WDPN31 PGTW 202100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.4N 134.1E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 761 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL DEPRESSION (TD) 22W (TWENTYTWO) REMAINS EXTREMELY BROAD
AND RELATIVELY DISORGANIZED AS IT HAS QUICKENED ITS PACE OF
WESTWARD MOVEMENT OVER THE LAST SIX HOURS. ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD CIRCULATION
DEFINED BY SPIRAL BANDS OF MODERATE CONVECTION, WHICH OUTLINE THE
PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INNER
CORE OF THE SYSTEM LIES WITHIN AN ELONGATED REGION OF TROUGHING,
WITH MULTIPLE VORTICES EVIDENT IN THE ANIMATED SHORTWAVE INFRARED
IMAGERY. A 201632Z AMSR2 COLOR ENHANCED 89GHZ MICROWAVE IMAGE
SHOWED THE DISORGANIZED NATURE OF THE INNER CORE OF THE SYSTEM, AND
THE WELL-DEFINED SPIRAL BANDING FEATURES WITH MODERATE CONVECTION
FIRING OFF NEAR THE ASSESSED CENTER. EVEN WITH THE HIGH-RESOLUTION
AMSR2 IMAGERY, THE INITIAL POSITION IS ASSESSED WITH JUST MEDIUM
CONFIDENCE DUE TO THE BROAD NATURE OF THE LLCC AND THE MULTIPLE
VORTICES. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE,
CONSISTENT WITH THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES AND
SLIGHTLY LOWER THAN THE BULK OF THE OBJECTIVE CIMSS ESTIMATES. THE
ENVIRONMENT IS GENERALLY FAVORABLE, WITH VERY WARM SSTS, LOW
EASTERLY SHEAR AND MODERATE TO STRONG EQUATORWARD AND EASTWARD
OUTFLOW. THE MAIN HINDRANCE AT PRESENT BEING THE BROAD NATURE OF
THE CIRCULATION AND SOME ENHANCED MID-LEVEL SHEAR AS INDICATED BY
BOTH THE GFS AND ECMWF MODEL SOUNDINGS AND THE 1200Z YAP SOUNDING.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: THE SYSTEM IS TRACKING WEST-SOUTHWEST
ALONG THE SOUTHEAST PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR)
CENTERED NEAR HONG KONG. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.0 - 25 KTS
   CIMSS SATCON: 32 KTS AT 201639Z
   CIMSS ADT: 28 KTS AT 201730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: EASTWARD OUTFLOW CHANNEL. BROAD NATURE OF THE
LLCC. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: OVER THE NEXT 24 HOURS, TD 22W IS FORECAST TO
TRACK TOWARDS THE WEST-SOUTHWEST ALONG THE SOUTHEASTERN SIDE OF THE
STR. BY TAU 36, THE APPROACH OF A DEEP MIDLATITUDE TROUGH OVER
EASTERN CHINA WILL SHIFT THE RIDGE NORTHEASTWARD, THEN SPLIT INTO A
SEPARATE RIDGE CENTER TO THE SOUTH OF SHIKOKU AND GENERATE A BREAK
IN THE STR NORTHEAST OF TAIWAN. THE ASSOCIATED JET MAX WILL PASS
OVER KOREA AROUND TAU 48, WHICH WILL MARK THE DEEPEST PENETRATION
OF THE TROUGH INTO THE TROPICS. DURING THIS TIME, THE DEEPENING OF
THE TROUGH AND THE ASSOCIATED BREAK IN THE RIDGE WILL INDUCE TD 22W
ONTO A MORE NORTHWESTWARD TRACK, BEGINNING BETWEEN TAU 24 AND 36.
