ATL: SAM - Models

[ronjon]

12z CMC - 971 mb off of Cape Cod heading NW at 216 hrs. Could a storm even maintain that intensity so far north - seems doubtful.

https://www.tropicaltidbits.com/analysis/models/?model=gem&region=us&pkg=mslp_pcpn_frzn&runtime=2021092412&fh=216

[jlauderdal]

See ya

https://i.postimg.cc/RZRCFZ3J/gfs-mslp-pcpn-watl-fh60-198.gif

A very reasonable solution for late September.

There is a 456-hour GEFS run posted on the global model's thread for people looking into October, doesn't look real active for the first half of the month .

[AutoPenalti]

Euro faster at 24 hours.

[sma10]

Hey Everyone, new member here. Have really enjoyed following this storm. I am by no means an expert, but I am trying to learn. On another note, I live in Broward County (SE Florida). Would you say that we are 100% in the clear?

Not even the NHC will say that you are 100% in the clear, however it is pretty unlikely at the moment that it impacts SFL. We have yet to see a single run with a Florida landfall and there aren't any ensembles hinting at that either.

Can you recall any instance of a hurricane taking a track that is well outside of all ensembles 7+ days out? I was looking up Andrew to see what the very early ensembles called for, but I can't find anything.

Andrew was in the stone age wrt modeling. The discussions even reference the BAM models lol.

Andrew was a fairly atypical track so the NHC really didn't latch on a certain SE FL landfall until about 36hrs prior. I do wonder if the more modern Euro/GFS would have caught it sooner, and I would think yes.

As for your question about reliability of 7+ day forecasts ... the errors for that time horizon can be massive, it's happened many times. The point is, sometimes model's 7 day forecast are excellent, sometimes they are horrific. My sense in this case is that they are likely correct - I doubt the advertised escape hatch will all of a sudden become a massive blocking ridge

[kevin]

Intensity readout of 12z HWRF and HMON. Looks like especially HMON is struggling with Sam, most likely due to the weaker structure of the storm around 12z which is probably delaying intensification in these model runs. I expect 18z and especially tomorrow's runs to be more indicative of the intensity. Even though I guess the discussion is moving more and more to the other thread anyways now. Once storms become big enough we always transition from forecasting to nowcasting.

--- 12z HWRF ---
PEAK PRESSURE; +90hr; 950.2MB; 111.2KT; CAT3
PEAK WIND; +99hr; 953.9MB; 112.2KT; CAT3
FINAL LOCATION; +120hr; 18.5N; 57.5W; 58 mi NW of 06z HWRF

Time / Pressure (mbar) / Wind (kt)
00 / 992 / 64
03 / 991 / 63
06 / 990 / 64
09 / 989 / 65
12 / 988 / 65
15 / 983 / 78
18 / 977 / 84 <- cat 2
21 / 976 / 80
24 / 975 / 75
27 / 972 / 81
30 / 969 / 86
33 / 965 / 97 <- cat 3
36 / 963 / 103
39 / 961 / 105
42 / 956 / 104
45 / 956 / 110
48 / 959 / 104
51 / 959 / 105
54 / 957 / 106
57 / 957 / 104
60 / 958 / 105
63 / 958 / 105
66 / 956 / 107
69 / 956 / 106
72 / 956 / 105
75 / 954 / 112
78 / 953 / 110
81 / 952 / 111
84 / 953 / 109
87 / 953 / 107
90 / 950 / 111
93 / 952 / 106
96 / 954 / 109
99 / 954 / 112
102 / 952 / 107
105 / 953 / 106
108 / 953 / 106
111 / 953 / 103
114 / 953 / 99
117 / 953 / 105
120 / 954 / 107
123 / 954 / 109
126 / 953 / 104

--- 12z HMON ---
PEAK PRESSURE; +126hr; 946.6MB; 118.1KT; CAT4
PEAK WIND; +90hr; 950.7MB; 118.9KT; CAT4
FINAL LOCATION; +120hr; 18.5N; 57.1W; 85 mi NW of 06z HMON

