#63 Postby dexterlabio » Tue May 12, 2020 10:23 am
WDPN31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 01W (VONGFONG), LOCATED APPROXIMATELY
495NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED
NORTH-NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP, SYMMETRICAL
CONVECTION OBSCURING A LOW LEVEL CIRCULATION CENTER BELOW. THE EIR
LOOP FURTHER INDICATES RAPIDLY COOLING CLOUD TOPS AND CONSOLIDATING
CONVECTION OVER THE PAST 6 HOURS, SUGGESTING INTENSIFICATION DURING
THIS PERIOD. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE
BASED ON SATELLITE FIXES FROM PGTW AND RJTD AS WELL AS EXTRAPOLATION
THROUGH A LOW LEVEL CIRCULATION FEATURE PRESENT IN A 120836Z SSMIS
37GHZ IMAGE. THE INITIAL INTENSITY OF 35 KNOTS IS ASSESSED WITH FAIR
CONFIDENCE AND IS HEDGED ABOVE A PGTW DVORAK CURRENT INTENSITY
ESTIMATE OF T2.0 DUE TO TIMELY CIMMS ADT ASSESSMENTS OF T2.7-T3.1 AND
THE IMPROVING CONVECTIVE STRUCTURE. TS VONGFONG IS TRAVERSING AN
ENVIRONMENT FAVORABLE FOR RAPID INTENSIFICATION WITH LOW (5-10 KTS)
VWS, ESTABLISHED EQUATORWARD AND POLEWARD OUTFLOW ALOFT AND WARM
(29-30C) SEA SURFACE TEMPERATURES (SSTS). THE SYSTEM IS TRACKING
ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR)
CENTERED OVER THE NORTHERN MARIANA ISLANDS THAT CONTINUES TO BUILD
WESTWARD.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE LAST PROGNOSTIC REASONING MESSAGE.
B. OVER THE NEXT 12 HOURS TS VONGFONG WILL TRACK GENERALLY
NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED
STR CENTERED NORTH OF GUAM. THIS STR IS CURRENTLY BUILDING WESTWARD
TOWARDS NORTHERN LUZON AND WILL RESULT IN SUBSEQUENT STEERING OF TS
01W TO A GENERALLY WESTWARD DIRECTION FROM TAU 24 UNTIL LANDFALL AT
SAMAR ISLAND AT TAU 48. THE ENVIRONMENT OVER THE NEXT 48 HOURS IS
EXPECTED TO REMAIN HIGHLY FAVORABLE FOR FURTHER DEVELOPMENT AND
INTENSIFICATION AS THE SYSTEM TRAVELS OVER THE WARM WATERS OF THE
PHILIPINE SEA. SEA SURFACE TEMPERATURES WILL REMAIN HIGH (28-29C)
WHILE VWS IS FORECAST TO REMAIN LOW (5-10 KTS) DURING THIS TIME.
THESE FACTORS, COUPLED WITH THE PRESENCE OF AN UPPER LEVEL POINT
SOURCE SITUATED ABOVE THE LLCC THAT CONTINUES TO PROVIDE STRONG
OUTFLOW, SETUP AN ENVIRONMENT FOR POSSIBLE RAPID INTENSIFICATION
OVER THE NEXT 48 HOURS. THIS FAVORABLE ENVIRONMENT IS OFFSET,
HOWEVER, BY THE INTERACTION OF TS VONGFONG WITH OUTFLOW FROM A
TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) CELL POSITIONED OVER THE
SOUTH CHINA SEA ON THE WESTERN PERIPHERY OF THE SYSTEM. THE PEAK
INTENSITY OF 65 KTS IS FORECAST TO OCCUR AT TAU 48 WHEREUPON THE
SYSTEM WILL STRUGGLE TO FURTHER INTENSIFY AS IT MAKES LANDFALL
DUE TO THE FRICTIONAL EFFECTS OF LAND. AFTER REACHING LANDFALL
AT TAU 48, TS VONGFONG WILL BEGIN TRACKING WEST-NORTHWESTWARD
THROUGH TAU 72 AS IT TRACKS ALONG THE STEERING STR. NUMERICAL
MODEL SOLUTIONS ARE IN FAIR AGREEMENT THROUGH TAU 72 WITH A 98 NM
SPREAD AT TAU 48 INCREASING TO A 166NM SPREAD BY TAU 72. THIS SPREAD
OF MODEL SOLUTIONS LENDS FAIR CONFIDENCE TO THIS PORTION OF THE JTWC
FORECAST TRACK.
C. AFTER TAU 72 TS VONGFONG WILL BEGIN A NORTHWESTWARD TRACK
UNTIL TAU 96 AS IT TRAVELS INLAND. THE FRICTIONAL EFFECTS OF LAND
INTERACTION WILL HINDER FURTHER DEVELOPMENT AND LEAD TO SLIGHT
WEAKENING OF THE SYSTEM, HOWEVER THIS WEAKENING WILL BE OFFSET BY
CONTINUED ROBUST POLEWARD OUTFLOW AND LOW VWS (5-10 KTS). OUTFLOW
FROM THE TUTT CELL POSITIONED OVER THE SOUTH CHINA SEA WILL CONTINUE
TO IMPINGE UPON THE OUTFLOW OF THE SYSTEM AS IT MOVES INLAND HOWEVER
THIS CELL IS FORECAST TO TRAVEL SOUTHWARD AND CEASE INTERACTION WITH
TS VONGFONG BY TAU 72, AT WHICH POINT IT WILL HAVE WEAKENED TO 60
KTS. BY TAU 96, THE SYSTEM WILL WEAKEN TO 50 KTS, PRIMARILY DUE TO
THE LONG TRACK OVER LAND DURING THIS PERIOD. AT THIS TIME IT WILL
BEGIN TO ROUND THE AXIS OF THE STR POSITIONED TO THE EAST AND TRACK
GENERALLY NORTH-NORTHEASTWARD. IT WILL RETAIN ITS INTENSITY OF 50 KTS
DURING THIS TIME DUE TO PERSISTENTLY LOW (5-10 KTS) VWS AND ROBUST
OUTFLOW. TS 01W WILL CONTINUE TO TRACK NORTH-NORTHEASTWARD AFTER THIS
TIME AND REACH THE WARM WATERS OF THE PHILIPPINE SEA NORTH OF APARRI
BY TAU 120. THE SPREAD IN MODEL SOLUTIONS INCREASES TO 166 NM BY TAU
72 AND THEN SIGNIFICANTLY INCREASES TO 298 NM BY TAU 96. THE
UNCERTAINTY IN MODEL SOLUTIONS IS DUE TO THE TIMING OF THE BUILDING
AND REORIENTATION OF THE STEERING RIDGE WITH EACH OF THE GLOBAL
MODELS PROVIDING A DIFFERENT CENTER POSITION OF THE RIDGE AT TAU
96-120. THIS INCREASING SPREAD IN MODEL SOLUTIONS AFTER TAU 72 LENDS
OVERALL LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.//
NNNN
0 likes
Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.
