WDPN32 PGTW 210300 (11 am Phil Time)
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W WARNING NR 04//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. TROPICAL STORM (TS) 24W (MITAG) HAS CONTINUED DEVELOPMENT OVER
THE PAST 12 HOURS. THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS BECOME
BETTER ORGANIZED WITH CONVECTIVE BANDING WRAPPING INTO THE LLCC FROM
THE EASTERN AND NORTHERN SEMICIRCLES, AS SEEN IN A 210025Z TMI MICRO-
WAVE IMAGE. OVER THE PAST 12 HOURS THE SYSTEM HAS BEGUN TO TRACK MORE
WESTWARD AS THE MIDLATITUDE TROUGH PREVIOUSLY OVER JAPAN HAS TRAN-
SITED EASTWARD, ALLOWING THE SUBTROPICAL RIDGE TO BUILD NORTH OF TS
24W.
B. THE SYSTEM IS CURRENTLY ON THE EQUATORWARD SIDE OF THE SUB-
TROPICAL RIDGE AXIS, WHICH REMAINS CENTERED ABOUT 21N FROM THE LUZON
STRAIT EASTWARD TO THE NORTHERN MARIANA ISLANDS. TS 24W HAS TRACKED
WESTWARD OVER THE PAST 12 HOURS UNDER ITS INFLUENCE. FAVORABLE POLE-
WARD OUTFLOW IS EVIDENT IN ANIMATED WATER VAPOR IMAGERY. THE CURRENT
INTENSITY IS BASED ON SATELLITE INTENSITY ESTIMATES OF 35 (PGTW AND
KNES) KNOTS. A 210025Z TMI PASS DEPICTS A RATHER SYMMETRIC CIR-
CULATION MEASURING APPROXIMATELY 350 NM ACROSS, AND THE PRIMARY MASS
OF DEEP CONVECTION WEIGHTED TOWARD THE NORTHERN SEMICIRCLE.
3. FORECAST REASONING.
A. THE SYSTEM IS CURRENTLY TRACKING WESTWARD UNDER THE INFLUENCE
OF SUBTROPICAL RIDGE TO THE NORTH.
B. TD 24W IS EXPECTED TO REMAIN SOUTH OF THE SUBTROPICAL RIDGE
AXIS THROUGHOUT THE FORECAST PERIOD. IN FACT, RIDGING EXTENDING EAST-
WARD FROM INDOCHINA IS EXPECTED TO REMAIN STRONG THROUGH TAU 48. THIS
STEERING ORIENTATION WILL KEEP THE SYSTEM ON A PREDOMINANTLY WESTWARD
TRACK TOWARD SOUTHERN LUZON. THE SYSTEM IS EXPECTED TO INTENSIFY AS
IT REMAINS OVER HIGH SEA SURFACE TEMPERATURES AND UNDERGOES FURTHER
CONSOLIDATION. ALTHOUGH THE UPPER LEVEL ENVIRONMENT SHOULD REMAIN
RATHER FAVORABLE, MODERATE VERTICAL WIND SHEAR (EASTERLY) DUE TO
SYNOPTIC-SCALE (200 MB) RIDGING TO THE EAST OF TD 24W MAY LIMIT THE
RATE OF INTENSIFICATION (CONVECTION MAY BE DISPLACED WESTWARD FROM
THE LLCC). THE FORECAST TRACK AND INTENSITY GUIDANCE IS IN FAIR
AGREEMENT THROUGH 72 HOURS.
C. IN THE EXTENDED PERIOD, THE AVAILABLE DYNAMIC AIDS DIVERGE
SIGNIFICANTLY AFTER TAU 48. THE NOGAPS MODEL SOLUTION CARRIES THE
SYSTEM TO THE WEST AND WITH TCLAPS AND ECMWF REPRESENT THE SOUTHERN
SOLUTION, WITH THE ECMWF TRACKER BEING THE NORTHERN MOST OF THIS
SOUTHERLY GROUPING. GFS, EGRR AND THE JAPANESE GLOBAL SPECTRAL MODELS
REPRESENT THE NORTHERN GROUPING AND REFLECT A RECURVATURE SCENARIO.
THE RECURVATURE SCENARIO IS CAUSED BY THE INFLUENCE OF AN APPROACHING
MIDLATITUDE TROUGH BETWEEN TAU 48 AND 72. THIS FORECAST FAVORS THE
SOUTHERN SOLUTION, TRACKING THE SYSTEM GENERALLY WESTWARD THROUGH
TAU 48, WITH A SLOW AND MORE
NORTHERLY TRACK INTO CENTRAL LUZON NEAR
TAU 72.
BY TAU 120 THE SYSTEM IS EXPECTED TO HAVE TRACKED BACK INTO
THE SOUTH CHINA SEA WEST OF MANILA. SLOW INTENSIFICATION IS EXPECTED
THROUGH THE NEAR TERM PRIOR TO LANDFALL NEAR TAU 72. AFTER TAU 72 THE
SYSTEM IS EXPECTED TO WEAKEN DUE TO LAND INTERACTIONS, WITH SOME RE-
INTENSIFICATION ANTICIPATED ONCE THE CIRCULATION REENTERS THE SOUTH
CHINA SEA AFTER TAU 96.
FORECAST TEAM: DELTA//
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