Tropical Storm NOCK-TEN Advisory Cu, 23.12.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 30W (NOCK-TEN) WARNING
NR 07//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 30W (NOCK-TEN), LOCATED APPROXIMATELY 849 NM
EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-
NORTHWESTWARD AT 18 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY SHOWS A DEEPENING OF CENTRAL CONVECTION
AS THE CYCLONE CONTINUES TO STRENGTHEN. A 221627Z AMSR-2 89GHZ
MICROWAVE IMAGE SHOWS DEEP, TIGHTLY-CURVED BANDING WRAPPING INTO THE
LOW LEVEL CIRCULATION CENTER WITH INDICATIONS THAT A MICROWAVE EYE
IS STARTING TO FORM. THE MICROWAVE IMAGE SUPPORTS THE CURRENT
POSITION WITH HIGH CONFIDENCE AND ALSO SUPPORTS THE INCREASE IN
INTENSITY TO 55 KNOTS. DVORAK INTENSITY ESTIMATES HAVE ALSO
INCREASED, RANGING FROM T3.0 TO T3.5 (45-55 KNOTS). TS NOCK-TEN IS
LOCATED IN A VERY FAVORABLE ENVIRONMENT WITH LOW (5-10 KNOTS)
VERTICAL WIND SHEAR (VWS), GOOD DIVERGENT OUTFLOW, AND VERY WARM SEA
SURFACE TEMPERATURES. THE CIMSS UPPER LEVEL WIND PRODUCT AND THE
WATER VAPOR LOOP INDICATE THAT A POINT SOURCE ANTI-CYCLONE MAY ALSO
BE DEVELOPING OVER THE SYSTEM. TS 30W IS TRACKING WEST-NORTHWESTWARD
ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 30W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD OVER THE NEXT
24 HOURS BEFORE FLATTENING OUT ON A MORE WESTWARD TRAJECTORY THROUGH
TAU 72. TS NOCK-TEN WILL CONTINUE TO INTENSIFY UNDER THE VERY
FAVORABLE ENVIRONMENTAL CONDITIONS WITH THE POTENTIAL FOR A PERIOD
OF RAPID INTENSIFICATION (WITHIN THE NEXT 24 TO 48 HOURS), DUE TO
HIGH OCEAN HEAT CONTENT AND THE DEVELOPING POINT SOURCE, PRIOR TO
REACHING THE EASTERN COAST OF THE PHILIPPINES NEAR TAU 72. WITH THE
EXCEPTION OF COTC AND THE ECMWF ENSEMBLE MEAN, DYNAMIC MODEL VORTEX
TRACKERS ARE IN CLOSE AGREEMENT WITH A 90-NM SPREAD IN SOLUTIONS AT
TAU 72. OVERALL, THERE IS HIGH CONFIDENCE DURING THIS PORTION OF THE
FORECAST.
   C. IN THE EXTENDED FORECAST, TS 30W IS FORECAST TO TURN SLIGHTLY
WEST-NORTHWESTWARD AS IT APPROACHES THE WESTERN EDGE OF THE STR.
HOWEVER, THE SYSTEM IS NOT EXPECTED TO COMPLETE A RE-CURVE DUE TO
THE PRESENCE OF VIGOROUS NORTHEAST MONSOON FLOW OVER THE SOUTH CHINA
SEA. TS 30W WILL WEAKEN AS IT TRACKS ACROSS THE PHILIPPINES,
DECREASING BELOW TYPHOON STRENGTH BY TAU 120, WHERE IT WILL
ENCOUNTER COOLER, DRIER AIR AND INCREASING VWS ASSOCIATED WITH THE
NORTHEAST SURGE. THE DIVERGENCE IN DYNAMIC MODEL VORTEX TRACKERS HAS
INCREASED TO 275-NM AT TAU 120 DUE TO COMPETING FLOW AT THE SURFACE
AND UPPER LEVELS. ADDITIONALLY, THE MULTI-MODEL CONSENSUS HAS
STARTED TO SHIFT NORTH AND SOUTH OF SUBIC BAY IN RESPONSE TO CHANGES
IN THE MODEL TRACKERS. DUE TO THIS INSTABILITY IN THE MODEL
CONSENSUS, THE JTWC FORECAST IS LAID CLOSE TO THE PREVIOUS FOUR
FORECASTS, JUST SOUTH OF THE MOST RECENT CONSENSUS TRACK, WITH LOW
OVERALL CONFIDENCE.//
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