ATL: DORIAN - Post-Tropical - Discussion

[jlauderdal]

AF plane turned around just before arriving so it looks like we're going to go the entire night with no new data once the current mission is over.

That's a shame, right when it was really getting interesting. We could be missing the bottom. I wonder what happened to make them turn around.

No worries, conditions are prime for a 4 or 5 at least the next 48 hours

[GCANE]

Appears eyewall is contracting a bit.
Lightning has stopped for awhile now.
Hard to distinguish if there is any mesovorts on WV.

[Hammy]

Attempting to ask this again. Sincere questions from someone who has lurked for many seasons.

Couple of basic questions.

1. Once the storm becomes a major of this intensity, isn’t it possible for it to start tracking poleward?
2. And also, if it sits over the Bahamas for days as a 4 or 5, is it likely to be able to retain the same degree of strength for that length of time?

A few TV mets have said stronger might end up more west this time since there's no large scale trough in the area, but I'm not 100% sure if that's the case or not.

As far as stalling, if it sits for several days it's likely to weaken due to drier air from land, as well as upwelling, but that's by no means an absolute guarantee. Frances in 2004 was a good example of this happening.

[GCANE]

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 31st day of the month at 1:26Z
Agency: National Oceanic and Atmospheric Administration (NOAA)
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number & Year: 05 in 2019
Storm Name: Dorian (flight in the North Atlantic basin)
Mission Number: 21
Observation Number: 17 ( See all messages of this type for this mission. )

A. Time of Center Fix: 31st day of the month at 1:06:19Z
B. Center Fix Coordinates: 25.40N 71.19W
B. Center Fix Location: 387 statute miles (622 km) to the E (86°) from Nassau, Bahamas.
C. Minimum Height at Standard Level: Not Available
D. Minimum Sea Level Pressure: 950mb (28.06 inHg)
E. Dropsonde Surface Wind at Center: From 170° at 18kts (From the S at 21mph)
F. Eye Character: Closed
G. Eye Shape & Diameter: Circular with a diameter of 12 nautical miles (14 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 108kts (124.3mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 7 nautical miles to the SSE (160°) of center fix at 1:04:38Z
J. Maximum Flight Level Wind Inbound: From 248° at 121kts (From the WSW at 139.2mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 8 nautical miles to the SSE (163°) of center fix at 1:04:19Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 125kts (143.8mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 6 nautical miles to the N (358°) of center fix at 1:07:46Z
N. Maximum Flight Level Wind Outbound: From 88° at 129kts (From the E at 148.5mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 7 nautical miles to the N (358°) of center fix at 1:08:00Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,447m (8,028ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 24°C (75°F) at a pressure alt. of 2,446m (8,025ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 11°C (52°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: Other - Not surface, 1500ft, 925mb, 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
T. Navigational Fix Accuracy: 0.01 nautical miles
T. Meteorological Accuracy: 1 nautical mile

[Blown Away]

Looks like a hair N of due west... NHC shows a WNW

[Nancy Smar]

URNT12 KWBC 310126
VORTEX DATA MESSAGE AL052019
A. 31/01:06:19Z
B. 25.40 deg N 071.19 deg W
C. NA
D. 950 mb
E. 170 deg 18 kt
F. CLOSED
G. C12
H. 108 kt
I. 160 deg 7 nm 01:04:38Z
J. 248 deg 121 kt
K. 163 deg 8 nm 01:04:19Z
L. 125 kt
M. 358 deg 6 nm 01:07:46Z
N. 088 deg 129 kt
O. 358 deg 7 nm 01:08:00Z
P. 14 C / 2447 m
Q. 24 C / 2446 m
R. 11 C / NA
S. 12345 / NA
T. 0.01 / 1 nm
U. NOAA2 2105A DORIAN OB 17
FIX FROM 8000FT
MAX FL WIND 129 KT 358 / 7 NM 01:08:00Z

[GCANE]

Eye diameter went from 20 to 12 nm
Dewpoint from 7 to 11C.
Very likely a EWRC will soon be occuring.

[hipshot]

AF plane turned around just before arriving so it looks like we're going to go the entire night with no new data once the current mission is over.

That's a shame, right when it was really getting interesting. We could be missing the bottom. I wonder what happened to make them turn around.

I thought they had tag team flights during the period.

[HurricaneFrances04]

Roughly 300* between VDMs

https://i.imgur.com/ejv1Q8R.png

[GCANE]

[SunnyThoughts]

K. Location & Time of the Maximum Flight Level Wind Inbound: 8 nautical miles to the SSE (163°) of center fix at 1:04:19Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 125kts (143.8mph)

[jlauderdal]

Looks like a hair N of due west... NHC shows a WNW

The nw quadrant is getting flat, cane is bumping against the ridge and being driven west...where will the western flank be in a few days?

[supercane4867]

I think NHC will go with 120kts at 11PM. Intensity appears to be leveling off

[Highteeld]

948mb wind adj

[1900hurricane]

Attempting to ask this again. Sincere questions from someone who has lurked for many seasons.

Couple of basic questions.

1. Once the storm becomes a major of this intensity, isn’t it possible for it to start tracking poleward?
2. And also, if it sits over the Bahamas for days as a 4 or 5, is it likely to be able to retain the same degree of strength for that length of time?

With regards to the first question, what you're probably thinking of is beta drift, which is indeed a real thing. In a purely unidirectional steering regime, a stronger circulation will tend to bend more poleward than a weaker circulation in the same regime. However, the current steering regime is not that straightforwards, with a deep layer ridge forcing a stronger system more westwards in the near term before things become more nebulous with multiple entities exerting only weak influences. If a sufficient break in ridging develops, it may try to take that route out, but it is very unclear whether that will transpire or not with the information we have now.

As for the second question, if it moves too slowly for too long a period of time, a hurricane will upwell cold water beneath it. While steering is weak, this is a possibility for Dorian, but I can't say personally how much of a possibility at this time.

[BobHarlem]

950mb seems really high for 140mph winds. It's usually the other way around, or is the gradient that strong?

[Highteeld]

savage dropsonde is savage

[SFLcane]

 https://twitter.com/johnmoralesnbc6/status/1167610302088851458

[dukeblue219]

I almost overlooked that second dropsonde, but it splashed at 131kt on the surface. Definitely supports that VDM message for 125kt and I'm guessing 11pm will have 145mph now?

[Frank P]

Yeah and it just wobbled north...

It looks west by north to me
west by north. n. The direction or point on the mariner's compass halfway between due west and west-northwest, or 78°45′ west of due north.