Recon Report Decoding

The following information is presented for those who need a comprehensive decoding of the topical recon and dropsonde reports. The term 'vortex' data message actually represents one vendors terminology for getting this data and should be ignored for all practical purposes. I believe most of us will be using the headers starting with URxxxx KMIA for obtaining the majority of the observations.

Over that past few years, I've been able to get the info I needed with the URNTxx and UZNTxx headers (all from KMIA). This does not mean that there are not other headers.

VORTEX DATA MESSAGE/RECON REPORT

The VORTEX message is actually a combination of three types of reports: the vortex data message, the supplemental vortex data message, and the reconassaince report. Each of these types of reports will now be discussed, beginning with the vortex data message.

The following information is designed to aid in the interpretation of the abbreviated and detailed vortex data messages. After a step by step explanation, a sample message will be displayed.

Both the abbreviated and detailed vortex data messages are transmitted in an alphabetical manner. In each report, a letter of the alphabet is followed by information about the center of the tropical circulation. This information includes such items as lat/long of the center, temperatures inside and outside of the eye of the storm, wind information, minimum pressures, etc. Here is a breakdown of the message:

The first line of the report gives the mission identifier...this

        consists of: 1-Agency; 2-aircraft number; 3-number of missions
        in this storm system; 4-depression number; 5-storm name.

        AF554 WX OB 03 KMIA means this mission is flown by the Air
        Force, with aircraft number 554; observation number 3, reported
        to Miami.

The second line gives the name of the type of report, either ABBREVIATED VORTEX DATA MESSAGE or DETAILED VORTEX DATA MESSAGE

Date and time of fix...06/1634Z means the report is from the sixth day of the month, at 1634Z.
B. Latitude of the vortex fix in degrees and minutes...26 DEG 00 MIN N Longitude of the vortex fix in degrees and minutes...88 DEG 00 MIN W
C. Minimum height of a standard pressure level, given in meters... 700 MB 3150 M means the lowest height of the 700 mb level was found to be 3150 meters above sea level.
D. Estimate of maximum surface wind observed in knots...30 KT means the highest estimated surface wind is 30 kts with this particular storm system.
E. Bearing and range from center of the maximum surface wind, given in degrees and nautical miles...180 DEG 18 NM means the 30 kt wind mentioned in D above is 18 nm south of the center of the storm.
F. Maximum flight level wind near storm center with direction from center given in degrees, and speed in knots...110 DEG 45 KT means that the wind is from 110 degrees at 45 knots.
G. Bearing and range from center of maximum flight level wind, given in degrees and nautical miles from the storm center...180 DEG 15 NM means the maximum wind given in F above was found 15 nautical miles south of the storm center.
H. Minimum sea level pressure computed from dropsonde or extrapolation from within 1500 feet of the sea surface, given in millibars... 1005 MB DROPSONDE means that the lowest pressure found was 1005 millibars and was determined from a dropsonde.
I. Maximum flight level temperature in Celcius / Pressure altitude in meters, OUTSIDE the eye...09 C / 3082 M means that at the flight level of 700 millibars, the highest temperature outside the eye is 9 degrees C at a pressure altitude of 3082 meters.
J. Maximum flight level temperature in Celcius / Pressure altitude in meters, INSIDE the eye...10 C / 3040 M means that at the flight level of 700 millibars, the highest temperature inside the eye is 10 degrees C at a pressure altitude of 3040 meters.
K. Dewpoint temperature in Celcius / Sea surface temperature in Celcius inside the eye...08 C / 26 C means that the dewpoint was 8 degrees C inside the eye, and the temperature of the sea surface was 26 degrees C.
L. Eye character...brief verbal description such as poorly defined, closed wall, open to NW, etc.
M. Eye shape orientation and diameter...Eye shapes are codes as follows: C-circular; CO-concentric; E-elliptical. Orientation of major axis of ellipse is transmitted in tens of degrees, and all diameters are transmitted in nautical miles. Examples.. E09/15/5 means elliptical eye oriented with major axis thru 90 degrees (and also 270 degrees), with length of major axis 15 nm, and length of minor axis 5 nm. CO8-14 means concentric eye with inner eye diameter 8 miles, and outer diameter 14 miles.
N. Confirmation of lat/long/time fix with format as in A and B above.
O. Fix determined by / fix level...There are five means of determining fixes and nine means of indicating fix level. The fix determination will be a series of one to five numbers depending on how many items were used to determine the position of the storm center. The coding is as follows: 1-Penetration, 2-Radar, 3-Wind, 4-Pressure, 5-Temperature. The fix level will be either one or two numbers, depending on whether or not the surface and flight level centers were the same. The surface center will be given if visible, both the surface and flight level centers will be indicated only when they're the same. The coding is as follows: 0-surface, 1-1500 ft, 8-850 mb, 7-700 mb, 5-500 mb, 4-400 mb, 3-300 mb, 2-200 mb, 9-Other. Example: 1245/07 means the fix was determined by four means..penetration, radar, temperature, and pressure. The fix level was both at the surface and at 700 mb.
P. Navigation fix accuracy in nm / Meteorological accuracy in nm... 5/10 means the center is located within 5 nm of the lat-long given for the center, with a meteorological accuracy to 10 nm.
Q. Remarks Section.

