ATL: CHANTAL - Post-Tropical - Discussion

[Sciencerocks]

51 knt flight level winds based on recon.

.9 X 51 knts = 45 knts.

I think this could strengthen another 5 to 10 knts before landfall.

[tropicwatch]

51 knt flight level winds based on recon.

.9 X 51 knts = 45 knts.

I think this could strengthen another 5 to 10 knts before landfall.

The upper-level winds appear to be more favorable and if it stalls who knows.

[ColdMiser123]

850 hPa center appears to be jumping toward the convection on the latest fix.

[Sciencerocks]

[Category5Kaiju]

Interestingly enough, there currently seems to be practically very little deep-layer shear over Chantal.

[Zonacane]

Interestingly enough, there currently seems to be practically very little deep-layer shear over Chantal.

https://i.imgur.com/ybl02MN.png

No shear and the Gulf Stream is a bad combo. How much time does this have over water?

[Jr0d]

TD3? Sure, I'd say name it right now . Best guess
for highest surface winds measured at landfall by any official OR private weather station for Chantal at landfall? My guess for top end measured sustained wind - 30 knots.... tops.

Still going with this. Buoy 41004 has measured sustained winds of 29kts so far. I still doubt we will see observed winds over 40kts however.
https://www.ndbc.noaa.gov/station_page. ... tion=41004

[sasha_B]

Interestingly enough, there currently seems to be practically very little deep-layer shear over Chantal.

https://i.imgur.com/ybl02MN.png

No shear and the Gulf Stream is a bad combo. How much time does this have over water?

About 12 to 18 hours per the NHC's 15z discussion: "On the forecast track, the center of Chantal is expected to move across the coast of South Carolina overnight or early Sunday morning."

[Sciencerocks]

[TomballEd]

https://imagizer.imageshack.com/img924/4277/6h1ZRw.gif

The shear looks like from the S now. But the LLC is still on the W edge of the convection. Waiting to see if the LLC gets covered.

[chaser1]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC

Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

[Jr0d]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC

Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

Yeah....land-based surf obs I will bet you are right.

The buoy 41004 however will likely see sustained above 30kts in my amateur opinion...but certainly less than 40kts

[Ubuntwo]

Buoy 41004 recorded a 1-min sustained wind of 35 kt, anemometer height of 4 meters. So yes, this is a tropical storm There is no requirement for max winds to occur over land - and in fact they seldom do.

[Nuno]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC


Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

The National Hurricane Center thinks so, so Ill go with them on this.

[Sciencerocks]

[sasha_B]

As has been noted in the recon thread, 55 kt FL winds in the northeast quadrant & an eye dropsonde indicating surface pressure at 1005 hPa with 12 kt winds supports a current intensity around 45 kt / 1004 hPa. ATCF Best Track point for 0z (before recon entered the storm) has been set to:

AL, 03, 2025070600, , BEST, 0, 323N, 787W, 40, 1005, TS, 34, NEQ, 90, 120, 0, 30, 1013, 120, 40, 50, 0, L, 0, , 0, 0, CHANTAL, M, 0, , 0, 0, 0, 0, genesis-num, 006,

[Jr0d]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC

Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

Buoy 41004 still has yet to have sustained winds over 30kts and is now south of the center with a down trend in wind. With Chantal passing north of the buoy, it never saw the NE quadrant where the strongest winds likely are.

You will likely be proven right, especially with the scarcity of weather obs sites where one would expect to find the strongest winds.

Buoy 41013, Frying Pan Shoals will north of the center is reporting sustained winds over 30kts as I write this.

https://www.ndbc.noaa.gov/station_page. ... tion=41013

[Ubuntwo]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC

Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

Buoy 41004 still has yet to have sustained winds over 30kts and is now south of the center with a down trend in wind. With Chantal passing north of the buoy, it never saw the NE quadrant where the strongest winds likely are.

You will likely be proven right, especially with the scarcity of weather obs sites where one would expect to find the strongest winds.

Buoy 41013, Frying Pan Shoals will north of the center is reporting sustained winds over 30kts as I write this.

https://www.ndbc.noaa.gov/station_page. ... tion=41013

You are looking at an eight-minute average wind speed, and these anemometers are at 4 meters, not 10 meters.

