NATL: GABRIELLE - Post-Tropical - Discussion

[sasha_B]

There's still no data from recon to support setting the intensity higher than 55 kts / 998 hPa. Not sure where this talk of a pinhole eye is coming from....NOAA did issue a corrected satellite bulletin at 1707z assigning the storm a T4.0 fix based on the presence of an "eye-like feature", but until recon finds something to back up the possible eye, it's hard to buy that this is anything more than a minimal hurricane. GOES shows a moderate amount of lightning, closer to the core than before & located in the area of deepest convection (where you'd expect to find it), but not exactly encircling a well-defined eyewall like you'd see in a case of explosive intensification.

[zzzh]

[zzzh]

Dropsonde shows 997mb/6kt, a 2mb drop from the last drop (about 1h 20min ago).

[sasha_B]

Special advisory issued by the NHC. Gabrielle is not a hurricane, but is up to 55 knots with a central pressure of 996 hPa.

[StormWeather]

65/996 is the new intensity

000
WTNT62 KNHC 201753
TCUAT2

Tropical Storm Gabrielle Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL072025
200 PM AST Sat Sep 20 2025


...HURRICANE HUNTER AIRCRAFT REPORT THAT GABRIELLE IS FARTHER EAST
AND A LITTLE STRONGER THAN INDICATED IN THE PREVIOUS ADVISORY...

Reports from NOAA and Air Force Reserve hurricane hunter aircraft
data show that the center of Gabrielle is located about 30 miles
farther east than indicated in the previous advisory. The maximum
sustained winds have increased to near 65 mph (105 km/h). The next
full advisory will be issued at 500 PM AST (2100 UTC).

SUMMARY OF 200 PM AST...1800 UTC...INFORMATION
---------------------------------------------------
LOCATION...25.2N 58.7W
ABOUT 595 MI...960 KM NNE OF THE NORTHERN LEEWARD ISLANDS
ABOUT 615 MI...990 KM SE OF BERMUDA
MAXIMUM SUSTAINED WINDS...65 MPH...105 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES

$$
Forecaster Beven

[zzzh]

[Travorum]

Gabrielle seems to be gradually deepening based on the dropsondes, and the AF VDM reported a closed elliptical eye (10nm by 6nm, so fairly small):

URNT12 KNHC 201808
VORTEX DATA MESSAGE AL072025
A. 20/17:23:00Z
B. 25.14 deg N 058.64 deg W
C. 700 mb 3080 m
D. 998 mb
E. 205 deg 29 kt
F. CLOSED
G. E30/10/6
H. 55 kt
I. 318 deg 3 nm 17:22:00Z
J. 065 deg 55 kt
K. 313 deg 24 nm 17:16:00Z
L. 46 kt
M. 165 deg 5 nm 17:24:30Z
N. 219 deg 49 kt
O. 140 deg 17 nm 17:28:00Z
P. 10 C / 3045 m
Q. 12 C / 3042 m
R. 7 C / NA
S. 12345 / 7
T. 0.02 / 1 nm
U. AF301 0107A GABRIELLE OB 04
MAX FL WIND 55 KT 313 / 24 NM 17:16:00Z

Still nothing so far to suggest hurricane intensity for now, just one 59kt FL wind reading and a 55kt SFMR on the first NOAA pass in the east that supports the 55kt intensity the NHC went with in the special advisory.

[cycloneye]

Dvorak SAB has 4.0.

A. 07L (GABRIELLE)

B. 20/1800Z

C. 25.2N

D. 58.7W

E. ONE/GOES-E

F. T4.0/4.0

G. IR/EIR/VIS/GMI

H. REMARKS...AN OW EYE SURROUNDED BY DG THAT IS EMBEDDED WITHIN OW
RESULTS IN A DT OF 4.0. THE MET IS 4.0 BASED ON A DEVELOPING TREND IN
APPARENT INTENSITY OVER THE PAST 24 HOURS. THE PT IS ALSO 4.0. THE FT
IS BASED ON THE DT. OF NOTE IS THAT AN EYE HAS BEEN APPARENT IN VISIBLE
G19 SATELLITE IMAGERY SINCE 1520Z.

I. ADDL POSITIONS

20/1339Z 24.7N 58.3W GMI


...HOSLEY

[LarryWx]

Someone asked why there’s recon when Gabrielle isn’t a threat to hit land.

[StormWeather]

Someone asked why there’s recon when Gabrielle isn’t a threat to hit land.

I was thinking about asking the same thing.

[Sciencerocks]

Someone asked why there’s recon when Gabrielle isn’t a threat to hit land.

Probably because it is such a slow season
1. Research
2. needs to spend the money before the end of the government year.

[Travorum]

Someone asked why there’s recon when Gabrielle isn’t a threat to hit land.

According to the TCPOD the NOAA planes (all three of them, the gulfstream is out too) are doing a research mission, apparently involving drones they're dropping in. The AF are on a normal fix mission, IDK the exact motivation. I guess in case of any effects to bermuda? Or it could just be practice/nothing else to do.

[cycloneye]

Maybe one of our pro mets may answer that interesting question.

[Travorum]

Some Tail doppler radar data from the NOAA planes that are in right now:




Gabrielle is pretty well vertically organized, the convection that has popped up today probably helped a lot with that. It also has a pretty impressive radar presentation. Overall the structure is surprisingly good considering everything Gabrielle has gone through in the past few days, and seems to be a just a bit ahead of where the hurricane models had it right now—I've put both HAFS models for the current time below to compare to the image on the right above (image above is 2km wind, but also tends to skew a bit lower based on the winds reported by recon). Dropsondes also indicate its a few mb deeper than models had it at.

[cycloneye]

 https://x.com/KacperWx/status/1969481701744148734

[Nimbus]

Tiny little eye in satellite imagery very tight circulation for a while. Dry inflow might have made it look more intense than it was.

[Travorum]

Eye now circular, 8nm diameter per last VDM:

F. CLOSED
G. C8

[TomballEd]

Using GFS not as a forecast but for current area soundings, it looks like southerly shear is not that bad, it is mid-level dry air that is keeping Gabrielle from really going to town. The dry air should keep the size low, which should reduce impacts in Bermuda even if the storm goes west of the cone, which seems unlikely. One thing about a small storm, it can spin up quickly when conditions improve.

[USTropics]

Maybe one of our pro mets may answer that interesting question.

I would state there are likely three main reasons for doing recon flights, even if the storm isn't likely to hit immediate land/United States.

Marine and aviation safety: this is mainly international shipping routes and potential military operations. Recon data helps issue timely advisories for these sectors, even if no land areas are threatened. You can see in the shipping track density map below this area does see decent traffic.


Operational and international benefits: It's always good to maintain efficiency and ensure equipment is operational for high-threat scenarios. Data is also shared globally, aiding forecasts in other regions (e.g., storms recurving toward Europe or affecting remote islands). Gabrielle does look to be a threat later on, even if not for the United States or Caribbean islands.



Data collection for forecasting improvements/research: Like others were stating, even if a storm isn't currently projected to impact land, flights gather critical real-time data on the cyclone's center, intensity, structure, central pressure, surface winds, steering currents, etc.. Essentially, this data enhances the accuracy of forecast models in the future (especially in slower seasons where we're lacking real-time data) and provides additional datasets for research in the future.

[mitchell]

^^^

That is REALLY remarkable model agreement! All the way to the end of the track between the Azores and Ireland.