Page Updated 06/27/05
JTWC cover page


  1. 1.  Certain words and phrases that appear frequently in this report are abbreviated as follows:
Abbreviation Meaning
ACFT Aircraft
APPR(S) Appear(s)
APRDX Approximately
BND(G)(S) Band, Banding, Bands
BRK(S) Break(s)
BRKN Broken
CINCFAC Commander in Chief, Pacific
CINCPACAF Commander in Chief, Pacific Air Force
CIRC Circular
CIRCN Circulation
CLD(S) Cloud(s)
CLR Clear
CLSD Closed
CNTR(S)(D) Center(s)(ed)
DEF Definite
DEC Degree
DVLP(G) Develop(ing)
DFUS Diffuse
DIA Diameter
DSPTG Dissipating
DSPTN Dissipation
E East
ELIP Elliptical
ELONG Elongated
EST or E Estimated
F Fair
FAFWC Fuchu Air Force Weather Central, Fuchu Air Station,Japan
FDR Feeder
54WRS 54th Weather Reconnaissance Squadron, Andersen Air Force Base, Guam, M. I.
56WRS 56th Weather Reconnaissance Squadron, Yokota Air Base, Japan
FM From
FNWF Fleet Numerical Weather Facility, Monterey, California
FWC/JTWC Fleet Weather Central/Joint Typhoon Warning Center, Guam, M, I.
INDEF Indefinite
ITCZ Intertropical Convergence Zone
JMA Japan Meteorological Agency
JMG PACOM Joint Meteorological Group, Pacific Command
K (KILO) Time Mariana Islands local time
KM Kilometer(s)
KT Knot(s)
L Poor
LGT Light
LND Land
M Meter(s)
MAX Maximum
MB Millibar (s)
MI Mile(s)
MIN Minimum
MISC Miscellaneous
MOD Moderate
MPT Mid-Pacific Trough
N North
NA Not applicable
NEG Negative
NMC National Meteorological Center
OVC Overcast
POS or P Positive
POSIT(S)(D) Position(s)(ed)
PRES Pressure
PROB Probable
PSBL Possible
QUAD(S) Quadrant(s)
RDR Radar
RPT Report
S South
SEMI Semicircle
SFC Surface
SLP Sea level pressure
SML Small
STA Station
STG Strong
STM Storm
TEMP Temperature
THK Thick .
U Unknown
V Visual . .
VSBL Visible
VW-1 Airborne Early Warning Squadron ONE, NAS Agana, Guam, M. I,
W West
WESTPAC Western North Pacific Area
WK Weak
WND Wind(s)
WX Weather
XTNSV Extensive
  3. 2. The following define and clarify certain words and phrases that appear in the Eye Fix Summaries in Chapter V.
    2. a. FIX NO. This number corresponds to the, number of the fix plotted on the "Best Track Chart."
    4. b. TIME - The date-time of the fix.
    6. c. POSIT - Latitude and longitude of the fix.
    8. d. UNIT, METHOD & ACCY:
      2. (1) UNIT - The unit that made the fix: 54 - 54WRS; 56 - 56WRS; VW - VW-l.
      4. (2) METHOD - The method used to make the fix: P - penetration; R - radar; LND/RDR - land radar; TIROS - TIROS Satellite.
      6. (3) ACCY - Center determination and estimated accuracy of the fix: P - positive; F - fair; L - poor/distance in nautical miles.
    9. e. FLT LVL - Altitude of aircraft at time of fix.
    11. f. FLT LVL WND - Maximum observed flight level wind in knots.
    13. g. OBS SFC WND - Maximum observed surface wind in knots.
    15. h. OBS MIN SLP - Minimum sea level pressure observed in MBS.
    17. i. MIN 700MB HGT -- Minimum 700mb height observed in meters.
    19. j. FLT LVL TT/TD - Flight level temperature/dew point" at fix location. (When flight level is near the 700mb level, the 700mb temperature dew point is recorded in place of the actual flight level data.
    21. k. Supplementary Explanations (Examples,used in Chapter V):
      2. 15x5 NE-SW - Major axis NE-SW 15 mi long; Minor axis NW-SE 5 mi long*
      4. 54-E-U - Fix made by 54WRS; Estimated; Center determination and accuracy not given.
      6. VW1-R-P4 - Fix made by VW-1; Radar; Center determination positive and navigation accuracy given as 4 miles.
      8. 54-P-F6 - Fix made by 54WRS; Penetration; Center determination fair and navigation accuracy 6 miles.
  1. 3. An investigation is the traverse of a reconnaissance aircraft over an area containing a suspected circulation.
  3. 4. A fix is the determination of the position of a tropical cyclone at a precise time. Generally, the,term "fix" is used when the position of the cyclone has been determined by a reconnaissance aircraft penetration or by airborne, land or ship radar. In the case of a reconnaissance aircraft penetration, the actual fix may be based on one or more of the following:. visual observation, radar, surface pressure, surface or upper level winds, constant pressure height, and ternperature/dewpoint.
  5. 5. The term "tropical cyclone" or "cyclone" as used in this publication has two definitions dependent upon usage.
    2. a. "Tropical cyclone" or "cyclone" is used to describe a suspected tropical cyclonic circulation which appears capable of intensification.
    4. b, "Tropical cyclone" or "cyclone" is used in the general sense, e.g., "Typhoon JOAN was the most intense tropical cyclone of 1959," or "Tropical cyclones more frequently develop during August and September."
      2. (1) A "Tropical Depression" (TD) as used by JTWC is a tropical cyclone with a confirmed, cyclonic circulation for which warnings are being issued and whose surface wind speeds do not exceed 33 knots. Tropical depressions are numbered.
      4. (2) A "Tropical Storm" (TS) is a tropical cyclone in which the maximum surface wind speed is no more than 63 knots, but greater than 33 knots. Tropical storms are named.
      6. (3) A "Typhoon" is a tropical cyclone located W of 180 DEG longitude in which the maximum surface wind speed is 64 knots or greater.
  6. 6. Recurvature - That point at which the cyclone ceases movement to the W of N and commences moving to the E of N.
  8. 7. Vortices:
    2. a. Embedded vortex of easterly wave - closed cyclonic circulation along easterly wave and separated from ITCZ.
    4. b. Junction vortex - closed cyclonic circulation at the "junction of easterly wave and ITCZ.
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