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Tracking the tropics - 2025


tiger_deF
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The global numerical guidance have been formulating a mid and upper level vortex along the M/A for several days worth of cycles...  It's unclear why they are so deep at the surface, however...when there's only modest at best baroclinic instability below the 700 mb in that region astride the M/A.  You need the fuller vertical integration to succeed a sub 990 mb -type powerful cyclone genesis.   mmm, so I'm a bit suspect of the Euro/GGEM/GFS as being too amplified.  They could be right .. but I also think a 00z UKMET -type solution is more possible. 

This is based on a couple of concepts. 

One, modeling tends to too much amplitude beyond D6 as a standard correction ... They'll lose some 20 ... 30% kinematic layout as that time range comes into the D4s.  How many times has the d-drip euphoria of the D8 bomb turned into a 4-6" jack in the winter for example. 

Two, if there's a hybrid lurking in destiny, it would probably have to come from a weaker initial 500 mb closure than the Euro-like solutions are presently selling.  It's almost like 'thermodynamic momentum'   Pig extra-tropical gyres have a lot of cooler mass/momentum, so it takes longer to modify the kinematics toward a warm profile.   If the initial trigger is a weaker mid level instability, the machinery (outflow aloft) from ongoing festering convection instantiates and starts to feedback with inflow into festering convection ... conversion doesn't have as much to overcome.   In some rare cases, a stronger initially cold core gyre may transition, provided the surrounding hemisphere is very supportive ( 1990 "perfect storm" scenario).  So it's not impossible - but rareness immediately assumes 'less likely' in this case.  

 

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  • 2 weeks later...

This NE eyewall dropsonde is about as high end as you get in the Atlantic basin. 

 

Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 27th day of the month at 16:13Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF98-5308
Storm Name: Melissa
Storm Number: 13 (flight in the North Atlantic basin)
Mission Number: 20
Observation Number: 27

Part A...
 

Date: Near the closest hour of 16Z on the 27th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 16.4N 78.1W
Location: 141 statute miles (226 km) to the SW (217°) from Kingston, Jamaica.
Marsden Square: 044 ( About )
 
Surface and Standard Isobaric Surfaces
Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1000mb This level does not exist in this area of the storm above the surface level.
927mb (27.38 inHg) Surface (Sea Level) 25.0°C (77.0°F) 25.0°C (77°F) 340° (from the NNW) 163 knots (188 mph)
925mb 17m (56 ft) 24.4°C (75.9°F) 24.4°C (76°F) 345° (from the NNW) 178 knots (205 mph)
850mb 756m (2,480 ft) 20.6°C (69.1°F) 20.5°C (69°F) 45° (from the NE) 181 knots (208 mph)
700mb 2,427m (7,963 ft) Other data not available.

Information About Radiosonde:
- Launch Time: 15:44Z
- About Sonde: A descending radiosonde tracked automatically by satellite navigation with no solar or infrared correction.

Remarks Section...
 
Dropsonde Location: Dropped in eyewall 45° (NE) from the eye center.

Highest altitude where wind was reported:
- Location: 16.42N 78.14W
- Time: 15:44:32Z

Lowest altitude where wind was reported:
- Location: 16.34N 78.29W
- Time: 15:49:01Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):
- Wind Direction: 5° (from the N)
- Wind Speed: 174 knots (200 mph)

Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 65° (from the ENE)
- Wind Speed: 125 knots (144 mph)
- Depth of Sounding: From 707mb to 927mb

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:
- Lowest 150m: 152 gpm - 2 gpm (499 geo. feet - 7 geo. feet)
- Wind Direction: 350° (from the N)
- Wind Speed: 185 knots (213 mph)

Sounding Software Version: AEV 40001
 

Part B: Data for Significant Levels...
 

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
927mb (Surface) 25.0°C (77.0°F) 25.0°C (77°F)
924mb 24.2°C (75.6°F) 24.2°C (76°F)
910mb 23.2°C (73.8°F) 23.2°C (74°F)
850mb 20.6°C (69.1°F) 20.5°C (69°F)
729mb 15.6°C (60.1°F) 15.6°C (60°F)
720mb 16.6°C (61.9°F) 13.3°C (56°F)
702mb 15.0°C (59.0°F) 12.8°C (55°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
927mb (Surface) 340° (from the NNW) 163 knots (188 mph)
926mb 340° (from the NNW) 164 knots (189 mph)
925mb 345° (from the NNW) 179 knots (206 mph)
922mb 345° (from the NNW) 194 knots (223 mph)
920mb 345° (from the NNW) 197 knots (227 mph)
917mb 345° (from the NNW) 193 knots (222 mph)
914mb 350° (from the N) 176 knots (203 mph)
912mb 0° (from the N) 185 knots (213 mph)
905mb 5° (from the N) 194 knots (223 mph)
890mb 15° (from the NNE) 159 knots (183 mph)
881mb 25° (from the NNE) 182 knots (209 mph)
873mb 25° (from the NNE) 164 knots (189 mph)
868mb 30° (from the NNE) 170 knots (196 mph)
864mb 30° (from the NNE) 166 knots (191 mph)
860mb 35° (from the NE) 170 knots (196 mph)
858mb 40° (from the NE) 183 knots (211 mph)
854mb 45° (from the NE) 177 knots (204 mph)
850mb 45° (from the NE) 181 knots (208 mph)
811mb 85° (from the E) 155 knots (178 mph)
707mb 125° (from the SE) 167 knots (192 mph)
 
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