THE JET MAX EXITS THE BASE OF THE TROUGH AND MOVES EAST TO JAPAN BY
TAU 72, WHICH WILL WEAKEN THE TROUGH AND PULL IT NORTHWARD. IN THE
LOW TO MID-LEVELS, A POST-FRONTAL HIGH PRESSURE AREA WILL BUILD
OVER EASTERN CHINA AND GENERATE EAST-NORTHEAST FLOW ACROSS THE
ENTIRE REGION AFTER TAU 96. THE COMBINATION OF THE WEAKENED TROUGH
NOT BEING STRONG ENOUGH TO PULL TD 22W NORTHWARD, ALONG WITH THE
STRONG BLOCKING FLOW IN THE LOW TO MID-LEVELS, WILL RESULT IN A
MORE WESTWARD TRACK AFTER TAU 72. THE SYSTEM IS EXPECTED TO MAKE
LANDFALL IN NORTHEASTERN LUZON JUST AFTER TAU 96, THEN CROSS OVER
THE ISLAND AND REEMERGE INTO THE SOUTH CHINA SEA BY TAU 120. IN
TERMS OF INTENSITY, THE ENVIRONMENT IS FORECAST TO REMAIN FAVORABLE
FOR THE NEXT 24 HOURS, BUT THE RATE OF INTENSIFICATION IS EXPECTED
TO BE SLOW DUE TO THE BROAD NATURE OF THE SYSTEM. BEGINNING AROUND
TAU 24, BUT ESPECIALLY AFTER TAU 36, EASTERLY SHEAR IS FORECAST TO
INCREASE SHARPLY, WHICH WILL BUT A LID ON THE INTENSIFICATION RATE
OF TD 22W, LEADING TO A STEADY OR POTENTIALLY EVEN WEAKENING PHASE
UP TO TAU 48 OR TAU 60. THEREAFTER, SHEAR IS EXPECTED TO WEAKEN
ONCE MORE, WHICH WILL ALLOW FOR A PERIOD OF INTENSIFICATION UP
THROUGH LANDFALL, WITH THE PEAK OF 65 KNOTS EXPECTED JUST PRIOR TO
LANDFALL. MOVEMENT ACROSS LUZON WILL TEAR THE SYSTEM APART FROM
BELOW, WITH A WEAK TROPICAL STORM OR EVEN WEAKER SYSTEM EMERGING
OFF THE WESTERN SIDE OF LUZON BY TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS PRESENTING A WEAK
BIFURCATION SCENARIO, WITH TWO CLEAR OUTLIER GROUPS AND A MIDDLE
GROUP OF MODEL SOLUTIONS. THE GFS AND GEFS ENSEMBLE MEAN REPRESENT
THE SOUTHERN OUTLIER GROUP, TAKING THE SYSTEM FURTHER TO THE
SOUTHWEST THAN THE REMAINING GUIDANCE MEMBERS, THEN TRACK THE
SYSTEM DUE WEST OVER LUZON, SOUTH OF VIGAN. THE NAVGEM, GALWEM AND
JGSM MEANWHILE MARK THE NORTHERN OUTLIER GROUP, TAKING THE SYSTEM
ON A DUE WEST TRACK FROM TAU 00, THEN INTO OR EAST OF TAIWAN BY TAU
120. THE REMAINDER OF THE CONSENSUS MEMBERS INCLUDING THE ECMWF,
ECMWF ENSEMBLE MEAN, THE EGRR AND UKMET ENSEMBLE AND THE CONSENSUS
MEAN, ALL TAKE THE MIDDLE GROUND AND PASS THE CENTER OVER NORTHEAST
LUZON AND OFF THE NORTHWEST TIP OF LUZON BY THE END OF THE
FORECAST. MODEL SPREAD AT TAU 72 IS JUST 105NM BUT INCREASES
SHARPLY TO 450NM BY TAU 120. HOWEVER, MULTI-MODEL ENSEMBLE DATA
SHOWS GENERAL AGREEMENT BETWEEN THE EPS, GEFS AND UKMET ENSEMBLE ON
A TRACK OVER NORTHERN LUZON, WITH ONLY THE CMC ENSEMBLE TAKING THE
SYSTEM NORTHWARD. THE JTWC FORECAST TRACK LIES ON THE SOUTHERN SIDE
OF THE MIDDLE GROUP OF TRACKERS, MOST CLOSELY ALIGNED WITH THE
ECMWF ENSEMBLE MEAN, WITH MEDIUM CONFIDENCE. LIMITED INTENSITY
GUIDANCE FOR THE MOST PART SHOWS A STEADY INTENSIFICATION TO THE
PEAK AT TAU 96. THIS SEEMINGLY DOES NOT ACCOUNT FOR THE EXPECTED
INCREASE IN SHEAR. THUS THE JTWC FORECAST LIES BELOW ALL OF THE
GUIDANCE UP TO TAU 60, THEN REJOINS THE CONSENSUS MEAN BY TAU 72.
THE PEAK OF 65 KTS IS SLIGHTLY BELOW THE HAFS AND HWRF SOLUTIONS
BUT IN LINE WITH THE CONSENSUS MEAN. 

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