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WxWatcher007

Major Hurricane Laura

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6 hours ago, Calderon said:

Michael was technically 15.5ft AGL at Mexico Beach, not 20. With wave action, then yes. 

The storm tide was just over 20 ft above MLW. So surge+high tide not including waves. 

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She's in a pretty prime position between the TUTT to her SSE and the trough to her NW to really enhance poleward outflow and upper heat transfer/upper ridging.  The dry air to her west could be a bit of a hindrance but as the established upper ridging in the gulf and the storm get more aligned and we possibly get 4 nice quadrants in the upper levels, to me that's the key ATM to get her to a Cat4.

 

COD-GOES-East-global-halfdiskeastnorth.08.20200826.104020-over=map-bars=.gif

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Just now, Jackstraw said:

She's in a pretty prime position between the TUTT to her SSE and the trough to her NNW to really enhance poleward outflow and upper heat transfer/upper ridging.  The dry air to her west could be a bit of a hindrance but as the established upper ridging in the gulf and the storm get more aligned and we possibly get 4 nice quadrants in the upper levels, to me that's the key ATM to get her to a Cat4.

 

COD-GOES-East-global-halfdiskeastnorth.08.20200826.104020-over=map-bars=.gif

Good post....one other "limiting" (relatively speaking re: RI) is the elliptical eye as noted in the VDM.  May hamper the rate of intensification and the potential depth of minimum pressure to be had, vs. if we had a circular eye.

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4 minutes ago, Jackstraw said:

She's in a pretty prime position between the TUTT to her SSE and the trough to her NW to really enhance poleward outflow and upper heat transfer/upper ridging.  The dry air to her west could be a bit of a hindrance but as the established upper ridging in the gulf and the storm get more aligned and we possibly get 4 nice quadrants in the upper levels, to me that's the key ATM to get her to a Cat4.

 

COD-GOES-East-global-halfdiskeastnorth.08.20200826.104020-over=map-bars=.gif

Clearest eye yet.

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I also want to stress I hope some magical 40KT shear nails this thing approaching LF.  Nobody needs a storm of this potential right now.  No wishcasting here.

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We should be getting several dropsondes soon and hopefully those will confirm whether or not the NOAA aircraft's 953 MB is off or if this thing just pulled a 2020. USAF coming in to the SE eyewall now.

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1 minute ago, David Reimer said:

We should be getting several dropsondes soon and hopefully those will confirm whether or not the NOAA aircraft's 953 MB is off or if this thing just pulled a 2020. USAF coming in to the SE eyewall now.

Yeah—I usually caveat the extrapolated stuff but exactly right. Extrapolated is just an estimate. Dropsondes confirm winds and pressure drops.

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5 minutes ago, WxWatcher007 said:

952.8mb extrapolated on the latest pass...

Whoa. The other plane just got 969mb in a sonde 60 minutes ago. Let's see what the new sonde says

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Other recon pass found a minimum extrapolated pressure of 961.4. Much more reasonable.

So even if the confirmed pressure is a few mb higher that’s still a pretty rapid drop in between passes. 

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USAF just extrapolated 961.3MB - which is still 7 millibars lower than the 968.6MB extrapolated about 65 minutes ago. I believe it is safe to say we have entered a 2020-level stupid deepening phase, because 7 millibars in an hour is still really dumb. Cool.... :hurrbear:

Winds don't seem to have responded upward just yet, but the USAF dropsonde in the NE Quad did have 123 knot winds at 780 millibars an hour ago. Those may be able to mix down more easily soon. Don't be surprised if we see winds suddenly spike over the next couple of hours as they catch up with pressure drops.

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This may be better asked elsewhere, but since this storm is current and relevant, is there any meteoritical reasoning as to why a great deal of tropical systems make landfall after nightfall?

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This may be better asked elsewhere, but since this storm is current and relevant, is there any meteoritical reasoning as to why a great deal of tropical systems make landfall after nightfall?
Depends on timing and forward speed

Sent from my LML212VL using Tapatalk

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Just now, LakeEffectKing said:

Although probably very small (<10% chance), the answer probably should be "very small".

It’s an impressive storm but I can’t see that type of intensification with only about 12 hours of possible intensification, an eye that’s not completely circular and cleared and the potential for some sort of eye replacement cycle. But I mean, this is plenty enough dangerous whether it’s a cat 4 or 5. Fortunately hopefully the sparsely populated Louisiana coastline is ground zero but obviously this will have large impacts well inland. Luckily Galveston-Houston appears to be out of the game for major impact 

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Just now, Voyager said:

This may be better asked elsewhere, but since this storm is current and relevant, is there any meteoritical reasoning as to why a great deal of tropical systems make landfall after nightfall?

Not really. Actually I think the U.S. has had more daylight landfalls than historically normal in recent years. Notably Irma (on Marco Island) and Michael.

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Here’s the center sonde confirming a very rapid drop but not at extrapolated levels.

Product: NOAA Temp Drop (Dropsonde) Message (UZNT13 KWBC)
Transmitted: 26th day of the month at 11:08Z
Agency: National Oceanic and Atmospheric Administration (NOAA) 
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF) 
Storm Number: 13
Storm Name: Laura (flight in the North Atlantic basin)
Mission Number: 22
Observation Number: 02 ( See all messages of this type for this mission. )

Part A...
 

