WPAC: LIONROCK - Post-Tropical

[euro6208]

WDPN34 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 44//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 12W (LIONROCK), LOCATED APPROXIMATELY 356 NM SOUTH OF
YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 17 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS
TIGHT SPIRAL BANDING WRAPPING INTO A WELL DEFINED 18 NM EYE WITH
DEEP CONVECTION STARTING TO WEAKEN. THE INITIAL POSITION IS BASED ON
SATELLITE EYE FIXES FROM PGTW AND RGTD WITH GOOD CONFIDENCE. THE
INITIAL INTENSITY IS ASSESSED AT 110 KNOTS AND IS BASED ON DROPPING
DVORAK ESTIMATES FROM ALL AGENCIES WITH THE CURRENT INTENSITY STILL
BEING HELD AT T6.0 (115 KNOTS). UPPER-LEVEL ANALYSIS INDICATES
SIGNIFICANT DISRUPTION TO OUTFLOW OVER THE LAST SIX HOURS. THE
DEEPENING TROUGH TO THE NORTHWEST IS CREATING STRONG SOUTHWESTERLY
FLOW AND RESTRICTING THE EQUATORWARD CHANNEL. A TUTT CELL TO THE
NORTHEAST IS FURTHER EXACERBATING THE RESTRICTED EXHAUST OVER THE
SYSTEM. CURRENTLY TY 12W IS TRACKING NORTHEASTWARD ALONG THE
EXTENSION OF A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. IN THE SHORT TERM FORECAST, TY 12W IS EXPECTED TO CONTINUE TO
TRACK NORTHEASTWARD UNDER THE INFLUENCE OF THE NER WHILE UNDERGOING
SIGNIFICANT WEAKENING IN THE NEXT 24 HOURS AS IT TRACKS INTO COOLER
WATERS AND UPPER-LEVEL CONDITIONS CONTINUE TO DETERIORATE. BEYOND
TAU 24, STEERING WILL BEGIN TO SHIFT TO A NORTHERN DEEP-LAYERED
RIDGE ANCHORED NEAR THE KURIL ISLANDS AND TURN TY 12W ON A
NORTHWESTERLY TRACK INTO THE DEEPENING TROUGH OVER JAPAN. LANDFALL
IS EXPECTED OVER NORTHERN HONSHU AROUND TAU 36 SOMEWHERE NEAR
SENDAI, JAPAN WITH THE INTENSITY NEAR 70 KNOTS. TY 12W IS EXPECTED
TO START EXTRATROPICAL TRANSITION AFTER TAU 36 AS IT BEGINS TO
INTERACT WITH BAROCLINIC ZONE WITHIN THE TROUGH. THE MOUNTAINOUS
TERRAIN OF NORTHERN HONSHU WILL SIGNIFICANTLY DISRUPT THE LOW LEVEL
WIND FLOW RESULTING IN SEVERELY WEAKENED SYSTEM BY TAU 48 AS IT
RESURFACES OVER THE SEA OF JAPAN WITH AN INTENSITY OF APPROXIMATELY
45 KNOTS. TY 12W IS EXPECTED TO BECOME FULLY EXTRATROPICAL BY TAU 72
AS IT TRACKS INTO MANCHURIA. DYNAMIC MODEL GUIDANCE HAS COME INTO
MUCH BETTER AGREEMENT OVER THE LAST TWELVE HOURS SHOWING TIGHTER
GROUPING DURING THE NORTHWEST TURN AND TRANSITION INTO THE TROUGH.
THE GFDN AND COAMPS-TC SOLUTIONS ARE THE FAR EASTWARD OUTLIERS
SHOWING A MUCH WIDER AND SLOWER TURN WHICH DOESN'T REFLECT THE
CURRENT SYNOPTIC SITUATION WELL. THE JGSM ENSEMBLE MEAN REMAINS THE
FAR WESTWARD SOLUTION SHOWING A TIGHTER TURN, BUT IS NOW CLOSER TO
THE REST OF THE GROUP, REFLECTING LESS VARIATION IN THE ENSEMBLE
MEMBERS. THE FORECAST TRACK IS PLACED CLOSE TO THE GLOBAL MODELS,
GFS, ECMFW, NAVGEM, UKMET, AND JGSM WHICH SHOW CLOSE GROUPING
THROUGH TAU 48 AS IT TRACKS OVER HONSHU. THERE STILL IS A DEGREE OF
UNCERTAINTY IN THE EXACT POSITION AND TIMING OF THE NORTHWESTWARD
TURN, BUT DUE TO BETTER AGREEMENT OF GLOBAL SOLUTIONS THERE IS GOOD
CONFIDENCE IN THE FORECAST TRACK.//
NNNN

[1900hurricane]

115 kt looks reasonable to me, although a case for 120 kt could be made given the slight low bias of Dvorak values (~3-4 kt) on storms at higher latitude.

