Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Depression 16w Warning Nr 05//

From: SIU Weather Processor <[email-masked]>
Date: Fri, 22 Oct 2010 09:34:06 -0500

WDPN32 PGTW 221500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W WARNING NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL DEPRESSION (TD) 16W, LOCATED APPROXIMATELY 755 NM
SOUTHEAST OF KADENA, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST
SIX HOURS. BASED ON THE CURRENT INFRARED SATELLITE PRESENTATION THE
SYSTEM MAINTAINS MARGINAL CLASSIFICATION AS A TROPICAL DEPRESSION. A
TROPICAL UPPER LEVEL TROPOSPHERIC TROUGH (TUTT) HAS MOVED OVERHEAD
AND HAS DEGRADED ENVIRONMENTAL CONDITIONS CONSIDERABLY. THE LOW
LEVEL CIRCULATION (LLCC) HAS BEEN LEFT EXPOSED AND WEAKENED BASED ON
LOW LEVEL CLOUD LINES. THERE IS ONLY LIMITED EVIDENCE OF A LINGERING
LLCC IN A 220754Z SSMIS 91H MICROWAVE IMAGE. DEEP CONVECTION HAS
BEEN DISPLACED SOUTH OF THE PERCEIVED LOCATION OF THE LLCC, AND
APPEARS TO BE FLANKING THE OUTER PERIPHERY OF THE CIRCULATION VICE
THE CENTRAL TURNING. DVORAK INTENSITY ESTIMATES FROM RJTD AND PGTW
ONLY INDICATE A 25 KNOT SYSTEM.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS BULLETIN. HOWEVER, THERE CONTINUES TO BE A HIGH
DEGREE OF UNCERTAINTY IN THE EXTENDED TRACK AND INTENSITY FORECAST.
   B.  TD 16W IS CURRENTLY TRACKING ALONG A LOW-LEVEL SUBTROPICAL
RIDGE POSITIONED TO THE NORTH. THE SYSTEM WILL CONTINUE TO TRACK
WESTWARD ALONG THIS RIDGE AND WILL STRUGGLE TO INTENSIFY TO MIMIMAL
TROPICAL STORM STRENGTH IN THE SHORT TERM. UPPER LEVEL CONDITIONS
ARE FORECAST TO IMPROVE WITHIN THE NEXT FEW DAYS. THIS WILL ALLOW
THE SYSTEM TO ORGANIZE AND INTENSIFY, ASSUMING IT HOLDS TOGETHER IN
THE INTERIM.
  C. ONCE THE SYSTEM STRENGTHENS IT WILL BEGIN TO TRACK ALONG THE
DEEP LAYER RIDGE TO THE NORTHEAST. AN UPPER LEVEL LONGWAVE TROUGH
WILL ERODE THE RIDGE AS IT PASSES TO THE EAST AND INITIATE A
POLEWARD TRACK. HOWEVER, A LOW LEVEL NORTHEASTERLY SURGE WILL
MITIGATE AGGRESSIVE RECURVATURE AND INTENSIFICATION (DUE TO STRONG
DIRECTIONAL SHEAR). THE FORECAST ACCORDINGLY LIES SOUTH OF THE MODEL
CONSENSUS BEYOND TAU 72 TO ACCOUNT FOR THE EFFECTS OF THIS SURGE
EVENT AND THE ECMWF, NOGAPS, AND GFS TRACKERS PULLING THE SYSTEM
NORTH TOO AGGRESSIVELY.//

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