WDPN33 PGTW 280300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W WARNING NR 02// 
RMKS/
1. FOR METEOROLOGISTS. 
2. 12 HOUR SUMMARY AND ANALYSIS. 
A. TROPICAL DEPRESSION (TD) 19W (NINETEEN), LOCATED APPROXIMATELY 390 NM
EAST OF YAP, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI), RECENT MICROWAVE IMAGERY
(272023Z SSMIS, 272311Z AMSU) AND A 272001Z QUIKSCAT IMAGE INDICATE THAT
THE SYSTEM HAS CONSOLIDATED OVER THE PAST 12 HOURS WITH IMPROVED CENTRAL
CONVECTION AND TD-LEVEL SURFACE WINDS NEAR THE CORE. THERE IS GOOD
CONFIDENCE IN THE CURRENT POSITION BASED ON RECENT MSI SHOWING DEFINED
LOW-LEVEL CLOUD LINES WRAPPING INTO SYSTEM WITH WEAK CONVECTIVE BANDING
OVER THE WESTERN SEMI-CIRCLE. THE CURRENT INTENSITY IS BASED ON THE LOWER
END OF DVORAK ESTIMATES RANGING FROM 30 (KNES) TO 35 KNOTS (PGTW)
SUPPORTED BY THE AFOREMENTIONED QUIKSCAT IMAGE. TD 19W IS LOCATED WITHIN
A FAVORABLE ENVIRONMENT WITH WEAK VERTICAL WIND SHEAR, GOOD OUTFLOW WITH
A DEVELOPING ANTICYCLONE OVER THE LLCC AND WARM SST/HIGH OCEAN HEAT
CONTENT VALUES. 
3. FORECAST REASONING 
A. THIS PROGNOSTIC REASONING BULLETIN ESTABLISHES THE FORECAST REASONING
FOR TD 19W. 
B. IN GENERAL, THIS IS A VERY COMPLEX FORECAST BASED ON THE LACK OF
RELIABLE MODEL GUIDANCE (NOGAPS, GFS AND WBAR), THE POOR INITIALIZATION
OF THE MODELS ON BOTH TD 18W AND 19W AND THE CLOSE PROXIMITY OF THE TWO
SYSTEMS (TD 19W IS CURRENTLY LOCATED ABOUT 445NM WEST OF TD 18W). THE
MODELS ARE CURRENTLY FAVORING THE DEVELOPMENT OF TD 19W AS THE STRONGER
SYSTEM AND ARE IN FAIR AGREEMENT ON THE WESTWARD TO WEST-NORTHWESTWARD
TRACK UNDER THE STEERING INFLUENCE OF THE LOW- TO MID-LEVEL SUBTROPICAL
RIDGE (STR) POSITIONED TO THE NORTH. THE EXTENDED RANGE ECMWF FIELDS
SUPPORT THE TAU 72 FORECAST POSITION WELL.
C. IN THE EXTENDED TAUS, MODEL GUIDANCE IS LIMITED TO NOGAPS AND THE
ECMWF MODEL FIELDS, WHICH BOTH SUPPORT THE NORTHWESTWARD TURN ALONG THE
SOUTHWESTERN PERIPHERY OF THE STR. THE SYSTEM IS FORECAST TO INTENSIFY TO
A PEAK OF 75 KNOTS UNDER FAVORABLE ENVIRONMENTAL CONDITIONS. STIPS
INTENSITY GUIDANCE SUPPORTS THE INTENSITY FORECAST. IT IS WORTH
RE-EMPHASIZING THE POORLY-INITIALIZED MODELS AND PROBLEMS RESOLVING BOTH
TD 18W AND 19W AS SEPARATE SYSTEMS AND DETERMINING WHICH SYSTEM WILL
DOMINATE. AN ALTERNATE SCENARIO WILL BE PROPOSED CONCERNING TD 18W WHICH
RELATES TO TD 19W (SEE WDPN32 PGTW 280300) FOR FURTHER DETAILS.//
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