Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Depression 17w (seventeen)

From: SIU Weather Processor <[email-masked]>
Date: Fri, 22 Oct 2010 21:40:09 -0500

WDPN33 PGTW 230300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED
APPROXIMATELY 700 NM EAST OF IWO TO, JAPAN, HAS TRACKED
NORTHEASTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS A FULLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH TIGHTLY WRAPPED CONVECTIVE BANDING
AND DEEP CONVECTION SHEARED 55 NM TO THE WEST. THE INITIAL INTENSITY
ESTIMATE IS BASED ON PGTW AND KNES DVORAK ESTIMATES RANGING FROM 30
TO 35 KNOTS. UPPER LEVEL ANALYSIS INDICATES TD 17W IS IN AN
UNFAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT, WITH HIGH EASTERLY
VERTICAL WIND SHEAR. AN UPPER LEVEL MID-LATITUDE TROUGH HAS WEAKENED
AND REORIENTED THE LOW- TO MID-LEVEL STEERING RIDGE AND ALLOWED TD
17W TO TURN NORTHEASTWARD UNDER THE STEERING INFLUENCE OF A LOW-
LEVEL SUBTROPICAL STEERING RIDGE.
3. FORECAST REASONING.
    A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST REASONING
SINCE THE PREVIOUS BULLETIN.
    B. TD 17W SHOULD CONTINUE TO TRACK NORTHEASTWARD ALONG THE
NORTHWESTERN PERIPHERY OF THE STEERING RIDGE. AS THE VERTICAL WIND
SHEAR REMAINS HIGH DUE TO THE MID-LATITUDE TROUGH, TD 17W SHOULD
WEAKEN BELOW WARNING CRITERIA WITHIN THE NEXT 24 HOURS. THE
AVAILABLE NUMERICAL MODEL GUIDANCE IS IN POOR AGREEMENT WITH ERRATIC
TRACKS, INDICATIVE OF A DISSIPATION SCENARIO.//

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