WDPN31 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W (HAGUPIT) WARNING NR 17// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 22W (HAGUPIT), LOCATED APPROXIMATELY 537 NM EAST- SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES A WEAKENING TREND WITH A MORE ASYMMETRIC CONVECTIVE STRUCTURE AND THE EYE HAS BEEN FILLED IN, LEAVING A SLIGHT DIMPLE OFFSET TO THE EAST OF THE SYSTEM. A 042301Z GMI AND 042242Z SSMIS IMAGES INDICATE THAT THE BULK OF THE DEEP CONVECTION IS DISPLACED OVER THE SOUTHWESTERN QUADRANT DUE TO MODERATE (20-25 KNOT) EASTERLY VERTICAL WIND SHEAR (VWS). THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION AND RECENT TRACK MOTION DUE TO THE DIMPLE FEATURE AND AFOREMENTIONED MICROWAVE IMAGERY. AS A RESULT OF THE RECENT WEAKENING TREND, DVORAK INTENSITY ESTIMATES HAVE DECREASED TO T6.0 WITH CURRENT INTENSITY ESTIMATES AT T7.0, AS SUCH, THE INITIAL INTENSITY HAS BEEN DECREASED SIGNIFICANTLY TO 125 KNOTS WITH POTENTIAL FOR FURTHER WEAKENING AS THERE IS INCREASED PRESSURE ON THE SYSTEM DUE TO THE STRONG SUBTROPICAL RIDGE (STR) TO THE NORTHEAST AND INCREASED VWS. TY HAGUPIT IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE (STR). 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY HAGUPIT WILL MAINTAIN A GENERALLY WEST TO WEST- NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 48. 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, ALLOWING THE SYSTEM TO TRACK SLIGHTLY POLEWARD. BASED ON THE INCREASE IN THE MODERATE VWS, TY 22W IS FORECAST TO WEAKEN THROUGH TAU 36 AND THEN CONTINUE TO WEAKEN AS TY HAGUPIT BEGINS LAND INTERACTION AT TAU 48 NORTH OF SAMAR. MODEL GUIDANCE CONTINUES TO COME INTO MUCH BETTER AGREEMENT WITH THE TRACK OF THE SYSTEM THROUGH TAU 72. 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 CENTRAL LUZON TO JUST NORTH OF PANAY, 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 SHEAR. THERE IS THE POSSIBILITY THAT THE SYSTEM WILL STILL MAINTAIN TYPHOON INTENSITY UPON REACHING THE SOUTH CHINA SEA BY TAU 120. HOWEVER INCREASED VWS DUE TO THE NORTHEASTERLY 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 ALTHOUGH THE DYNAMIC MODELS ARE IN BETTER AGREEMENT.// NNNN
Posted on: Fri, 05 Dec 2014 07:40:45 +0000
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