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WxWatcher007

Harvey - Main Thread

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So many supercells coming off the Gulf on the east side of the system with good circulations. One near Brazoria right now and another just SE of Galvaston. Very impressive looking cells for outer bands.

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Just now, Morris said:

 

Only know of a handful of times that happened, and all of them were with very significant tornadoes.

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Just now, NJwx85 said:

So looks like 115kts at 5PM, possibly 120.

With no surface obs that support it? Doubt it...Maybe 105 or 110

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Latest sonde--dropped in max wind band

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
955mb (Surface) 25.4°C (77.7°F) 24.9°C (77°F)
850mb 21.4°C (70.5°F) 20.9°C (70°F)
723mb 15.4°C (59.7°F) 15.4°C (60°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
955mb (Surface) Unavailable
954mb 45° (from the NE) 109 knots (125 mph)
947mb 50° (from the NE) 116 knots (133 mph)
939mb 50° (from the NE) 114 knots (131 mph)
933mb 55° (from the NE) 125 knots (144 mph)
927mb 55° (from the NE) 122 knots (140 mph)
920mb 65° (from the ENE) 129 knots (148 mph)
916mb 70° (from the ENE) 123 knots (142 mph)
910mb 70° (from the ENE) 135 knots (155 mph)
900mb 70° (from the ENE) 117 knots (135 mph)
892mb 70° (from the ENE) 127 knots (146 mph)
887mb 80° (from the E) 117 knots (135 mph)
876mb 90° (from the E) 116 knots (133 mph)
872mb 95° (from the E) 106 knots (122 mph)
866mb 95° (from the E) 101 knots (116 mph)
850mb 90° (from the E) 100 knots (115 mph)
723mb 105° (from the ESE) 85 knots (98 mph)
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I did some quick calculations - looks like each color tick is about 1.1 to 1.2mph. When the scale roles over from - to + that's about 2.2mph delta. The highest + value I see in the - velocity field is +130.9mph, and the highest possible + velocity radarscope handles is +139.8mph. That means that the highest winds that radar is showing look to be around -153.1mph. Just an estimate!

2 minutes ago, Morris said:

 

 

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5 minutes ago, Stebo said:

So many supercells coming off the Gulf on the east side of the system with good circulations. One near Brazoria right now and another just SE of Galvaston. Very impressive looking cells for outer bands.

Very high echo tops for a trop. system. Hence all of the lightning in the outer bands and occasionally in the core. Very healthy convection.

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Just now, wxmx said:

With no surface obs that support it? Doubt it...Maybe 105 or 110

Well using the 90% standard rule from 126kts FL gives you 113.4 

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1 minute ago, WxWatcher007 said:

Latest sonde--dropped in max wind band

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
955mb (Surface) 25.4°C (77.7°F) 24.9°C (77°F)
850mb 21.4°C (70.5°F) 20.9°C (70°F)
723mb 15.4°C (59.7°F) 15.4°C (60°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
955mb (Surface) Unavailable
954mb 45° (from the NE) 109 knots (125 mph)
947mb 50° (from the NE) 116 knots (133 mph)
939mb 50° (from the NE) 114 knots (131 mph)
933mb 55° (from the NE) 125 knots (144 mph)
927mb 55° (from the NE) 122 knots (140 mph)
920mb 65° (from the ENE) 129 knots (148 mph)
916mb 70° (from the ENE) 123 knots (142 mph)
910mb 70° (from the ENE) 135 knots (155 mph)
900mb 70° (from the ENE) 117 knots (135 mph)
892mb 70° (from the ENE) 127 knots (146 mph)
887mb 80° (from the E) 117 knots (135 mph)
876mb 90° (from the E) 116 knots (133 mph)
872mb 95° (from the E) 106 knots (122 mph)
866mb 95° (from the E) 101 knots (116 mph)
850mb 90° (from the E) 100 knots (115 mph)
723mb 105° (from the ESE) 85 knots (98 mph)

That supports 110kts at surface

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Just now, WxWatcher007 said:

Latest sonde--dropped in max wind band

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
955mb (Surface) 25.4°C (77.7°F) 24.9°C (77°F)
850mb 21.4°C (70.5°F) 20.9°C (70°F)
723mb 15.4°C (59.7°F) 15.4°C (60°F)
 
