harmlessly or threatens the United States. For now...I will slow the track down considerably after 96 hours.
Forecaster Tang
Hour Position Intensity
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Initial 22.6N 52.7W 30 kt
12 hr 22.9N 54.1W 35 kt
24 hr 23.2N 55.5W 35 kt
36 hr 23.6N 56.9W 40 kt
48 hr 24.2N 58.8W 45 kt
72 hr 25.7N 61.9W 50 kt
96 hr 27.3N 64.1W 60 kt
120 hr 28.6N 64.7W 65 kt
Track:
Comments and suggestions welcomed as always.
