WPAC: DANAS - Post-Tropical

[euro6208]

WDPN31 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION TROPICAL
DEPRESSION 06W (DANAS) WARNING NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 06W (DANAS), LOCATED APPROXIMATELY 587 NM
SOUTH-SOUTHWEST OF KADENA AB, HAS TRACKED WEST-NORTHWESTWARD AT 12
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL
SATELLITE IMAGERY DEPICTS A BROAD CIRCULATION WITH DEEP CONVECTION
DISPLACED TO THE WEST OF THE PARTLY OBSCURED LOW LEVEL CIRCULATION
CENTER (LLCC) AND SHALLOW RAIN BANDS STARTING TO WRAP IN FROM THE
SOUTH. THE INITIAL POSITION IS PLACED WITH POOR CONFIDENCE BASED ON
THE BROAD CIRCULATION CENTER AS EVIDENCED IN THE MSI LOOP AND A
PARTIAL 160529Z AMSR2 89 GHZ MICROWAVE IMAGE. OF NOTE, A 160021Z
METOP-A AND 160135Z METOP-B ASCAT PASS CAUSED A SIGNIFICANT WESTWARD
SHIFT IN THE 160000Z BEST TRACK POSITION AND THE WIND FIELD DEPICTED
BY THOSE ASCAT PASSES SUGGESTED THAT THIS SYSTEM MAY BE BEGINNING TO
TRANSITION FROM A MONSOON DEPRESSION INTO A TROPICAL CYCLONE. THE
INITIAL INTENSITY OF 25 KTS IS CONSISTENT WITH THE KNES DVORAK
INTENSITY OF T1.5 (25 KTS) AND THE AFOREMENTIONED ASCAT PASSES WHICH
SHOWED 25-30 KT WINDS IN THE CONVECTION TO THE SOUTH AND WEST OF THE
LLCC AND 10-20 KTS TO THE NORTHEAST. ENVIRONMENTAL CONDITIONS FOR TD
06W ARE MARGINAL WITH GOOD EQUATORWARD OUTFLOW AND WARM SEA SURFACE
TEMPERATURE (30-31 CELSIUS) BEING OFFSET BY MODERATE TO STRONG
VERTICAL WIND SHEAR (20-30 KTS). TD 06W IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
B. BY TAU 24, TD 06W SHOULD BE TRACKING MORE NORTHWARD AS IT
ROUNDS THE STR AXIS. THE JTWC TRACK FORECAST CLOSELY FOLLOWS THE
CONSENSUS TRACK BUT SPREAD IN THE MODEL TRACK GUIDANCE GROWS QUITE
RAPIDLY, LIKELY DUE TO THE BROAD NATURE OF THE CIRCULATION.
CONTINUED HIGH VWS WILL PREVENT TD 06W FROM INTENSIFYING
SIGNIFICANTLY THROUGH TAU 48. AFTER TAU 48, SOMEWHAT IMPROVED
ENVIRONMENTAL CONDITIONS ARE EXPECTED TO ALLOW SOME INTENSIFICATION
TO 45 KTS AS TD 06W APPROACHES THE EAST COAST OF CHINA. THE JTWC
INTENSITY FORECAST CLOSELY FOLLOWS THE INTENSITY GUIDANCE THROUGH
TAU 48. AFTER TAU 48, THE MESOSCALE MODELS BRING TD 06W INLAND OVER
CHINA, RENDERING THE INTENSITY GUIDANCE THOSE MODELS PROVIDE USELESS
BASED ON THE JTWC TRACK FORECAST. AS A RESULT, BEYOND TAU 48 THE
INTENSITY FORECAST IS BASED ON THE EXPECTATION THAT ENVIRONMENTAL
CONDITIONS WILL BE MARGINALLY FAVORABLE. OVERALL, THERE IS LOW
CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST BASED ON LARGE
SPREAD IN THE MODEL GUIDANCE AND HIGH UNCERTAINTY IN THE INITIAL
POSITION.
C. AFTER TAU 72, TD 06W IS EXPECTED TO CONTINUE TRACKING
NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STR, BRUSH THE EAST
COAST OF CHINA, AND MOVE INTO THE YELLOW SEA WITH WEAK TROPICAL
STORM FORCE WINDS. THE MODEL TRACK GUIDANCE HAS SIGNIFICANT SPREAD
BETWEEN THE EASTERNMOST (GFS) AND WESTERNMOST (ECMWF AND GFS
ENSEMBLE MEANS) MEMBERS. THE JTWC TRACK FORECAST CONTINUES TO FOLLOW
THE CONSENSUS TRACK, WHICH CLOSELY FOLLOWS THE ECMWF, GALWEM, JGSM,
AND NAVGEM SOLUTIONS. THE INTENSITY FORECAST ANTICIPATES SLIGHT
WEAKENING AS THE SYSTEM BRUSHES THE CHINA COAST AND MOVES INTO THE
YELLOW SEA BUT MAINTAINS THE INTENSITY AT WEAK TROPICAL STORM
STRENGTH FOR THE DURATION OF THE EXTENDED FORECAST PERIOD. FOR THIS
PORTION OF THE FORECAST, THERE IS LOW CONFIDENCE IN THE JTWC TRACK
FORECAST DUE TO HIGH UNCERTAINTY IN THE MODEL GUIDANCE AND THE
INITIAL POSITION OF THE SYSTEM.//
NNNN

