ATL: JOAQUIN - Post-Tropical - Discussion

[CrazyC83]

Since the eye positions are definitely to the east of the forecast track, does this change anything down the road?

[AutoPenalti]

What I find interesting was that it took just few miles north just to develop an eye.

So my unsupported theory would be that the Bahamian islands prevented Joaquin from forming an eye and intensifying further.

[NotoSans]

Maximum flight-level wind at 144 kt with SFMR as high as 138 kt. SFMR possibly rain-contaminated but flight-level supports 130 kt.

[CrazyC83]

000
URNT15 KNHC 031451
AF304 1311A JOAQUIN HDOB 37 20151003
144230 2529N 07132W 6977 02857 9758 +113 +113 223118 121 078 056 00
144300 2531N 07133W 6978 02846 9741 +116 +116 228121 121 080 051 03
144330 2532N 07134W 6974 02833 9714 +123 +123 230123 124 080 055 03
144400 2533N 07135W 6971 02817 9687 +127 +127 228122 124 074 066 03
144430 2534N 07137W 6968 02802 9663 +130 +130 228119 122 064 077 03
144500 2535N 07138W 6959 02788 9640 +128 +128 226124 126 087 083 00
144530 2537N 07139W 6967 02743 9599 +128 +128 228138 142 093 050 03
144600 2538N 07139W 6966 02705 9556 +132 +132 230142 144 138 041 00
144630 2539N 07140W 6965 02673 9512 +136 +136 234132 144 134 035 00
144700 2541N 07141W 6969 02636 9456 +138 //// 234117 128 129 012 01
144730 2542N 07142W 6970 02607 //// +138 //// 229096 110 122 008 05
144800 2543N 07144W 6969 02579 //// +140 //// 230071 089 106 000 05
144830 2544N 07145W 6971 02562 9334 +160 +152 238048 064 095 003 00
144900 2545N 07146W 6972 02560 9327 +167 +150 253031 038 058 002 03
144930 2546N 07147W 6974 02557 9330 +163 +146 262021 030 027 000 00
145000 2548N 07148W 6969 02564 9335 +155 +149 269017 019 024 001 00
145030 2550N 07148W 6972 02557 9339 +153 +145 264010 015 021 001 03
145100 2552N 07148W 6972 02559 9336 +155 +143 141003 011 019 001 00
145130 2553N 07149W 6970 02562 9337 +158 +146 100014 018 024 000 03
145200 2555N 07150W 6963 02577 9338 +166 +141 084038 050 032 002 00
$$
;

144 kt FL, 138 kt SFMR. Special advisory by 11:30 am? Pressure 933mb.

[CrazyC83]

Latest data supports an intensity of 130 kt. SFMR agreed a tad too high.

[SouthDadeFish]

Maximum flight-level wind at 144 kt with SFMR as high as 138 kt. SFMR possibly rain-contaminated but flight-level supports 130 kt.

With extrapolated pressure down to 932 mb. Making a run at category-five status?

[Chris_in_Tampa]

[CrazyC83]

Maximum flight-level wind at 144 kt with SFMR as high as 138 kt. SFMR possibly rain-contaminated but flight-level supports 130 kt.

With extrapolated pressure down to 932 mb. Making a run at category-five status?

Seems that way. Definitely the strongest Joaquin has been yet.

[SouthDadeFish]

Interesting to note the lowest extrapolated pressure occurred with ~40 kt flight level winds. The vortex is becoming increasingly tilted by the shear, which should ultimately halt the current intensification process.

[CrazyC83]

Given that no advisory forecast an intensity this high, I'd put out a new Special Advisory package shortly personally with a 130 kt initial intensity, mention a new peak intensity of 135 kt in the next few hours then adjust the intensities afterward to 48-72 hours.

[brunota2003]

Look at the rain rates, I usually consider anything over 10 to be inflated by the rain (and thus needed adjusting). In this case, the rates are in the 40s! Would need to adjust that 138 and 134 way down in that case. The 122 looks good, though. With the 129 only having rates of 12, and the 122 being 8, I could see an argument for 125 knot winds there. A 0.9 reduction of the 144 knot flight level winds also gives you 129 knot surface winds...so 125 sounds good (0.85 is 122 knots, FYI).

[Chris_in_Tampa]

[Yellow Evan]

I'd consider upgrading to 140 if a dropsonde suggest high surface mixing.

[SouthDadeFish]

Given that no advisory forecast an intensity this high, I'd put out a new Special Advisory package shortly personally with a 130 kt initial intensity, mention a new peak intensity of 135 kt in the next few hours then adjust the intensities afterward to 48-72 hours.

