
WDPN31 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 30W (THIRTY)
WARNING NR 001//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 30W (THIRTY), LOCATED APPROXIMATELY 276 NM
SOUTHEAST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
FLARING CENTRAL CONVECTION EMANATING FROM THE LOW LEVEL CIRCULATION
CENTER (LLCC) WITH WEAK AND FRAGMENTED BANDING ON THE NORTHERN
PERIPHERY. THE INITIAL INTENSITY ASSESSMENT OF 25 KNOTS IS BASED ON
A 210032Z METOP-A ASCAT IMAGE AND THE LOWER ENVELOPE OF DVORAK
ESTIMATES RANGING FROM T1.5 TO T2.0 (25 TO 30 KNOTS). ENVIRONMENTAL
CONDITIONS ARE FAVORABLE WITH SSTS NEAR 30 CELSIUS, LOW VERTICAL
WIND SHEAR, AND MODERATE DIFFLUENCE ALOFT. CURRENTLY TD 30W IS
TRACKING NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP-
LAYERED SUBTROPICAL RIDGE.
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY ON THIS SYSTEM.
B. TD 30W WILL CONTINUE TO TRACK NORTHWESTWARD ALONG THE STEERING
RIDGE FOR THE REMAINDER OF THE FORECAST. GRADUAL INTENSIFICATION IS
EXPECTED OVER THE NEXT FEW DAYS AS CONDITIONS REMAIN FAVORABLE AND
THE SYSTEM CONSOLIDATES. THE PEAK INTENSITY IS EXPECTED TO REACH 75
KNOTS BY TAU 72.
C. IN THE EXTENDED FORECAST TD 30W WILL MAKE LANDFALL OVER LUZON
AROUND TAU 120 AT OR NEAR ITS PEAK INTENSITY OF 75 KNOTS. DYNAMIC
MODEL GUIDANCE SHOWS GOOD AGREEMENT IN A TRACK NORTHWESTWARD OVER
THE PHILIPPINES. HOWEVER, MESOSCALE MODELS COAMPS-TC AND HWRF SHOW A
TRACK SLIGHTLY POLEWARD FROM THE GROUPING POSSIBLY DUE TO WEAKENING
IN THE STEERING RIDGE. OVERALL THERE IS HIGH CONFIDENCE IN FORECAST
TRACK. //
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