TS Ophelia

[GaWx]

 The models are pretty much unanimous in developing a non-tropical surface low off of the SE US coast late this week that could then transition into either or both a STC and a TC. Ultimately, the biggest impact to land could end being heavy rain well up the E cost as @jconsorhas mentioned elsewhere.
 
 I found these seven TCs that formed from a nontropical origin that later hit the SE US as an H: 

-Arthur 2014: early July; developing weak Nino; cat 2 into NC

-Gaston 2004: late Aug; weak Niño; cat 1 into SC

-Diana of 1984: early to mid Sep; incoming Nina; cat 2 into NC after being cat 4 offshore

-Cindy of 1959: early Jul; neutral ENSO; cat 1 into SC

-Yankee Hurricane of 1935: formed from nontropical low E of Bermuda Oct 30 that hit SE FL as a cat 2 H Nov 4th! Warm neutral ENSO

-Storm #5 of 1913: early Oct; formed from nontropical low off NE US and hit SC as cat 1/developing Nino

-Storm #2 of 1898: late Aug; cold neutral; cat 1 into GA


 So, a TC that is purely nontropical in origin has resulted in a landfalling H on the SE US coast ~every 18 years on average over the last 125 years. The strongest landfalls were the three cat 2 hits: Arthur of 2014, Diana of 1984, and the Yankee H of 1935. Landfalls: 3 SC, 2 NC, 1 GA, 1 FL

 TS landfalls on the SE coast from nontropical origins have occurred much more often than the once/18 years of H landfalls. But that’s intuitive because it typically takes a good bit of time for transition to tropical and there often isn’t a lot of time over water with them developing close to home. There have been 12 in 73 years or ~1 every 6 years on average. So, these stats suggest that the chance of a nontropical originating TC landfalling on the SE US as a TS is ~3 times higher than landfalling there as a H:

2022: Colin

2021: Danny

2015: Ana

2007: Gabrielle

2002: Kyle

1981: Bret

1976: Dottie

1967: Doria

1965: #9

1962: #2

1960: Brenda

1952: #3


 To clarify for the readers, the stats I presented are only for those that actually made landfall on the SE US. So, they wouldn’t apply, say, to any that go NE and stay offshore, which may increase the chance for a H vs those that hit the SE.

 Based on everything I’ve seen for the current situation along with my analysis of over seven decades of history, I predict that IF this were to ever transition to a TC and IF it then were to landfall on the SE US that it would landfall there as a TS rather than a H. Also, if it were to landfall there, I predict either NC or SC with further N in SC favored over further S. This doesn’t look to me like a FL or GA landfall though nothing is certain because nothing is ever certain especially this far out.

 

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Mon Sep 18 2023

Western Atlantic: A non-tropical area of low pressure is forecast to form near the southeastern coast of the United States late this week. This system could acquire some subtropical characteristics this weekend if it remains offshore while it moves slowly northward or northwestward. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...30 percent.

 

 0Z UKMET has a strong TD/weak TS from this that landfalls in NC. The strength of this model for an undeveloped potential storm is nearly always conservatively low. Thus, I’d take its strong TD/weak TS forecast with a grain and figure that a mid grade STS/TS would be just as likely:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 126 HOURS
FORECAST POSITION AT T+126 : 30.6N 79.9W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.09.2023 132 31.7N 78.8W 1002 32
0000UTC 24.09.2023 144 34.4N 78.1W 1002 33
1200UTC 24.09.2023 156 37.8N 77.5W 1006 34
0000UTC 25.09.2023 168 40.6N 76.6W 1007 23

[GaWx]

 12Z UKMET: unlike 0Z that forms S of Charleston and then moves NNE into NC, this forms just off NC followed by NNE, NE, and ENE movement to well offshore the NE US/Canada that never allows it to landfall anywhere through hour 168:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 120 HOURS
FORECAST POSITION AT T+120 : 34.9N 74.9W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.09.2023 120 34.9N 74.9W 1005 36
0000UTC 24.09.2023 132 37.3N 73.8W 1005 36
1200UTC 24.09.2023 144 38.9N 71.2W 1009 33
0000UTC 25.09.2023 156 39.4N 67.9W 1011 30
1200UTC 25.09.2023 168 39.6N 62.3W 1013 34

[MattPetrulli]

