ATL: DELTA - Post-Tropical - Discussion

[Nimbus]

CDO and winds are finally catching up to the RI.
Might track through the Yucatan channel with Gamma providing steering flow parallel to the flow from the High off Florida.
How far west into the gulf any Fujiwara effect will have on Delta is a calculation for the models.
18z HWRF went to 92.5 without a stall there.

[Kazmit]

Pressure down to 975 mb.

[supercane4867]

[CrazyC83]

It looks like Recon may be having a tough time finding the true center. I'd estimate it to be at 16.5N 79.9W.

[Aric Dunn]

It looks like Recon may be having a tough time finding the true center. I'd estimate it to be at 16.5N 79.9W.

Yep still yet slower and slower than the models.. Delta continues to lag a good deal behind.

[3090]

Pretty much, yes. I'm expecting more east shifts once models see gamma is moving south and will die over Yucatan.

Has nothing to do with Gamma long term. Look at the high pressure building west over Florida for the long term forecast track.

Yes it does because it speeds delta up and affects where the turn happens.

The longer term forecast and even shorter term is the ridge, Delta is riding the southern periphery of. The Gamma thing, is more related to intensification at this point and has no bearing on the track of Delta. If Gamma was still a thing by the time Delta enters the GOM, it would be different, but its remnants are forecast to be absorbed into Delta! Again, Gamma will have nothing to do with the track of Delta at this point, tomorrow, Wednesday or beyond.

[3090]

CDO and winds are finally catching up to the RI.
Might track through the Yucatan channel with Gamma providing steering flow parallel to the flow from the High off Florida.
How far west into the gulf any Fujiwara effect will have on Delta is a calculation for the models.
18z HWRF went to 92.5 without a stall there.

Remnants of Gamma are forecast to be absorbed into Delta. Not seeing the influence of Gamma having any effect on Delta’s path, into the GOM.

[CrazyC83]

Dropsonde suggests 977 mb for the current pressure. Winds look to be 70 kt.

[supercane4867]

[Aric Dunn]

Has nothing to do with Gamma long term. Look at the high pressure building west over Florida for the long term forecast track.

Yes it does because it speeds delta up and affects where the turn happens.

The longer term forecast and even shorter term is the ridge, Delta is riding the southern periphery of. The Gamma thing, is more related to intensification at this point and has no bearing on the track of Delta. If Gamma was still a thing by the time Delta enters the GOM, it would be different, but its remnants are forecast to be absorbed into Delta! Again, Gamma will have nothing to do with the track of Delta at this point, tomorrow, Wednesday or beyond.

unfortunately people keep dismissing Gamma.

the ridging is not strong enough to account for the increased forward motion in the models. you can clearly see the interaction in every last model. So yes Gamma will have an effect on it by means of track and speed. How much is the question.

At the same time the models have been persistant with Gamma moving into the BOC but that cleraly has not happened and Gamma still appears to be moving south.

with it moving over land it will wind down even faster and have less of a sling shot effect clearly seen in the models.

The models lack of even being able to resolve the motion of Gamma does not exaclty increase confidence in Delta.

So we wait until tomorrow, probably evening... but by morning Gamma should be well inland and really dying off.. based on current motion and trends.

Easterly shifts are quite possible.

[SoupBone]

Yes it does because it speeds delta up and affects where the turn happens.

The longer term forecast and even shorter term is the ridge, Delta is riding the southern periphery of. The Gamma thing, is more related to intensification at this point and has no bearing on the track of Delta. If Gamma was still a thing by the time Delta enters the GOM, it would be different, but its remnants are forecast to be absorbed into Delta! Again, Gamma will have nothing to do with the track of Delta at this point, tomorrow, Wednesday or beyond.

unfortunately people keep dismissing Gamma.

the ridging is not strong enough to account for the increased forward motion in the models. you can clearly see the interaction in every last model. So yes Gamma will have an effect on it by means of track and speed. How much is the question.

At the same time the models have been persistant with Gamma moving into the BOC but that cleraly has not happened and Gamma still appears to be moving south.

with it moving over land it will wind down even faster and have less of a sling shot effect clearly seen in the models.

The models lack of even being able to resolve the motion of Gamma does not exaclty increase confidence in Delta.

So we wait until tomorrow, probably evening... but by morning Gamma should be well inland and really dying off.. based on current motion and trends.

Easterly shifts are quite possible.

What are the models like the GFS-Para picking up on then? It sends it almost into the Texas coast riding up into SWLA.

[sunnyday]

How far to the east might the shifts be?

