remove description lines and add time to the first column - date

Question

AWk experts, I have a file as descried below and I wonder if it is possible to easily convert it to the form that I want:
The file containing multiple variables over one month (one observance ONLY in one day, but some days may be missing). The format for each day is the same except the date/value. However there is some description lines (containing words and numbers) at the end of each day, and the number of description lines varies among different days.
KBO BTA Observations at 12Z 01 Feb 2020
-----------------------------------------------------------------------------
PRES HGHT TEMP DWPT RELH MIXR DRCT SKNT THTA THTE THTV
hPa m C C % g/kg deg knot K K K
-----------------------------------------------------------------------------
1000.0 92
925.0 765
850.0 1516
754.0 2546 13.0 9.3 78 9.85 150 2 310.2 340.6 312.0
752.0 2569 14.0 9.2 73 9.80 149 2 311.5 342.0 313.4
700.0 3173 -9.20 7.5 89 9.38 120 6 312.6 341.9 314.4
Station information and sounding indices
Station elevation: 2546.0
Lifted index: 1.83
Pres [hPa] of the Lifted Condensation Level: 693.42
1000 hPa to 500 hPa thickness: 5798.00
Precipitable water [mm] for entire sounding: 21.64
8022 KBO BTA Observations at 00Z 02 Feb 2020
-----------------------------------------------------------------------------
PRES HGHT TEMP DWPT RELH MIXR DRCT SKNT THTA THTE THTV
hPa m C C % g/kg deg knot K K K
-----------------------------------------------------------------------------
1000.0 97
925.0 758
850.0 1515
753.0 2546 10.8 6.8 76 8.30 190 3 307.9 333.4 309.5
750.0 2580 12.6 7.9 73 8.99 186 3 310.2 338.1 311.9
Here is what I want: remove all the description lines and read the date/time information and put it as the first column.
Time PRES HGHT TEMP DWPT RELH MIXR DRCT SKNT THTA THTE THTV
20200201t12Z 754.0 2546 13.0 9.3 78 9.85 150 2 310.2 340.6 312.0
20200201t12Z 752.0 2569 14.0 9.2 73 9.80 149 2 311.5 342.0 313.4
20200201t12Z 700.0 3173 -9.2 7.5 89 9.38 120 6 312.6 341.9 314.4
20200202t00Z 753.0 2546 10.8 6.8 76 8.30 190 3 307.9 333.4 309.5
20200202t00Z 750.0 2580 12.6 7.9 73 8.99 186 3 310.2 338.1 311.9
Any help is appreciated.
Kelly

Answer 1

something like this...
$ awk 'function m(x)
{return sprintf("%02d",int(index("JanFebMarAprMayJunJulAugSepOctNovDec",x)-1)/3+1)}
NR==1 {print "time PRES TEMP WDIR WSPD RELH"}
/^-+$/ {f=!f}
f {date=p[n] m(p[n-1]) p[n-2]}
!f {n=split($0,p)}
NF==11 && !/[^ 0-9.-]/ {print date,$0}' file | column -t
time PRES TEMP WDIR WSPD RELH
20200201 1000 10 230 5 90
20200201 900 9 200 6 85
20200201 800 9 100 6 87
20200202 1000 9.2 233 5 90
20200202 900 9.1 200 4 80
20200202 800 9 176 2 80
Explanation
function just returns the month number from the month string by looking up the index of and converting to formatted number
f keeps track of the dashed lines so that from the previous line we can parse the date,
finally to find the data lines the heuristic is number of fields and no non-number signs (digits, spaces, dots or negative signs).

Answer 2

$ cat tst.awk
/^-+$/ && ( ((++dashCnt) % 2) == 1 ) {
mthNr = (index("JanFebMarAprMayJunJulAugSepOctNovDec",p[n-1])+2)/3
time = sprintf("%04d%02d%02d", p[n], mthNr, p[n-2])
}
/^[[:upper:][:space:]]+$/ && !doneHdr++ { print "Time", $0 }
/^[0-9.[:space:]]+$/ { print time, $0 }
{ n = split($0,p) }
.
$ awk -f tst.awk file | column -t
Time PRES TEMP WDIR WSPD RELH
20200001 1000 10 230 5 90
20200001 900 9 200 6 85
20200001 800 9 100 6 87
20200002 1000 9.2 233 5 90
20200002 900 9.1 200 4 80
20200002 800 9 176 2 80