TS Fengshen(26W) and TD 27W East of the Philippines: updates at 13/02UTC

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WESTERN NORTH PACIFIC

TS FENGSHEN(26W)
As of 00:00 UTC Nov 13, 2019:
Location: 17.3°N 156.0°E
Maximum Winds: 40 kt ( 75km/h)
Gusts: 50 kt ( 95km/h)
Minimum Central Pressure: 1000 mb
WDPN31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN)
WARNING NR 007//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 601
NM EAST-NORTHEAST OF SAIPAN, CNMI, HAS TRACKED WEST-NORTHWESTWARD
AT 18 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY SHOWS A MEDIUM-SIZED SYSTEM WITH PERSISTENT DEEP
CONVECTION; HOWEVER, RAIN BANDS ARE SHORT AND CONSTRAINED CLOSE TO
THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE DEFINED LLC FEATURE IN THE 122216Z GPM
89GHZ COLORIZED MICROWAVE IMAGE AND ON TOP OF A TIGHT CLUSTER OF
AGENCY FIXES. THE INITIAL INTENSITY OF 40KTS IS BASED ON THE DVORAK
INTENSITY ESTIMATES OF T2.0/45KTS FROM PGTW AND T2.5/35KTS FROM
RJTD. THE SYSTEM IS, OVERALL, IN A FAVORABLE AREA FOR FURTHER
DEVELOPMENT WITH WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES, LOW
(10-15 KNOT) VERTICAL WIND SHEAR (VWS) AND GOOD EQUATORWARD OUTFLOW.
THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 26W WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STR
THROUGH TAU 36 WHEN IT WILL BEGIN TO TURN POLEWARD THEN
NORTHEASTWARD AS IT ROUNDS THE WESTERN EDGE OF THE STR AXIS. THE
OVERALL FAVORABLE ENVIRONMENT WILL PROMOTE GRADUAL INTENSIFICATION
TO A PEAK 80KTS BY TAU 72. THERE IS A SIGNIFICANT SPREAD AMONG THE
NUMERICAL MODELS AND NOTABLE DIFFERENCES IN TRACK SPEED, LENDING LOW
CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST.
   C. AFTER TAU 72, TS 26W WILL TURN MORE EAST-NORTHEASTWARD AND
WILL RAPIDLY WEAKEN AS IT INTERACTS WITH AN APPROACHING MIDLATITUDE
TROUGH AND STRONG VWS. THE SYSTEM IS EXPECTED TO BEGIN EXTRA-
TROPICAL TRANSITION BY TAU 96, HOWEVER, GLOBAL MODELS ARE BUILDING A
LOW-LEVEL RIDGE TO THE NORTH THAT IS EXPECTED TO IMPEDE THE FORWARD
MOTION. BY TAU 120, THE SYSTEM WILL BE REDUCED TO 30KTS. DUE TO THE
COMPLEX, EVOLVING STEERING PATTERN, THE NUMERICAL MODEL SOLUTIONS
VARY WIDELY, LENDING LOW CONFIDENCE IN THE EXTENDED PORTION OF THE
JTWC FORECAST TRACK./
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TD 27W
As of 00:00 UTC Nov 13, 2019:
Location: 12.6°N 129.2°E
Maximum Winds: 30 kt
Minimum Central Pressure: 1001 mb
WDPN32 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 27W (TWENTYSEVEN), LOCATED APPROXIMATELY
493 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS A DISORGANIZED SYSTEM WITH
DEEP AND FLARING CONVECTION THAT IS SHEARED 35NM WESTWARD FROM AND
PARTLY EXPOSING A BROAD, ELONGATED, AND RAGGED LOW LEVEL CIRCULATION
(LLC).
THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE ON THE PARTLY
EXPOSED LLC. THE INITIAL INTENSITY OF 30KTS IS BASED ON THE DVORAK
ESTIMATE OF T2.0/30KTS FROM RJTD PASSES. ANALYSES INDICATE A
MARGINAL ENVIRONMENT WITH WARM (>30C) SST AND STRONG WESTWARD
OUTFLOW OFFSET BY A COLD DRY NORTHERLY SURGE OVER THE PHILIPPINE SEA
AND MODERATE TO STRONG (15-25KT) VERTICAL WIND SHEAR ALOFT. THE
CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A LOW REFLECTION
OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE ON THIS SYSTEM
AND SETS THE FORECAST PHILOSOPHY.
   B. TD 27W WILL TRACK MORE NORTHWESTWARD AS IT GRADUALLY DEVELOPS
AND TRACKS ALONG THE SOUTHWEST EDGE AND HIGHER REFLECTION OF THE
STR. THE MARGINAL ENVIRONMENT WILL FUEL A MODEST INTENSIFICATION TO
A PEAK OF 50KTS BY TAU 72 AS IT DRIFTS EAST OF LUZON.
   C. AFTER TAU 72, TD 27W WILL CONTINUE TRACKING NORTHWESTWARD
ALBEIT AT A SLOWER PACE. INCREASING VWS AND NORTHERLY SURGE NEAR THE
SURFACE WILL BEGIN TO ERODE THE SYSTEM, REDUCING ITS FORWARD SPEED
AND ITS INTENSITY - DOWN TO 30KTS BY TAU 120 AS IT ENTERS THE LUZON
STRAIT. NUMERICAL MODELS ARE IN BROAD AGREEMENT WITH THE DIRECTION
OF TRACK; HOWEVER, THERE IS A WIDE SPREAD IN THE MODEL ENVELOPE
(400NM BY TAU 120) WITH NAVGEM ON THE EXTREME LEFT AND AFUM/EGRR ON
THE RIGHT MARGIN - A POSSIBLE BIFURCATION SOLUTION. THIS, PLUS THE
UNCERTAINTY IN THE STORM MOTION ASSOCIATED WITH A DEVELOPING
CYCLONE, LEND LOW CONFIDENCE IN THE JTWC FORECAST TRACK.//
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