12z GFS

[StantonParkHoya]

26 minutes ago, GaWx said:

 12Z UKMET: unlike 0Z that forms S of Charleston and then moves NNE into NC, this forms just off NC followed by NNE, NE, and ENE movement to well offshore the NE US/Canada that never allows it to landfall anywhere through hour 168:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 120 HOURS
FORECAST POSITION AT T+120 : 34.9N 74.9W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.09.2023 120 34.9N 74.9W 1005 36
0000UTC 24.09.2023 132 37.3N 73.8W 1005 36
1200UTC 24.09.2023 144 38.9N 71.2W 1009 33
0000UTC 25.09.2023 156 39.4N 67.9W 1011 30
1200UTC 25.09.2023 168 39.6N 62.3W 1013 34

GFS kind of trending this way run-over-run. 
 

Could see an OBX skirting situation. Seems like every system this year has had a late eastern shift. 
 

Nigel was originally showing a track west of Bermuda to only end up hundreds of miles east.

[Normandy]

An eastern shift here is the rare occurrence where it could yield to a stronger landfall further north.  Nice little sleeper system here

[StantonParkHoya]

Euro is…different. Low just meanders and weakens off GA coast.

[chris21]

4 minutes ago, StantonParkHoya said:

Euro is…different. Low just meanders and weakens off GA coast.

Somewhat similar to the Canadian but weaker on the Euro. Strong high in New England may prevent a quick escape north.

[olafminesaw]

The GFS is quicker to develop, and well west. I think the faster it can develop the more chance it has to move inland.

[MattPetrulli]

11 minutes ago, olafminesaw said:

The GFS is quicker to develop, and well west. I think the faster it can develop the more chance it has to move inland.

Look at that wind field. Good thing the ceiling for this is only a low-end category 1 (if even), any further organization would be disastrous due to the large wind field. 

[StantonParkHoya]

4 hours ago, MattPetrulli said:

Look at that wind field. Good thing the ceiling for this is only a low-end category 1 (if even), any further organization would be disastrous due to the large wind field. 

20-40 mph winds?

[MattPetrulli]

14 minutes ago, StantonParkHoya said:

20-40 mph winds?

Further organization=stronger system which is a huge unlikely hypothetical.

That's def a larger area of gale force winds than your usual TC. Think Nicole last year.

EDIT: For the record I think the realistic ceiling is a mid-strong tropical storm. I don't see a problem with what I said and don't understand the weenie emotes. I am just pointing out it's gonna have a big wind field. 

[Ed, snow and hurricane fan]

WPC QPF and 0Z GFS forecast show heaviest rain just offshore Carolinas to S New England.  If this is impactful, I suspect it will be because of fresh water flooding.

[StantonParkHoya]

6z GFS just keeps it offshore and away from CONUS. Have seen a few models want to do this.

[RevWarReenactor]

25 minutes ago, StantonParkHoya said:

6z GFS just keeps it offshore and away from CONUS. Have seen a few models want to do this.

The GFS seems to be having some trouble knowing what is going on, it develops multiple lows.

[NorthHillsWx]

9 hours ago, MattPetrulli said:

Further organization=stronger system which is a huge unlikely hypothetical.

That's def a larger area of gale force winds than your usual TC. Think Nicole last year.

EDIT: For the record I think the realistic ceiling is a mid-strong tropical storm. I don't see a problem with what I said and don't understand the weenie emotes. I am just pointing out it's gonna have a big wind field. 

I think “large area of gales” and term you used “disastrous” was the reason for being weenied. Large gales/mid range tropical storms are impactful, and can be damaging, but disastrous is, ehhh, overkill?

[MattPetrulli]

I think “large area of gales” and term you used “disastrous” was the reason for being weenied. Large gales/mid range tropical storms are impactful, and can be damaging, but disastrous is, ehhh, overkill?

The disasterous was in reference to the hypothetical, not the actual scenario.


.

[WxWatcher007]

06z GFS had a more consolidated low that tracked offshore, rather than some type of rainy landfall in the Carolinas. The consolidated low is an outlier, but interesting to see.