[HurricaneAndre2008]

Logo
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Oct. 6, 2020
2:15 Z
Map: Google Earth Logo Cesium Logo

10/06 01:44 | 11 | 979mb | 71kts (71kts) | 71kts (71kts)
Raw?
Note: "In. Flt" is max inbound flight level wind. "In. Sfc" is max inbound surface wind, estimated by SFMR or visually. If outbound wind is reported, then highest wind, inbound or outbound from center, is in parenthesis. Winds usually averaged over 10s period. Extrap. MSLPs have (e) next to them. Add missed obs.
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 6th day of the month at 2:08Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5306
Storm Number & Year: 26 in 2020
Storm Name: Delta (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 11

A. Time of Center Fix: 6th day of the month at 1:44:20Z
B. Center Fix Coordinates: 16.61N 79.94W
B. Center Fix Location: 208 statute miles (334 km) to the SSE (153°) from George Town, Cayman Islands (U.K.).
C. Minimum Height at Standard Level: 2,929m (9,610ft) at 700mb
D. Minimum Sea Level Pressure: 979mb (28.91 inHg)
E. Dropsonde Surface Wind at Center: From 200° at 18kts (From the SSW at 21mph)
F. Eye Character: Open in the northwest
G. Eye Shape: Elliptical (oval shaped)
G. Orientation of Major Axis in Elliptical Eye: 90° to 270° (E to W)
G. Length of Major Axis in Elliptical Eye: 16 nautical miles (18 statute miles)
G. Length of Minor Axis in Elliptical Eye: 12 nautical miles (14 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 71kts (81.7mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 11 nautical miles (13 statute miles) to the NE (52°) of center fix at 1:37:30Z
J. Maximum Flight Level Wind Inbound: From 144° at 71kts (From the SE at 81.7mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 9 nautical miles to the NE (53°) of center fix at 1:38:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 67kts (77.1mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 3 nautical miles to the WSW (251°) of center fix at 1:48:00Z
N. Maximum Flight Level Wind Outbound: From 315° at 61kts (From the NW at 70.2mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 5 nautical miles to the WSW (242°) of center fix at 1:48:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 3,041m (9,977ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,047m (9,997ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 7°C (45°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Level: 700mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 1 nautical mile

Remarks Section:

Maximum Flight Level Wind: 71kts (~ 81.7mph) which was observed 9 nautical miles to the NE (53°) from the flight level center at 1:38:00Z

[HurricaneAndre2008]

Logo
Menu
Oct. 6, 2020
2:15 Z
Map: Google Earth Logo Cesium Logo

10/06 01:44 | 11 | 979mb | 71kts (71kts) | 71kts (71kts)
Raw?
Note: "In. Flt" is max inbound flight level wind. "In. Sfc" is max inbound surface wind, estimated by SFMR or visually. If outbound wind is reported, then highest wind, inbound or outbound from center, is in parenthesis. Winds usually averaged over 10s period. Extrap. MSLPs have (e) next to them. Add missed obs.
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 6th day of the month at 2:08Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5306
Storm Number & Year: 26 in 2020
Storm Name: Delta (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 11

A. Time of Center Fix: 6th day of the month at 1:44:20Z
B. Center Fix Coordinates: 16.61N 79.94W
B. Center Fix Location: 208 statute miles (334 km) to the SSE (153°) from George Town, Cayman Islands (U.K.).
C. Minimum Height at Standard Level: 2,929m (9,610ft) at 700mb
D. Minimum Sea Level Pressure: 979mb (28.91 inHg)
E. Dropsonde Surface Wind at Center: From 200° at 18kts (From the SSW at 21mph)
F. Eye Character: Open in the northwest
G. Eye Shape: Elliptical (oval shaped)
G. Orientation of Major Axis in Elliptical Eye: 90° to 270° (E to W)
G. Length of Major Axis in Elliptical Eye: 16 nautical miles (18 statute miles)
G. Length of Minor Axis in Elliptical Eye: 12 nautical miles (14 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 71kts (81.7mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 11 nautical miles (13 statute miles) to the NE (52°) of center fix at 1:37:30Z
J. Maximum Flight Level Wind Inbound: From 144° at 71kts (From the SE at 81.7mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 9 nautical miles to the NE (53°) of center fix at 1:38:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 67kts (77.1mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 3 nautical miles to the WSW (251°) of center fix at 1:48:00Z
N. Maximum Flight Level Wind Outbound: From 315° at 61kts (From the NW at 70.2mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 5 nautical miles to the WSW (242°) of center fix at 1:48:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 3,041m (9,977ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 3,047m (9,997ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 7°C (45°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Level: 700mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 1 nautical mile