[doomhaMwx]

ECMWF consistently predicting 200-300mm+ of rainfall for much of Northern and Central Luzon on the next 2 days.

[Tailspin]

TROPICAL CYCLONE DANAS
(2019-07-16 09:30:22 UTC)
==========================
HKO:
160600Z 17.1N 125.9E 30KT
(+024H) 18.4N 123.7E 40KT
(+048H) 20.8N 121.8E 46KT
(+072H) 24.5N 120.4E 35KT
(+096H) 27.6N 120.4E 24KT
(+120H) 31.4N 120.6E 13KT
JTWC:
160600Z 17.0N 125.3E 25KT
(+024H) 18.9N 123.0E 30KT
(+048H) 22.6N 122.1E 40KT
(+072H) 26.6N 121.8E 45KT
(+096H) 30.7N 121.8E 40KT
(+120H) 35.4N 122.7E 35KT
JMA:
160600Z 17.1N 125.7E 35KT
(+024H) 19.0N 123.2E 40KT
(+048H) 22.1N 122.1E 45KT
(+072H) 25.9N 122.5E 45KT
(+096H) 29.9N 122.5E 40KT
(+120H) 33.0N 121.6E 35KT
NMC:
160600Z 17.1N 125.1E 35KT
(+024H) 18.5N 122.7E 39KT
(+048H) 21.7N 121.0E 45KT
(+072H) 25.7N 118.8E 35KT
(+096H) 29.0N 118.1E 23KT
CWB:
160600Z 17.0N 125.0E 35KT
(+024H) 18.8N 122.6E 45KT
(+048H) 22.4N 121.3E 45KT
(+072H) 25.9N 119.8E 45KT
(+096H) 29.4N 118.4E 35KT
(+120H) 32.4N 117.9E 29KT
KMA:
160600Z 17.0N 125.3E 35KT
(+024H) 18.9N 122.8E 39KT
(+048H) 21.9N 121.3E 43KT
(+072H) 25.6N 120.8E 37KT
(+096H) 29.0N 120.8E 35KT
(+120H) 33.5N 121.2E 35KT

[wxman57]

Both JMA and JTWC appear to have the center about 1 deg too far east, missing Luzon. Satellite indicates it is nearing the coast of Luzon at around 17N/122.8E. I don't see it missing Luzon as per JMA's and JTWC's forecast.

[Hayabusa]

It looks like the GFS splits Danas into two storms

[Hayabusa]

[Hayabusa]

It looks like the GFS splits Danas into two storms

Tagged as 90W
Still a headache on which Danas coc would be, forecast show Danas coc seems to be trying "reform" over the south china sea / west side of Luzon where much of its convection right now. As for the current coc forecast show it would merge with 90W, so which Danas is which?

[NotoSans]

Once again, huge bust for global models and subjective forecasts due to the circulation's interaction with Luzon...

