WPAC: Ampil - Low

[Twisted-core]

ASCAT data are prone to land contamination. Surface observations from China suggested that landfall pressure is near 980 mb, which, combined with surface observations from Okinawa, clearly suggested that it was NOT a typhoon.

It tightened up on approach. Without actual surface obs @ the point of impact how can you be certain there was no 64kt wind amongst the 50
flags before land fiction was in play.

[doomhaMwx]

Maintaining TS strength over Eastern China...

TS 1810 (Ampil)
Issued at 06:50 UTC, 23 July 2018

<Analysis at 06 UTC, 23 July>
Scale -
Intensity -
Center position N35°20' (35.3°)
E118°40' (118.7°)
Direction and speed of movement NNW 15 km/h (9 kt)
Central pressure 992 hPa
Maximum sustained wind speed 18 m/s (35 kt)
Maximum wind gust speed 25 m/s (50 kt)
≥ 30 kt wind area E 220 km (120 NM)
W 110 km (60 NM)

[doomhaMwx]

Persistent deep convection north of the center despite being overland for quite some time now.
Radar image from Shandong province:

[NotoSans]

ASCAT data are prone to land contamination. Surface observations from China suggested that landfall pressure is near 980 mb, which, combined with surface observations from Okinawa, clearly suggested that it was NOT a typhoon.

It tightened up on approach. Without actual surface obs @ the point of impact how can you be certain there was no 64kt wind amongst the 50
flags before land fiction was in play.

ASCAT are prone to land contamination, i.e. those 50 knots wind barbs are likely too high in the first place as they are very close to the shore.

[euro6208]

WDPN32 PGTW 230900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W (AMPIL) WARNING
NR
23//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION (TD) 12W (AMPIL), LOCATED APPROXIMATELY 399 NM
WEST OF KUNSAN AB, SOUTH KOREA, HAS TRACKED NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS THE LOW LEVEL STRUCTURE OF TD 12W REMAINS SYMMETRIC. HOWEVER,
THERE IS LIMITED DEEP CONVECTION LOCATED TO THE NORTH OF THE LOW
LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH
FAIR CONFIDENCE BASED ON A 230600Z HIMAWARI VISIBLE SATELLITE IMAGE
WHICH SHOWS THE BROAD NATURE OF THE LLCC. THE INITIAL INTENSITY OF 30
KNOTS IS BASED ON A WEAKENING TREND OVER LAND, COASTAL SURFACE
OBSERVATIONS BETWEEN 25 TO 30 KNOTS, AND HEDGED BELOW AN ADT CURRENT
INTENSITY (CI) ESTIMATE OF T2.7 (39 KNOTS). ENVIRONMENTAL ANALYSIS
REVEALS THAT TD 12W HAS WEAK POLEWARD OUTFLOW AND NO EQUATORWARD
OUTFLOW. HOWEVER, VERTICAL WIND SHEAR IS FAVORABLE, BETWEEN 5 AND 10
KNOTS. TD 12W IS CURRENTLY OVER LAND WHICH WILL INHIBIT DEVELOPMENT.
HOWEVER, SEA SURFACE TEMPERATURES OFF THE COAST OF CHINA ARE BETWEEN
25 TO 27 DEGREES CELSIUS. TD 12W IS TRACKING NORTHWESTWARD ALONG THE
WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) WHICH IS LOCATED TO
THE EAST.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TD 12W WILL CONTINUE TO TRACK NORTHWESTWARD UNDER THE INFLUENCE
OF THE AFOREMENTIONED STR. TD 12W WILL REMAIN OVER LAND THROUGH TAU
18 WHICH WILL ALLOW FOR A STEADY DECREASE IN INTENSITY. WEAK UPPER
LEVEL OUTFLOW WILL ALSO CONTRIBUTE TO THE WEAKENING TREND. NEAR TAU
18, TD 12W WILL EMERGE BACK OVER WATER AS IT TRACKS ACROSS BOHAI BAY
WHERE SEA SURFACE TEMPERATURES ARE BETWEEN 25 TO 27 DEGREES CELSIUS.
INTERACTION WITH BOHAI BAY WILL TEMPORARILY PAUSE THE WEAKENING
TREND. BY TAU 24, TD 12W WILL TRACK BACK OVER LAND AND ROUND THE
WESTERN EDGE OF THE STR AND TRACK NORTHEASTWARD AS IT CONTINUES TO
DECREASE IN INTENSITY. TD 12W WILL DISSIPATE OVER LAND BY TAU 36.
DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK. //
NNNN

[euro6208]

WTPN32 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FINAL WARNING//
RMKS/
1. TROPICAL DEPRESSION 12W (AMPIL) WARNING NR 025
05 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
231800Z --- NEAR 38.2N 117.5E
MOVEMENT PAST SIX HOURS - 335 DEGREES AT 15 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
REPEAT POSIT: 38.2N 117.5E
---
FORECASTS:
12 HRS, VALID AT:
240600Z --- 40.7N 118.0E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 24 HR POSIT: 035 DEG/ 15 KTS
---
24 HRS, VALID AT:
241800Z --- 43.0N 120.4E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
232100Z POSITION NEAR 38.8N 117.6E.
TROPICAL DEPRESSION 12W (AMPIL), LOCATED APPROXIMATELY 433 NM
WEST OF INCHON, SOUTH KOREA, HAS TRACKED NORTH-NORTHWESTWARD AT
15 KNOTS OVER THE PAST SIX HOURS.TD 12W CURRENTLY LIES OVER LAND
JUST WEST OF THE EXTREME WESTERN BOHAI BAY. THE SYSTEM IS FORECAST
TO ACCELERATE TO THE NORTH AND THEN NORTHEAST WHILE DISSIPATING OVER
NORTHERN CHINA WITHIN THE NEXT 24 HOURS. THIS IS THE FINAL WARNING
ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE
SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
REFER TO TROPICAL STORM 11W (SON-TINH) WARNINGS (WTPN33 PGTW) FOR
SIX-HOURLY UPDATES. REFER TO TROPICAL CYCLONE 13W (THIRTEEN) FOR THE
FINAL WARNING ON THAT SYSTEM (WTPN31 PGTW). REFER TO TROPICAL STORM
14W (WUKONG) WARNINGS (WTPN34 PGTW) FOR SIX-HOURLY UPDATES. REFER TO
TROPICAL DEPRESSION 15W (FIFTEEN) WARNINGS (WTPN35 PGTW) FOR SIX-
HOURLY UPDATES.//
NNNN