Post Storm Hurricane Report
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ACPQ70 PGUM 201316
PSHPQ

POST TROPICAL CYCLONE REPORT...TROPICAL STORM SANBA (02W)
NATIONAL WEATHER SERVICE TIYAN GU
1100 PM CHST TUE MARCH 20 2018

PRELIMINARY/FINAL REPORT ON THE EFFECTS OF TROPICAL STORM SANBA
(02W) FROM 6 TO 12 FEB 2018.

THE SYSTEM THAT WOULD BECOME TS SANBA FORMED IN A PRE-EXISTING
NEAR-EQUATORIAL TROUGH WELL SOUTH OF CHUUK AND POHNPEI. ON 6 FEB A
WEAK CIRCULATION CENTER BECAME BETTER ORGANIZED AND JTWC RAISED IT
TO `LOW POTENTIAL`, AND PLACED THE CENTER NEAR 3N156E. THE SYSTEM
WAS SLOW TO DEVELOPED AS THE SYSTEM REMAINED UNDER STRONG VERTICAL
SHEAR, WHILE PUSHING CONVECTION AWAY FROM THE CENTER TO THE NORTH
AND WEST DURING THE NEXT SEVERAL DAYS. THE EXACT POSITION OF THE
SURFACE CENTER WAS DIFFICULT TO LOCATE DURING THIS TIME EXCEPT FOR
EITHER A RARE VIEW OF THE EXPOSED SURFACE CUMULUS OR DURING AN EVEN
RARER OVERHEAD SCAT PASS. HOWEVER ON 7 FEB AT AROUND 17Z, THE CENTER
PASSED VERY CLOSE TO CHUUK AS EVIDENCED IN BOTH THE SURFACE OBS AND
UPPER AIR SOUNDINGS. BY THAT TIME, JTWC HAD THOUGHT IT HAD MOVED
WELL TO THE NORTH AND WEST OF CHUUK AND SO THEY NEEDED TO RELOCATE
THE CENTER NEARER TO CHUUK BEFORE ISSUING A TCFA AT 07/22Z. TWENTY-
FOUR HOURS LATER, THE FIRST WARNING WAS ISSUED ON TD02W AT 08/1800Z
TO THE SOUTHEAST OF GUAM NEAR 10.8N 147.8E. HOWEVER SHEARING
CONTINUED TO EXIST MAKING POSITIONING DIFFICULT, AS ROTATING
CONVECTION CONTINUED TO IMPLY A FALSE MOVEMENT TOWARDS GUAM.
FORTUNATELY, SOME BRIEF VIEWS IN THE HI-RESOLUTION VISUAL IMAGERY
SHOWED INDICATIONS THAT THE SURFACE CENTER WAS STILL DRIFTING TO THE
WEST OR EVEN WEST-SOUTHWEST STAYING NEAR 10N. FINALLY A CLEAR
SCATTEROMETER AND MICROWAVE PASS SHOWED THE CENTER HAD PROBABLY RE-
FORMED FARTHER TO THE SOUTHWEST IN A NORTH-SOUTH ORIENTATED TROUGH,
WELL SOUTH OF THE MARIANAS NEAR 8.8N 143.3E. TD02W CONTINUED TO BE A
DIFFICULT SYSTEM TO LOCATE AS IT DRIFTED TOWARDS THE REPUBLIC OF
PALAU. AT ONE POINT IT WAS THOUGHT TO HAVE REACHED TYPHOON INTENSITY
JUST TO THE EAST OF KOROR. FORTUNATELY, SHORTLY AFTER THAT FALSE
SATELLITE ESTIMATE, THE WELL EXPOSED LOW LEVEL CENTER BECAME CLEARLY
EVIDENT IN  VISUAL IMAGERY WELL TO THE SOUTH AND EAST OF KOROR. ON
11 FEB 00Z IT WAS CLEARLY LOCATED NEAR 6N 137E. AFTER THIS, THE
SYSTEM MOVED TOWARDS THE WEST AND JUST SOUTH OF KOROR AND XM STATION
XM21 AROUND 11FEB12Z AS EITHER A 30KT TD OR A WEAK 35KT TS. IT WAS
ALSO AT THIS TIME THAT JMA FINALLY NAMED THE SYSTEM, SANBA. PEAK
WINDS OF 30KT WERE MEASURED AT THE XM STATION, ON THE OUTER REEF,
AND 32KT AT THE KOROR WEATHER STATION WERE RECEIVED AT THIS TIME OF
CPA.

A. LOWEST SEA LEVEL PRESSURE/MAXIMUM SUSTAINED WINDS AND PEAK GUSTS
---------------------------------------------------------------------
METAR OBSERVATIONS...
NOTE: ANEMOMETER HEIGHT IS 10 METERS AND WIND AVERAGING IS 2 MINUTES
---------------------------------------------------------------------
LOCATION  ID    MIN    DATE/     MAX      DATE/     PEAK    DATE/
LAT  LON        PRES   TIME      SUST     TIME      GUST    TIME
DEG DECIMAL     (MB)   (UTC)     (KT)     (UTC)     (KT)    (UTC)
---------------------------------------------------------------------
CHUUK (PTKK)     1004.5 07/1754Z 12KT (NO PEAK)...SEVERAL TIMES
 .5N 151.9E                                       PRIOR TO CPA.