Yeah, I'd probably assess a max intensity of 120 kt or so at 06Z. Subjective Dvorak analysis never yielded anything higher than a T6.0 I believe, but due to ADT, AMSU, and SSMIS microwave scores (the 0622Z pass was particularly impressive), mean SATCON values actually pushed up as high as 127 kt. A 120 kt intensity estimate for that time essentially splits the difference.





Needless to say, Lionrock is not a 115 kt storm anymore.

[euro6208]

WDPN34 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 46//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 12W (LIONROCK), LOCATED APPROXIMATELY 281 NM
SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 12 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS RAPIDLY DECAYING DEEP CONVECTION OVER THE NORTHERN
SEMI-CIRCLE OF A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC). A 290458Z SSMI 85GHZ IMAGE SHOWS A PARTIAL EYEWALL OVER THE
SOUTH QUADRANT OF THE LLCC WITH DEEP CONVECTIVE BANDING OVER THE
SOUTHERN SEMI-CIRCLE. OVERALL, THERE IS GOOD CONFIDENCE IN THE
CURRENT POSITION BASED ON THE MSI. ANIMATED WATER VAPOR IMAGERY
INDICATES A WEAK POLEWARD CHANNEL, HOWEVER, UPPER-LEVEL TROUGHING IS
PRESSING ON THE WESTERN SEMI-CIRCLE AND EASTERN SEMI-CIRCLE OF THE
SYSTEM. THE CURRENT INTENSITY IS ASSESSED AT 85 KNOTS HEDGED JUST
BELOW DVORAK CURRENT INTENSITY ESTIMATES OF 90 KNOTS BASED ON THE
WEAKENED STRUCTURE AND A 290540Z SATCON ESTIMATE OF 77 KNOTS. TY 12W
IS TRACKING NORTHEASTWARD ALONG A POLEWARD EXTENSION OF A NEAR
EQUATORIAL RIDGE TO THE SOUTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE. THIS FORECAST TRACK REMAINS HIGHLY
CONSISTENT WITH THE PREVIOUS JTWC FORECAST TRACK. THE 34-KNOT WIND
RADII REMAIN EXPANSIVE OVER THE SOUTHERN SEMI-CIRCLE AS EVIDENCED IN
RECENT SCATTEROMETER IMAGERY.
B. TY 12W IS FORECAST TO TURN NORTHWARD AND TRACK ALONG THE
WESTERN PERIPHERY OF A BROAD RIDGE TO THE EAST THROUGH TAU 24. THE
LATEST 500MB ANALYSIS SHOWS THIS REX BLOCK BUILT NORTH INTO THE
SAKHALIN ISLAND REGION WITH RIDGING EXTENDING WESTWARD, WHICH WILL
PROVIDE THE PRIMARY STEERING INFLUENCE THROUGH TAU 48. ADDITIONALLY,
AN EXPANSIVE UPPER LOW, WHICH REMAINS QUASI-STATIONARY OVER THE EAST
SEA, WILL ENHANCE THE STEERING FLOW AND PRODUCE AN ACCELERATED TRACK
ACROSS THE EAST SEA. DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT
WITH THE TRACK ACROSS NORTHERN HONSHU AND THE EAST SEA, THEREFORE,
THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. ADDITIONALLY,
ENSEMBLE GUIDANCE IS ALSO IN EXCELLENT AGREEMENT WITH THE FORECAST
TRACK. TY 12W IS FORECAST TO CONTINUE WEAKENING AS IT TRACKS
POLEWARD AND ENCOUNTERS COOLER SST AND INCREASING VERTICAL WIND
SHEAR ASSOCIATED WITH THE LARGE BAROCLINIC LOW. TY 12W WILL MAKE
LANDFALL AFTER TAU 24 AND IS FORECAST TO RAPIDLY WEAKEN DUE TO LAND
INTERACTION AS IT TRACKS OVER THE MOUNTAINOUS TERRAIN OF NORTHERN
HONSHU. TY 12W SHOULD BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU
24 AND WILL COMPLETE ETT BY TAU 48 AS IT MERGES WITH THE BAROCLINIC
LOW.//
NNNN

[1900hurricane]

Definitely starting the process of extratropical transition.

