Possible development off the Southeast US Coast (Is Invest 99L)

[Sciencerocks]

[LarryWx]

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 pretty good organization and low SLP of 1002 mb:

https://www.pivotalweather.com/model.ph ... &dpdt=&mc=

[LarryWx]

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 pretty good organization and low SLP of 1002 mb:

https://www.pivotalweather.com/model.ph ... &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.ph ... &dpdt=&mc=

[LarryWx]

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 66 HOURS
FORECAST POSITION AT T+ 66 : 32.2N 76.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 23.09.2023 72 34.2N 75.6W 1004 43
1200UTC 23.09.2023 84 36.3N 75.0W 1001 48
0000UTC 24.09.2023 96 39.1N 73.1W 998 42
1200UTC 24.09.2023 108 42.1N 69.4W 998 39
0000UTC 25.09.2023 120 45.5N 64.0W 995 41
1200UTC 25.09.2023 132 46.8N 63.5W 993 45
0000UTC 26.09.2023 144 46.3N 60.6W 999 41
1200UTC 26.09.2023 156 45.9N 55.9W 1005 29
0000UTC 27.09.2023 168 CEASED TRACKING

[LarryWx]

12Z UKMET is back to being offshore with a TC:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 72 HOURS
FORECAST POSITION AT T+ 72 : 35.5N 74.1W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 23.09.2023 72 35.5N 74.1W 1006 42
0000UTC 24.09.2023 84 37.7N 72.3W 1003 38
1200UTC 24.09.2023 96 40.9N 67.9W 1004 34
0000UTC 25.09.2023 108 43.6N 62.1W 1004 36
1200UTC 25.09.2023 120 43.9N 58.3W 1004 39
0000UTC 26.09.2023 132 CEASED TRACKING

[cycloneye]

POSSIBLE LOW LEVEL INVEST MISSION
NEAR 32.0N 77.0W FOR 22/1730Z.

[wxman57]

I'm 100% confident that a low pressure will develop off the SE U.S. coast and that it will produce TS strength wind offshore and along the beaches. The only question is whether or not the NHC lets it go as a frontal low or decides to give it a name. The impacts will be the same, either way. For now, it seems they're content in identifying it as frontal, thus only a 40% chance that they will name it. I still think that the NHC will call this Ophelia by Friday evening. Maybe Saturday morning at the latest.

[Nimbus]

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Wed Sep 20 2023

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Nigel, located over the central subtropical Atlantic.

1. Eastern Tropical Atlantic:
A tropical wave is currently located a couple of hundred miles
southeast of the Cabo Verde Islands. This system is expected
to merge with another disturbance located a few hundred miles to its
west in a few days. Environmental conditions are forecast to
be conducive for gradual development, and a tropical depression is
likely to form late this week or this weekend while the system moves
generally westward at 10 to 15 mph across the eastern and central
tropical Atlantic.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...high...70 percent.

2. Western Atlantic:
A non-tropical low pressure system is expected to form within a
large area of disorganized showers and thunderstorms to the east
of the Florida peninsula within the next day or two. This system
could acquire some subtropical characteristics on Friday while it
moves generally northward. Regardless of development, this low is
likely to bring gusty winds to gale force, heavy rain, and high surf
to portions of the Southeast and Mid-Atlantic United States late
this week and into this weekend. Additional information on this
system can be found in High Seas Forecasts and products from your
local National Weather Service office.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...medium...40 percent.

High Seas Forecasts issued by the National Weather Service
can be found under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

Forecaster Pasch



Quick Links and Additional Resource

[wxman57]

12Z EC has a frontal low offshore with winds approaching 40 kts Friday evening. Dewpoints along the coast around 60 degrees. Lots of cool air flowing offshore.

[Sciencerocks]

[WalterWhite]

I'm 100% confident that a low pressure will develop off the SE U.S. coast and that it will produce TS strength wind offshore and along the beaches. The only question is whether or not the NHC lets it go as a frontal low or decides to give it a name. The impacts will be the same, either way. For now, it seems they're content in identifying it as frontal, thus only a 40% chance that they will name it. I still think that the NHC will call this Ophelia by Friday evening. Maybe Saturday morning at the latest.

The NHC never names storms unless they fit the criteria for a tropical cyclone and have over 35-knot 1-minute sustained wind speeds.

[wxman57]

I'm 100% confident that a low pressure will develop off the SE U.S. coast and that it will produce TS strength wind offshore and along the beaches. The only question is whether or not the NHC lets it go as a frontal low or decides to give it a name. The impacts will be the same, either way. For now, it seems they're content in identifying it as frontal, thus only a 40% chance that they will name it. I still think that the NHC will call this Ophelia by Friday evening. Maybe Saturday morning at the latest.

The NHC never names storms unless they fit the criteria for a tropical cyclone and have over 35-knot 1-minute sustained wind speeds.

Since when? They've named a clearly frontal low in a recent season in the same area. If the low is producing significant impacts to people along the beach areas, they'll name it if they think that will make those people pay attention to the dangerous conditions more.

[CronkPSU]

i notice the AOI map in orange seems to press right up to the coast but never over it regardless of how the coast bends...is that because it theoretically wouldn't form over land?

[Iceresistance]

i notice the AOI map in orange seems to press right up to the coast but never over it regardless of how the coast bends...is that because it theoretically wouldn't form over land?

It is very rare for a Tropical Cyclone to form over land, the most recent case was Julia 2016

[cycloneye]

 https://twitter.com/GregPostel/status/1704661700484427982

[Hypercane_Kyle]

12Z EC has a frontal low offshore with winds approaching 40 kts Friday evening. Dewpoints along the coast around 60 degrees. Lots of cool air flowing offshore.

Florida might get its first taste of fall out of this, unbelievably.

[Ubuntwo]

[LarryWx]

0Z UKMET: becomes a TC 36 hours earlier vs 12Z; back on the coast NC to NJ

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS
FORECAST POSITION AT T+ 24 : 30.4N 74.8W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 22.09.2023 24 30.4N 74.8W 1007 38
1200UTC 22.09.2023 36 32.4N 75.0W 1004 44
0000UTC 23.09.2023 48 33.4N 75.9W 997 45
1200UTC 23.09.2023 60 35.4N 76.0W 995 43
0000UTC 24.09.2023 72 37.8N 75.7W 994 40
1200UTC 24.09.2023 84 39.1N 74.6W 1001 32
0000UTC 25.09.2023 96 39.9N 73.5W 1007 33
1200UTC 25.09.2023 108 40.0N 72.2W 1009 34
0000UTC 26.09.2023 120 39.5N 69.6W 1011 34
1200UTC 26.09.2023 132 CEASED TRACKING

[LarryWx]

0Z Euro at 48: strongest run yet at 997 mb 150 mi SE of Wilmington, NC

[cycloneye]

Invest 99L is up