14W, Lingling(15W) and Invest 91W updates

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WESTERN NORTH PACIFIC

TD 14W
As of 00:00 UTC Sep 02, 2019:
Location: 15.9°N 167.9°E
Maximum Winds: 30 kt ( 55km/h)
Gusts : 40kt ( 75km/h)
Minimum Central Pressure: 1003 mb
WDPN31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (FOURTEEN) WARNING
NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 14W (FOURTEEN), LOCATED APPROXIMATELY
214 NM SOUTH-SOUTHEAST OF WAKE ISLAND, HAS TRACKED WEST-NORTHWESTWARD AT
15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A COMPACT, SHEARED SYSTEM WITH A NEARLY FULLY EXPOSED LLCC,
DISPLACED TO THE NORTHWEST OF FLARING DEEP CONVECTION. THE INITIAL POSITION
WAS RELOCATED WITH THIS WARNING BASED ON THE EMERGENCE OF THE CLEARLY
DEFINED LLCC, AND THE BEST TRACK WAS ADJUSTED TO REFLECT THIS MOVEMENT.
WITH THE LLCC NOW EXPOSED, AND COMBINED WITH AN ASSESSMENT OF A 012219Z
AMSU-B 89 GHZ MICROWAVE PASS, CONFIDENCE IN THE INITIAL POSITION HAS
IMPROVED SIGNIFICANTLY. THE AFOREMENTIONED MICROWAVE PASS SHOWED A VERY SMALL
AMOUNT OF DEEP CONVECTION TO THE SOUTH-SOUTHEAST OF THE LLCC, WHICH SUPPORTS
THE DECOUPLING OF THE LLCC FROM THE CONVECTIVE CORE. THE INITIAL INTENSITY OF
30 KNOTS IS ASSESSED WITH FAIR CONFIDENCE BASED ON DVORAK CURRENT INTENSITY
ESTIMATES OF T2.0 (30 KNOTS) FROM KNES, T1.5 (25 KNOTS) FROM PGTW, AUTOMATED
ESTIMATES OF T1.9 (29 KNOTS) AND A SATELLITE CONSENSUS ESTIMATE OF 32 KNOTS).
ENVIRONMENTAL ANALYSIS REVEALS THE SYSTEM LIES IN A FAVORABLE AREA,
WITH LOW (5-10 KNOTS) VWS, MODERATE TO STRONG POLEWARD OUTFLOW AND WARM SSTS
(28-30C).
TD 14W IS CURRENTLY TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHERN
PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THE INITIAL POSITION HAS BEEN RELOCATED
 SINCE THE PREVIOUS WARNING DUE TO THE EMERGENCE OF THE LLLC AWAY FROM
THE CONVECTIVE SIGNATURE BUT THIS HAS NOT CHANGED THE OVERALL FORECAST
 PHILOSOPHY.
   B. TD 14W WILL TRACK GENERALLY NORTHWESTWARD THROUGH TAU 72 UNDER
THE STEERING INFLUENCE OF A DEEP-LAYER STR ANCHORED IN PLACE TO THE
NORTH. A VERY SMALL UPPER-LEVEL ANTICYCLONE APPEARS TO HAVE DEVELOPED
JUST NORTH OF TD 14W AND LED TO THE NORTHERLY SHEAR CURRENTLY AFFECTING
THE SYSTEM. HOWEVER, OVER THE NEXT 12-24 HOURS, THE ANTICYCLONE
WILL MOVE TO THE EAST, ALLOWING THE SYSTEM TO TAP INTO THE DIFFLUENT
 POLEWARD OUTFLOW ASSOCIATED WITH A TUTT CELL NORTHWEST OF THE SYSTEM.
ONCE THIS OCCURS, EXPECT TD 14W TO INTENSIFY THROUGH TAU 36 TO 40 KNOTS.
AT THIS POINT TD 14W WILL MOVE INTO A LESS FAVORABLE POSITION IN RELATION
TO THE TUTT CELL LEADING TO A DECREASE IN OUTFLOW AND A LEVELING OFF OF
INTENSITY THROUGH TAU 48. THEREAFTER AND TD 14W WILL AGAIN SLOWLY INTENSIFY
THROUGH TAU 72 AS THE TUTT CELL BEGINS TO MOVE TO THE SOUTHWEST OF TD 14W,
PLACING THE SYSTEM ONCE AGAIN IN A FAVORABLE OUTFLOW ENVIRONMENT. VWS REMAINS
LOW AND SSTS REMAIN FAVORABLE, WITH OUTFLOW BEING THE PRIMARY INTENSITY DRIVER
THROUGH TAU 72.    