For a 1-minute average wind (what NHC's TC intensities are based on), view the supplemental section in m/s https://www.ndbc.noaa.gov/data/realtime2/41013.supl

Current peak 1-min winds at 41013 are 36.9kt @ 11:36 PM
41004 peaked at 35.0kt @ 8:06 PM.
Both have measured tropical storm-force winds.

[chaser1]

Bring all of your 850mb Dopler, dropsonde, or buoy data obs, along with projected southerly rather then southwesterly upper wind shear. I still challange "Chantal" to bring full on sustained 1-minute period greater than 35mph at landfall. THAT MEANS SURFACE MEASURED WINDS MEASURED BY ANY LAND BASED PRIVATE OR OFFICIAL STATION RECORDING EQUIPMENT WITHIN 20 NM OF THE REPORTED LLC

Three named storms thus far in 2025. Show me actual surface data that supports any of them verifying as legit thus far. Perhaps Chantal will be the first, but I don't believe it will.

Buoy 41004 still has yet to have sustained winds over 30kts and is now south of the center with a down trend in wind. With Chantal passing north of the buoy, it never saw the NE quadrant where the strongest winds likely are.

You will likely be proven right, especially with the scarcity of weather obs sites where one would expect to find the strongest winds.

Buoy 41013, Frying Pan Shoals will north of the center is reporting sustained winds over 30kts as I write this.

https://www.ndbc.noaa.gov/station_page. ... tion=41013

You are looking at an eight-minute average wind speed, and these anemometers are at 4 meters, not 10 meters.

For a 1-minute average wind (what TC intensities are based on), view the supplemental section https://www.ndbc.noaa.gov/data/realtime2/41013.supl

Current peak 1-min winds at 41013 are 36.9kt @ 11:36 PM.
41004 peaked at 35.0kt @ 8:06 PM.

Given that these tropical storm force winds extend up to 140 miles (especially north and east of center), a significant number of people will likely be impacted by downed trees thus presenting a risk both on the roads as well as causing power outages affecting many as well. Hopefully damages and casualties will not be extensive along with the expected 1'-2' Storm Surge and further potential for inland flooding.

[LarryWx]

Flash flooding is the biggest concern from Chantal. This covers NE SC and SE NC. The main area of solid rain is just entering these areas:

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE WILMINGTON NC
1250 PM EDT SAT JUL 5 2025

NCZ099-109-110-SCZ054-058-059-061215-
/O.NEW.KILM.FA.A.0002.250705T1700Z-250708T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COLUMBUS-INLAND BRUNSWICK-COASTAL BRUNSWICK-COASTAL HORRY-CENTRAL
HORRY-NORTHERN HORRY-
INCLUDING THE CITIES OF MYRTLE BEACH, LONG BEACH, SHALLOTTE, OAK
ISLAND, AYNOR, LONGS, SOUTHPORT, LORIS, BUCKSPORT, CHADBOURN,
BOILING SPRING LAKES, GARDEN CITY, SOCASTEE, SUNSET BEACH, GREEN
SEA, NORTH MYRTLE BEACH, LELAND, WHITEVILLE, LITTLE RIVER, TABOR
CITY, LAKE WACCAMAW, AND CONWAY
1250 PM EDT SAT JUL 5 2025

..FLOOD WATCH IN EFFECT THROUGH MONDAY EVENING

* WHAT...FLASH FLOODING CAUSED BY EXCESSIVE RAINFALL IS POSSIBLE.

* WHERE...PORTIONS OF SOUTHEAST NORTH CAROLINA, INCLUDING THE
FOLLOWING AREAS, COASTAL BRUNSWICK, COLUMBUS AND INLAND BRUNSWICK
AND NORTHEAST SOUTH CAROLINA, INCLUDING THE FOLLOWING AREAS,
CENTRAL HORRY, COASTAL HORRY AND NORTHERN HORRY.

* WHEN...THROUGH MONDAY EVENING.

* IMPACTS...EXCESSIVE RUNOFF MAY RESULT IN FLOODING OF RIVERS,
CREEKS, STREAMS, AND OTHER LOW-LYING AND FLOOD-PRONE LOCATIONS.

* ADDITIONAL DETAILS...
- HEAVY RAIN FROM TROPICAL STORM CHANTAL WILL INCREASINGLY
EFFECT THE AREA LATE TONIGHT INTO SUNDAY.
- WEATHER.GOV/SAFETY/FLOOD

PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.