[euro6208]

WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (DANAS)
WARNING NR 02//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 06W (DANAS), LOCATED APPROXIMATELY 603 NM SOUTH-
SOUTHWEST OF KADENA AB, HAS TRACKED WESTWARD AT 15 KNOTS (KTS) OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
REVEALS AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP
CONVECTION CONCENTRATED IN THE NORTHWEST QUADRANT AND SHALLOW RAIN
BANDS TO THE SOUTH AND EAST OF THE LLCC. THERE IS FAIR CONFIDENCE IN
THE INITIAL POSITION BASED ON A 161245Z METOP-B ASCAT IMAGE THAT
DEPICTS A LARGE REGION OF 30 KT WINDS TO THE SOUTH OF A RELATIVELY
BROAD LLCC. THE INITIAL INTENSITY OF 30 KTS IS CONSISTENT WITH THE
METOP-B IMAGE AND KNES AND RJTD DVORAK INTENSITY ESTIMATES OF T2.0
(30 KTS). ENVIRONMENTAL CONDITIONS ARE MARGINAL WITH GOOD
EQUATORWARD AND WESTWARD OUTFLOW AND WARM SEA SURFACE TEMPERATURE
(30-31 CELSIUS) BEING PARTIALLY OFFSET BY MODERATE TO HIGH VERTICAL
WIND SHEAR (15-25 KTS). TD 06W IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. IN THE NEXT 12 HOURS OR SO, TD 06W SHOULD BEGIN TURNING
NORTHWARD AS IT ROUNDS THE STR AXIS. AFTER MAKING THE NORTHWARD
TURN, THE TRACK SHOULD REMAIN NORTHWARD THROUGH TAU 72. BY TAU 72,
TD 06W IS EXPECTED TO MAKE LANDFALL SOUTH OF SHANGHAI, CHINA. FOR
THIS PORTION OF THE FORECAST, THE JTWC TRACK FORECAST IS HEDGED WEST
OF THE CONSENSUS TRACK TO OFFSET TWO EASTERN OUTLIERS, GFS (THROUGH
TAU 72) AND GALWEM (THROUGH TAU 36, COMES BACK INTO AGREEMENT WITH
THE OTHER MEMBERS AFTER TAU 36). CONTINUED MARGINAL ENVIRONMENTAL
CONDITIONS WILL ALLOW FOR SLOW INTENSIFICATION TO 45 KTS JUST PRIOR
TO LANDFALL AT TAU 72. OVERALL, THERE IS LOW CONFIDENCE IN THIS
PORTION OF THE JTWC TRACK FORECAST BASED ON HIGH UNCERTAINTY IN THE
FORECAST GUIDANCE.
C. AFTER TAU 72, TD 06W IS EXPECTED TO CONTINUE TRACKING
NORTHWARD ALONG THE WESTERN PERIPHERY OF THE STR, BRIEFLY FOLLOW THE
EAST COAST OF CHINA, AND MOVE INTO THE YELLOW SEA JUST PRIOR TO TAU
96, WITH WEAK TROPICAL STORM FORCE WINDS. THE INTENSITY IS EXPECTED
TO WEAKEN SLIGHTLY DUE TO LAND INTERACTION AS TD 06W BRUSHES THE
CHINESE COAST AND MOVES INTO THE YELLOW SEA AS A WEAK TROPICAL STORM.
THE MODEL TRACK GUIDANCE HAS SIGNIFICANT SPREAD, LARGELY DUE TO THE
EASTERN OUTLIER (GFS). THE JTWC TRACK FORECAST IS PLACED WEST OF THE
CONSENSUS TRACK TO OFFSET THE INFLUENCE OF GFS. CONFIDENCE IN THE
TRACK REMAINS LOW FOR THIS PORTION OF THE FORECAST DUE TO HIGH
UNCERTAINTY IN THE EXTENDED MODEL GUIDANCE.//
NNNN

[euro6208]

WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS)
WARNING NR 04//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 06W (DANAS), LOCATED APPROXIMATELY 255 NM NORTHEAST OF
MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST
SIX HOURS. THE CURRENT, HIGH-CONFIDENCE POSITION IS BASED ON A
170000Z PGTW SATELLITE FIX ON AN EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) EVIDENT IN VISIBLE SATELLITE IMAGERY. THE INTENSITY OF 35
KNOTS IS CONSISTENT WITH SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM
MULTIPLE REPORTING AGENCIES, WHICH RANGE FROM 30 TO 35 KNOTS. TS 06W
TURNED SHARPLY POLEWARD ALONG THE PERIPHERY OF A REORIENTING STEERING
RIDGE TO THE EAST OVER THE PAST SIX HOUR. THE PRIMARY DEEP CONVECTION
ASSOCIATED WITH THE SYSTEM HAS BEEN DISPLACED TO THE WEST OF THE LLCC
BY PERSISTENT, MODERATE TO STRONG (20-25 KNOTS) EASTERLY VERTICAL
WIND SHEAR (VWS). WARM SEA SURFACE TEMPERATURES AND WESTWARD AND
EQUATORWARD DIFFLUENCE ALOFT REMAIN AS FAVORABLE OFFSETS TO THE VWS.
3. FORECAST REASONING.
A. THE FORECAST TRACK HAS SHIFTED EASTWARD FROM THE PREVIOUS
WARNING AND MEDIUM RANGE INTENSITIES HAVE INCREASED SLIGHTLY DUE TO
LESS ANTICIPATED LAND INTERACTION. FORECAST WIND RADII HAVE ALSO
EXPANDED A BIT BASED ON LOWER ANTICIPATED LAND INFLUENCE ON THE
CIRCULATION. HOWEVER, THERE IS NO CHANGE TO THE OVERALL FORECAST
PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 06W WILL CONTINUE TRACKING GENERALLY POLEWARD THROUGHOUT THE
NEXT 72 HOURS AS IT FOLLOWS THE PERIPHERAL FLOW ASSOCIATED WITH A
REORIENTING SUBTROPICAL RIDGE TO THE EAST. SLOW INTENSIFICATION IS
LIKELY IN THE NEAR-TERM AS VERTICAL WIND SHEAR OFFSETS THE FAVORABLE
INFLUENCES OF PASSAGE OVER WARM WATER AND STRONG OUTFLOW ALOFT. THE
NUMERICAL MODEL GUIDANCE PACKAGE HAS SHIFTED SLIGHTLY EASTWARD FROM
THE PREVIOUS CYCLE, WITH THE ECMWF AND GFS SOLUTIONS BRACKETING THE
SET OF FORECASTS AS THE WESTERNMOST AND EASTERNMOST SOLUTIONS,
RESPECTIVELY. THE CURRENT FORECAST FOLLOWS THE MOST PROBABLE
ORIENTATION OF THE LARGE-SCALE FLOW PATTERN, LIES SLIGHTLY TO THE
EAST OF THE PREVIOUS JTWC FORECAST AND LIES SLIGHTLY TO THE WEST OF
THE MULTI-MODEL CONSENSUS. THE LOW-LEVEL CIRCULATION PATTERN NEAR TS
06W REMAINS COMPLEX, WHICH IS INFLUENCING THE OUTCOME OF THE MODEL
FORECASTS. GIVEN NOTED SPREAD IN THE GUIDANCE, CONFIDENCE IN THE JTWC
TRACK FORECAST IS LOW.
C. IN THE EXTENDED RANGE, TS 06W IS EXPECTED TO CONTINUE POLEWARD
AND EASTWARD AND UNDERGO A SLOW EXTRATROPICAL TRANSITION AS IT
ENCOUNTERS A DEVELOPING MID-LATITUDE TROUGH. SLIGHTLY WEAKENING IS
ANTICIPATED, ALTHOUGH FAVORABLE BAROCLINIC INTERACTION WITH THE
DEVELOPING TROUGH SHOULD ALLOW THE SYSTEM TO MAINTAIN GALE FORCE OR
STRONGER WINDS THROUGHOUT THE TRANSITION. THE STORM TRACK DURING THE
EXTENDED PERIOD IS HIGHLY DEPENDENT ON THE SOMEWHAT UNCERTAIN NEAR TO
MEDIUM-TERM TRACK, SO CONFIDENCE IN THE EXTENDED PORTION OF THE
FORECAST TRACK IS ALSO LOW.//
NNNN

[euro6208]

[euro6208]