What I don't understand is why they didn't wait for recon to sample to SE eyewall again before issuing the 11 am advisory. They put it out pretty early. They could have kept the discussion and other information the same and waited on the final numbers. It's most likely more difficult than what I'm saying though.

[CrazyC83]

000
URNT15 KNHC 031502
AF304 1311A JOAQUIN HDOB 38 20151003
145230 2556N 07152W 6976 02583 9352 +177 +138 076066 071 040 002 00
145300 2557N 07154W 6972 02627 9363 +210 +114 063091 098 055 003 00
145330 2558N 07156W 6980 02663 9395 +229 +075 050097 102 070 004 03
145400 2559N 07158W 6985 02685 9434 +220 +091 045092 095 /// /// 03
145430 2600N 07200W 6947 02766 9471 +217 +060 043088 090 074 000 03
145500 2600N 07202W 6977 02759 9521 +198 +080 040082 088 077 003 00
145530 2600N 07204W 6975 02792 9570 +173 +113 032071 081 079 002 00
145600 2601N 07207W 6971 02821 9611 +156 +122 017074 077 076 003 00
145630 2601N 07209W 6967 02850 9633 +158 +116 013071 075 070 006 03
145700 2602N 07210W 6959 02865 9659 +140 +121 011067 070 068 004 00
145730 2603N 07211W 6966 02867 9666 +149 +109 014065 066 066 005 00
145800 2604N 07212W 6968 02878 9689 +138 +115 017062 065 063 002 00
145830 2605N 07213W 6978 02871 //// +122 //// 020055 060 061 004 01
145900 2606N 07214W 6967 02902 9728 +127 +119 022057 059 060 004 00
145930 2608N 07215W 6970 02908 9740 +123 +119 030052 056 059 005 01
150000 2609N 07216W 6968 02921 //// +116 //// 036050 053 059 004 01
150030 2610N 07217W 6970 02924 //// +107 //// 037046 048 056 003 01
150100 2612N 07217W 6970 02931 //// +110 //// 041046 047 055 004 01
150130 2613N 07219W 6965 02944 9810 +106 //// 042047 049 055 004 01
150200 2614N 07221W 6971 02943 9827 +115 //// 044049 051 053 010 05
$$
;

Maybe they didn't find the true center? Notice the high winds increase before the pressure does.

[SouthDadeFish]

I'd consider upgrading to 140 if a dropsonde suggest high surface mixing.

Flight level winds and previous dropsondes don't support this intensity.

[Yellow Evan]

I'd consider upgrading to 140 if a dropsonde suggest high surface mixing.

Flight level winds and previous dropsondes don't support this intensity.

Shouldn't matter with an SFMR at 138. The 90% rule isn't going to apply to every storm. Some storms have higher ratios, some have lower.

[CrazyC83]

I'd consider upgrading to 140 if a dropsonde suggest high surface mixing.

They might place a dropsonde in there, but the flight level winds of 144 translate to 131 at the surface. Given that there were reliable SFMR readings in the mid to high 120s, 130 kt is likely the best intensity estimate. The 134 and 138 SFMR readings had high rainfall rates which likely made them overestimates.

[Chris_in_Tampa]

Look at the rain rates, I usually consider anything over 10 to be inflated by the rain (and thus needed adjusting). In this case, the rates are in the 40s! Would need to adjust that 138 and 134 way down in that case. The 122 looks good, though. With the 129 only having rates of 12, and the 122 being 8, I could see an argument for 125 knot winds there. A 0.9 reduction of the 144 knot flight level winds also gives you 129 knot surface winds...so 125 sounds good (0.85 is 122 knots, FYI).

I heard from NOAA several days ago that they bias correct the SFMR winds in real time now for HDOB messages, on all aircraft, for rain. (Well, I asked about the AF and NOAA aircraft.) I don't know how well it works, but keep that in mind. The value you are seeing in the HDOB message has already been corrected.

A paper about it can be found here (early version which is free):
http://www.researchgate.net/publication ... cipitation

Or for meteorologists with access, here is the final version:
http://journals.ametsoc.org/doi/abs/10. ... 14-00028.1

[SouthDadeFish]

I'd consider upgrading to 140 if a dropsonde suggest high surface mixing.

Flight level winds and previous dropsondes don't support this intensity.

Shouldn't matter with an SFMR at 138. The 90% rule isn't going to apply to every storm. Some storms have higher ratios, some have lower.

Did you see the rain rates in the high SFMR readings? And you can look at the previous sondes dropped in the SE eyewall to show how winds aren't fully mixing to the surface.