Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Depression 19w

From: SIU Weather Processor <[email-masked]>
Date: Sun, 12 Dec 2010 19:53:04 -0600

WDPN31 PGTW 130300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W
/WARNING NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL DEPRESSION (TD) 19W, LOCATED APPROXIMATELY 240 NM
EAST OF HO CHI MINH, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT
06 KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL
SATELLITE IMAGERY INDICATES THAT THE DEEP CONVECTION HAS
SIGNIFICANTLY DECREASED WITHIN THE PAST SIX HOURS AND HAS SHEARED 90
NM TO THE WEST-NORTHWEST OF AN ILL-DEFINED LOW LEVEL CIRCULATION
CENTER (LLCC). THE INITIAL INTENSITY WAS BASED ON PGTW AND KNES
DVORAK ESTIMATES OF 25 KNOTS. ADDITIONALLY, A SHIP LOCATED 30 NM TO
THE NORTH-NORTHWEST OF THE LLCC WAS REPORTING 20-KNOT NORTH-
NORTHEASTERLY WINDS AND A SEA LEVEL PRESSURE OF 1005 MB. TD 19W IS
LOCATED SOUTH OF THE UPPER-LEVEL RIDGE AXIS AND IS UNDER MODERATE TO
HIGH VERTICAL WIND SHEAR (VWS).
3. FORECAST REASONING.
   A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
   B. TD 19W IS TRACKING WEST-NORTHWESTWARD UNDER THE STEERING
INFLUENCE OF THE LOW-LEVEL (700 MB) SUBTROPICAL RIDGE (STR)
POSITIONED NORTH OF THE SYSTEM. A 12/12Z 700MB ANALYSIS DEPICTS THE
STR EXTENDING ACROSS THE NORTHERN SOUTH CHINA SEA INTO NORTHERN
VIETNAM. AVAILABLE MODEL GUIDANCE (TO INCLUDE NOGAPS, ECMWF, GFS,
JGSM AND UKMO) IS CONSISTENT IN MAINTAINING THE STR THROUGH THE
FORECAST PERIOD. THEREFORE, TD 19W IS FORECAST TO CONTINUE TRACKING
GENERALLY WESTWARD. A DECREASE IN THE VWS SHOULD ALLOW THE SYSTEM TO
RE-COUPLE WITH THE DEEP CONVECTION AND MAINTAIN INTENSITY, THEN
DISSIPATE OVER VIETNAM BY TAU 24.//

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
To unsubscribe from WX-TROPL send e-mail to [email-masked] with
"unsub wx-tropl" in the body of your message. For help with WX-TROPL
write to [email-masked]. For more information on tropical weather products, see the NHC Homepage at http://www.nhc.noaa.gov.