ATL: SAM - Remnants - Discussion

[KWT]

Yeah Ascat isn't even borderline for an upgrade, its a 100% stone wall TS 35kts (maybe 40kts). Talk of it being 30kts is clearly nonsense when you've got such a strong Ascat return as that...

[Shell Mound]

Samwise Gamgee is here

Code: Select all

Tropical Storm EIGHTEEN
As of 12:00 UTC Sep 23, 2021:

Location: 10.8°N 37.4°W
Maximum Winds: 40 kt  Gusts: N/A
Minimum Central Pressure: 1004 mb
Environmental Pressure: N/A
Radius of Circulation: N/A
Radius of Maximum wind: 30 nm
34 kt Wind Radii by Quadrant:

Looking back to 1851, in the month of September I found six systems of ≥ TS status that passed within 100 n mi of Sam’s estimated position (10.8°N 37.4°W) as of 12:00 UTC, yet remained within the southern semicircle. Of these six systems, two—Storm #3 of 1883 and Storm #5 of 1906—eventually made landfalls on the CONUS, each as a hurricane. Storm #3 of 1883 was the strongest of the two, peaking as a MH in the Caribbean before striking NC as a 90-kt Category-2 on 11 September. Storm #5 of 1906 made LF on SC as an 80-kt Category-1 on 17 September. Two of the remaining three systems curved OTS, while the third, Kirk (2018), struck the northern Windward Islands as a degenerating TS. Therefore, if Sam were somehow to become a hurricane and impact the Caribbean, it would be in a better position to eventually strike the CONUS as a hurricane. Based on the limited sample hitherto mentioned, the Carolinas might be the primary target.

[Extratropical94]

Boom. Straight to 45 kts.

TROPICAL STORM SAM FORECAST/ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182021
1500 UTC THU SEP 23 2021

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 10.9N 38.1W AT 23/1500Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE WEST OR 280 DEGREES AT 14 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1003 MB
MAX SUSTAINED WINDS 45 KT WITH GUSTS TO 55 KT.

[Iceresistance]

Sam has very high potential, is now expected to peak at 125 mph

FORECAST POSITIONS AND MAX WINDS

INIT 23/1500Z 10.9N 38.1W 45 KT 50 MPH
12H 24/0000Z 11.3N 40.3W 50 KT 60 MPH
24H 24/1200Z 11.9N 42.9W 60 KT 70 MPH
36H 25/0000Z 12.3N 45.0W 70 KT 80 MPH
48H 25/1200Z 12.7N 46.7W 80 KT 90 MPH
60H 26/0000Z 13.2N 48.2W 90 KT 105 MPH
72H 26/1200Z 13.7N 49.4W 100 KT 115 MPH
96H 27/1200Z 15.3N 52.1W 105 KT 120 MPH
120H 28/1200Z 17.4N 55.2W 110 KT 125 MPH

[zzh]

INIT 23/1500Z 10.9N 38.1W 45 KT 50 MPH
12H 24/0000Z 11.3N 40.3W 50 KT 60 MPH
24H 24/1200Z 11.9N 42.9W 60 KT 70 MPH
36H 25/0000Z 12.3N 45.0W 70 KT 80 MPH
48H 25/1200Z 12.7N 46.7W 80 KT 90 MPH
60H 26/0000Z 13.2N 48.2W 90 KT 105 MPH
72H 26/1200Z 13.7N 49.4W 100 KT 115 MPH
96H 27/1200Z 15.3N 52.1W 105 KT 120 MPH
120H 28/1200Z 17.4N 55.2W 110 KT 125 MPH

[cycloneye]

Very important for the members who live in the Islands. We have to be very vigilant about this storm.

Similar to
yesterday, the ECMWF model and its ensemble mean flanks the
southwest side of the guidance envelop, while the GFS is on the
northeast side by day 5. These differences appear to be partially
related to the mid-level ridge intensity on the western end, which
could begin to be eroded by a mid-latitude trough off the eastern
United States in 120-h. In addition, differences in both the size
and intensity of Sam may also play a role in its ultimate track
evolution. For this advisory, the latest NHC track forecast remains
close to the consensus aids TCVN and TCVE, which represents a slight
shift westward and a bit faster motion compared to the previous
forecast. Because Sam is forecast to slow down, it remains too early
to determine what impacts, direct or indirect, could be felt by the
Lesser Antilles by this cyclone.

[Shell Mound]

Boom. Straight to 45 kts.

TROPICAL STORM SAM FORECAST/ADVISORY NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL182021
1500 UTC THU SEP 23 2021

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL STORM CENTER LOCATED NEAR 10.9N 38.1W AT 23/1500Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE WEST OR 280 DEGREES AT 14 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1003 MB
MAX SUSTAINED WINDS 45 KT WITH GUSTS TO 55 KT.

I couldn’t resist. After all, our friends in the Islands will likely need a bit of humour to deal with Son of Sam over the upcoming week...

[SouthDadeFish]

Sam looks excellent on satellite right now. It appears an inner core is forming. All those Euro ensemble forecasts of a weak TC over the next 3-4 days seem pretty questionable right now.

[Hypercane_Kyle]

Sam looks excellent on satellite right now. It appears an inner core is forming. All those Euro ensemble forecasts of a weak TC over the next 3-4 days seem pretty questionable right now.

Agreed. The GFS is spot on with short term intensity, which obviously has a big impact on track too.

[tropicwatch]

As long as it keeps barreling westward, the forecast track should continue to stay on the western portion of the forecast. I think the northern portion of the Lesser Antilles might be in for a hurricane.

[Blown Away]

IMO, Sam is currently moving faster than models predicted which may lead to farther W before the NW turn.

[AutoPenalti]

The Euro may need to adjust here.

[cycloneye]

Very interesting.

 https://twitter.com/webberweather/status/1440804865869946883

[AutoPenalti]

Very interesting.

https://twitter.com/webberweather/status/1440804865869946883

That tweet was from yesterday's 12z so the synoptic pattern could have changed since then, I haven't had a chance to look at 0z.

[InfernoFlameCat]

A Proto eye appears to have formed. Similar to Larry’s eye development when Larry was a Ts.

[SconnieCane]

The Euro ensemble forecasts of stronger=north make no sense to me. Further south = over warmer waters and further from the possible TUTT.

[Sciencerocks]

[Shell Mound]

The Euro ensemble forecasts of stronger=north make no sense to me. Further south = over warmer waters and further from the possible TUTT.

Recent runs have been showing a deeper TUTT axis extending farther south. Incidentally, while this trend induces more of a southerly shortwave component to Sam's trajectory, it also results in stronger shear over the storm. So in this case a weaker Sam would be more likely to track farther west. Given the pattern, I still fail to see how Sam could follow the bullish solutions intensity-wise and impact the Caribbean. The situation seems to be either/or so far. Stronger = OTS, weaker = Caribbean.

[Hypercane_Kyle]

Worth noting that while 2020 had more named storms at this point, 2021 has had more major hurricanes (3 vs 2, with Sam likely to be the 4th).

[kevin]

Sam is organizing very quickly. With near-perfect conditions ahead of him I think it's becoming increasingly likely that Sam will be the storm of the season (in terms of intensity & long tracking, not per se damage/impacts).