ATL: JOAQUIN - Post-Tropical - Discussion

[JonathanBelles]

It was pretty clear that Joaquin tried to start an eyewall replacement cycle on tonight's recon and mid afternoon microwave imagery. At the time Joaquin was a borderline system for such a cycle in terms of intensity with most hurricanes that undergo such a cycle being mid category 4 or above. I have to wonder if it started the cycle and then slowed down and sucked up the heat intensity of the area and then couldn't finish the cycle and weakened and/or lost structural intensity.

Goes to show that it doesn't always take great oceanic and atmospheric conditions to keep a system going. Internal conditions can cause problems too.

[Chris_in_Tampa]

935mb, 8 knots of surface wind

UZNT13 KNHC 020315
XXAA 52037 99229 70745 08024 99935 26621 22008 00/// ///// /////
92094 26019 20005 85839 23221 01007 70522 16057 15504 88999 77999
31313 09608 80259
61616 AF300 0911A JOAQUIN OB 16
62626 CENTER MBL WND 26003 AEV 07775 DLM WND 01002 934697 WL150 2
1505 085 REL 2287N07453W 025918 SPG 2287N07453W 030204 =
XXBB 52038 99229 70745 08024 00935 26621 11850 23221 22710 17446
33697 15458
21212 00935 22008 11914 29001 22904 25002 33900 30007 44889 31505
55877 32509 66855 31501 77850 01007 88697 15502
31313 09608 80259
61616 AF300 0911A JOAQUIN OB 16
62626 CENTER MBL WND 26003 AEV 07775 DLM WND 01002 934697 WL150 2
1505 085 REL 2287N07453W 025918 SPG 2287N07453W 030204 =
;

[CrazyC83]

URNT15 KNHC 020319
AF300 0911A JOAQUIN HDOB 49 20151002
031030 2229N 07455W 6966 02937 9842 +065 +049 301104 107 069 018 03
031100 2228N 07456W 6959 02957 9846 +072 +047 301100 102 064 008 00
031130 2227N 07457W 6968 02954 9849 +079 +052 301097 099 063 009 00
031200 2226N 07458W 6973 02958 9845 +091 +052 304096 096 063 008 03
031230 2225N 07500W 6967 02975 9845 +100 +051 305093 095 061 008 03
031300 2224N 07501W 6958 02994 9875 +081 +055 303089 092 058 009 00
031330 2223N 07502W 6975 02982 9887 +077 +067 305088 091 057 008 03
031400 2222N 07503W 6961 03002 9896 +075 +059 305080 087 053 009 03
031430 2221N 07504W 6974 02992 9898 +079 +062 306079 080 056 005 03
031500 2220N 07505W 6966 03011 9906 +079 +058 307079 080 051 004 03
031530 2219N 07507W 6966 03015 9905 +087 +056 308076 078 052 003 03
031600 2218N 07508W 6970 03018 9911 +088 +053 306075 075 051 004 03
031630 2217N 07509W 6967 03022 9917 +085 +057 302070 075 051 004 03
031700 2216N 07510W 6967 03029 9910 +096 +051 301070 071 049 004 03
031730 2215N 07512W 6964 03033 9919 +092 +048 302069 070 048 005 03
031800 2214N 07513W 6967 03038 9924 +091 +044 304069 069 048 005 03
031830 2212N 07514W 6966 03043 9940 +083 +046 307068 069 048 004 03
031900 2211N 07515W 6967 03042 9946 +082 +048 308069 071 045 005 03
031930 2210N 07516W 6970 03054 9949 +089 +047 307071 072 047 003 03
032000 2208N 07516W 6965 03058 9947 +092 +045 303071 072 /// /// 03
$$
;

[ozonepete]

It was pretty clear that Joaquin tried to start an eyewall replacement cycle on tonight's recon and mid afternoon microwave imagery. At the time Joaquin was a borderline system for such a cycle in terms of intensity with most hurricanes that undergo such a cycle being mid category 4 or above. I have to wonder if it started the cycle and then slowed down and sucked up the heat intensity of the area and then couldn't finish the cycle and weakened and/or lost structural intensity.

Goes to show that it doesn't always take great oceanic and atmospheric conditions to keep a system going. Internal conditions can cause problems too.

Excellent conjecture. Could very well be what happened.

[Chris_in_Tampa]

Here is that high SFMR location:

[p1nheadlarry]

It was pretty clear that Joaquin tried to start an eyewall replacement cycle on tonight's recon and mid afternoon microwave imagery. At the time Joaquin was a borderline system for such a cycle in terms of intensity with most hurricanes that undergo such a cycle being mid category 4 or above. I have to wonder if it started the cycle and then slowed down and sucked up the heat intensity of the area and then couldn't finish the cycle and weakened and/or lost structural intensity.

