Tropical Storm HAGUPIT Advisory Thu Dec 04

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 22W (HAGUPIT) WARNING NR
16//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 22W (HAGUPIT), LOCATED APPROXIMATELY 582 NM
EAST- SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED
SATELLITE IMAGERY INDICATES A SLIGHT WEAKENING TREND WITH A MORE
ASYMMETRIC CONVECTIVE STRUCTURE. HOWEVER, THE SYSTEM HAS MAINTAINED
A 10-NM ROUND EYE AND CORE CONVECTION. A 041748Z AMSU-B AND 041721Z
TMI IMAGE INDICATES THAT THE BULK OF THE DEEP CONVECTION IS
DISPLACED OVER THE SOUTHWESTERN QUADRANT DUE TO MODERATE (20-25
KNOT) EASTERLY VERTICAL WIND SHEAR (VWS). BASED ON THE SMALL EYE,
THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK
MOTION. AS A RESULT OF THE RECENT WEAKENING TREND, DVORAK INTENSITY
ESTIMATES HAVE DECREASED TO T6.5 WITH CURRENT INTENSITY ESTIMATES
REMAIN AT T7.5, AS SUCH, THE INITIAL INTENSITY HAS BEEN DECREASED
SLIGHTLY TO 145 KNOTS WITH POTENTIAL FOR FURTHER WEAKENING DUE TO
THE INCREASED VWS. OF NOTE, THE 35 WIND RADII HAS INCREASED BASED ON
THE MOST RECENT MICROWAVE IMAGERY AND ASCAT PASS. STY HAGUPIT IS
CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. STY HAGUPIT WILL MAINTAIN A GENERALLY WEST TO WEST-
NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR
THROUGH TAU 48. MODEL GUIDANCE CONTINUES TO COME INTO BETTER
AGREEMENT WITH THE STRENGTH OF THE STR TO THE NORTHWEST OF THE
SYSTEM, CURRENTLY OVER SOUTHEAST ASIA. BETWEEN TAUS 24-48, THE
SYSTEM IS EXPECTED TO SLOW SLIGHTLY AS AN APPROACHING, WEAK
SHORTWAVE TROUGH PASSING TO THE NORTH WILL PRODUCE A WEAKNESS IN THE
STEERING RIDGE. BASED ON THE INCREASE IN THE MODERATE VWS, STY 22W
IS FORECAST TO WEAKEN SLOWLY THROUGH TAU 36 THEN STEADY BEFORE STY
HAGUPIT BEGINS LAND INTERACTION AT TAU 48 IVO SAMAR. PAST TAU 48,
EXPECT THE SYSTEM TO SHIFT SLIGHTLY TO THE NORTHWEST INTO A SMALL
WEAKNESS IN THE STR AND CONTINUE TO WEAKEN AS THE SYSTEM TRACKS
ALONG THE BICOL PENINSULA.
   C. IN THE EXTENDED FORECAST, THE BULK OF THE DYNAMIC MODELS HAVE
COME INTO CLOSER AGREEMENT ON A GENERALLY WESTWARD TRACK OVER THE
PHILIPPINES. WHILE THERE IS STILL SOME DISAGREEMENT IN THE EXACT
PLACEMENT OF THE SYSTEM, RANGING BETWEEN THE CAGAYAN VALLEY IN
NORTHERN LUZON TO JUST NORTH OF CEBU, THERE IS BETTER CONFIDENCE IN
THE JTWC FORECAST TRACK, WHICH LAYS CLOSE TO THE MULTI-MODEL
CONSENSUS. AS EXPECTED, THE SYSTEM WILL CONTINUE TO GRADUALLY WEAKEN
DUE TO LAND INTERACTION AS WELL AS INCREASED SHEER. THERE IS THE
POSSIBILITY THAT THE SYSTEM WILL STILL MAINTAIN A RELATIVELY HIGH
INTENSITY UPON REACHING THE SOUTH CHINA SEA, HOWEVER INCREASED VWS
DUE TO THE NORTH EASTERLY SURGE EVENT MAY PRECLUDE ANY FURTHER
DEVELOPMENT. OVERALL, THERE IS STILL LOW CONFIDENCE IN THE EXTENDED
FORECAST TRACK DUE TO THE WIDE SPREAD OF THE MODELS IN THE
UNCERTAINTY OF THE EXACT TRACK WESTWARD WITH THE DYNAMIC MODELS IN
FAIR AGREEMENT.//
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