WDPN31 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR
05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (DANAS), LOCATED APPROXIMATELY 504 NM SOUTH-
SOUTHWEST OF KADENA AB, HAS TRACKED NORTH-NORTHEASTWARD AT 09 KNOTS
(KTS) OVER THE PAST SIX HOURS. THERE IS HIGH CONFIDENCE IN THE
INITIAL POSITION BASED ON A FULLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) EVIDENT IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY.
THERE IS LITTLE TO NO CONVECTION NEAR THE LLCC BUT THERE ARE TWO
AREAS OF DEEP CONVECTION (90W TO THE EAST, 91W WEST OF THE
PHILIPPINES) ALONG THE PERIPHERY OF THE CIRCULATION. PREVIOUS ASCAT
PASSES AND MICROWAVE IMAGERY REVEAL THAT NEITHER INVEST HAS A
DEFINED LLCC ALTHOUGH BOTH BEAR MONITORING. THE INITIAL INTENSITY OF
35 KTS IS HEDGED SLIGHTLY ABOVE MULTI-AGENCY DVORAK CURRENT
INTENSITY ESTIMATES FROM T1.5-T2.0 (25-30 KTS) BASED ON THE STRONG
WINDS MEASURED BY PREVIOUS ASCAT PASSES AND THE FACT THAT THE DVORAK
TECHNIQUE IS NOT WELL-SUITED TO ESTIMATE INTENSITY FOR MONSOON
DEPRESSIONS. THE ENVIRONMENT IS MARGINAL OVERALL WITH GOOD
EQUATORWARD OUTFLOW, IMPROVING POLEWARD OUTFLOW, AND WARM (30-31
CELSIUS) SEA SURFACE TEMPERATURE BEING PARTIALLY OFFSET BY MODERATE
(15-25 KTS) VERTICAL WIND SHEAR (VWS). TS 06W IS TRACKING ALONG THE
WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
A. THE FORECAST TRACK HAS SHIFTED TO THE EAST ABOUT 115 NM CLOSER
TO KADENA AB AT TAU 36, HOWEVER, THERE IS NO CHANGE TO THE OVERALL
FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS 06W WILL CONTINUE TRACKING GENERALLY POLEWARD THROUGH THE
NEXT 72 HOURS AS IT FOLLOWS THE PERIPHERY OF THE STR. SLOW
INTENSIFICATION IS EXPECTED AS THE SYSTEM ENTERS AN AREA OF MORE
FAVORABLE VWS. THE PEAK INTENSITY OF 50 KTS IS EXPECTED AROUND TAU
48. NUMERICAL MODEL TRACK GUIDANCE HAS HIGH SPREAD AFTER TAU 36,
PRIMARILY DUE TO TWO MEMBERS THAT REPRESENT THE WESTERN (ECMWF
ENSEMBLE MEAN) AND EASTERN (GFS) OUTLIERS. THE BULK OF THE GUIDANCE
ALIGNS WELL WITH THE CONSENSUS TRACK. THE JTWC TRACK FORECAST
CLOSELY FOLLOWS THE CONSENSUS TRACK BUT CONFIDENCE IS LOW DUE TO THE
HIGH SPREAD IN THE MODEL GUIDANCE, A RELATIVELY WEAK AND RE-
ORIENTING SUBTROPICAL STEERING RIDGE, AND HIGH UNCERTAINTY IN THE
POSITION OF THE LLCC AS THE MONSOON DEPRESSION CONSOLIDATES.
C. IN THE EXTENDED RANGE, TS 06W IS EXPECTED TO TURN NORTHEASTWARD
AND SLOWLY UNDERGO EXTRATROPICAL TRANSITION AS IT ENCOUNTERS A MID-
LATITUDE TROUGH. SLIGHT WEAKENING IS ANTICIPATED, ALTHOUGH
BAROCLINIC INTERACTION WITH THE TROUGH SHOULD ALLOW THE SYSTEM TO
MAINTAIN GALE FORCE OR STRONGER WINDS THROUGHOUT THE TRANSITION. THE
MODEL TRACKERS DEPICT A HIGHLY UNCERTAIN STORM TRACK IN THE EXTENDED
PERIOD, SO CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST
TRACK IS LOW.//
NNNN

[euro6208]

Sandwiched between 2 developing invest.

[JoshwaDone]

https://i.imgur.com/FoSFFvj.gif
https://imgur.com/FoSFFvj

how did you make the GIF tho?

[doomhaMwx]

ECMWF consistently predicting 200-300mm+ of rainfall for much of Northern and Central Luzon on the next 2 days.

https://i.imgur.com/XnGcPYt.png

Of course this did/will not materialize as Danas' deep convection decoupled too far west from the center. The expected copious rainfall amounts will fall over the South China Sea instead.

[NotoSans]

Recent ASCAT shows that Danas has merged with Invest 90W. Winds of 35-40KT under deep convection but the circulation appears elongated.