Sample report:

AF554 WX OB 03 KMIA
DETAILED VORTEX DATA MESSAGE

06/1634Z
B. 26 DEG 00 MIN N
   88 DEG 00 MIN W
C. 700 MB 3150 M
D. 30 KT
E. 180 DEG 18 NM
F. 110 DEG 45 KT
G. 180 DEG 15 NM
H. 1005 MB DROPSONDE
I. 09 C/ 3082 M
J. 10 C/ 3040 M
K.  8 C/ 26 C
L. POORLY DEFINED
M. C08-14
N. 26 DEG 00 MIN N
   88 DEG 00 MIN W
O. 1245/07
P. 5/10
Q. NONE

The supplemental vortex data message differs from many of the other types of messages in that all data is from the flight level of the aircraft.

The format for decoding these reports is quite similar to the traditional RAOB decode. Height, temperature, dewpoint, wind direction and speed are decoded almost identically.

The generic format of this type of report for the north Atlantic is as follows:

URNT14 KMIA DDTTTT
AA ### MMXX NAME
SUPPLEMENTARY VORTEX DATA MESSAGE

01LaLaLa 1LoLoLoLo 1jHHH 1TTTdTd ddfff
02LaLaLa 2LoLoLoLo 2jHHH 2TTTdTd ddfff
03LaLaLa 3LoLoLoLo 3jHHH 3TTTdTd ddfff
04LaLaLa 4LoLoLoLo 4jHHH 4TTTdTd ddfff
05LaLaLa 5LoLoLoLo 5jHHH 5TTTdTd ddfff

etc...etc...etc

MFLaLaLa MLoLoLoLo MFfff

Some comments about the above code:

Data are collected at 15 nm intervals both approaching and departing the storm. When approaching, data normally starts at 105 nm from the center and at 15 nm intervals thereafter. When departing the storm, data normally starts 15 nm from the center and at 15 nm intervals thereafter.

The indicator numbers at the beginning of each group are simply used to distinguish one group from another. For example, the first data report is labeled 01, and everything at that same lat/long location has the number 1 in front. The next data sample (15 nm later) is labeled 02/2, the next sample is 03/3, etc.

The line by line decode breaks down as follows:

UR 14 is the name of this report. Atlantic reports are coded URNT14 KMIA is the location of the recipient of the message (Miami) DDTTTT is the day and time of the report in Greenwich AA is the Agency providing the report. AF is Air Force, NOAA is NOAA ### is the aircraft number flying the mission MM is the number of the mission for this storm XX is the depression number, or simply XX if not a depression or greater NAME is the name of the storm, if any
LaLaLa is the latitude of the report in degrees/tenths LoLoLoLo is the longitude of the report in degrees/tenths jHHH is the pressure height data in the following format:

j=0 means sea level data follows with HHH in whole millibars
j=1 means 200 mb data follows with HHH in geopotential decameters
j=2 means 850 mb data follows with HHH in geopotential meters
j=3 means 700 mb data follows with HHH in geopotential meters
j=4 means 500 mb data follows with HHH in geopotential decameters
j=5 means 400 mb data follows with HHH in geopotential decameters
j=6 means 300 mb data follows with HHH in geopotential decameters
j=7 means 250 mb data follows with HHH in geopotential decameters
j=8 D - Value in geopotential decameters; if neg, 500 is added to HHH
j=9 means no absolute altitude data available, or geopotential data is not within +/- 30 meters/4 mb accuracy requirements