Date: Near the closest hour of 11Z on the 26th day of the month
Highest Mandatory Level For Which Wind Was Reported: 700mb
Coordinates: 26.2N 91.2W
Location: 270 statute miles (435 km) to the SSW (195°) from New Orleans, LA, USA.
Marsden Square: 082 ( About )
 
Surface and Standard Isobaric Surfaces
Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1000mb -305m (-1,001 ft) This level does not exist in this area of the storm above the surface level.
966mb (28.53 inHg) Surface (Sea Level) 28.2°C (82.8°F) 26.3°C (79°F) 180° (from the S) 25 knots (29 mph)
925mb 389m (1,276 ft) 25.2°C (77.4°F) 24.2°C (76°F) 190° (from the S) 20 knots (23 mph)
850mb 1,137m (3,730 ft) 25.4°C (77.7°F) About 18°C (64°F) 205° (from the SSW) 18 knots (21 mph)
700mb 2,820m (9,252 ft) 16.2°C (61.2°F) About 11°C (52°F) 225° (from the SW) 13 knots (15 mph)

Information About Radiosonde:
- Launch Time: 10:57Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 
Dropsonde Location: Dropped in center.

Highest altitude where wind was reported:
- Location: 26.19N 91.22W
- Time: 10:57:32Z

Lowest altitude where wind was reported:
- Location: 26.21N 91.21W
- Time: 11:02:38Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 185° (from the S)
- Wind Speed: 22 knots (25 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 205° (from the SSW)
- Wind Speed: 16 knots (18 mph)
- Depth of Sounding: From 644mb to 965mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 161 gpm - 11 gpm (528 geo. feet - 36 geo. feet)
- Wind Direction: 185° (from the S)
- Wind Speed: 25 knots (29 mph)

Sounding Software Version: AEV 30404
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
966mb (Surface) 28.2°C (82.8°F) 26.3°C (79°F)
905mb 23.8°C (74.8°F) 23.6°C (74°F)
878mb 26.4°C (79.5°F) About 20°C (68°F)
850mb 25.4°C (77.7°F) About 18°C (64°F)
840mb 25.6°C (78.1°F) About 16°C (61°F)
741mb 18.2°C (64.8°F) 13.6°C (56°F)
644mb 12.8°C (55.0°F) About 8°C (46°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
966mb (Surface) 180° (from the S) 25 knots (29 mph)
892mb 210° (from the SSW) 17 knots (20 mph)
850mb 205° (from the SSW) 18 knots (21 mph)
802mb 195° (from the SSW) 19 knots (22 mph)
775mb 205° (from the SSW) 17 knots (20 mph)
764mb 225° (from the SW) 16 knots (18 mph)
711mb 210° (from the SSW) 12 knots (14 mph)
657mb 260° (from the W) 10 knots (12 mph)
644mb 300° (from the WNW) 4 knots (5 mph)

Dropsonde Diagram...

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Another center sonde just posted. 964mb w/ 8kt wind. The VDM was 969 about an hour ago. Yikes.

Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 26th day of the month at 11:17Z
Agency: United States Air Force 
Aircraft: Lockheed WC-130J Hercules with reg. number AF96-5301 
Storm Number: 13
Storm Name: Laura (flight in the North Atlantic basin)
Mission Number: 21
Observation Number: 16 ( See all messages of this type for this mission. )

Part A...
 

Date: Near the closest hour of 11Z on the 26th day of the month
Highest Mandatory Level For Which Wind Was Reported: 700mb
Coordinates: 26.2N 91.3W
Location: 272 statute miles (437 km) to the SSW (196°) from New Orleans, LA, USA.
Marsden Square: 082 ( About )
 
Surface and Standard Isobaric Surfaces
Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1000mb -330m (-1,083 ft) This level does not exist in this area of the storm above the surface level.
964mb (28.47 inHg) Surface (Sea Level) 28.0°C (82.4°F) 25.8°C (78°F) 340° (from the NNW) 8 knots (9 mph)
925mb 365m (1,198 ft) 25.4°C (77.7°F) 24.1°C (75°F) 335° (from the NNW) 9 knots (10 mph)
850mb 1,109m (3,638 ft) 23.6°C (74.5°F) 19.9°C (68°F) 290° (from the WNW) 8 knots (9 mph)
700mb 2,802m (9,193 ft) 18.6°C (65.5°F) About 10°C (50°F) 100° (from the E) 6 knots (7 mph)

Information About Radiosonde:
- Launch Time: 11:03Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 
Dropsonde Location: Dropped in center.

Highest altitude where wind was reported:
- Location: 26.21N 91.29W
- Time: 11:03:39Z

Lowest altitude where wind was reported:
- Location: 26.21N 91.28W
- Time: 11:07:59Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 330° (from the NNW)
- Wind Speed: 9 knots (10 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 325° (from the NW)
- Wind Speed: 4 knots (5 mph)
- Depth of Sounding: From 696mb to 963mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 155 gpm - 5 gpm (509 geo. feet - 16 geo. feet)
- Wind Direction: 330° (from the NNW)
- Wind Speed: 10 knots (12 mph)

Sounding Software Version: AEV 30400
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
964mb (Surface) 28.0°C (82.4°F) 25.8°C (78°F)
867mb 22.4°C (72.3°F) 21.8°C (71°F)
850mb 23.6°C (74.5°F) 19.9°C (68°F)
808mb 24.6°C (76.3°F) About 17°C (63°F)
717mb 20.0°C (68.0°F) About 11°C (52°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
964mb (Surface) 340° (from the NNW) 8 knots (9 mph)
957mb 330° (from the NNW) 11 knots (13 mph)
901mb 335° (from the NNW) 9 knots (10 mph)
889mb 335° (from the NNW) 4 knots (5 mph)
850mb 290° (from the WNW) 8 knots (9 mph)
696mb 90° (from the E) 7 knots (8 mph)

Dropsonde Diagram...

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Timing is just bad luck!  Nothing more or less goes into the landfall timing.  There is no scientific method that determines when landfall occurs, a bunch of variables go into why it happens!

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