[From the diaries by susanhu. I never got past Algebra I but I’ll take these numbers on the blind faith so popular these days! Seriously, this is impressive, and quite interesting, work by MilongaMan!]
Update [2005-9-22 2:35:13 by MilongaMan]:2: Latest recon gives max wind speed at 700mb of 170 knots, equivalent to 172-178 mph surface wind speed.
Update [2005-9-21 17:23:30 by MilongaMan]: Latest recon gives max wind speed at 700mb of 161 knots, equivalent to 163-168 mph surface wind speed. See this. Check the Vortex Message (Latest From the Eye) link from this page
Here is some info for those who like to get as close to the raw data as possible and calculate their own maximum sustained surface wind speed projections. Keep reading:
The Recon flights that measure different parameters inside a hurricane are either NOAA flights or AF flights. I found the raw flight data on Rita at the website of the 53rd Weather Reconnaissance Squadron.
The latest flight is at Supplementary Vortex (Storm Wind Profile) (Also see item F on The Latest From The Eye.)
The explanation of what the numbers are is here.
Jump below the fold to see in part what the report reads, with explanations, and to learn how the surface wind speed is calculated from the data:
038 URNT14 KNHC 211834
Report number, sent to NHC, on Sep 21 at 18:34 GMT (11:34am PDT or 2:34pm EDT)
SUPPLEMENTARY VORTEX DATA MESSAGE
INBOUND
LAT LON jHHH TTDD ddfff
01256 10878 13121 11007 04043
02254 20876 23076 21007 04053
03253 30874 33071 31008 04052
04251 40872 43054 40707 03052
05249 50870 53020 51008 04062
06247 60868 63002 61010 03064
07246 70866 73952 71010 04067
08244 80864 83813 81212 03102
The aircraft made 8 passes, inbound, each approximately 15 nm apart, until it reached the center of the hurricane, then 7 more passes from the center out (see the raw report; not excerpted here).
The height is at 700 millibars (j=3 in jHHH numbers above).
MF243 M0863 MF153
This is a maximum sustained wind reading of 153 knots. Multiply by 1.1515 to get around 176 mph.
AF300 1418A RITA OB 08
AF means this mission was flown by the Air Force Reserve
300 is the aircraft number (tail number 50300)
1418A means this was the 14th mission for this tropical system, and this was the 18th tropical cyclone of the season in the Atlantic
RITA was the name of the storm
OB 08 means this was the 8th observation from this mission
Here’s how to estimate surface wind speed from the 700mb reading of 176 mph. On this NHC page you will find that the current estimate, for the 700mb to surface extrapolation, is to multiply the reading by 0.88-0.91 (eyewall); typically by 0.91.
In this case this gives 155-160 mph, which is in the CAT 5 range (>=155 mph). Update [2005-9-21 19:22:4 by MilongaMan]:: This was subsequently revised to 161 knots, equivalent to 163-168 mph at the surface.
In general the formula would be:
W_surf_max_lower_bound = W_700mb_max * (1.1515 * 0.88) = W_700mb_max * 1.01332
W_surf_max_upper_bound = W_700mb_max * (1.1515 * 0.91) = W_700mb_max * 1.04786
where W_700mb_max is in knots, coming from aircraft recon missions, and W_surf_max is in miles per hour.
The flight recon schedule (both NOAA and AF) is at this NHC page. Also see here for other days and more links.
Hope this helps, and please let me know if you find errors.
[cross-posted on Dkos]
