Tropical Storm DOKSURI Advisory jue, 28-06

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 07W (DOKSURI)
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 07W (DOKSURI), LOCATED APPROXIMATELY
345 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-
NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A FULLY-EXPOSED LOW
LEVEL-CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION SHEARED
APPROXIMATELY 170 NM TO THE WEST DUE TO STRONG (20-25 KNOT)
NORTHEASTERLY VERTICAL WIND SHEAR (VWS). A 272340Z SSMIS 37 GHZ
IMAGE INDICATES A VERY WEAK LOW-LEVEL STRUCTURE WITH VERY SHALLOW,
FRAGMENTED CONVECTION ALONG THE SOUTHERN PORTION OF THE EXPOSED
LLCC. THE INITIAL POSITION IS BASED ON THE EXPOSED LLCC IN MSI
IMAGERY WITH HIGH CONFIDENCE. THE INITIAL INTENSITY WAS LOWERED TO
TD STRENGTH DUE TO THE EXPOSED, BUT WELL-DEFINED, LLCC. THE LLCC
HISTORY OF THIS SYSTEM HAS BEEN ONE OF MULTIPLE MESO-VORTICES
CONTAINED WITHIN ONE LARGER, YET ELONGATED, CIRCULATION. THERE
REMAINS SOME CONCERN ABOUT A POSSIBLE RE-FORMATION OF ANOTHER LLCC
UNDER THE DEEPEST CONVECTION, CURRENTLY OVER NORTHERN LUZON, AS IT
EMERGES OFF THE NORTHWESTERN PHILIPPINE COAST. HOWEVER, CLOUD TOPS
HAVE BEEN WARMING OVER THE PAST THREE HOURS AND THIS FLARE OF DEEP
CONVECTION MAY HAVE BEEN TOPOGRAPHICALLY INDUCED. UPPER-LEVEL
ANALYSIS INDICATES THAT VWS HAS INCREASED TO STRONG LEVELS OVER THE
PAST 06-12 HOURS AS MID- TO HIGH-LEVEL SUBTROPICAL RIDGING BUILDS
IN NORTH OF THE SYSTEM. ADDITIONALLY, PRESSURE FROM A WESTWARD
MOVING TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL, EVIDENT IN
ANIMATED WATER VAPOR IMAGERY, CONTINUES TO IMPINGE ON TD 07W. THE
EQUATORWARD OUTFLOW REMAINS FAIR BUT POLEWARD OUTFLOW IS NOW
COMPLETELY CUT OFF, AND THE MID-LATITUDE TROUGH PROPAGATING
NORTHEAST OF THE SYSTEM IS TOO SHALLOW AND TOO FAR POLEWARD FOR TD
07W TO TAP INTO. SEA SURFACE TEMPERATURES (SSTS) AND OCEAN HEAT
CONTENT (OHC) REMAIN EXTREMELY FAVORABLE AS THE SYSTEM IS CURRENTLY
TRACKING OVER THE WESTERN PACIFIC WARM POOL.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING.
   B. TD 07W IS CURRENTLY STEERING ALONG THE SOUTHERN PERIPHERY OF
A LOW- TO MID-LEVEL EAST-WEST ORIENTATED SUBTROPICAL RIDGE (STR),
WHICH EXTENDS WESTWARD OVER TAIWAN AND EASTERN CHINA. THROUGHOUT
THE FORECAST, TD 07W SHOULD CONTINUE TO TRACK GENERALLY WEST-
NORTHWESTWARD UNDER THE INFLUENCE OF THE STR AND MAKE LANDFALL NEAR
HONG KONG. TD 07W IS EXPECTED TO MARGINALLY INTENSIFY TO 35 KNOTS
BY TAU 24 AS VWS MAY TEMPORARILY SLACKEN TO MODERATE LEVELS DUE TO
A MORE FAVORABLE POSITION UNDERNEATH THE STEERING STR. TD 07W
SHOULD DISSIPATE OVERLAND JUST NORTH OF HONG KONG BY TAU 72 AS A
WEAK TD. NUMERICAL MODEL GUIDANCE REMAINS CLUSTERED WITHIN A TIGHT
ENVELOPE AND THEREFORE THE OFFICIAL JTWC TRACK FORECAST IS BASED ON
THE MODEL CONSENSUS AND SLIGHTLY DEVIATES FROM THE PREVIOUS
FORECAST IN REGARDS TO THE LANDFALL POSITION NEAR HONG KONG. EVEN
THOUGH THERE IS GOOD MODEL AGREEMENT IN REGARDS TO THE TRACK, THE
COMPLEX HISTORY OF THE LLCC STRUCTURE AND STRONG VWS DEGRADE THE
TRACK FORECAST CONFIDENCE TO LOW DUE TO THE POSSIBILITY THAT TD 07W
MAY NOT SURVIVE THE CURRENT HOSTILE ENVIRONMENT.//
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