Tropical Storm PEIPAH Advisory 14.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED APPROXIMATELY
279 NM EAST OF SAIPAN, HAS TRACKED NORTHWESTWARD AT 06 KNOTS (KTS)
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY REVEALS DEEP CONVECTION TO THE SOUTH OF A PARTIALLY EXPOSED
LOW LEVEL CIRCULATION CENTER (LLCC). A 141701Z SSMI 85 GHZ MICROWAVE
IMAGE DEPICTS SHALLOW BANDING TO THE NORTH OF THE LLCC. BASED ON
THOSE IMAGES, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION. A
141127Z METOP-C ASCAT IMAGE AND A 141200Z METOP-B ASCAT IMAGE SHOWED
A BROAD REGION OF 25-30 KT WINDS WRAPPING AROUND THE SOUTHERN HALF
OF THE CIRCULATION. THE 25 KT INITIAL INTENSITY ALIGNS WITH THE
ASCAT PASSES AND A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T1.0
(25 KTS). STRONG (25-50 KT) VERTICAL WIND SHEAR (VWS) IS OFFSETTING
EXCELLENT EQUATORWARD OUTFLOW AND WARM (30-31 CELSIUS) SEA SURFACE
TEMPERATURE (SST) TO MAKE THE ENVIRONMENT UNFAVORABLE FOR
INTENSIFICATION. TD 17W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY
OF A SHALLOW, NORTHWEST-TO-SOUTHEAST ORIENTED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
   B. FOR THE DURATION OF THE FORECAST, TD 17W WILL TRACK
NORTHWESTWARD ALONG THE PERIPHERY OF THE STR. THE UNFAVORABLE
ENVIRONMENT IS EXPECTED TO KEEP INTENSITY TO 30 KTS OR LESS. THE
INTENSITY FORECAST IS JUST BELOW THE INTENSITY CONSENSUS, OFFSETTING
THE UNLIKELY HWRF PEAK OF 45 KTS AT TAU 24, BUT SLIGHTLY ABOVE THE
BULK OF THE INTENSITY GUIDANCE. DISSIPATION WILL LIKELY OCCUR
SOMETIME AFTER TAU 48, IF NOT SOONER, AS THE CURRENTLY UNDER
CONTINUED UNFAVORABLE ENVIRONMENTAL CONDITIONS. NUMERICAL MODEL
GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH TAU 24. AFTER TAU 24,
SPREAD INCREASES AS TWO MODEL SOLUTIONS DIVERGE SLIGHTLY FROM THE
OTHERS (UKMET IS SLIGHTLY MORE POLEWARD AND THE 140000Z ECMWF
ENSEMBLE MEAN IS SLIGHTLY MORE WESTWARD). THE JTWC TRACK FORECAST IS
PLACED CLOSE TO CONSENSUS, NEAR THE BULK OF THE GUIDANCE, WITH FAIR
CONFIDENCE.//
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