MF means that maximum flight level wind data follows
TTTdTd is the temperature/dewpoint in degrees Celcius. Add 50 if negative
ddfff is the true direction of flight level wind in tens of degrees with fff being the speed of wind in knots
/ means data unknown or unobtainable

The following is a sample message with a partial decode following:

URNT14 KMIA 211730
AF 966 0411 FREDERIC OB 14
SUPPLEMENTARY VORTEX DATA MESSAGE
01178 10899 13107 10908 36027
02177 20895 23100 20908 35042
03178 30891 33092 30807 36052
04177 40887 43088 40907 35070
05178 50883 53070 50908 36088
06178 60880 63000 61010 35108
07178 70877 73882 71211 35120
MF178 M0877 MF120
OBS 01 AT 1530Z OBS 07 AT 1600Z
OBS 01 SFC WIND 36025
01177 10872 13000 11010 18120
02178 20868 23070 21009 17098
03178 30862 33088 30909 18080
04177 40858 43093 40908 17050
05177 50854 53102 50908 17048
06178 60850 63108 60905 18031
07177 70844 73114 70902 18025
MF177 M0872 MF120
OBS 1 AT 1630Z OBS 07 AT 1700Z
OBS 07 SFC WIND 16025
REMARKS HEAVY RAIN OUTBOUND

The first three lines identify the report in detail...

URNT14 is the report header
KMIA signifies the report is being sent to Miami 211730 means this is the 21st day...1730Z AF means this mission is being flown by the Air Force 966 is the aircraft number
0411 means this is the fourth mission for this tropical system, and this is the 11th tropical depression of the season FREDERIC means that depression number 11 has gained tropical storm status and is named Frederic
OB 14 means this is the 14th observation from this mission (4th)

The first data line decodes as follows:

01178...latitude is 17.8 degrees
10899...longitude is 89.9 degrees
13107...700 mb report at a height of 3107 meters 10908...temperature is 9 C / dewpoint is 8 C 36027...wind is 360 degrees at 27 kts

The second data line decodes as follows:

02177...latitude is 17.7 degrees
20895...longitude is 89.5 degrees
23100...700 mb report at a height of 3100 meters 20908...temperature is 9 C / dewpoint is 8 C 35042...wind is 350 degrees at 42 kts

...the remainder of the message for groups 03 thru 07 decodes in the exact same manner...

MF178...maximum wind latitude is 17.8 degrees M0877...maximum wind longitude is 87.7 degrees MF120...maximum wind speed at these coordinates was 120 kts OBS 01 AT 1530Z...first set of data taken at 1530Z OBS 07 AT 1600Z...last set of data taken at 1600Z OBS 01 SFC WIND 36025...surface wind at 1530Z was 360 degrees/25 kts

Reconnaissance reports, provide valuable information about the structure of tropical weather systems. This is the raw coded report sent from the aircraft to the National Hurricane Center. This message contains meteorological information including pressure, temperature, wind, clouds and turbulence. In addition, information about the capabilities of the aircraft are included, such as radar ability, means of wind speed determination, etc.

Some of these reports are mandatory, and others are intermediate. Also, some reports provide additional data at the end that is not considered mandatory, but is useful.

The following is the generic code used in the reports. Each item will be discussed separately, with a sample report decoded at the end.

SYMBOLIC FORM

Section One..Mandatory

9XXX9 GGggI YQLaLaLa LoLoLoBf hhhdd ddfff TTTdTdw /jHHH

Section Two..Additional (appended to section one when available)

1kNsNsNs ChhHH ..... ..... 4ddff 6WsSsWdd 7IrItSbSe 7hhHH 8ddSrOe 8EwElci 9ViTwTwTw

Section Three..Intermediate

9XXX9 GGggI YQLaLaLa LoLoLoBf hhhdd ddfff TTTdTdw /jHHH

As can be seen above, each message consists of groups of five numbers. The positioning of each number in a group, and also the indicator numbers at the beginning of some groups, helps in the decode of the report.

Beginning with section one, the mandatory reports, here is the breakdown of the code:

9XXX9...The 9's on either end of this group are simply indicator numbers. The XXX can be any of three possibilities depending on the aircraft. 222..means this is a mandatory report without radar capability. 555..means this is an intermediate report with or without radar capability. 777..means this is a mandatory report with radar capability.

