Tropical Storm MITAG Advisory pt., 27.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (NINETEEN)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 19W (NINETEEN), LOCATED APPROXIMATELY 906
NM SOUTHEAST OF KADENA AB, JAPAN, HAS TRACKED WESTWARD AT 21 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS THAT TD 19W CONTINUES TO CONSOLIDATE AND IMPROVE IN STRUCTURE
WITH BANDS OF DEEP CONVECTION WRAPPING IN FROM THE NORTH AND THE
SOUTH. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE AND IS
BASED ON A 270603Z 85GHZ SSMI MICROWAVE IMAGE SHOWING DEEP CONVECTION
AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC) WITH GOOD CONVECTIVE
BANDING TO THE NORTH AND SOUTH. THE INITIAL INTENSITY OF 25 KNOTS IS
BASED ON DVORAK CURRENT INTENSITY (CI) ESTIMATES OF T1.5 FROM PGTW
AND RJTD. ENVIRONMENTAL ANALYSIS SHOWS THAT TD 19W IS EXPERIENCING
FAVORABLE VERTICAL WIND SHEAR (5 TO 15 KNOTS). TD 19W HAS EXCELLENT
EQUATORWARD OUTFLOW BUT LIMITED POLEWARD OUTFLOW. SEA SURFACE
TEMPERATURES REMAIN FAVORABLE FOR DEVELOPMENT, BETWEEN 28 AND 30
DEGREES CELSIUS. TD 19W IS QUICKLY TRACKING WEST-NORTHWESTWARD WHILE
UNDER THE INFLUENCE OF A SUBTROPICAL RIDGE (STR) WHICH IS POSITIONED
TO THE NORTH.
3. FORECAST REASONING.
   A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
   B. IN THE SHORT TERM, TD 19W WILL CONTINUE TO RAPIDLY TRACK
WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE AFOREMENTIONED
STR. FORWARD TRACK SPEED HAS BEEN ABNORMALLY FAST OVER THE PAST 12
HOURS. DURING THIS PERIOD DYNAMIC MODEL GUIDANCE HAS NOT ACCURATELY
CAPTURED THE FORWARD SPEED OF THE SYSTEM. FAVORABLE VERTICAL WIND
SHEAR, UPPER LEVEL OUTFLOW, AND SEA SURFACE TEMPERATURES WILL ALLOW
TD 19W TO STAIDLY INTENSIFY. AFTER TAU 48, TD 19W WILL BEGIN TO ROUND
THE WESTERN EDGE OF THE STR AND BEGIN TO TRACK NORTH-NORTHWESTWARD.
DYNAMIC MODEL GUIDANCE INDICATES A BIFURCATION WITH NAVGEM AND JGSM
OUTLIERS TO THE EAST WITH THE REMAINING CONSENSUS MEMBERS TIGHTLY
GROUPED JUST TO THE WEST OF THE MULTI-MODEL CONSENSUS. DYNAMIC MODEL
GUIDANCE HAS A SPREAD OF 265 NM BY TAU 72 WITH ECMWF ON THE WESTERN
EDGE OF THE MODELS AND JGSM ON THE EASTERN EDGE. THE JTWC FORECAST
TRACK IS PLACED SLIGHTLY TO THE WEST OF THE MULTI-MODEL CONSENSUS.
DUE TO THE ABNORMALLY FAST TRACK SPEED AND THE SPREAD IN MODEL
GUIDANCE THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST
TRACK.
   C. BEYOND TAU 72, TD 19W WILL BEGIN TO ROUND THE WESTERN EDGE OF
THE STR AND BEGIN TO TRACK NORTH-NORTHEASTWARD. UPPER LEVER OUTFLOW
WILL CONTINUE TO IMPROVE AND ALLOW TD 19W TO REACH 90 KNOTS BY TAU
96. AN APPROACHING WEST TO EAST MOVING SHORTWAVE THROUGH WILL HELP TO
ACCELERATE TD 19W NORTHEASTWARD AFTER TAU 96. DYNAMIC MODEL GUIDANCE
REMAINS IN POOR AGREEMENT THROUGH TAU 120 WITH A SPREAD OF 480 NM.
ECMWF CONTINUES TO BE ON THE WESTERN EDGE OF THE MODELS WITH JGSM AND
NAVGEM STILL OUTLIERS TO THE EAST. THE JTWC FORECAST TRACK REMAINS
SLIGHTLY TO THE WEST OF THE MULTI-MODEL CONSENSUS. BASED ON THE WIDE
SPREAD IN MODEL GUIDANCE THERE IS LOW CONFIDENCE IN THIS PORTION OF
THE JTWC FORECAST TRACK.//
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