Tropical Storm MAWAR Advisory Fri Jun 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (FOUR) WARNING
NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 04W, LOCATED APPROXIMATELY 290 NM EAST
OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
INDICATES A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
IMPROVED CONVECTIVE BANDING WRAPPING INTO WELL-DEFINED LLCC.
CONSEQUENTLY, THE 01/00Z DVORAK INTENSITY ESTIMATES HAVE INCREASED
TO T2.0 (30 KNOTS) SUPPORTING THE CURRENT INTENSITY ASSESSMENT OF 30
KNOTS. A 010005Z SSMIS IMAGE DEPICTS IMPROVED DEEP CONVECTIVE
BANDING SURROUNDING THE CENTER. UPPER-LEVEL ANALYSIS INDICATES A
FAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK VERTICAL WIND SHEAR
(VWS) AND EXCELLENT, NEARLY RADIAL OUTFLOW ENHANCED BY A TUTT CELL
NEAR GUAM AND AN ANTICYCLONE IN THE SOUTHERN HEMISPHERE.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 04W IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY OF
THE LOW-LEVEL SUBTROPICAL RIDGE, WHICH EXTENDS WESTWARD TO TAIWAN
FROM A STRONG PERSISTENT HIGH NEAR 30N 170W. THE 31/12Z 500 MB
ANALYSIS INDICATES THAT THE DOMINANT STEERING INFLUENCE IS THE
EASTERN SUBTROPICAL RIDGE (STR). THIS ANALYSIS ALSO SHOWS THAT THE
WESTERN STR HAS RETROGRADED WESTWARD (WEST OF HONG KONG) DUE TO
PREVAILING WESTERLY FLOW EXTENDING OVER THE EAST CHINA SEA AND
TAIWAN. THIS SYNOPTIC PATTERN IS FORECAST TO REMAIN STATIC THROUGH
THE FORECAST PERIOD WITH A MIDLATITUDE SHORTWAVE TROUGH FORECAST TO
DEEPEN OVER THE EAST CHINA SEA NEAR TAU 72. THEREFORE, THERE IS HIGH
CONFIDENCE IN THE SHARP RE-CURVE SCENARIO WITH A LOW PROBABILITY OF
A TRACK INTO THE SOUTH CHINA SEA. AVAILABLE MODEL GUIDANCE IS IN
TIGHT AGREEMENT WITH THE EXCEPTION OF THE INTERPOLATED UKMO TRACKER,
WHICH TRACKS MORE NORTHWARD NEAR OKINAWA. THIS NORTHWARD TRACK AFTER
TAU 72 IS AN ARTIFICE OF THE INTERPOLATOR CODE AND DOESN'T FIT WITH
THE UKMO ENSEMBLE SOLUTIONS, WHICH ARE PREDOMINANTLY EAST OF THE
UKMO TRACKER SOLUTION REFLECTING A SHARP TURN DUE TO THE WESTERLY
FLOW. THIS FORECAST IS POSITIONED CLOSE TO THE MODEL CONSENSUS
THROUGH TAU 72. TD 04W IS FORECAST TO INTENSIFY TO A PEAK INTENSITY
OF 85 KNOTS BY TAU 72.
   C. IN THE EXTENDED PERIOD, TD 04W IS EXPECTED TO ROUND THE
NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AND BEGIN TO
INTERACT WITH MIDLATITUDE WESTERLY FLOW. THEREFORE, THE SYSTEM WILL
BEGIN TO WEAKEN AND TRACK OVER COOLER SST (LESS THAN 25C) WHILE
BEGINNING EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 96. THE SYSTEM IS
EXPECTED TO COMPLETE ETT AFTER TAU 120 AS IT BECOMES EMBEDDED WITHIN
THE BAROCLINIC ZONE WELL SOUTH OF JAPAN AND ACCELERATES EASTWARD.
THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE TRACK DUE TO THE
RELATIVELY ZONAL WESTERLY JET FORECAST BY ALL THE DYNAMIC MODELS TO
REMAIN ENTRENCHED OVER (AND WELL SOUTH OF) JAPAN. ADDITIONALLY, THE
SYSTEM SHOULD TRACK EAST OF OKINAWA BUT MAY PRODUCE INCREASED WINDS
AS THE EXTREME NORTHWESTERN PERIPHERY OF THE SYSTEM INTERACTS WITH A
DEVELOPING MIDLATITUDE HIGH.//
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