GUAM (PGUM)     1008.6  09/0454Z  06021G29KT 10/0054Z (MAX)
13.5 144.8E            (NOTE: LOWER AT PGUA)

YAP(PTYA)        1005.2 10/1753Z  06012G22KT 101851Z AND
 9.5N 138.1E                      16014G20KT AT 11/0037Z

KOROR,PALAU (PTKR) 1002.8 11/1053Z  35013KT 11/0853Z  G32KT 11/1155Z
7.3N 134.4E

XM21 (PALAU) (APPROX) 1001.3  11/1200Z  04530G41KT 11/1200Z (MAX)
7.27N 134.24E (SPECIAL STATION ON WESTERN REEF)

REMARKS: NO DATA AVAILABLE FROM NGULU, FAIS, ULITHI OR KAYANGEL.

B. MARINE OBSERVATIONS...
---------------------------------------------------------------------
LOCATION  ID    MIN    DATE/     MAX      DATE/     PEAK    DATE/
LAT  LON        PRES   TIME      SUST     TIME      GUST    TIME
DEG DECIMAL     (MB)   (UTC)     (KT)     (UTC)     (KT)    (UTC)
---------------------------------------------------------------------
REMARKS:

REPORTED SEAS AND SWELLS
IPAN BUOY - EASTERLY SWELLS OF 12 TO 15FT

C. STORM TOTAL RAINFALL
---------------------------------------------------------------------
LOCATION      ID        TIME PERIOD               RAINFALL
LAT LON                                             (IN)
DEG DECIMAL
---------------------------------------------------------------------

CHUUK (PTKK)    06/12Z THRU 08/00Z    0.75 INCHES
7.5N 151.9E

GUAM (PGUM)    08/12Z THRU 09/12Z 0.28 INCHES
 13.5 144.8E

YAP(PTYA)       09/12Z THRU 11/12Z  2.18 INCHES
9.5N 138.1E

KOROR,PALAU (PTKR)  10/12Z THRU 11/15Z   3.89 INCHES
7.3N 134.4E

XM21 (PALAU) APPROX IN 24HR 5.2 INCHES THRU 11/1200Z (NO RAIN AFTER)
7.27N 134.24E


REMARKS:NO OTHER REPORTS.

D. INLAND FLOODING...COASTAL EROSION REPORTED
---------------------
NONE REPORTED OR EXPECTED.

---------------------------------------------------------------------

E. MAXIMUM STORM SURGE AND STORM TIDE...
---------------------------------------------------------------------
LOCATION                      SURGE   TIDE   DATE/   BEACH
                              (FT)    (FT)   TIME    EROSION
---------------------------------------------------------------------
NONE NOTED.

F. TORNADOES...
---------------------------------------------------------------------
LOCATION                        DATE/         EF SCALE
LAT LON (DEG DECIMAL)           TIME(UTC)    (IF KNOWN)
DESCRIPTION
---------------------------------------------------------------------
NONE.


G. STORM IMPACTS BY ISLAND...
---------------------------------------------------------------------
LOCATION           DEATHS           INJURIES             EVACUATIONS
DESCRIPTION
---------------------------------------------------------------------
REMARKS: NONE REPORTED.

H. REMARKS...

THE FOLLOW BULLETINS WERE ISSUED BY WFO GUAM

  15 - TC PUBLIC ADVISORIES (TCP)...BETWEEN 7 FEB - 12 FEB
  12 - TC INTERMEDIATE PUBLIC ADVISORIES
  12 - HLS TYPHOON LOCAL STATEMENTS
   4 - SPS SPECIAL WEATHER STATEMENTS FOR THE MARIANAS (1)
       AND FOR THE MICRONESIAN STATES OF CHUUK, YAP AND PALAU (3)


       NOTE: SMALL CRAFT ADVISORIES AND HIGH SURF ADVISORIES/
            WARNINGS WERE ISSUED FOR THE SOUTHERN MARIANA ISLANDS
            AND YAP AND KOROR (AFTER THE TS CANCELLATIONS.

TIMES IN UTC
09FEB0200 (9 FEB 200PM CHST) TS WATCH FOR YAP...FAIS...
                                   ULITHI AND NGULU
09FEB 1222 (9 FEB 1022 PM CHST) ADDED TS WATCH FOR KAYANGEL
10FEB 0907 (10 FEB 709 PM CHST) ADDED TS WATCH FOR KOROR
10FEB 1545 (11 FEB 145 AM CHST) TS WARNING FOR KAYANGEL AND KOROR
10FEB 2159 (11 FEB 759 AM CHST) CANC TS WATCH FOR FAIS AND ULITHI
11FEB 0426 (11 FEB 226 PM CHST) CANC TS WATCH FOR YAP AND NGULU
11FEB 1900 (12 FEB 500 AM CHST) TS WARNING CANCELLED FOR KOROR AND
                                          KAYANGEL

06FEB0600 JTWC LOW AREA
07FEB0600 JTWC MEDIUM AREA
07FEB2230 JTWC TCFA
08FEB1800 JTWC TD 02W
10FEB1800 JTWC TS 02W
11FEB1200 JMA TS SANBA
12FEB0600 LAST JTWC WRNG IN AOR

NOTE: NO OTHER SIGNIFICANT REPORTS

LEGEND:
I-INCOMPLETE DATA
E-ESTIMATED

$$

EDSON
WFO GUAM


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