Tropical Storm DANAS Advisory 03.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE)
WARNING NR 1//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION 23W (TWENTYTHREE), LOCATED APPROXIMATELY 239
NM EAST-NORTHEAST OF ANDERSEN AFB, GUAM HAS TRACKED WESTWARD AT 05
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY REVEALS DEEP CENTRALIZED CONVECTION HAS BEEN PERSISTENT OVER
THE PAST SIX TO TWELVE HOURS, WITH A BAND OF ORGANIZING DEEP
CONVECTION ALONG THE NORTHERN PERIPHERY. THE OVERALL ORGANIZATION
HAS BEEN SLOWLY IMPROVING OVER THE PAST 24 HOURS, AND A RECENT
031100Z ASCAT PASS REVEALED A SYMMETRIC LOW LEVEL CIRCULATION CENTER
(LLCC). THE STRONGEST WINDS REMAIN ON THE NORTHERN PERIPHERY AS MID-
LATITUDE EASTERLIES HAVE BEEN ENHANCING THE GRADIENT, LEADING TO A
SMALL SWATH OF 25 TO 30 KNOT WINDS. THE WINDS ALONG THE SOUTHERN
HALF OF THE SYSTEM REMAIN WEAK WITH THE ASCAT PASS INDICATING SPEEDS
BETWEEN 05 TO 15 KNOTS. UPPER LEVEL ANALYSIS INDICATES A TUTT CELL
TO THE EAST OF THE SYSTEM HAS BEEN ENHANCING THE EASTERN OUTFLOW
CHANNEL, WITH TD 23W LOCATED ON THE EASTERN EXTENT OF A SUBTROPICAL
RIDGE (STR) LOCATED TO THE EAST OF THE PHILIPPINES CREATING MODERATE
VERTICAL WIND SHEAR (VWS) 10 TO 15 KNOTS OVER THE LLCC. TD 23W IS
TRACKING ALONG THE SOUTHERN PERIPHERY OF A SECOND STR LOCATED TO THE
NORTH OF THE SYSTEM.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
   B. TD 23W IS EXPECTED TO REMAIN ON A WESTWARD TRACK OVER THE NEXT
12 TO 24 HOURS. A MID-LATITUDE TROUGH OVER THE KOREAN PENINSULA AND
SOUTHERN JAPAN WILL START TO FILL AND LIFT TO THE NORTHEAST,
ALLOWING THE STR TO THE NORTH OF TD 23W TO RE-ORIENT. AS THE STR RE-
ORIENTS, TD 23W WILL START TRACKING ON A MORE WEST-NORTHWESTWARD
HEADING THROUGH TAU 72. FAVORABLE SEA SURFACE TEMPERATURES (28 TO 29
CELSIUS) ALONG THE FORECAST TRACK, WITH IMPROVING UPPER LEVEL
SUPPORT WILL ALLOW TD 23W TO STEADILY INTENSIFY THROUGH TAU 72.
   C. AFTER TAU 72, TD 23W WILL REMAIN ALONG THE SOUTHWESTERN
PERIPHERY OF THE STR, TRACKING TOWARDS OKINAWA. THE CURRENT FORECAST
TRACK HAS THE SYSTEM PASSING OVER OKINAWA AROUND TAU 108.
INTENSIFICATION IS EXPECTED TO PERSIST THROUGH TAU 120, BRINGING THE
SYSTEM TO A MAXIMUM INTENSITY OF 75 KNOTS BASED ON THE FAVORABLE SST
VALUES, LOW VWS AND GOOD UPPER LEVEL SUPPORT. BETWEEN TAU 96 AND 120
MODEL GUIDANCE INDICATES A MID-LATITUDE TROUGH WILL PASS TO THE
NORTH OF THE STR, CAUSING A SHIFT IN THE STR TO THE EAST CREATING A
SLIGHT WEAKNESS ON THE WESTERN PERIPHERY OF THE STR. THIS WEAKNESS
WILL ALLOW TD 23W TO TURN NORTHWARD AFTER CROSSING OKINAWA. MODEL
GUIDANCE SHOWS A FAIRLY TIGHT GROUPING THROUGH TAU 96, WITH ALL
MODELS SUGGESTING THE TURN NORTHWARD BY TAU 120, BUT THERE IS A
SLIGHT VARIATION IN THE SHARPNESS OF THE CURVE. BASED ON THE WEAKLY
DEFINED ORGANIZATION OF THE SYSTEM, AND BEING THE FIRST FORECAST,
THERE IS LOW CONFIDENCE IN THE FORECAST TRACK.//
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