   C. BEYOND TAU 72, TD 14W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG
THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYER STR TO THE NORTHEAST. AFTER TAU 72,
AN UPPER-LEVEL ANTICYCLONE DEVELOPS IN THE WAKE OF TD 14W AND TRAILS THE SYSTEM
THROUGH TAU 120, PROVIDING A MODERATE LEVEL OF WESTWARD AND POLEWARD OUTFLOW,
WHICH ALONG WITH LOW TO MODERATE (10-20 KNOTS) VWS AND HIGH SSTS (28-29 CELSIUS),
COMBINE TO ALLOW FOR STEADY INTENSIFICATION THROUGH THE FORECAST PERIOD. DYNAMIC
MODEL GUIDANCE IS IN GOOD AGREEMENT WITH ALL MODELS AGREEING ON THE GENERAL
NORTHWESTWARD TRACK AND ONLY SOME MINOR DIFFERENCES IN THE EXACT TRACK, LEADING
TO HIGH CONFIDENCE IN THE FORECAST TRACK. AVAILABLE INTENSITY GUIDANCE IS IN POOR
AGREEMENT, WITH THE HWRF AND COTC MODELS SHOWING RAPID INTENSIFICATION TO OVER 100
KNOTS BY TAU 120, AND THE DECAY SHIPS PEAKING OUT AT AROUND 75 KNOTS. THE OFFICIAL
INTENSITY FORECAST LIES ABOUT 10 KNOTS LESS THAN THE INTENSITY CONSENSUS AND CLOSE
TO THE HWRF SOLUTION THROUGH TAU 96.//
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TD LINGLING ( 15W)
As of 00:00 UTC Sep 02, 2019:
Location: 15.9°N 125.6°E
Maximum Winds: 30 kt ( 55km/h)
Gusts: 40 kt ( 75km/h)
Minimum Central Pressure: 1005 mb
WDPN32 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (LINGLING)
WARNING NR 1//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 15W (LINGLING), LOCATED APPROXIMATELY
282 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-NORTHWESTWARD
AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A BROAD AND CONSOLIDATING SYSTEM
WITH A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION AND FLARING DEEP
CONVECTION FORMING A RING AROUND MOST OF THE PERIPHERY OF THE SYSTEM.
A 012201Z CORIOLIS 37 GHZ MICROWAVE IMAGE SHOWED A BROAD BAND OF
DEEP CONVECTION ON THE EASTERN PERIPHERY AND WEAKER FORMATIVE
BANDING ON THE WESTERN SIDE. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE CORIOLIS MICROWAVE IMAGE AND AN
ANALYSIS OF ASCAT AMBIGUITIES FROM A 020028Z ASCAT-B PASS. THE
INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED ON A DVORAK CURRENT
INTENSITY ESTIMATE OF T2.0 (30 KNOTS) FROM PGTW, SUPPORTED BY THE
ASCAT PASS, WHICH SHOWED A BROAD AREA OF 25-30 KNOT WINDS IN THE
NORTHEASTERN QUADRANT. ENVIRONMENTAL ANALYSIS REVEALS THE SYSTEM
LIES IN A FAVORABLE ENVIRONMENT, WITH LOW (5-10 KNOTS) VWS, WARM
SSTS (29-30 CELSIUS) AND MODERATE POLEWARD AND EQUATOR OUTFLOW.
TD 15W IS TRACKING GENERALLY NORTHWARD ALONG THE WESTERN PERIPHERY
OF A SOUTHWARD EXTENSION OF THE SUBTROPICAL RIDGE (STR) CENTERED EAST OF JAPAN.
3. FORECAST REASONING.
   A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE
FORECAST PHILOSOPHY.
   B. OVER THE NEXT 36 HOURS, TD 15W WILL CONTINUE TRACKING
NORTH-NORTHWEST ALONG THE WESTERN PERIPHERY OF AN EXTENSION
OF THE STR CENTERED FAR TO THE NORTH. AFTER TAU 36, THE STR
EXTENSION PINCHES OFF TO FORM A NEAR-EQUATORIAL RIDGE (NER)
CENTERED OVER THE PHILIPPINES RESULTING IN A WEAKENING IN THE
OVERALL RIDGE PATTERN. THIS WILL ALLOW TD 15W TO SLOW DOWN
SIGNIFICANTLY AS IT MOVES NORTHWARD TO THE EAST OF TAIWAN.
BY TAU 72, THE STEERING STR BEGINS TO ERODE AHEAD OF AN APPROACHING
DEEP-LAYER TROUGH, AND REORIENTS TO A NORTH-SOUTH AXIS,
ALLOWING TD 15W TO TURN NORTH-NORTHEAST AND ACCELERATE THROUGH TAU 72.
TD 15W IS FORECAST TO STEADILY INTENSIFY UNDER FAVORABLE ENVIRONMENTAL
CONDITIONS OF LOW VWS, WARM SSTS AND STRONG UPPER-LEVEL OUTFLOW, PEAKING
AT 60 KNOTS BY TAU 72.