Goes to show that it doesn't always take great oceanic and atmospheric conditions to keep a system going. Internal conditions can cause problems too.

Do you think it's possibly beginning to feel the trough and that might have had something to do with it? Since the eye started shrinking (~5PM) it has gone from SW to W.

[ozonepete]

I have to hit the hay, but my last ob is that this TC is getting pushed westward really hard. It just does not "want" to go north yet. In true flow dynamics that means the westward push by the building ridge to its northeast is still very strong while the digging trough from the middle of the U.S. is not so strong and thus so far cannot force it to move northward. When will it turn?

[Hammy]

Interestingly there seems to be stronger winds on this pass (closer to the official intensity) than the previous one.

[psyclone]

Barring upwelling, I think there's a good chance that Joaquin could have a second peak tomorrow at a higher intensity than today's. As of right now the opening of the poleward outflow channel looks like it will be very well timed with the end of eyewall replacement. Joaquin is still firing deep convection with a ring of cold medium grey on the BD curve, so if upwelling is to affect it, it hasn't started yet.

*EDIT: Huh, NHC mentions no eyewall replacement.

I guess with shallower waters those warm temperatures start to decrease with not just upwelling but the storm itself taking up that energy. Might be making that turn soon or tomorrow, if it heads away from the Bahamas it could find more fuel before ultimately accelerating and weakening (likely between Bermuda and the Maritimes, even if we can't officially rule out a closer path to the US. If it turns now I think the ECMWF solution that many other models have caught up with will be the right).

Gotta appreciate how the NHC handles changes in tracks. Modest changes until the consensus becomes more confident for it to require a shift.

I think you nailed it. Those shallow waters may not have much cold water to upwell but the hurricane itself will suck the heat right out of it with blasting wind, heavy rain, cooler air temps than would otherwise be the case and a denial of solar heating due to cloud cover. Earlier this summer during the heavy rain events around tampa bay our nearshore gulf temp dropped 10 degrees in a few days. it's not tough to imagine the storm doing something similar in the Bahamas and that could be making a difference now.

[CrazyC83]

000
URNT15 KNHC 020329
AF300 0911A JOAQUIN HDOB 50 20151002
032030 2208N 07514W 6967 03050 9936 +095 +054 299070 071 /// /// 03
032100 2208N 07512W 6968 03044 9930 +095 +042 298074 074 /// /// 03
032130 2207N 07509W 6968 03043 9931 +092 +043 297074 075 048 006 03
032200 2206N 07507W 6967 03038 9932 +088 +045 294075 075 048 005 00
032230 2206N 07504W 6967 03037 9940 +079 +041 293076 076 049 005 03
032300 2205N 07502W 6968 03035 9943 +076 +043 291076 076 047 006 00
032330 2204N 07459W 6967 03034 9937 +079 +046 289077 077 047 006 03
032400 2203N 07457W 6969 03029 9940 +075 +050 286076 077 047 007 00
032430 2203N 07454W 6966 03035 9933 +080 +049 283076 076 046 007 00
032500 2202N 07452W 6966 03034 9929 +084 +048 281075 076 046 006 03
032530 2201N 07449W 6969 03031 9928 +086 +048 279075 075 046 005 03
032600 2201N 07447W 6966 03036 9929 +085 +051 278076 076 043 006 03
032630 2200N 07444W 6967 03037 9926 +090 +045 276072 075 043 007 00
032700 2159N 07442W 6969 03034 9927 +088 +049 273074 075 041 007 03
032730 2159N 07440W 6976 03027 9935 +083 +062 272074 075 038 013 00
032800 2158N 07437W 6978 03026 9937 +083 +059 272075 077 039 010 00
032830 2157N 07435W 6967 03038 9935 +086 +058 271072 075 043 006 03
032900 2156N 07433W 6987 03019 9934 +090 +060 272071 073 042 006 03
032930 2155N 07431W 6964 03051 9929 +095 +039 275070 072 /// /// 03
033000 2153N 07429W 6964 03050 9939 +086 +056 271072 073 044 004 00
$$
;

[TimeZone]

The core is looking rather poor on that microwave posted. Almost surprisingly bad for such a strong system.

[Chris_in_Tampa]

Last pass:

[blp]

I have to hit the hay, but my last ob is that this TC is getting pushed westward really hard. It just does not "want" to go north yet. In true flow dynamics that means the westward push by the building ridge to its northeast is still very strong while the digging trough from the middle of the U.S. is not so strong and thus so far cannot force it to move northward. When will it turn?

As always great post. Could not agree more. This is still not settled until we see the turn. Might linger longer than expected.

[AutoPenalti]

Ridge building in?