[1900hurricane]

 https://twitter.com/pppapin/status/1151655278372216833

[euro6208]

WDPN31 PGTW 180300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR
08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (DANAS), LOCATED APPROXIMATELY 179 NM
SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWARD AT 18 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
SHOWS THE CENTRAL CONVECTION CONTINUES TO BE SHEARED EASTWARD OF A
MOSTLY OBSCURED LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS
PLACED WITH FAIR CONFIDENCE BASED ON A RAGGED LLC FEATURE IN THE
172144Z SSMIS AND TRIANGULATED BETWEEN MULTIPLE SURFACE OBSERVATIONS.
THE INITIAL INTENSITY OF 35 KNOTS IS BASED THE DVORAK ESTIMATES OF
T2.5/35KTS FROM PGTW AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE
CYCLONE IS IN AN AREA OF MODERATE (20-25 KNOT) VERTICAL WIND SHEAR
(VWS) AND SUBSIDENCE ALONG THE NORTHWEST QUADRANT CAUSED BY AN INDUCED
MID-LATITUDE TROUGH OVER TAIWAN. HOWEVER, A STRONG POLEWARD OUTFLOW
AND WARM SEA SURFACE TEMPERATURES (SSTS AT 30C) ARE PROVIDING
VENTILATION AND FUEL TO THE STRUGGLING CONVECTION. TS 06W IS TRACKING
ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 06W WILL CONTINUE TRACKING POLEWARD THROUGH TAU 12 BEFORE
BEGINNING A NORTHEASTWARD TURN AS IT ROUNDS THE STR AXIS. THE
MARGINAL ENVIRONMENT WILL PROMOTE SLIGHT INTENSIFICATION TO 40 KNOTS
AT TAUS 12-24. AFTERWARD, COOLING SSTS, INCREASING VWS, THEN LAND
INTERACTION WILL GRADUALLY WEAKEN THE SYSTEM AND BY TAU 72, DISSIPATE
OVER THE RUGGED TERRAIN OF SOUTH KOREA EAST OF KUNSAN. NUMERICAL
MODELS ARE IN TIGHT AGREEMENT WITH MINIMAL SPREADING, LENDING HIGH
CONFIDENCE TO THE JTWC TRACK FORECAST.//
NNNN

[euro6208]

WDPN31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR
09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (DANAS), LOCATED APPROXIMATELY 200 NM
WEST-SOUTHWEST OF KADENA AB, HAS TRACKED NORTHWARD AT 18 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH DEEP
CONVECTION CONFINED TO THE EASTERN SEMICIRCLE. RECENT MSI (18/06-
08Z) INDICATES THE LLC MAY BE DECOUPLING AND DRIFTING NORTH-
NORTHWESTWARD, WHICH ADDS SOME UNCERTAINTY TO THE EARLY PHASE OF THE
FORECAST TRACK. A 180723Z SSMIS 91GHZ IMAGE ALSO INDICATES A
PARTIALLY-EXPOSED LLC WITH EXTENSIVE DEEP CONVECTIVE BANDING OVER
THE EAST AND SOUTHEAST QUADRANTS. A 180158Z ASCAT IMAGE CONTINUES TO
SHOW A HIGHLY ASYMMETRICAL WIND FIELD WITH AN EXTENSIVE SWATH OF 30
TO 40 KNOT WINDS OVER THE EASTERN SEMICIRCLE, WHICH EXTEND 180-200NM
EAST. OVERALL, THERE IS GOOD CONFIDENCE IN THE 18/06Z POSITION BASED
ON RADAR IMAGERY, SURFACE OBSERVATIONS AND MSI. THE INITIAL
INTENSITY IS ASSESSED AT 40 KNOTS, HEDGED ABOVE DVORAK INTENSITY
ESTIMATES OF T2.5 (35 KNOTS) BASED ON THE AFOREMENTIONED ASCAT DATA.
UPPER-LEVEL ANALYSIS DEPICTS A GENERALLY FAVORABLE ENVIRONMENT WITH
LOW VERTICAL WIND SHEAR AND FAIR OUTFLOW. TS 06W IS TRACKING
NORTHWARD ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED
SUBTROPICAL RIDGE.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. FORECAST WIND RADII ARE BASED
ON THE WIND RADII CONSENSUS (RVCN).
B. TS 06W IS FORECAST TO TRACK NORTHWARD TO NORTH-NORTHEASTWARD
THROUGH TAU 48 ALONG THE NORTHWEST PERIPHERY OF THE SUBTROPICAL
RIDGE (STR). AFTER TAU 48, THE SYSTEM WILL BEGIN TO ROUND THE STR
AND WILL BEGIN TO INTERACT WITH RELATIVELY WEAK MIDLATITUDE
WESTERLIES OVER THE KOREAN PENINSULA. THERE IS MODERATE UNCERTAINTY
IN THE FORECAST TRACK DUE TO THE ASYMMETRIC NATURE OF THE SYSTEM
WITH POTENTIAL FOR A WESTWARD TRACK SHIFT AND LANDFALL ALONG THE
SOUTHWEST COAST OF KOREA IF THE SYSTEM REMAINS DECOUPLED.
FURTHERMORE, THE EXPANSIVE GALE FORCE WINDS OVER THE EASTERN
SEMICIRCLE ARE EXPECTED TO PERSIST DUE TO AN ENHANCED GRADIENT WITH
A STRONG HIGH TO THE EAST. TS 06W IS FORECAST TO INTENSIFY SLIGHTLY
TO A PEAK OF 45 KNOTS BUT SHOULD WEAKEN STEADILY THROUGH TAU 48.
AFTER LANDFALL, THE SYSTEM WILL WEAKEN RAPIDLY OVER THE MOUNTAINOUS
TERRAIN OF KOREA AND SHOULD DISSIPATE BY TAU 72. OVERALL, THERE IS
MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK WITH A SPREAD OF
200NM AT TAU 48.//
NNNN