   C. AFTER TAU 72, A DEEP TROUGH IS FORECAST TO DIG OVER EASTERN CHINA,
WHICH WILL ERODE THE STEERING STR AND ALLOW THE SYSTEM TO TURN ONTO A MORE
NORTHEASTWARD TRACK TOWARDS THE SOUTHERN YELLOW SEA THROUGH TAU 120. THE
SYSTEM IS EXPECTED TO MAINTAIN INTENSITY OF 60 KNOTS FROM TAU 72 TO TAU 96.
THEREAFTER DRY AIR ENTRAINMENT, COOLER SSTS AND INCREASING VWS WILL ALL
CONSPIRE TO WEAKEN THE SYSTEM. DYNAMIC MODEL GUIDANCE IS IN POOR
AGREEMENT THROUGHOUT THE FORECAST PERIOD, BUT PARTICULARLY BEYOND TAU 48,
WITH OVER 1100 NM ALONG TRACK DIFFERENCES BETWEEN GFS AND NAVGEM BY TAU 120.
THERE IS ALSO SIGNIFICANT CROSS TRACK DISAGREEMENT BETWEEN GFS ON THE EASTERN
SIDE, AND ECMWF ON THE WESTERN PORTION OF THE ENVELOPE. THE OFFICIAL TRACK
LIES CLOSE TO THE ECMWF THROUGH TAU 72, THEN INSIDE AND SLOWER THAN THE MULTIMODEL
CONSENSUS THROUGH TAU 120. AN ALTERNATE SCENARIO FAVORED BY THE GFS MODEL RESULTS
IN THE SYSTEM MOVING INTO A WEAK STEERING ENVIRONMENT BETWEEN THE STR AND NER AND
DRIFTING VERY SLOWLY NORTHWARD THROUGH TAU 72, THEN MOVING JUST NORTH OF ISHIGAKIJIMA
BY TAU 120. WITH THE SIGNIFICANT DISAGREEMENT IN THE GUIDANCE AND POTENTIAL
ALTERNATE SCENARIO, THERE IS OVERALL LOW CONFIDENCE IN THE FORECAST TRACK.//
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INVEST 91W
As of 00:00 UTC Sep 02, 2019:
Location: 18.8°N 111.0°E
Maximum Winds: 25 kt
Minimum Central Pressure: 1000 mb
WTPN21 PGTW 011900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91W) REISSUED//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/311851Z AUG 19//
REF/B/JOINT TYPHOON WRNCEN PEARL HARBOR HI/311921Z AUG 19//
REF/C/JOINT TYPHOON WRNCEN PEARL HARBOR HI/010851Z SEP 19//
NARR/REFS A, B, AND C ARE TROPICAL CYCLONE FORMATION ALERTS//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 19.1N 113.0E TO 17.0N 107.0E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT
IMAGERY AT 011800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 18.8N 112.4E. THE SYSTEM IS MOVING WESTWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED
NEAR 18.8N 118.3E, IS NOW LOCATED NEAR 18.8N 112.4E, APPROXIMATELY
228 NM SOUTH-SOUTHWEST OF HONG KONG. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A BROAD, ASYMMETRICAL LOW LEVEL
CIRCULATION (LLC) WITH FLARING CONVECTION CONFINED TO THE NORTH. A
011338Z ASCAT PASS FURTHER DETAILS THE ASYMMETRICAL STRUCTURE OF THE
DISTURBANCE, WITH A BROAD SWATH OF 25-30 KNOT WINDS DISPLACED NORTH
OF AN ELONGATED LLC WITH WEAK RETURN FLOW. 91W IS CURRENTLY BELOW A
TIGHT GRADIENT OF MODERATE (10-25 KNOT) WESTERLY VERTICAL WIND SHEAR
WITH NEUTRAL DIVERGENCE ALOFT. SEA SURFACE TEMPERATURES REMAIN
FAVORABLY WARM (29-31C) IN THE NORTHERN PORTION OF THE SOUTH CHINA
SEA. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 91W WILL MAINTAIN THE
ASYMMETRICAL CHARACTERISTICS OF A MONSOON DEPRESSION FOR THE NEAR
FUTURE, BEFORE CONSOLIDATING OVER HAINAN AND MAKING A POSSIBLE TURN
TO THE NORTHEAST IN THE LATE TAUS. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH.
THIS SUPERSEDES REF A (WTPN21 PGTW 311900).
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
021900Z.
4. SEE REF B (WTPN22 PGTW 311930) FOR DETAILS ON A TROPICAL CYCLONE
FORMATION ALERT LOCATED NEAR 9.5N 130.7E. SEE REF C (WTPN23 PGTW
010900) FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT LOCATED
NEAR 15.6N 171.5E.//
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