Tropical Storm ONE Advisory Mon Jul 20

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01C (HALOLA)
WARNING NR 40//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
  TROPICAL STORM (TS) 01C (HALOLA), LOCATED APPROXIMATELY 462 NM
EAST-SOUTHEAST OF IWO TO, HAS TRACKED WEST-NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO A WELL-DEFINED
CENTER, THEREFORE, THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION
AND RECENT TRACK MOTION. THE 192123Z SSMIS WIND PRODUCT SHOWS AN
EXPANDING CORE OF STRONG WINDS (30 TO 35 KNOTS). RECENT TOTAL
PRECIPITABLE WATER IMAGERY ALSO REVEALS A MORE SYMMETRIC, DEEP
MOISTURE SIGNATURE, WHICH IS SUPPORTING THE REVIVED CONVECTIVE
ORGANIZATION. THE CURRENT INTENSITY IS NOW ASSESSED AT 35 KNOTS
BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM 30 TO 35 KNOTS AS
WELL AS THE SSMIS WIND PRODUCT. ANIMATED WATER VAPOR IMAGERY SHOWS
IMPROVED POLEWARD OUTFLOW AS WELL AS ENHANCED EQUATORWARD OUTFLOW
OVER THE SOUTHEAST QUADRANT ASSOCIATED WITH A DEEP UPPER-LEVEL
TROUGH POSITIONED TO THE EAST. TS 01C IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF THE DEEP-LAYERED STR.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. THE SYSTEM HAS BEEN UPGRADED
TO TROPICAL STORM STRENGTH.
   B. TS HALOLA WILL CONTINUE TRACKING ON A WEST-NORTHWESTWARD
TRAJECTORY UNDER THE STEERING INFLUENCE OF THE DOMINANT STR THROUGH
TAU 72. THE SYSTEM IS FORECAST TO INTENSIFY SLOWLY OVER THE NEXT 12
TO 24 HOURS THEN AFTER TAU 24, TS 01C SHOULD BEGIN TO INTENSIFY AT A
FASTER RATE, REACHING A PEAK INTENSITY OF 75 KNOTS BY TAU 72 DUE
TO IMPROVED POLEWARD OUTFLOW. DYNAMIC MODEL GUIDANCE IS IN TIGHT
AGREEMENT THROUGH TAU 72 WITH A 95 NM SPREAD IN SOLUTIONS AT TAU 72.
   C. IN THE EXTENDED TAUS, EXPECT A MORE NORTHWESTWARD TO NORTHWARD
TRACK AS THE SYSTEM APPROACHES THE WESTERN PERIPHERY OF THE STR.
DYNAMIC MODEL GUIDANCE DIVERGES AFTER TAU 72 DUE TO THE INCREASING
UNCERTAINTY IN THE TIMING AND SPEED OF THE RE-CURVE. TS HALOLA
SHOULD WEAKEN SLIGHTLY DUE TO INCREASING VERTICAL WIND SHEAR AND
SLIGHTLY COOLER SST NEAR 26C. OVERALL CONFIDENCE IN THE JTWC
FORECAST TRACK IS LOW DUE PRIMARILY TO THE UNCERTAINTY IN THE RE-
CURVE PHASE NEAR JAPAN. THE SYSTEM IS NOT EXPECTED TO UNDERGO EXTRA-
TROPICAL TRANSITION SOUTH OF JAPAN DUE TO THE WEAK BAROCLINICITY AND
WEAK MIDLATITUDE WESTERLIES.//
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