GGggI...GG is the hour of the report; gg is the minute of the report; I is an indicator regarding aircraft height and dewpoint sensing capability. 0..No dewpoint capability / aircraft below 10000 meters 1..No dewpoint capability / acft at or abv 10000 meters 2..No dewpoint cap / acft blo 10000 m / fl temp blo -50C 3..No dewpoint cap / acft aoa 10000 m / fl temp blo -50C 4..Dewpoint capability / aircraft below 10000 meters 5..Dewpoint capability / acft at or above 10000 meters 6..Dewpoint cap / acft below 10000 m / fl temp blo -50C 7..Dewpoint cap / acft aoa 10000 m / fl temp blo -50C

YQLaLaLa...Y is the day of the week..Sunday=1...Saturday=7 Q is the quadrant of the globe the aircraft is located using the following decode... 0..0-90N / 0-90W 1..0-90N / 90W-180 2..0-90N / 180-90E 3..0-90N / 90E-0 4..Not used 5..0-90S / 0-90W 6..0-90S / 90W-180 7..0-90S / 180-90E 8..0-90S / 90E-0 LaLaLa is the latitude in tenths of degrees. 268 would be 26.8 degrees

LoLoLoBf...LoLoLo is the longitude of the aircraft in tenths of degrees. 880 would be 88.0 degrees, 110 would be 11.0 or 111.0 depending on the quadrant of the globe indicator in the last group. B..Turbulence group as follows.. 0..No turbulence 1..Mdt turbulence..in clear air..infrequent 2..Mdt turbulence..in clear air..frequent 3..Mdt turbulence..in cloud..infrequent 4..Mdt turbulence..in cloud..frequent 5..Severe turbulence..in clear air..infrequent 6..Severe turbulence..in clear air..frequent 7..Severe turbulence..in cloud..infrequent 8..Severe turbulence..in cloud..frequent f..Conditions along route of flight as follows.. 0..In the clear 8..In and out of clouds 9..In clouds all the time /..Impossible to determine due to darkness or some other cause.

hhhdtda...hhh gives the pressure altitude of the aircraft to the

nearest decameter dtda..gives information about the wind group that follows. dt specifies if the wind is 0) Spot wind; 1) Average wind; or / meaning no wind report. da specifies how the winds were obtained, with 0) Winds obtained using doppler radar or inertial systems; 1) Winds obtained using other navigation equipment / techniques; / Navigator unable to determine wind or wind not compatible.

ddfff...Wind direction and speed at the flight level of the aircraft. This is coded using the standard meteorological conventions.

TTTdTdw...The temperature, dewpoint, present weather group at flt lvl.

TT is the temperature in Celcius. If the temperature is negative, 50 is added to the absolute value of the temperature, and any hundreds digits are omitted. For example, a temperature of -60 would be coded as 10 (60+50=110 with hundreds omitted) To determine if the temperature is really +10 or -110, see the indicator number in the time group above. Msg temps are denoted as //. TdTd is the dewpoint at flight level. Dewpoints are encoded the same as temperature. When the dewpoint is colder than -49.4C, it is reported as // and a plain language remark is added with the actual dewpoint, i.e. DEW POINT -53C. w is the present weather group with the following meanings.. 0..Clear 1..Scattered clouds 2..Broken clouds 3..Overcast / Undercast 4..Fog, thick dust or haze 5..Drizzle 6..Rain (continuous or intermittent from stratoform clouds) 7..Snow, or rain and snow mixed 8..Rain (continuous or intermittent from cumuliform clouds) 9..Thunderstorm /..Unknown for any cause, including darkness

/jHHH.../ is an indicator for this group j is the code for the level being reported by HHH in this group. The code is as follows... 0..Sea level pressure in millibars (1000's omitted) 1..200 mb lvl in geopotential decameters (1000s omitted) 2..850 mb lvl in geopotential meters (1000's omitted) 3..700 mb lvl in geopotential meters (1000's omitted) 4..500 mb lvl in geopotential decameters 5..400 mb lvl in geopotential decameters 6..300 mb lvl in geopotential decameters 7..250 mb lvl in geopotential decameters (1000s omitted) 8..D value in geopotential decameters (if negative, 500 is added to HHH) 9..No absolute altitude available, or geopotential data not within + or - 30 meters / 4 mb accuracy requirements. HHH..Geopotential height or sea level pressure of the level specified in the j indicator just above.