[p1nheadlarry]

Barring upwelling, I think there's a good chance that Joaquin could have a second peak tomorrow at a higher intensity than today's. As of right now the opening of the poleward outflow channel looks like it will be very well timed with the end of eyewall replacement. Joaquin is still firing deep convection with a ring of cold medium grey on the BD curve, so if upwelling is to affect it, it hasn't started yet.

*EDIT: Huh, NHC mentions no eyewall replacement.

I guess with shallower waters those warm temperatures start to decrease with not just upwelling but the storm itself taking up that energy. Might be making that turn soon or tomorrow, if it heads away from the Bahamas it could find more fuel before ultimately accelerating and weakening (likely between Bermuda and the Maritimes, even if we can't officially rule out a closer path to the US. If it turns now I think the ECMWF solution that many other models have caught up with will be the right).

Gotta appreciate how the NHC handles changes in tracks. Modest changes until the consensus becomes more confident for it to require a shift.

I think you nailed it. Those shallow waters may not have much cold water to upwell but the hurricane itself will suck the heat right out of it with blasting wind, heavy rain, cooler air temps than would otherwise be the case and a denial of solar heating due to cloud cover. Earlier this summer during the heavy rain events around tampa bay our nearshore gulf temp dropped 10 degrees in a few days. it's not tough to imagine the storm doing something similar in the Bahamas and that could be making a difference now.

Maybe due to how the sea breeze-fueled t-storms can help to cool off once they've passed, we get them up here in the summer sometimes. Unless they're (s)west to (n)east moving storms that often are accompanied by a drier air mass behind it, the sea breeze types seem more humid (makes sense) but the temp does change.

It's a catch-22 for this hurricane: its slow movement might be at least partially why it appears to be weakening, but a slow moving hurricane over populated areas is never a good thing.

[1900hurricane]

I'm not saying it's not going to happen in the future, but I'm highly doubting that upwelling/water with significantly reduced heat content is significantly affection Joaquin right now. The first place that would be noticed would be with a warming CDO, and that's not at all what's been happening recently.

[CrazyC83]

URNT15 KNHC 020339
AF300 0911A JOAQUIN HDOB 51 20151002
033030 2152N 07427W 6965 03054 9935 +095 +040 271072 073 046 004 00
033100 2150N 07425W 6963 03059 9942 +092 +051 267069 071 045 003 03
033130 2149N 07423W 6966 03060 9946 +093 +045 266068 069 046 003 00
033200 2148N 07422W 6967 03059 9953 +091 +041 268067 068 044 003 03
033230 2146N 07420W 6967 03065 9960 +088 +046 265069 070 042 004 00
033300 2145N 07418W 6966 03072 9965 +086 +050 260066 067 042 004 03
033330 2144N 07416W 6967 03069 9976 +081 +042 259065 066 040 004 03
033400 2143N 07414W 6965 03075 9980 +080 +035 259064 065 036 004 03
033430 2141N 07413W 6967 03073 9975 +085 +036 262067 068 040 005 03
033500 2140N 07411W 6963 03080 9970 +087 +040 264066 068 040 005 00
033530 2139N 07409W 6970 03066 9966 +090 +044 268064 066 047 005 03
033600 2138N 07407W 6975 03061 9961 +093 +042 267070 074 047 005 03
033630 2137N 07405W 6942 03104 9982 +076 +057 261064 076 043 012 03
033700 2136N 07403W 6959 03084 9966 +092 +045 262067 068 049 007 00
033730 2135N 07400W 6987 03053 9982 +082 +050 259063 067 048 009 00
033800 2134N 07359W 6956 03094 9993 +075 +055 250063 068 038 015 00
033830 2133N 07357W 6957 03092 0000 +068 +057 245058 062 034 021 00
033900 2132N 07355W 6958 03087 9995 +071 +062 242059 061 041 016 00
033930 2131N 07353W 6972 03076 9998 +070 +061 244056 063 041 011 03
034000 2130N 07352W 6978 03072 9998 +074 +056 253052 058 048 010 03
$$
;

[Chris_in_Tampa]

[p1nheadlarry]

I'm not saying it's not going to happen in the future, but I'm highly doubting that upwelling/water with significantly reduced heat content is significantly affection Joaquin right now. The first place that would be noticed would be with a warming CDO, and that's not at all what's been happening recently.

As others have mentioned, the "squashed" look might be due to the ridge to its north that's kept it further in the Bahamas than even the ECMWF initially thought and the trough over the eastern seaboard. Upwelling surely going on (I'll have to look at sst images tomorrow, it's time for my head to rest and prepare for a wet n wild weekend) but might not be as big of a factor as the battling between these two features. I wouldn't think overly-churned waters would warrant an decaying eyewall like this that fast.

Good night all, and stay safe down there in the Bahamas if you live there

[Chris_in_Tampa]