Time / Pressure (mbar) / Wind (kt)
00 / 993 / 65
03 / 998 / 62
06 / 995 / 58
09 / 994 / 59
12 / 991 / 61
15 / 987 / 68
18 / 988 / 62
21 / 987 / 60
24 / 985 / 65
27 / 982 / 73
30 / 975 / 76
33 / 972 / 85 <- cat 2
36 / 975 / 82
39 / 972 / 91
42 / 969 / 82
45 / 968 / 80
48 / 968 / 85
51 / 966 / 94
54 / 966 / 86
57 / 964 / 102 <- cat 3
60 / 964 / 87
63 / 964 / 99
66 / 961 / 98
69 / 962 / 102
72 / 959 / 107
75 / 956 / 111
78 / 954 / 110
81 / 952 / 112
84 / 951 / 111
87 / 952 / 113 <- cat 4
90 / 951 / 119
93 / 950 / 116
96 / 949 / 102
99 / 950 / 105
102 / 950 / 103
105 / 948 / 104
108 / 950 / 111
111 / 952 / 99
114 / 953 / 106
117 / 950 / 115
120 / 947 / 111
123 / 947 / 118
126 / 947 / 118

[AutoPenalti]

Slightly SW at 120.

[Duke95]

Not even the NHC will say that you are 100% in the clear, however it is pretty unlikely at the moment that it impacts SFL. We have yet to see a single run with a Florida landfall and there aren't any ensembles hinting at that either.

Can you recall any instance of a hurricane taking a track that is well outside of all ensembles 7+ days out? I was looking up Andrew to see what the very early ensembles called for, but I can't find anything.

Andrew was in the stone age wrt modeling. The discussions even reference the BAM models lol.

Andrew was a fairly atypical track so the NHC really didn't latch on a certain SE FL landfall until about 36hrs prior. I do wonder if the more modern Euro/GFS would have caught it sooner, and I would think yes.

As for your question about reliability of 7+ day forecasts ... the errors for that time horizon can be massive, it's happened many times. The point is, sometimes model's 7 day forecast are excellent, sometimes they are horrific. My sense in this case is that they are likely correct - I doubt the advertised escape hatch will all of a sudden become a massive blocking ridge

 https://twitter.com/DerekOrtt/status/1441442112579334157

[TheDreamTraveler]

12z CMC is very concerning as a 971 MB Hurricane Landfall over New Hampshire/Maine . . .

That is the risk to the Northeast with that set-up. It's low, but it's there.

It's low because you need to get a cutoff low of around a certain strength in order for that solution to verify. Can't be too weak, or it won't be able to bring the storm in. Can't be too strong either though, or it will shear Sam apart.

Ridge to the Northeast also needs to be substantial so that Sam doesn't drift too far east and miss the phase. There's a lot that needs to come together for that solution to happen.

Yeah in Levi's latest video today he said how there's still a small risk though not very likely of Sam pivoting around the ULL into land. And with how chaotic the pattern is and how unpredictable where the cutoff will be it's not entirely off the table yet. We'll just have to keep watching

[kevin]

12z Euro+144

[AutoPenalti]

Euro further N at 168

[kevin]

Euro further N at 168

Yes, a clear jump north compared to yesterday's 12z run. I'm becoming increasingly confident that, if this threatens land, it'll be the Caribbean islands.

[MJGarrison]

Euro further N at 168

Yes, a clear jump north compared to yesterday's 12z run. I'm becoming increasingly confident that, if this threatens land, it'll be the Caribbean islands.

Compared to the 0z run, its further south/slightly slower.


Sent from my iPad using Tapatalk

[chris_fit]

Can you recall any instance of a hurricane taking a track that is well outside of all ensembles 7+ days out? I was looking up Andrew to see what the very early ensembles called for, but I can't find anything.

Last Year. Here is Eta. Take a look at the 5 day forecast points for the models (120hrs)

The Red Circled X is where Eta ended up being.

[ronjon]

Look out New England on the Euro.

[AutoPenalti]

Oof. NE needs to watch this.

[Hypercane_Kyle]

12z Euro looks similar to the Canadian. Ridge to the north, rotating around an ULL.

Not a done deal that this OTS by any means.

[ColdMiser123]

Euro with landfall into Maine, huge nod to the CMC evolution at 12z.

[IcyTundra]

To all the people saying OTS is a done deal spoiler alert: it isn't. New England and Bermuda need to keep a close eye on this one.

[Hypercane_Kyle]

The timing of the cutoff ULL is going to be critical. FWIW, the GFS actually makes the ULL in question its own tropical cyclone and is the only model showing this.

[drezee]

 https://twitter.com/andretrotter/status/1441478524372598791