[GaWx]

 After the 0Z run not turning this into a TC and the prior 12Z having it become a TC but staying offshore, this new 12Z UKMET is back to having a TC, is a bit stronger, and it moves N to a landfall near the NC OB Saturday 9/23 followed by a crawl up the coast to DelMarVa pen/dissipation on Mon 9/25. This very slow movement and track is likely bringing very heavy rains to the mid-Atlantic coastal area:


NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER  78 HOURS
              FORECAST POSITION AT T+ 78 : 32.5N  77.0W

                        LEAD                 CENTRAL     MAXIMUM WIND
      VERIFYING TIME    TIME   POSITION   PRESSURE (MB)  SPEED (KNOTS)
      --------------    ----   --------   -------------  -------------
    0000UTC 23.09.2023   84  32.7N  76.4W     1006            47
    1200UTC 23.09.2023   96  35.4N  76.1W     1003            42
    0000UTC 24.09.2023  108  37.3N  76.3W     1001            40
    1200UTC 24.09.2023  120  37.9N  76.2W     1007            33
    0000UTC 25.09.2023  132  37.7N  76.1W     1012            32
    1200UTC 25.09.2023  144  38.2N  75.7W     1015            32
    0000UTC 26.09.2023  156              CEASED TRACKING

[Newman]

The 12z Canadian is pretty wet for the Mid-Atlantic this weekend

[NJwx85]

1 hour ago, Newman said:

The 12z Canadian is pretty wet for the Mid-Atlantic this weekend

So is the 12z GFS

[GaWx]

Looks pretty close to a STS at hour 90 of the 12Z Euro centered off N FL. Note the 35 knot wind barbs off N FL/GA/SC and the good organization and low SLP of 1002 mb:
 

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sfcwind_mslp&rh=2023091912&fh=90&r=swatl&dpdt=&mc=

[GaWx]

36 minutes ago, GaWx said:

Looks pretty close to a STS at hour 90 of the 12Z Euro centered off N FL. Note the 35 knot wind barbs off N FL/GA/SC and the good organization and low SLP of 1002 mb:
 

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=sfcwind_mslp&rh=2023091912&fh=90&r=swatl&dpdt=&mc=

The 12Z Euro op at hour 90 near 100 miles E of N FL is on the SW side of the EPS member envelope as the EPS mean is 100 miles NE of there:
 

 https://www.pivotalweather.com/model.php?m=epsens&p=sfcmslp-meanmem&rh=2023091912&fh=90&r=us_se&dpdt=&mc=

[StantonParkHoya]

Euro never brings the STS onshore 

[GaWx]

20 minutes ago, StantonParkHoya said:

Euro never brings the STS onshore 

Yeah it only skirts the NC OB. But even so, a few areas in E NC get up to 4-8” of rainfall on the Euro:

https://www.pivotalweather.com/model.php?m=ecmwf_full&p=qpf_120h-met&rh=2023091912&fh=132&r=nwatl&dpdt=&mc=

[Kevin Reilly]

19 minutes ago, StantonParkHoya said:

Euro never brings the STS onshore 

Looks a lot like the 6z GFS now with that said the Euro is kind of on another solution than the Canadian and GFS at 12z

[StantonParkHoya]

Kind of just pinpointing the heavy rain situation at this point. Looks like a STS from Wilmington to offshore NC on the table with 1-5 inches of rain from NC to CT.

[olafminesaw]

The 6z Euro is really keeping it weak and offshore 

[WxWatcher007]

Euro is the most strung out, while the GFS trend the last day has been a stronger low Friday/Saturday. Any organization enhances the rainfall risk and coastal wind potential. 

 

 

 

There’s still a lot of spread in rainfall and overall organization of this low across guidance for a 72h forecast. 

[WinterWolf]

Isn’t that kind of the norm now? I mean 3-5 yrs ago, we’d know pretty much know what to expect from this at 72 hrs.  Now it’s pretty much like every system has to be 12 hrs out to have any confidence anymore…it’s frustrating. 

[olafminesaw]

33 minutes ago, WinterWolf said:

Isn’t that kind of the norm now? I mean 3-5 yrs ago, we’d know pretty much know what to expect from this at 72 hrs.  Now it’s pretty much like every system has to be 12 hrs out to have any confidence anymore…it’s frustrating. 

I really think it just feels this way. We've gotten a lot more detailed maps and so much more data to sift through over the past few years. Most of the time it's people paying too much attention to outliers. In this case I do think we have a lower confidence forecast than normal