Hurricane Dean Recon Discussion

[cycloneye]

Yeah, no open wave here. The quick motion may help the islands a bit as nasty weather should move quickly through. I know it will be rough but at least this one is moving along.

Yes,that is the only good news for them.

[x-y-no]

Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 16th day of the month at 17:00Z
Aircraft: Air Force Aircraft (Last digit of aircraft registration number is 304)
Storm Number: 04
Storm Name: Dean (in the North Atlantic basin)
Mission Number: 1
Observation Number: 03

Mandatory Data...

Observation Time: Thursday, 16:56Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 14.7N 57.0W (View map)
Location: 208 miles (334 km) to the ENE (57°) from Bridgetown, Barbados.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 3,040 meters
Flight Level Wind: From 70° at 55 knots (From the ENE at ~ 63.2 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 10°C
Flight Level Dew Point: 4°C
Weather (within 30 nautical miles): Shower(s) (continuous or intermittent precipitation - from cumuliform clouds)
700 mb Surface Altitude: 3,138 geopotential meters

Optional Data...

Estimated Surface Wind: From 30° at 35 knots (From the NNE at ~ 40.2 mph)

Remarks: SWS 032KTS

[cyclonic chronic]

getting to the meaty part of the storm! i also am suprised at how high the winds are at the distance the plane was at. we may have a bigger wind field than previously thought.

[SouthFloridawx]

86mph ... I wonder if that decodes and adjusts for altitude?

[cyclonic chronic]

970.7mb, am i reading that right? if so they arent even in the center yet.

[Scorpion]

Thats a tight center too.. wouldn't be surprised at 950's

[Scorpion]

964 I heard

[cyclonic chronic]

thats like a 15mb drop since 11am adv. would that be considered rapid or moderate intensification?

[Brent]

80 kt on the west side!!!!!

Watch out islands.

[Aric Dunn]

they are passing into the eye.. come the next set of minobs..

they are flying pretty high

[SouthFloridawx]

The USA Air Force codes have changed as of 2007, details for decoding based on the 2007 NHOP are as follows. No data using the new code has been released yet so I've added in data to show what it should look like compared with the 2006 format.

USA Air Force

SXXX50 KNHC 190617
AF308 0724A WILMA HDOB 34 KNHC
0608 1651N 08202W 03049 5104 216 059 118 116 062 02997 0000000000 - 2006 Format
0608. 1653N 08203W 03054 5127 215 070 112 112 074 02978 0000000000 - 2006 Format
0609 1654N 08205W 03053 5164 214 083 100 100 089 02941 0000000000 - 2006 Format
0609. 1655N 08206W 03046 5226 213 104 114 114 112 02872 0000000000 - 2006 Format
0610 1656N 08207W 03058 5338 206 132 106 106 143 02771 0000000100 - 2006 Format
0610. 1657N 08209W 03077 5592 201 158 108 108 168 02536 0000000100 - 2006 Format
0611 1658N 08210W 03002 5862 197 054 204 156 103 02190 0000000100 - 2006 Format
0611. 1658N 08212W 03061 5871 102 000 226 112 010 02239 0000110010 - 2006 Format
0612 1658N 08214W 03036 5833 353 058 186 142 098 02254 0000000100 - 2006 Format
061230 1658N 08215W 7000 03000 9000 +108 +108 352159 161 145 100 00 - 2007 Format


Taking the last line:

1) 06:12:30 GMT
2) 16.97N
3) 82.25W
4) Static pressure in aeroplane of 700.0hPa
5) Geopotential height of 3000m
6) 30 second surface pressure mean extrapolation of 900.0hPa
7) 30 second mean air temperature of +10.8C
8) 30 second mean dew point of +10.8C
9) 30 second mean wind direction of 352 degrees
10) 30 second mean wind of 159kts
11) Ten second gust of 161kts
12) Peak ten second Stepped Frequency Microwave Radiometer [SFMR] surface wind of 145kts
13) SFMR precipitation rate of 100mmh[sup]-1[/sup]
14) Suspect data codes are as follows:

First column indicates status of positional variables as follows:
0 All parameters of nominal accuracy
1 Lat/lon questionable
2 Geopotential altitude or static pressure questionable
3 Both lat/lon and GA/PS questionable

Second column indicates status of meteorological variables as follows:
0 All parameters of nominal accuracy
1 T or TD questionable
2 Flight-level winds questionable
3 SFMR parameter(s) questionable
4 T/TD and FL winds questionable
5 T/TD and SFMR questionable
6 FL winds and SFMR questionable
9 T/TD, FL winds, and SFMR questionable


Changes from 2006 format:

1) Tme with 30 second time interval now denoted by a 00 or 30 instead of a full stop for 30 seconds past each minute
2) Latitude - As before
3) Longitude - As before
4) Pressure to nearest 0.1hPa with leading 1 missing added
5) [s]Pressure altitude removed[/s]
6) [s]Absolute D value removed[/s]
7) Geopotential height in metres added
8) 30 second Extrapolated surface pressure mean to .1hPa with leading 1 missing added (If aeroplane is above 550hPa then is coded as the absolute D value in metres where negative D values are shown by adding 5000 to the value)
9) 30 second air temperature mean with positive and negative signs now added, note this is moved from later in the old format
10) 30 second dew point with with positive and negative signs now added, note this is moved from later in the old format
11) Thirty second mean wind direction - As before
12) Peak thirty second wind average - As before
13) Peak ten second wind average in kts - As before
14) Peak ten second SFMR surface wind in kts added
15) Peak ten second SFMR surface precipitation corresponding with the ten second peak surface wind reading in mmh[sup]-1[/sup] (Shown as 999 if can not be calculated) added

NOAA

Please note I'm unsure of the format for this this year as it is not mentioned at all in the 2007 NHOP, that is if they will be providing this data at all, or the format could now be the same as above.

URNT40 KWBC 251410
NOAA3 0612A KATRINA
140030 2728 07907 4776 +0151 097033 +188 +168 098034 023 004
140100 2726 07907 4814 +0149 095031 +183 +167 096031 021 004
140130 2725 07907 4809 +0144 093033 +183 +176 094034 026 004
140200 2723 07908 4811 +0142 087033 +187 +179 092033 030 006
140230 2721 07908 4808 +0145 096033 +184 +184 095034 035 008
140300 2719 07908 4805 +0140 100031 +185 +184 096032 031 007
140330 2717 07908 4809 +0135 103034 +184 +181 104037 030 004
140400 2715 07908 4803 +0128 103035 +189 +178 104036 029 004
140430 2713 07908 4808 +0125 100033 +190 +175 102033 030 003
140500 2711 07909 4808 +0123 098033 +189 +178 100033 031 004
140530 2709 07909 4811 +0120 099035 +190 +174 102037 031 004
140600 2708 07909 4808 +0114 108039 +193 +171 108040 032 004

Taking the last line again:

1) 14:06:00 GMT
2) 27.15N
3) 79.15W
4) Pressure altitude of 1465m [4808 feet]
5) D value of +35m [+114 feet] (Geopotential Altitude - Pressure Altitude)
6) Wind direction 108 degrees
7) 30 second wind speed of 39kts
8) Air temperature of +19.3C
9) Dewpoint temperature of +17.1C
10) Peak wind ten second from 108 degrees
11) Peak ten second average wind speed of 40kts
12) Estimated surface wind speed of 32kts from the SFMR
13) Estimated precipitation rate of 4mmh[sup]-1[/sup] (Shown as 999 if can not be calculated)


Flight Level to Surface Approximations

The other thing always asked is the reduction factor. Derek Ortt mentioned a paper by Franklin et al. (2003) but I'm not sure many will have seen the post as the thread was moving so quickly. The paper can be found in Weather and Forecasting 18 pp 32-44 and is a very good read if you can access it through your academic institution etc here.

The approximate reductions from Table 2 are given as follows although they can be altered for different storms if the wind profiles from the dropsondes indicate they should.

Flight level--------------Eyewall-----------Outer vortex (convection)-----Outer vortex (not in convection)
700hPa (3,000m)--------0.90------------------0.85------------------------------------0.80
850hPa (1,500m)--------0.80------------------0.80------------------------------------0.75
925hPa (750m)----------0.75------------------0.75------------------------------------0.75
300m----------------------0.80------------------0.80------------------------------------0.80

[Derek Ortt]

the RFQ is the NW quad, so surface winds may only be 80KT for now.

But if the 960s pressure is confirmed, then we should see the winds quickly catch up

[cyclonic chronic]

now 950mb? holly cow! this sure got strong in a hurry. i think recon got that rare opprotunity to be in a rapidly intensifying hurricane! wonder when the winds will catch up to the pressure. doesnt the pressure drop first, then the winds follow accordingly?

[EyELeSs1]

Minimum central pressure estimated by the Air Force reconnaissance
aircraft was 970 mb...28.64 inches.

[brunota2003]

From 2 pm Advisory:

A NEW STEPPED-FREQUENCY MICROWAVE RADIOMETER
INSTRUMENT ON BOARD OF THE AIR FORCE RECONNAISSANCE AIRCRAFT JUST
MEASURED 90 MPH...150 KM/HR SURFACE WINDS WHILE MAKING ITS FIRST
ENTRANCE TO THE HURRICANE.

[SouthFloridawx]

Still waiting on that VDM...

[Brent]

now 950mb? holly cow! this sure got strong in a hurry. i think recon got that rare opprotunity to be in a rapidly intensifying hurricane! wonder when the winds will catch up to the pressure. doesnt the pressure drop first, then the winds follow accordingly?

Not 950, we read it wrong, leaving off the first number. 969 seems to be correct though, still lower than estimated.

[SouthFloridawx]

I can't wait to read about the NE quad.

[Derek Ortt]

the 974 is likely too high, as is usually the case from dropsondes in strong hurricanes. Nearly impossible to get the sondes into the core

[brunota2003]

I can't wait to read about the NE quad.

Why the NE Quad? Why not the NW Quad? (considering, by its motion, that is the RFQ)