WDPN31 PGTW 090300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (LIONROCK) WARNING 
NR 008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.7N 109.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 217 NM EAST-SOUTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: XX FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATED LOW-LEVEL CIRCULATION (LLC) WITH CONVECTIVE BANDING
WEST OF THE LLC. A 090041Z GMI 89GHZ IMAGE INDICATES MOST OF THE
CONVECTIVE STRUCTURE MOVED TO THE NORTHWEST OVER THE GULF OF TONKIN
WHILE THE LLC REMAINS POSITIONED OVER NORTHWEST HAINAN ISLAND.
SURFACE OBSERVATIONS ON HAINAN ISLAND ARE VERY WEAK WITH A MINIMUM
SLP OF 994MB NEAR AT HAIKOU, HAINAN. OVERALL, THERE IS HIGH
CONFIDENCE IN THE INITIAL POSITION BASED ON THE MSI AND RADAR
IMAGERY. THERE IS MODERATE CONFIDENCE IN THE INITIAL INTENSITY
BASED ON RJTD AND RCTP DVORAK INTENSITY ESTIMATES. ENVIRONMENTAL
CONDITIONS REMAIN FAVORABLE WITH NEAR RADIAL OUTFLOW, AND LOW TO
MODERATE VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: TS 22W IS TRACKING ALONG THE SOUTHWEST
PERIPHERY OF A LOW TO MID-LEVEL SUBTROPICAL RIDGE POSITIONED TO
THE NORTH AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: OVER LAND
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: INTERACTION WITH LAND

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 22W CONTINUES TO TRACK SLOWLY
WEST-NORTHWESTWARD OVER HAINAN, EXITING WITHIN THE NEXT FEW HOURS
INTO THE GULF OF TONKIN. OVER THE NEXT 12 HOURS, LIONROCK WILL MOVE
BACK OVER THE WARM WATERS AND THE UPPER LEVEL OUTFLOW WILL ENHANCE
THE INTENSITY GRADUALLY TO 40 KNOTS. TS 22W IS EXPECTED TO CONTINUE
MOVING ON A WEST-NORTHWESTWARD TRACK AND THEN TURN SLIGHTLY MORE TO
THE WEST-SOUTHWEST JUST BEFORE MAKING LANDFALL JUST SOUTHEAST OF
HANOI, VIETNAM. ONCE THE SYSTEM MAKES LANDFALL IT WILL RAPIDLY
DECREASE INTENSITY AS IT INTERACTS WITH THE RUGGED TERRAIN AND
BEGIN THE DISSIPATION PROCESS STARTING AT TAU 36 AND DISSIPATE NEAR
THE FAR WESTERN BORDER OF VIETNAM AND LAOS BY TAU 48.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT ON
THE FORECAST TO MAKE LANDFALL JUST SOUTH OF HANOI, VIETNAM, WITH A
VERY SMALL CROSS-TRACK SPREAD OF ONLY 61NM THROUGH TAU 24. THE JTWC
FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS,
BUT SLIGHTLY EQUATORWARD TOWARD THE BULK OF THE MODEL SOLUTIONS,
WHICH ARE ON THE SOUTHERN EDGE OF THE AIDS ENVELOPE. UKMET, GFS,
AND THE GFS ENSEMBLE REMAIN THE THREE MOST SIGNIFICANT POLEWARD
OUTLIERS FROM CONSENSUS. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
NNNN