Tropical Storm FENGSHEN Advisory vie, 15-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN)
WARNING NR 012//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 141 NM
EAST-SOUTHEAST OF ALAMAGAN, HAS TRACKED WESTWARD AT 15 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
INDICATES THAT DEEP CONVECTION HAS RE-BUILT OVER THE LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH IMPROVED DEEP CONVECTIVE BANDING. A
140508Z SSMI 37GHZ COMPOSITE IMAGE DEPICTS A CYAN RING SURROUNDING A
MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD
CONFIDENCE AND ALSO MAY SIGNAL A PERIOD OF MORE SIGNIFICANT
INTENSIFICATION. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED
ON A RECENT ASCAT IMAGE SHOWING 50-55 KNOT WINDS OVER THE EASTERN
SEMICIRCLE AS WELL AS DVORAK CURRENT INTENSITY ESTIMATES RANGING
FROM 3.0 TO 3.5 (45-55 KNOTS). TS 26W IS LOCATED IN AN AREA OF LOW
TO MODERATE (10-15 KNOTS) VERTICAL WIND SHEAR, WARM SEA SURFACE
TEMPERATURES (28-29C) AND MODERATE WESTWARD AND EQUATORWARD
DIFFLUENCE ALOFT. TS 26W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF
A DEEP-LAYERED SUBTROPICAL STEERING RIDGE SITUATED TO THE NORTH.
3. FORECAST REASONING.
   A.  THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 26W IS FORECAST TO GRADUALLY RECURVE AROUND THE WESTERN
PERIPHERY OF THE BROAD STR THROUGH TAU 72. LOW VERTICAL WIND SHEAR,
PASSAGE OVER WARM WATER AND IMPROVING POLEWARD OUTFLOW WILL LIKELY
FUEL STEADY INTENSIFICATION THROUGH TAU 48 WITH A PEAK INTENSITY OF
80 KNOTS EXPECTED AT TAU 48. AFTER TAU 48, A WEAKENING TREND WILL
BEGIN AS THE SYSTEM ENCOUNTERS INCREASING WESTERLY VERTICAL WIND
SHEAR. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THIS
OVERALL SCENARIO THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THE
INITIAL PORTION OF THE TRACK FORECAST.
   C. IN THE EXTENDED FORECAST PERIOD, TS 26W IS EXPECTED TO WEAKEN
QUICKLY UNDER STRONG WESTERLY VERTICAL WIND SHEAR. THE PRIMARY
STEERING INFLUENCE WILL SHIFT TO A LOW-LEVEL HIGH THAT IS FORECAST
TO BUILD TO THE NORTH AFTER TAU 72, STEERING TS 26W BACK TO THE
WEST. NUMERICAL MODELS AGREE WITH THIS OVERALL FORECAST SCENARIO,
BUT VARY IN THEIR DEPICTIONS OF THE RATE OF WEAKENING AND EXACT
TRACK DURING THE EXTENDED PERIOD. THE CURRENT TRACK FORECAST LIES
NEAR THE MULTI-MODEL CONSENSUS AND THE PREVIOUS JTWC TRACK FORECAST,
WITH LOW CONFIDENCE IN THE EXTENDED PERIOD BASED ON THE NOTED MODEL
SPREAD.//
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