[euro6208]

WDPN34 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (LIONROCK) WARNING NR 48//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON (TY) 12W (LIONROCK), LOCATED APPROXIMATELY 382 NM
SOUTH-SOUTHEAST OF MISAWA, JAPAN, HAS TRACKED NORTHWARD AT 16 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY DEPICTS RAPIDLY DECAYING DEEP CENTRAL CONVECTION THAT IS
DISPLACED JUST EAST OF THE LOW-LEVEL CIRCULATION CENTER. THE INITIAL
POSITION IS BASED ON THE EIR LOOP AND ON A LOW REFLECTIVITY
CIRCULATION FEATURE ON THE 291739Z AMSU-B MICROWAVE PASS WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 65 KNOTS IS BASED ON AN OVERALL
ASSESSMENT OF AGENCY AND OBJECTIVE DVORAK ESTIMATES AND REFLECTS THE
WEAKENED STATE OF THE SYSTEM. UPPER LEVEL ANALYSIS INDICATES TY 12W
IS SOUTH OF THE RIDGE AXIS IN AN AREA OF LOW TO MODERATE (10-15 KNOT)
WESTERLY VERTICAL WIND SHEAR (VWS). ADDITIONALLY, A TROUGH TO THE
WEST IS CAUSING SUBSIDENCE ALONG THE WESTERN SEMI-CIRCLE. THERE IS,
HOWEVER, MODERATE SOUTHEASTWARD OUTFLOW. THESE DYNAMICS ARE EVIDENT
ON EIR AND WATER VAPOR ANIMATIONS. THE CYCLONE IS TRACKING ALONG THE
WESTERN PERIPHERY OF A RIDGE EXTENSION TO THE EAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE
THE PREVIOUS PROGNOSTIC REASONING MESSAGE EXCEPT THAT THE TERMINATION
PHASE OF THE FORECAST HAS BEEN CHANGED FROM EXTRA-TROPICAL TRANSITION
TO DISSIPATION.
B. TY LIONROCK IS EXPECTED TO BEGIN TRACKING MORE NORTHWESTWARD
OVER THE NEXT 12 HOURS AS STEERING TRANSITIONS TO THE SUBTROPICAL
RIDGE TO THE NORTHEAST ANCHORED NEAR 45N SOUTH OF KAMCHATKA. THE
SYSTEM WILL CROSS JAPAN NEAR SENDAI AND DRIFT ACROSS THE SEA OF JAPAN
(SOJ) BEFORE MAKING A FINAL LANDFALL IN RUSSIA NEAR VLADIVOSTOK.
ALTHOUGH VWS IS EXPECTED TO RELAX BEFORE JAPAN, UPPER-LEVEL
SUBSIDENCE AND COOLING SEA SURFACE TEMPERATURES (SSTS) WILL CONTINUE
TO WEAKEN THE SYSTEM. AFTERWARD, RAPID DECAY IS EXPECTED AS THE
SYSTEM TRACKS ACROSS RUGGED TERRAIN, COOLER SSTS, AND HIGH VWS
(GREATER THAN 40 KNOTS) IN THE SOJ. TY 20W WILL DISSIPATE BEFORE IT
MAKES LANDFALL IN RUSSIA. DYNAMIC GUIDANCE REMAINS IN TIGHT
AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST
TRACK.//
NNNN

[Hammy]

How will the surge compare to Sandy? I've been reading that this is coming in close to where the tsunami was at a few years back and they really don't need anything like that there.

[1900hurricane]

How will the surge compare to Sandy? I've been reading that this is coming in close to where the tsunami was at a few years back and they really don't need anything like that there.

