Tropical Storm ONE Advisory Sat Jul 18

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01C (HALOLA)
WARNING NR 34//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01C (HALOLA), LOCATED APPROXIMATELY 862
NM EAST-SOUTHEAST OF IWO TO, HAS TRACKED WESTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
SHOWS DISSIPATING CONVECTION ALONG THE PERIPHERY OF THE CYCLONE WITH
A RESURGENCE OF DEEP CONVECTION NEAR THE CENTER. THE IMAGERY
CONTINUES TO SHOW BROAD TURNING WHICH LENDS TO FAIR CONFIDENCE IN
THE INITIAL POSITION. AN 180902Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS
INCREASED CURVATURE TO THE ASSOCIATED CONVECTION, BUT THE LOW LEVEL
CIRCULATION CENTER REMAINS ILL-DEFINED. THE CURRENT INTENSITY IS
HELD AT 30 KNOTS BASED ON NO SIGNIFICANT CHANGE TO THE STRUCTURE OF
THE SYSTEM. WATER VAPOR IMAGERY SHOWS THAT THE TUTT CELL REMAINS
DIRECTLY TO THE NORTH OF THE LLCC WHICH IS PRODUCING CONVERGENT FLOW
OVER THE NORTHERN SEMI-CIRCLE AND MODERATE WESTERLY VERTICAL WIND
SHEAR. TD 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.
   B. TD HALOLA WILL CONTINUE TRACKING ON A WESTWARD TO WEST-
NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE
DOMINANT STR THROUGH TAU 72. DUE TO THE WEAK NATURE OF THE SYSTEM
AND THE STRONG LOW-LEVEL STR, THE SYSTEM MAY CONTINUE TO MOVE
SLIGHTLY EQUATORWARD PRIOR TO INTENSIFYING AND GAINING LATITUDE.
OVER THE NEXT 12 TO 24 HOURS, TD 01C WILL CONTINUE TO STRUGGLE TO
INTENSIFY, POTENTIALLY EVEN WEAKENING, DUE TO THE EFFECTS OF THE
TUTT CELL. BEYOND TAU 24, THE TUTT CELL IS FORECAST TO DISSIPATE,
REDUCING THE SUBSIDENCE ALOFT AND ALLOWING THE SYSTEM TO SLOWLY
BEGIN TO INTENSIFY. IN ADDITION, TD HALOLA IS FORECAST TO GAIN A
STRONG EQUATORWARD OUTFLOW CHANNEL AND ENCOUNTER REDUCED VERTICAL
WIND SHEAR (VWS).
   C. BEYOND TAU 72, EXPECT A MORE NORTHWESTWARD TRACK AS THE SYSTEM
APPROACHES THE WESTERN PERIPHERY OF THE STR. THIS WILL ALLOW THE
SYSTEM TO GAIN A POLEWARD OUTFLOW CHANNEL DOWNSTREAM FROM THE
STEERING STR; CONTINUING THE INTENSIFICATION. BEYOND TAU 96, TD 01C
WILL BEGIN TO WEAKEN DUE TO THE COMBINED EFFECTS OF INCREASING VWS
AND COOLING SEA SURFACE TEMPERATURES. DYNAMIC MODEL GUIDANCE IS IN
VERY TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD, LEADING TO HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK. HOWEVER, HIGH UNCERTAINTY AND
LOW CONFIDENCE REMAINS IN THE INTENSITY FORECAST DUE TO THE COMPLEX
INTERACTION BETWEEN TD HALOLA AND THE TUTT CELL.//
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