WDPN32 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05E (DORA) WARNING NR 
051//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.0N 175.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 879 NM WEST OF JOHNSTON ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT DORA
CONTINUES TO DECAY, WITH SOUTHWESTERLY VERTICAL SHEAR OF AROUND 20
KT PERIODICALLY CAUSING THE LOW-LEVEL CIRCULATION CENTER (LLCC) TO
BECOME EXPOSED SOUTHWEST OF THE DEEP CONVECTION. CONVECTION IS NOW
BURSTING PERIODICALLY OVER THE COMPACT LLCC, A TYPICAL PATTERN OF
SHEARED TROPICAL CYCLONES. THE INITIAL INTENSITY IS LOWERED TO 55
KT BASED ON AGENCY DVORAK ESTIMATES. NO RECENT SCATTEROMETER OR SAR
DATA IS AVAILABLE.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   PHFO: T4.5 - 77 KTS
   CIMSS ADT: 77 KTS AT 122330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM DORA (05E) CONTINUES TO DECAY
IN THE FACE OF 20 KT SOUTHWESTERLY VERTICAL SHEAR. WEAKENING IS
EXPECTED TO CONTINUE FOR THE NEXT 36 HOURS OR SO AS THIS SHEAR
PERSISTS AHEAD OF AN UPPER-LEVEL LOW THAT HAS CUT OFF 680 NM TO THE
NORTHWEST OF DORA. THE SUBTROPICAL RIDGE TO THE NORTHEAST WILL
CONTINUE TO GUIDE DORA WEST-NORTHWESTWARD TO NORTHWESTWARD DURING
THAT TIME. AFTER 36-48 HOURS, A TURN NORTHWARD IS EXPECTED AS DORA
NEARS THE AFOREMENTIONED UPPER-LEVEL LOW AND ROUNDS THE WESTERN
FLANK OF THE SUBTROPICAL RIDGE. BY THIS POINT, DORA'S TRACK AND
INTENSITY WILL BE STRONGLY LINKED, AS A STRONGER STORM WOULD TRACK
FARTHER EAST AND REMAIN EAST OF THE UPPER-LEVEL LOW, SUCH AS IN THE
GFS MODEL. THIS WOULD BRING DORA INTO A REGION OF LOWER VERTICAL
SHEAR AS THE UPPER-LEVEL FLOW BACKS TO SOUTHERLY OR SOUTHEASTERLY,
AND THE UPSHEAR ENVIRONMENT WOULD MOISTEN, FACILITATING A PERIOD OF
REINTENSIFICATION. ON THE OTHER HAND, THERE REMAINS A CHANCE THAT
DORA DISSIPATES BEFORE THIS OPPORTUNITY TO REINTENSIFY, AS SHOWN BY
THE ECMWF MODEL. THE JTWC FORECAST CONTINUES TO LEAN TOWARDS A MORE
RIGHTWARD TRACK WITH SOME REINTENSIFICATION DURING THE 48-96 HOUR
PERIOD, AS THE ECMWF INITIALIZES DORA WEAKER THAN IT ACTUALLY IS,
LEADING TO EARLY DISSIPATION. THE TRACK AND INTENSITY FORECASTS ARE
OF LOW CONFIDENCE IN THE 72-120 HOUR PERIOD DUE TO UNCERTAINTY IN
WHETHER DORA WILL SURVIVE THAT LONG, AS WELL AS HOW QUICKLY IT WILL
BE PULLED NORTHEASTWARD ALONG A FRONTAL BOUNDARY THAT IS FORECAST
TO BE DRAPED ACROSS THE NORTHERN PACIFIC BETWEEN 30N AND 40N DURING
THAT PERIOD. THIS FORECAST IS SLOWER THAN THE PREVIOUS ONE AT 96-120 
HOURS. EXTRATROPICAL TRANSITION IS FORECAST TO BEGIN BY 120 HOURS DUE 
TO THE INTERACTION WITH THIS FRONT.

MODEL DISCUSSION: THE JTWC FORECAST TRACK IS A BIT EAST OF THE
MULTI-MODEL CONSENSUS, LEANING TOWARDS THE GFS AND GFS ENSEMBLE DUE
TO THEIR BETTER REPRESENTATION OF DORA'S INTENSITY. THE JTWC
INTENSITY FORECAST IS CLOSE TO THE MEAN OF THE GFS, HAFS, AND
COAMPS-TC SOLUTIONS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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