I'm not sure really. There is a little bit of Continental Shelf off the coast, but then it drops off immediately into a deep trench, so I'm not sure which is the more important factor as far as bathymetry goes. Per meteorologist (and site user) Robert Speta, this portion of Japan has never seen a direct tropical cyclone landfall of any intensity, so there are no analogs to fall back on there. Surge mechanisms also are very different from what drives tsunamis, so the big one from five years ago isn't a good comparison either. Perhaps someone with more in-depth surge expertise or surge modeling capabilities could figure out something more definitive than me because I'm in the dark and don't know what to expect really.

If I were to venture a guess though, I think the surge will be considerably less significant than the one observed in Sandy '12.

[euro6208]

WDPN34 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (LIONROCK) WARNING
NR 50//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 12W (LIONROCK), LOCATED APPROXIMATELY 164 NM
SOUTH OF MISAWA, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 18 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS AN ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC) WITH
A WEAKENING CONVECTIVE STRUCTURE THAT IS PUSHING NORTH OF THE LLCC.
WATER VAPOR IMAGERY SHOWS THAT THE SYSTEM HAS CONNECTED WITH THE
BOUNDARY EXTENDING FROM A LOW PRESSURE SYSTEM LOCATED IN THE SEA OF
JAPAN. THE CURRENT POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON
A 300536Z GPM 91GHZ MICROWAVE IMAGE, RADAR IMAGERY FROM TOHUKU,
JAPAN, AND THE PARTIALLY EXPOSED LLCC IN THE MSI LOOP. THE INTENSITY
HAS BEEN HELD AT 55 KNOTS BASED ON UNCHANGED CURRENT INTENSITY
ESTIMATES RANGING FROM 55 TO 65 KNOTS AND A 300102Z ASCAT BULLSEYE
SHOWING A LARGE SWATH OF 55 KNOT WINDS ALONG THE NORTHERN SEMI-
CIRCLE. ADDITIONALLY, THE INTENSITY IS SUPPORTED BY OBSERVATIONS
FROM SENDAI, JAPAN (APPROXIMATELY 45NM NORTHWEST OF THE LLCC) WHICH
HAVE SHOWN A MAXIMUM WIND GUST OF 40 KNOTS OVER THE PAST COUPLE
HOURS. TS LIONROCK IS IN A MARGINALLY-POOR ENVIRONMENT WITH A STRONG
VERTICAL WIND SHEAR (VWS) GRADIENT (20-60 KNOTS) TO THE WEST AND
SUBSIDENCE DUE TO UPPER LEVEL TROUGHING EXTENDING OVER THE WESTERN
AND SOUTHERN PORTIONS OF THE SYSTEM. DIVERGENT OUTFLOW ALONG THE
NORTHERN PERIPHERY HAS SUSTAINED THE CONVECTION SEEN IN SATELLITE
IMAGERY. TS LIONROCK IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF
A DEEP-LAYERED SUB-TROPICAL RIDGE TO THE NORTHEAST.
3. FORECAST REASONING.
A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. OVER THE NEXT FEW HOURS, TS LIONROCK WILL MAKE LANDFALL JUST
NORTH OF SENDAI, JAPAN AND MOVE INTO THE SEA OF JAPAN. AS THE SYSTEM
CROSSES HONSHU, THE COMBINATION OF LAND INTERACTION, INCREASED VWS
AND INTERACTION WITH THE MID-LATITUDE LOW PRESSURE SYSTEM IN THE SEA
OF JAPAN WILL RESULT IN A RAPID DECAY OF THE SYSTEM. JUST PRIOR TO
TAU 24, THE SYSTEM WILL MAKE A FINAL LANDFALL NEAR VLADIVOSTOK,
RUSSIA. ALTHOUGH TS 12W WILL UNDERGO EXTRA-TROPICAL TRANSITION AS IT
INTERACTS WITH THE AFOREMENTIONED LOW PRESSURE SYSTEM, IT WILL
CONCURRENTLY DISSIPATE OVER LAND DUE TO THE POOR ENVIRONMENTAL
CONDITIONS. DYNAMIC MODEL GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT
THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

[1900hurricane]

The saga is over.

LOW
Issued at 15:45 UTC, 30 August 2016

<Analysis at 15 UTC, 30 August>
Scale -
Intensity -
LOW
Center position N42°00' (42.0°)
E138°00' (138.0°)
Direction and speed of movement NW 75 km/h (40 kt)
Central pressure 976 hPa