Significant Wind Levels
Level Wind Direction Wind Speed
955mb (Surface) Unavailable
954mb 45° (from the NE) 109 knots (125 mph)
947mb 50° (from the NE) 116 knots (133 mph)
939mb 50° (from the NE) 114 knots (131 mph)
933mb 55° (from the NE) 125 knots (144 mph)
927mb 55° (from the NE) 122 knots (140 mph)
920mb 65° (from the ENE) 129 knots (148 mph)
916mb 70° (from the ENE) 123 knots (142 mph)
910mb 70° (from the ENE) 135 knots (155 mph)
900mb 70° (from the ENE) 117 knots (135 mph)
892mb 70° (from the ENE) 127 knots (146 mph)
887mb 80° (from the E) 117 knots (135 mph)
876mb 90° (from the E) 116 knots (133 mph)
872mb 95° (from the E) 106 knots (122 mph)
866mb 95° (from the E) 101 knots (116 mph)
850mb 90° (from the E) 100 knots (115 mph)
723mb 105° (from the ESE) 85 knots (98 mph)

Those winds just aloft are extremely intense, well into Cat 4 territory should they mix down to the surface at some point.

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Just now, csnavywx said:

Very high echo tops for a trop. system. Hence all of the lightning in the outer bands and occasionally in the core. Very healthy convection.

Yeah, really shocking to be honest, don't usually see cells over 35,000' let alone 40-45,000' like the cells currently are showing.

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I was worried once the new eyewall had cleared out all the leftover convective cells and cloud debris, a warming temperature gradient would allow for more significant deepening. Looks like that is occurring now at the worst possible time.

Thankfully the core will not pass over high population density at peak intensity, but I really hope those folks that stayed in Port O'Connor, Port Lavaca and the barrier are prepared. They're about to experience one of the most terrifying nights of their lives.


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Another one

Dropsonde Location: Dropped in eyewall 225° (SW) from the eye center.
 

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
961mb (Surface) 25.6°C (78.1°F) 24.6°C (76°F)
850mb 21.6°C (70.9°F) 20.3°C (69°F)
696mb 13.8°C (56.8°F) 13.8°C (57°F)

 

Significant Wind Levels
Level Wind Direction Wind Speed
961mb (Surface) Unavailable
959mb 285° (from the WNW) 87 knots (100 mph)
956mb 275° (from the W) 102 knots (117 mph)
949mb 290° (from the WNW) 111 knots (128 mph)
945mb 290° (from the WNW) 110 knots (127 mph)
937mb 290° (from the WNW) 101 knots (116 mph)
929mb 295° (from the WNW) 115 knots (132 mph)
916mb 300° (from the WNW) 117 knots (135 mph)
903mb 305° (from the NW) 116 knots (133 mph)
888mb 305° (from the NW) 104 knots (120 mph)
859mb 310° (from the NW) 93 knots (107 mph)
850mb 310° (from the NW) 95 knots (109 mph)
761mb 320° (from the NW) 100 knots (115 mph)
696mb 325° (from the NW) 85 knots (98 mph)

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One more

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

Significant Temperature And Relative Humidity Levels
Level Air Temperature Dew Point
956mb (Surface) 25.6°C (78.1°F) 24.4°C (76°F)
850mb 21.0°C (69.8°F) 19.7°C (67°F)
754mb 16.4°C (61.5°F) 12.5°C (54°F)
697mb 13.0°C (55.4°F) 13.0°C (55°F)

 

Significant Wind Levels
Level Wind Direction Wind Speed
956mb (Surface) Unavailable
954mb 70° (from the ENE) 105 knots (121 mph)
949mb 70° (from the ENE) 120 knots (138 mph)
938mb 75° (from the ENE) 121 knots (139 mph)
932mb 80° (from the E) 134 knots (154 mph)
931mb 80° (from the E) 132 knots (152 mph)
927mb 80° (from the E) 115 knots (132 mph)
925mb 85° (from the E) 111 knots (128 mph)
905mb 100° (from the E) 121 knots (139 mph)
898mb 100° (from the E) 114 knots (131 mph)
887mb 100° (from the E) 130 knots (150 mph)
866mb 105° (from the ESE) 119 knots (137 mph)
850mb 105° (from the ESE) 120 knots (138 mph)
697mb 130° (from the SE) 122 knots (140 mph)

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13 minutes ago, wxmx said:

With no surface obs that support it? Doubt it...Maybe 105 or 110

Good call looks like 110k and 941 MB Pressure at 5pm

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23 minutes ago, Stebo said:

 

With these two things combined, I wouldn't be shocked if this comes in at 135/140mph.

