Tropical Storm NOCK-TEN Advisory Qui, 22-12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 30W (NOCK-TEN) WARNING
NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 30W (NOCK-TEN), LOCATED APPROXIMATELY 13 NM
WEST-SOUTHWEST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY INDICATES DEEP CONVECTION BUILDING OVER THE LOW-LEVEL
CIRCULATION CENTER (LLCC). A 220711Z GPM COMPOSITE IMAGE SHOWS
MULTIPLE CONVECTIVE BANDS WRAPPING INTO THE LLCC WITH A DEFINED
CENTER POSITIONED JUST TO THE WEST OF YAP, WHICH SUPPORTS THE
CURRENT POSITION WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS
ASSESSED AT 40 KNOTS BASED ON AN AVERAGE OF DVORAK INTENSITY
ESTIMATES RANGING FROM T2.5 (35 KNOTS) TO T3.0 (45 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. 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 TRACK WEST-NORTHWESTWARD TO WESTWARD ALONG THE
SOUTHERN PERIPHERY OF THE STEERING STR THROUGHOUT THE FORECAST
PERIOD. 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 48 HOURS), DUE TO HIGH
OCEAN HEAT CONTENT, PRIOR TO REACHING THE EASTERN COAST OF THE
PHILIPPINES. WITH THE EXCEPTION OF GFDN, DYNAMIC MODEL VORTEX
TRACKERS ARE IN TIGHT AGREEMENT WITH A 55-NM SPREAD IN SOLUTIONS AT
TAU 72. GFDN, WHICH INDICATES SIGNIFICANTLY LOWER INTENSITY VALUES,
IS ERRONEOUSLY DRIVING THE SYSTEM SOUTHWESTWARD WITHIN THE LOW-LEVEL
FLOW AFTER TAU 48. OVERALL, THERE IS HIGH CONFIDENCE DURING THIS
PORTION OF THE FORECAST.
   C. AFTER TAU 72, 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 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 BUT SHOULD MAINTAIN
MINIMAL TYPHOON STRENGTH AS IT RE-EMERGES OVER WATER NEAR TAU 96.
ADDITIONAL WEAKENING IS EXPECTED AS THE SYSTEM ENCOUNTERS COOLER,
DRIER AIR AND INCREASING VWS ASSOCIATED WITH THE NORTHEAST SURGE.
DYNAMIC MODEL VORTEX TRACKERS DIVERGE SLIGHTLY IN THE EXTENDED
PERIOD WITH A SPREAD IN SOLUTIONS OF 150-NM AT TAU 120. DUE TO THE
IMPROVED AGREEMENT IN THE DYNAMIC GUIDANCE, THERE IS NOW HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK.//
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