Tropical Storm VONGFONG Advisory 07 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 425 NM NORTH
OF YAP, HAS TRACKED WESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS.
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS INCREASING DEEP
CONVECTION AS THE LOW LEVEL CIRCULATION CENTER REMAINS EMBEDDED IN A
LARGE CENTRAL DENSE OVERCAST FEATURE. HOWEVER, A 061538Z GCOM
MICROWAVE IMAGE REVEALS INCREASED BANDING AND BUILDING STRUCTURE
AROUND AN IRREGULAR 36 GHZ EYE FEATURE. THE INITIAL POSITION IS
BASED ON PERSISTENCE FROM THE AFOREMENTIONED MICROWAVE EYE FEATURE
AND POSITION FIXES FROM PGTW AND RJTD. THE INITIAL INTENSITY REMAINS
ASSESSED AT 90 KNOTS BASED ON THE HIGHER END OF DVORAK INTENSITY
ESTIMATES THAT RANGE FROM 77 TO 90 KNOTS. UPPER-LEVEL ANALYSIS
INDICATES THE SYSTEM REMAINS IN AN AREA OF MODERATE (15 TO 20 KNOT)
VERTICAL WIND SHEAR (VWS) THAT IS BEING OFFSET BY EXCELLENT
EQUATORWARD OUTFLOW AND THE MOTION OF THE SYSTEM. TY 19W IS
CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 19W WILL CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR THROUGH TAU 48. AFTERWARDS, IT IS
EXPECTED TO TURN MORE POLEWARD AS THE STR WEAKENS IN RESPONSE TO A
MID-LATITUDE TROUGH WHICH WILL BE APPROACHING FROM THE NORTHWEST.
UPPER-LEVEL CONDITIONS ARE EXPECTED TO IMPROVE WITH THE DEVELOPMENT
OF A POLEWARD OUTFLOW CHANNEL ALLOWING FOR FURTHER INTENSIFICATION
AS THE SYSTEM IS EXPECTED TO REACH 130 KNOTS BY TAU 48. MODEL
GUIDANCE IS IN FAIRLY TIGHT AGREEMENT THROUGH TAU 48 LENDING TO HIGH
CONFIDENCE IN THIS PORTION OF THE FORECAST.
   C. TY 19W IS EXPECTED TO TRACK POLEWARD ALONG THE WESTERN EDGE OF
THE AFOREMENTIONED STEERING STR WHICH IS EXPECTED TO BE WEAKENING AS
ANOTHER MID-LATITUDE SHORTWAVE TROUGH DIGS IN FROM THE NORTH.
INCREASING VWS WILL GRADUALLY WEAKEN THE CYCLONE AS IT GAINS
LATITUDE. MODEL GUIDANCE GENERALLY OVERALL AGREES WITH A POLEWARD
TURN AT THIS TIME FRAME BUT AT VARYING EXTENTS AND SPEEDS. DUE TO
THIS, THE FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL
CONSENSUS WITH LOW CONFIDENCE.//
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