LEK's post from earlier should've set off alarm bells about the real possibility of it landfalling stronger than forecast (even if it doesn't quite get to what he was expecting). He is pretty good with this stuff.

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Very strong discussion from the NHC. They give Harvey a chance to continue intensification though it isn't quite reflected in the forecast points. 

Hurricane Harvey Discussion Number  22
NWS National Hurricane Center Miami FL       AL092017
400 PM CDT Fri Aug 25 2017

Despite its concentric eyewall structure, Harvey's winds have
increased during the day.  NOAA and Air Force Reserve Hurricane
Hunter planes have measured maximum flight-level winds of 129 kt
and SFMR winds to 102 kt.  Based on these data, Harvey's maximum
surface winds are estimated to be 110 kt.  Harvey's central pressure
has also continued to fall, and the latest estimate based on
dropsonde data is 941 mb.

Harvey still has not slowed down, and the initial estimate is
325/9 kt.  Based on the forecast track, Harvey is expected to make
landfall along the middle Texas coast tonight.  After that, the
track models insist that the hurricane will slow down considerably
during the next 24 hours, and it is likely to move very little
between 36 and 120 hours.  In fact, there has been a somewhat
notable change in the guidance, with very few of the models showing
Harvey lifting out toward the northeast by the end of the 5-day
forecast period.  As a result, the NHC track forecast has been
pulled back a bit and keeps Harvey near or just inland of the Texas
coast through the middle of next week.  This slow motion only
exacerbates the heavy rainfall and flooding threat across southern
and southeastern Texas.

Harvey may continue to strengthen during the 6-12 hours it has
before landfall, but regardless it is expected to make landfall at
major hurricane strength.  Gradual weakening is anticipated after
the center moves inland, but Harvey's slow motion will keep a
significant portion of its circulation over water, which may slow
the weakening rate.  As a result, the NHC intensity forecast leans
closer to the global model guidance instead of the statistical-
dynamical guidance, which seems to weaken Harvey too fast.  Harvey
could maintain tropical storm strength for the entire 5-day
forecast period due to its proximity to the northwestern Gulf of
Mexico.

Key Messages:

1. Harvey will make landfall tonight, bringing life-threatening
storm surge, rainfall, and wind hazards to portions of the Texas
coast. Tropical-storm-force winds have moved onshore in portions of
the warning areas and conditions will continue to deteriorate as
the eye of Harvey approaches the middle Texas coast tonight.

2. A Storm Surge Warning is in effect for much of the Texas coast.
Life-threatening storm surge flooding could reach heights of 6 to 12
feet above ground level at the coast between the north entrance of
the Padre Island National Seashore and Sargent. For a depiction of
areas at risk, see the Storm Surge Watch/Warning Graphic at
hurricanes.gov. Due to the slow motion of Harvey and a prolonged
period of onshore flow, water levels will remain elevated for
several days.

3. Catastrophic and life-threatening flooding is expected across the
middle and upper Texas coast from heavy rainfall of 15 to 30 inches,
with isolated amounts as high as 40 inches, through Wednesday.
Please refer to products from your local National Weather Service
office and the NOAA Weather Prediction Center for more information
on the flooding hazard.

FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 27.5N  96.5W  110 KT 125 MPH
 12H  26/0600Z 28.2N  97.0W  100 KT 115 MPH...INLAND
 24H  26/1800Z 28.8N  97.5W   75 KT  85 MPH...INLAND
 36H  27/0600Z 28.9N  97.8W   60 KT  70 MPH...INLAND
 48H  27/1800Z 28.6N  97.8W   50 KT  60 MPH...INLAND
 72H  28/1800Z 28.1N  96.9W   40 KT  45 MPH...INLAND
 96H  29/1800Z 28.5N  96.0W   40 KT  45 MPH...OVER WATER
120H  30/1800Z 29.5N  95.5W   35 KT  40 MPH...INLAND

$$
Forecaster Berg

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Harvey might be close to peak intensity unless another wobble to the right occurs, the NW portion of the eyewall is less than 100 miles offshore.

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