Tropical Storm PEIPAH Advisory 09 Απρ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (PEIPAH)
WARNING NR 24//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 05W (PEIPAH), LOCATED APPROXIMATELY 676
NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT
04 KNOTS OVER THE PAST SIX HOURS. THE 08/12Z POSITION WAS
RELOCATED ABOUT 70 NM SOUTHEAST BASED ON A 081218Z ASCAT IMAGE.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS WEAK
CONVECTIVE BANDING WRAPPING INTO THE SOUTH QUADRANT OF THE SLOWLY-
CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC). A 081843Z SSMI
IMAGE SHOWS FRAGMENTED DEEP CONVECTIVE BANDING WRAPPING INTO A
PARTIALLY-EXPOSED LLCC. A 081218Z ASCAT IMAGE DEPICTS AN ELONGATED,
BUT DEFINED CIRCULATION WITH 25 KNOT WINDS. THE INITIAL POSITION IS
BASED ON THE EIR AND IS EXTRAPOLATED FROM THE ASCAT IMAGE. THE
INITIAL INTENSITY IS ASSESSED AT 25 KNOTS BASED ON THE ASCAT IMAGERY
AND RECENT DVORAK ESTIMATES. UPPER-LEVEL ANALYSIS REVEALS A MARGINAL
ENVIRONMENT CHARACTERIZED BY MODERATE (20 KNOTS) EASTERLY VERTICAL
WIND SHEAR OFFSET BY STRONG DIFFLUENCE AND GOOD POLEWARD OUTFLOW. TD
05W IS SITUATED WITHIN A WEAK STEERING ENVIRONMENT AND IS TRACKING
SLOWLY NORTHWESTWARD TOWARD A BREAK IN THE SUBTROPICAL RIDGE.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 05W IS FORECAST TO REMAIN IN THE WEAK STEERING ENVIRONMENT
THROUGH TAU 48 BUT IS FORECAST TO TRACK SLOWLY NORTHWESTWARD TOWARD
THE WEAKNESS IN THE SUBTROPICAL RIDGE (STR). DYNAMIC GUIDANCE IS IN
FAIR AGREEMENT WITH SOLUTIONS INDICATING NORTHWESTWARD TRACKS. THE
JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL
CONSENSUS. TD 05W SHOULD SLOWLY INTENSIFY TO A PEAK OF 35 KNOTS BY
TAU 36 AS THE TRACK SPEEDS INCREASE AND AS THE SYSTEM TRACKS INTO
LOWER VERTICAL WIND SHEAR WHILE MAINTAINING ROBUST POLEWARD OUTFLOW.
   C. IN THE EXTENDED TAUS, TD 05W IS EXPECTED TO TURN WEST-
NORTHWESTWARD AND TO ACCELERATE AS THE STR RE-BUILDS NORTH OF THE
SYSTEM. 05W SHOULD WEAKEN GRADUALLY PRIOR TO TRACKING OVER THE
PHILIPPINES AND DISSIPATED BY TAU 96. DUE TO THE UNCERTAINTY IN THE
INITIAL POSITION AS WELL AS MAJOR TRACK AND TRACK SPEED DIFFERENCES
BETWEEN THE DYNAMIC MODELS, THERE IS LOW CONFIDENCE IN THE JTWC
TRACK FORECAST.//
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