Tropical Storm THIRTYFIVE Advisory Wed Dec 26

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 35W (THIRTYFIVE)
WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 35W (THIRTYFIVE), LOCATED APPROXIMATELY
728 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT
06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS A PARTLY EXPOSED, WEAK, BROAD, RAGGED, AND ILL-DEFINED
LOW-LEVEL CIRCULATION (LLC) WITH POORLY-ORGANIZED FLARING DEEP
CONVECTION SHEARED TO THE NORTHWEST OF THE LLC. FRAGMENTED FORMATIVE
BANDS CAN BE SEEN SPIRALING IN FROM THE SOUTHERN FLANKS. THE INITIAL
POSITION IS PLACED WITH LOW CONFIDENCE BY EXTRAPOLATING FROM THE
FORMATIVE BANDS AND MULTIPLE SPINNERS SURROUNDING THE LLC.  THE
INITIAL INTENSITY OF 25 KNOTS IS BASED ON DVORAK ESTIMATES OF
T1.5/25KTS FROM PGTW AND RJTD. UPPER-LEVEL ANALYSIS REVEALS A
MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG (20 TO 25
KNOT) SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY GOOD POLEWARD
OUTFLOW. SSTS IN THE PHILIPPINE SEA ARE PERENNIALLY FAVORABLE AT
28-30 CELSIUS. TD 35W IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF
THE SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. AS THE STR BUILDS, TD 35W IS FORECAST TO TRACK GENERALLY ON A
MORE WEST-NORTHWESTWARD DIRECTION IN THE PHILIPPINE SEA TOWARD THE
VISAYAN ISLANDS, MAKING LANDFALL OVER SOUTHERN SAMAR JUST BEFORE TAU
48 THEN DRAG ACROSS THE ISLAND CHAIN AND, BY TAU 72, WILL BE IN THE
SULU SEA JUST NORTHEAST OF PALAWAN ISLAND. DESPITE THE GOOD OUTFLOW
AND WARM SSTS, MODERATE VWS IS EXPECTED TO PERSIST, LIMITING
INTENSIFICATION OF ONLY UP TO 35 KNOTS PRIOR TO LANDFALL. AFTERWARD,
THE ADDITION OF LAND INTERACTION WILL REDUCE THE INTENSITY DOWN TO 30
KNOTS.
   C. AFTER TAU 72, AS THE STR BUILDS, TD 35W WILL TRACK MORE
WESTWARD AND EXIT INTO THE SOUTH CHINA SEA (SCS) BEFORE TURNING MORE
WEST-SOUTHWESTWARD AFTER TAU 96. THE SYSTEM WILL REGAIN ONLY MINIMAL
TS STRENGTH, EVEN AFTER IT CLEARS LANDMASS AND VWS DECREASES, DUE TO
EXPOSURE TO A STRONG NORTHEAST WIND SURGE EVENT IN THE SCS. WITH
NAVGEM AS THE SOLE NORTHWARD OUTLIER, NUMERICAL MODEL GUIDANCE IS IN
TIGHT AGREEMENT; HOWEVER, THERE ARE SIGNIFICANT DIFFERENCES IN ALONG
TRACK SPEEDS DUE TO THE PROLONGED FORMATIVE STAGE OF THE CYCLONE AND
ITS ANTICIPATED TRACK ACROSS RUGGED ISLAND-TERRAIN. THEREFORE, THERE
IS LOW CONFIDENCE IN ALL PORTIONS OF THE JTWC FORECAST TRACK THAT IS
LAID JUST SOUTH OF THE MODEL CONSENSUS TO OFFSET NAVGEM.//
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