The following sample report will now be decoded:

AF360 WX OB 04 KMIA
97779 19324 40267 88600 55100 01012 56761 /4587

The above report states that the aircraft is Air Force with an identification number 360. This is the 4th observation being reported to Miami.

This is a mandatory report and the aircraft is equipped with radar. The report time is 1932Z on Wednesday, the acft is blo 10000 meters and has dewpoint measuring capability. The report is from quadrant 0 which is in the northern hemisphere between 0 and 90W, at latitude 26.7N and longitude 88.6W. No turbulence or clouds were reported.

The geopotential height of the aircraft at flt lvl is 5510 meters. Spot winds of 12 kts from 010 degrees were measure using doppler radar. The flight level is 5510 meters where the temperature is -6C and the dewpoint is -26C. Present weather is clear. The height of the 500 millibar surface is 5870 meters above sea level.

Section Two..Additional (appended to section one when available)

1kNsNsNs ChhHH ..... ..... 4ddff 6WsSsWdd 7IrItSbSe 7hhHH 8ddSrOe 8EwElci 9ViTwTwTw

This section is not always included, but when it is available, it is appended onto sections one or three with no special distinctive heading. Thus, if the mandatory or intermediate reports have extra groups, it is assumed that the format of these groups takes on the form of the generic code listed immediately above.

The decode of section two..additional data..is as follows:

1kNsNsNs...1 is the indicator for this cloud group. k is the total number of cloud levels observed Ns is the eighths coverage of the most significant cloud present Ns is the eighths coverage of the second most significant cloud present Ns is the eighths coverage of the third most significant cloud present

NOTE..IF MORE THAN THREE CLOUD LAYERS ARE OBSERVED, ANOTHER 1 GROUP WILL FOLLOW THAT REPORTS THE REMAINING LAYER INFORMATION

Chshshtht...C is the cloud type corresponding to the first Ns report above. C is determined from the table below: 0..cirrus 1..cirrocumulus 2..cirrostratus 3..altocumulus 4..altostratus 5..nimbostratus 6..stratocumulus 7..stratus 8..cumulus 9..cumulonimbus /..Cloud type unknown due to darkness or other phenomena. hshs is the base of the cloud given in hundreds of feet if the number is below 50, i.e. 34 is 3400 feet. Numbers coded between 51 and 55 are not used. Numbers coded between 56 and 79 are cloud bases in in thousands of feet when 50 is subtracted from the number, i.e. 62 is a base of 12000 ft (62-50=12) htht is the top of the cloud using the same decode as the base given above.

AT THIS POINT THERE WILL BE A FIVE NUMBER CLOUD GROUP (CHsHsHtHt) FOR EACH CLOUD LAYER AS INDICATED IN THE 1kNsNsNs GROUP. EACH OF THESE CLOUD GROUPS WILL FOLLOW THE FORM AS DETAILED IMMEDIATELY ABOVE, WITH CLOUD TYPE, FOLLOWED BY BASE HEIGHT AND TOP HEIGHT.

4ddff...4 is the indicator that surface wind data follows dd is the wind direction to the nearest ten degrees. 50 is added is the wind is over 100 kts. ff is the wind speed in knots. Wind speeds above 130 kts are not coded.

6WsSsWddw...6 is the group indicator
Ws gives any significant weather changes as listed in the following table... 0..No change 1..Marked wind shift 2..Beginning or ending of marked turbulence 3..Marked temperature change (non-altitude) 4..Precipitation begins or ends 5..Change in cloud forms 6..Fog or ice fog begins or ends 7..Warm front 8..Cold front 9..Front, type not specified Ss is the distance of occurence of Ws above, where 0..No report 1..Previous position 2..Present position 3..30 nm 4..60 nm 5..90 nm 6..120 nm 7..150 nm 8..180 nm 9..More than 180 nm Wd is the distant weather, where 0..No report 1..Signs of a tropical cyclone 2..Ugly threatening sky 3..Duststorm or sandstorm 4..Fog or ice fog 5..Waterspout 6..Cirrostratus shield or bank 7..Altostratus / altocumulus shield or bank 8..Line of heavy cumulus 9..Cumulonimbus heads or thunderstorms dw is the bearing of Wd above, where 0..No report 1..NE 2..E 3..SE 4..S 5..SW 6..W 7..NW 8..N 9..All directions