Remarks Section:

Maximum Flight Level Wind: 71kts (~ 81.7mph) which was observed 9 nautical miles to the NE (53°) from the flight level center at 1:38:00Z

[Aric Dunn]

The longer term forecast and even shorter term is the ridge, Delta is riding the southern periphery of. The Gamma thing, is more related to intensification at this point and has no bearing on the track of Delta. If Gamma was still a thing by the time Delta enters the GOM, it would be different, but its remnants are forecast to be absorbed into Delta! Again, Gamma will have nothing to do with the track of Delta at this point, tomorrow, Wednesday or beyond.

unfortunately people keep dismissing Gamma.

the ridging is not strong enough to account for the increased forward motion in the models. you can clearly see the interaction in every last model. So yes Gamma will have an effect on it by means of track and speed. How much is the question.

At the same time the models have been persistant with Gamma moving into the BOC but that cleraly has not happened and Gamma still appears to be moving south.

with it moving over land it will wind down even faster and have less of a sling shot effect clearly seen in the models.

The models lack of even being able to resolve the motion of Gamma does not exaclty increase confidence in Delta.

So we wait until tomorrow, probably evening... but by morning Gamma should be well inland and really dying off.. based on current motion and trends.

Easterly shifts are quite possible.

What are the models like the GFS-Para picking up on then? It sends it almost into the Texas coast riding up into SWLA.

Same deal. look at the model run.. Gamma helps to thrust Detla on a more WNW motion faster getting Delta farther west before the trough comes in.

[Dean4Storms]

I've heard of the old rule that a ridge expected to erode with a trough swinging through is usually under estimated by models and vice versa with an expected building ridge. So I'm thinking the models will come back eastward in this scenario, how much is the million dollar question.

[DestinHurricane]

I've heard of the old rule that a ridge expected to erode with a trough swinging through is usually under estimated by models and vice versa with an expected building ridge. So I'm thinking the models will come back eastward in this scenario, how much is the million dollar question.

Gamma is quite a bit slower than today's models suggested. If it's slower the turn will occur farther to the E. Also like you said the ridge will probably break down more than expected. I think it will shift quite a bit east but as you said remains to be seen exactly how much. I'd say anywhere from Morgan City to Panama City Florida, which is a wide range.

[3090]

https://i.imgur.com/AYIBCOR.gif

WHOOOOOOAAAA!!! Ominous looking structure there. Will be very interesting to see what unfolds overnight and tomorrow morning.

[Steve]

I've heard of the old rule that a ridge expected to erode with a trough swinging through is usually under estimated by models and vice versa with an expected building ridge. So I'm thinking the models will come back eastward in this scenario, how much is the million dollar question.

Gamma is quite a bit slower than today's models suggested. If it's slower the turn will occur farther to the E. Also like you said the ridge will probably break down more than expected. I think it will shift quite a bit east but as you said remains to be seen exactly how much. I'd say anywhere from Morgan City to Panama City Florida, which is a wide range.

If you have been watching the upper modeling last 3-4 days, the depicted coming trough got shallower, and the longwave is delayed. The steering ridge is pushing from the east but at least at 12z it had a component north of the system too. It’s October so you don’t figure the Atlantic push is going to get it all the way across the Gulf. So how far west does it get 91? 92? farther? before the highs progression and push allows for the slip north and NNE/NE and how far north is the system at that point? Obviously if it was to only get to like 90.5 and hooked and maybe crossed Plaquemines Parish, MS/AL could have a second landfall. If it comes in any farther west, it will track NE through SC or SE LA after landfall. I don’t know.

[3090]

I've heard of the old rule that a ridge expected to erode with a trough swinging through is usually under estimated by models and vice versa with an expected building ridge. So I'm thinking the models will come back eastward in this scenario, how much is the million dollar question.

Gamma is quite a bit slower than today's models suggested. If it's slower the turn will occur farther to the E. Also like you said the ridge will probably break down more than expected. I think it will shift quite a bit east but as you said remains to be seen exactly how much. I'd say anywhere from Morgan City to Panama City Florida, which is a wide range.

You two are contrarian to the pro-mets and the data relative to the building ridge. Not only that, the latest EURO model, has shifted pretty significantly west. So unless you have some sound weather data the pros do not have, you can forget about any trends to the east for the immediate future/next 48 hours. It is going to follow the southern periphery of the ridge all the way into the CGOM. It will then slow a bit and take a turn to the NW, then N, then NNE once it makes landfall. The only thing in question is, where along the coast of Louisiana does it make landfall? I am thinking central, south of Lafayette.