Tropical Storm Kalmaegi & Typhoon Fengshen: updates at 17/03UTC

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WESTERN NORTH PACIFIC

TY FENGSHEN (26W)
As of 00:00 UTC Nov 17, 2019:
Location: 26.6°N 152.2°E
Maximum Winds: 90 kt ( 170km/h)
Gusts: 110 kt ( 205km/h)
Minimum Central Pressure: 970 mb
CATEGORY US: 2
WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FENGSHEN) WARNING NR 023//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 26W (FENGSHEN), LOCATED APPROXIMATELY 599 NM EAST-
NORTHEAST OF IWO TO, JAPAN, HAS TRACKED EASTWARD AT 26 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
THE SYSTEM HAS RAPIDLY DECAYED AS IT BECAME MORE RAGGED AND
ELONGATED AND WITH FAST WARMING CONVECTIVE TOPS. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A PINHOLE EYE THAT
HAS SINCE DISAPPEARED IN THE MSI LOOP, ADJUSTED FOR TILT AND LINED
UP WITH A MICROWAVE EYE IN THE 162120Z SSMIS 37GHZ COLORIZED IMAGE.
THE INITIAL INTENSITY OF 90KTS IS BASED ON AN OVERALL ASSESSMENT OF
AGENCY DVORAK ESTIMATES THAT INDICATE A RAPIDLY WEAKENING TREND. TY
26W DRIFTED INTO AN AREA OF STRONG (>45KTS) VERTICAL WIND SHEAR
(VWS) AND COOLING SSTS (<27C) THAT ARE PARTLY OFFSET BY EXCELLENT
POLEWARD OUTFLOW. THE CYCLONE IS ACCELERATING ON THE POLEWARD SIDE
OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST.
3. FORECAST REASONING.
   A.  THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY FENGSHEN WILL TRACK MORE EAST-SOUTHEASTWARD UNDER THE STR.
AFTER TAU 12, AS THE SYSTEM RAPIDLY ERODES DUE TO INCREASING VWS AND
COOLING SSTS, A SECONDARY, MID- TO LOW-LAYERED STR TO THE NORTH WILL
ASSUME STEERING AND LOOP THE CYCLONE SOUTHWESTWARD THEN WESTWARD.
THE NEGATIVE COMBINED EFFECTS OF HIGH VWS AND COOL SSTS WILL RESULT
IN DISSIPATION BY TAU 48, POSSIBLY SOONER. THE MAJORITY OF THE
NUMERICAL MODELS ARE IN BROAD AGREEMENT WITH THIS LOOPING TRACK BUT
WITH SIGNIFICANT DIFFERENCES IN THE TRACK SPEED AND THE TIMING OF THE
LOOP. IN VIEW OF THIS COMPLEX STEERING AND THE LARGE VARIANCE IN THE
NUMERICAL MODEL SOLUTIONS, THERE IS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST.//
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TS KALMAEGI (27W)
As of 00:00 UTC Nov 17, 2019:
Location: 15.5°N 125.4°E
Maximum Winds: 45 kt ( 85km/h)
Gusts: 55 kt ( 100km/h)
Minimum Central Pressure: 997 mb
WDPN32 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (KALMAEGI)
WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 27W (KALMAEGI), LOCATED APPROXIMATELY 261 NM
EAST-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A LARGE AREA OF DEEP
CONVECTION THAT HAS BEGUN TO CONSOLIDATE AND MOVE OUT OF A QUASI-
STATIONARY (QS) STATE. THE INITIAL POSITION IS PLACED WITH GOOD
CONFIDENCE BASED ON LOW CLOUD ELEMENT TRACING IN THE MSI LOOP AND
LINED UP WITH A LOW CIRCULATION FEATURE IN THE TOTAL PRECIPITABLE
WATER ANIMATION FROM CIMSS. THE INITIAL INTENSITY OF 45KTS IS BASED
ON THE DVORAK ESTIMATE OF T3.0/45KTS FROM PGTW AND REFLECTS THE
IMPROVED CONDITION. ANALYSES INDICATE A MARGINALLY FAVORABLE
ENVIRONMENT WITH MODERATE (15-20KT) RELATIVE VERTICAL WIND SHEAR
(VWS) AND COOL/DRY NORTHEASTERLY SURGE OVER THE PHILIPPINE SEA
OFFSET BY A VIGOROUS POLEWARD OUTFLOW AND WARM (29C) SSTS. THE
CYCLONE IS NOW TRACKING ALONG THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 27W WILL CONTINUE NORTHWESTWARD UP TO TAU 36. AFTERWARD,
ANOTHER STR TO THE WEST WILL BUILD, REORIENT NORTHWARD, AND GRADUALLY
STEER THE CYCLONE WESTWARD, MAKING LANDFALL OVER NORTHERN LUZON NEAR
TUGUEGARAO JUST BEFORE TAU 48, THEN SOUTHWESTWARD THROUGH LUZON BEFORE
EXITING INTO THE SOUTH CHINA SEA BEFORE TAU 72. THE MARGINALLY
FAVORABLE ENVIRONMENT WILL INTENSIFY TO A PEAK OF 65KTS BY TAU 36
BEFORE LANDFALL. AFTERWARD, INCREASING VWS AND LAND INTERACTION WILL
ERODE THE SYSTEM DOWN TO 40KTS BY TAU 72.
   C. AFTER TAU 72, TS KALMAEGI IS EXPECTED TO CONTINUE SOUTHWESTWARD
UNDER THE SECONDARY STR IN THE SOUTH CHINA SEA WHERE THE COLD/DRY
NORTHERLY SURGE IS MORE VIGOROUS. THIS, PLUS THE HIGH VWS, WILL RESULT
IN DISSIPATION BY TAU 120. THE NUMERICAL MODELS ARE IN BETTER AGREEMENT
BUT WITH NOTABLE DIFFERENCES IN TRACK SPEED. GIVEN THE UNCERTAINTIES IN
THE STORM MOTION COMING OUT OF A QS STATE, THE ANTICIPATED SWITCH IN
THE STEERING MECHANISM, AND THE TRACK ACROSS THE RUGGED LUZON TERRAIN,
THERE IS OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST.//
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