7IrItSbSe...7 is the icing group indicator Ir is the rate of icing, where 7..Light 8..Moderate 9..Severe / Unknown or contrails It is the type of icing, where 0..None 1..Rime ice in clouds 2..Clear ice in clouds 3..Mixed ice in clouds 4..Rime ice in precipitation 5..Clear ice in precipitation 6..Mixed ice in precipitation 7..Frost (icing in clear air) 8..Nonpersistent contrails (under 1/4 nm long) 9..Persistent contrails Sb is the distance to beginning of ice, using the same table as dw above Se is the distance to ending of ice, using the same table as dw above

7hihiHiHi...7 is the icing group indicator hihi is the base of the icing, the same format as that used to report cloud bases hshs noted previously HiHi is the top of the icing, the same format as that used to report cloud bases hshs noted previously

8drdrSrOe...8 is the echo group indicator drdr is the bearing of the echo center in tens of degrees azimuth Sr is the distance to echo center, where 0..0 nm 1..10 nm 2..20 nm 3..30 nm 4..40 nm 5..50 nm 6..60-80 nm 7..80-100 nm 8..100-150 nm 9..Greater than 150 nm /..Unknown Oe is the orientation of echo, where 0..Circular 1..NNE-SSW 2..NE-SW 3..ENE-WSW 4..E-W 5..ESE-WNW 6..SE-NW 7..SSE-NNW 8..S-N /..Unknown

8EwElceie...8 is the echo indicator group Ew is the echo width or diameter using the same format as Sr above El is the length of major axis using the same format as Sr above ce is the character of the echo, where 1..Scattered area 2..Solid area 3..Scattered line 4..Solid line 5..Scattered all quadrants 6..Solid, all quads /..Unknown ie is the intensity of the echo, where 2..Weak 5..Moderate 8..Strong /..Unknown

9ViTwTwTw...9 is the group indicator
Vi is the inflight visibility, where 1..0 to 1 nm 2..1 to 3 nm 3..over 3 nm TwTwTw is the sea surface temperature in tenths of degrees

Section Three..Intermediate

9XXX9 GGggI YQLaLaLa LoLoLoBf hhhdd ddfff TTTdTdw /jHHH

The decode of section three is exactly the same as that in section one..mandatory information..as described above.

DROPSONDE OBSERVATION

Dropsondes released by reconnaissance aircraft are encoded in a manner similar to the mandatory and significant level raob data commonly used. These reports contain important pressure, temperature and moisture information. The XXAA message gives mandatory pressure level information, while the XXBB message gives significant pressure level data.

The following is a decode of the mandatory portion of the dropsonde report:

GENERIC CODE...

XXAA YYGGI 99LaLaLa QLoLoLoLo MMMUU 99PPP TTTDD ddfff P1P1hhh TTTDD ddfff P2P2hhh TTTDD ddfff...PnPnhhh TTTDD ddfff 88PPP TTTDD ddfff 77PPP ddfff 4vvvv

The first line of the report gives the mission identifier...this consists of: 1-Agency; 2-aircraft number; 3-number of missions in this storm system; 4-depression number; 5-storm name. AF554 WX OB 03 KMIA means this mission is flown by the Air Force, with aircraft number 554; observation number 3, reported to Miami.

XXAA...mandatory level data follows

YYGGI...YY is the day of the month, GG is the time in Z, I is a wind indicator, with a / meaning wind information is missing.

99LaLaLa...99 is a group indicator with LaLaLa being the latitude in tenths of a degree.

QLoLoLoLo...Q is the quadrant of the globe of this report, with 1 being North latitude and East longitude, 3 being South latitude and East longitude, 5 being South latitude and West longitude, 7 being North latitude and West longitude,

LoLoLoLo is the longitude in tenths of a degree.

MMMUU...MMM is the Marsden square number of the reporting location, UU is the units digit of the latitude and longitude respectively.

99PPP...99 means that surface data follows, PPP is the pressure at the surface in tenths of a millibar (9 or 10 is assumed in front of the number).