[euro6208]

WDPN31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (DANAS) WARNING NR
11//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 06W (DANAS), LOCATED APPROXIMATELY 225 NM
WEST-NORTHWEST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWARD AT
10 KNOTS KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION REMAINS SHEARED
AND OFFSET EASTWARD OF A MOSTLY EXPOSED LOW LEVEL CIRCULATION (LLC).
A LARGE FEEDER BAND TRAILS THE LLC SOUTHWESTWARD TOWARD TAIWAN AND
INTO A TROPICAL DISTURBANCE (INVEST 91W). THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE LLC FEATURES IN THE EIR LOOP
AND A COMPOSITE RADAR REFLECTIVITY LOOP FROM JMA. THE INITIAL
INTENSITY OF 35 KNOTS IS BASED THE DVORAK ESTIMATES OF T2.5/35KTS
FROM PGTW AND RJTD AND CONSISTENT WITH RECENT ASCAT DATA. UPPER LEVEL
ANALYSIS INDICATES THE CYCLONE IS IN AN AREA OF MODERATE (20-25 KNOT)
VERTICAL WIND SHEAR (VWS) WITH SUBSIDENCE ALONG THE NORTHWEST
QUADRANT CAUSED BY AN INDUCED MID-LATITUDE TROUGH DIGGING IN FROM THE
NORTHWEST. HOWEVER, A STRONG POLEWARD OUTFLOW AND WARM SEA SURFACE
TEMPERATURES (SSTS AT 30C) ARE PROVIDING VENTILATION AND FUEL TO THE
ASSOCIATED CONVECTION. TS 06W IS TRACKING ALONG THE WESTERN PERIPHERY
OF A SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 06W WILL BEGIN TO TRACK NORTH-NORTHEASTWARD TO NORTHEASTWARD
AS IT ROUNDS THE STR AXIS. THE MARGINAL ENVIRONMENT WILL PROMOTE
SLIGHT INTENSIFICATION TO 45 KNOTS AT TAUS 12-24. AFTERWARD, COOLING
SSTS, INCREASING VWS, THEN LAND INTERACTION WILL GRADUALLY THEN
RAPIDLY WEAKEN THE SYSTEM AND, BY TAU 72, DISSIPATE IN THE SEA OF
JAPAN AFTER IT CROSSES THE RUGGED TERRAIN OF SOUTH KOREA. NUMERICAL
MODELS ARE IN GOOD AGREEMENT WITH SPREADING TO OVER 300 NM AT TAU 72,
LENDING MODERATE CONFIDENCE TO THE JTWC TRACK FORECAST UP TO TAU 36
THEN LOW CONFIDENCE AFTERWARD.//
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