TTTDD...TTT is the sfc temperature in tenths of a degree Celcius. If the third digit (tenths) is odd, the number is negative; if its even, the number is positive. DD is the dewpoint depression. If 50 or less, its the depression in degrees and tenths; if 56 or more, subtract 50 and its the depression in whole degrees.

ddfff...ddfff is the wind direction/speed at the surface using the standard meteorological format.

P1P1hhh...the first mandatory pressure level data follows, with 00 being 1000 mb, 85 being 850 mb, 70 being 700 mb, etc. hhh is the height of this level in meters above sea level.

TTTDD...the temperature and dewpoint depression at this level using the format mentioned above.

ddfff...the wind direction/speed as outlined above.

OTHER MANDATORY LEVEL DATA FOLLOWS HERE FOLLOWING THE FORMAT <PPhhh TTTDD ddfff> FOR EACH LEVEL.

88PPP...88 is the indicator meaning tropopause data follows; PPP is the pressure at the tropopause. 88999 means that tropopause information is unavailable.

TTTDD...temperature and dewpoint depression at the tropopause.

ddfff...wind direction and speed at the tropopause.

77PPP...77 is the indicator meaning maximum wind level data follows; PPP is the pressure at the level of maximum wind. 77999 means that maximum wind information is not available.

ddfff...the wind direction and speed of the maximum wind

4vvvv...4 is the indicator meaning wind shear information follows. The first vv group is the wind shear from the level of max wind to 3000 ft below the level of max wind; the second vv group is the wind shear from 3000 feet above the level of max wind down to the level of max wind. This group is optional.

AF977 WX OB 05 KMIA
XXAA  1717/ 99260 70892 08169 99018 27836 00158 26833 85574 17220
70206 08040 88999 77999

The following is a decode of the above sample report:

Report from Air Force aircraft number 977, weather observation #5 sent to Miami on the 17th at 17Z, wind data msg. Report is from latitude 26.0N and 89.2W which is in quadrant 7 of the globe in Marsden square number 81. The units digit of the latitude is 6, the units digit of the longitude is 9. Surface pressure is 1001.8 mb with a temperature of 27.8 degrees C and a dewpoint depression of 3.6 degrees C. The height of the 1000 mb level is 158 meters above sea level with a temperature of 26.8C and dewpoint depression of 3.3 degrees C. 850 mb level is at 1574 meters above sea level, temperature 17.2 C and dewpoint depression of 2.0 C. 700 mb height is 3206 meters with a temperature 8.0 C and dewpoint depression of 4.0 C. Tropopause and max wind information missing (likely because the dropsonde was released from 700 mb, a standard level for recon reports).

The following is a decode of the significant portion of the dropsonde report:

GENERIC CODE...

XXBB YYGG/ 99LaLaLa QLoLoLoLo MMMUU 00PPP TTTDD ddfff 11PPP TTTDD ddfff...NNPPP TTTDD ddfff

XXBB...signifies that significant level data follows.

YYGG/ 99LaLaLa qLoLoLo MMMUU follows the exact same format as in the mandatory data above, essentially day, time, lat-long information.

00PPP...00 signifies that surface data follows, with the PPP being the pressure at the surface.

TTTDD...the temperature and dewpoint at the surface, using the convention as outlined under the mandatory levels above.

ddfff...wind direction and speed at the surface.

11PPP...11 means that the data to follow is for the next highest significant level...with the pressure at that level indicated by PPP in whole millibars.

TTTDD...the temperature and dewpoint depression in Celcius at the first significant pressure level.

ddfff...the wind direction and speed at the first significant level.

22PPP...22 means that the data to follow is for the next highest

significant level...with the pressure at that level indicated by PPP in whole millibars.

TTTDD...the temperature and dewpoint depression in Celcius at the second significant pressure level.

ddfff...the wind direction and speed at the second significant level.

SIGNIFICANT LEVEL DATA CONTINUES WITH THE FORMAT <NNPPP TTTDD ddfff> THROUGH THE REMAINDER OF THE REPORT.

A sample report is shown below:

AF977 WX OB 05 KMIA
XXBB  1717/ 99260 70892 08169 00018 27836 11799 13405 22733 09411
33716 08650 44699 08040=

Back to the Weather Weenie (Tropical) page Last Modified: Sun, 13 Jun 1999