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Major Hurricane Sam


Jtm12180
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Hurricane Sam Advisory Number  21
NWS National Hurricane Center Miami FL       AL182021
500 PM AST Mon Sep 27 2021

...SAM BEGINNING TO REGROUP AFTER WEAKENING...
...SOME REINTENSIFICATION EXPECTED THROUGH TONIGHT...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...16.3N 52.7W
ABOUT 700 MI...1125 KM E OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...957 MB...28.26 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND OUTLOOK
----------------------
At 500 PM AST (2100 UTC), the center of Hurricane Sam was located
near latitude 16.3 North, longitude 52.7 West. Sam is moving toward
the northwest near 9 mph (15 km/h), and this motion is expected to
continue for the next few days, with an increase in forward speed
beginning on Thursday.  A turn to the north is expected by Friday.
On the forecast track, Sam will pass well to the northeast of the
northern Leeward Islands Wednesday and Thursday.

An Air Force Reserve Hurricane Hunter aircraft indicates that the 
maximum sustained winds are near 120 mph (195 km/h) with higher 
gusts.  Sam is a category 3 hurricane on the Saffir-Simpson 
Hurricane Wind Scale.  Some strengthening is expected through 
tonight. Thereafter, fluctuations in intensity are possible through 
Thursday.

Hurricane-force winds extend outward up to 30 miles (45 km) from the
center and tropical-storm-force winds extend outward up to 105 miles
(165 km).

The minimum central pressure measured by the aircraft is 957 mb 
(28.26 inches).
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Hurricane Sam Discussion Number  21
NWS National Hurricane Center Miami FL       AL182021
500 PM AST Mon Sep 27 2021

Sam's weakening trend ended earlier today, with the intensity likely 
bottoming out between the issuance of the previous advisory and now. 
Over the past few hours, microwave data and satellite imagery 
indicate that the inner core and eyewall of the hurricane are making 
a comeback. There is now a clear eye in visible imagery, convective 
cloud tops colder than -65 degrees C wrap completely around the 
center, and the convective mass is becoming more circular once 
again. An Air Force Reserve Hurricane Hunter aircraft currently 
investigating Sam indicates the central pressure has dropped to 957 
mb, with peak 700-mb flight-level winds of 106 kt, SFMR values of 
100 kt, and dropsonde surface winds of 102 kt. Given possible minor 
undersampling and the recent dropping of the hurricane's pressure, 
the initial advisory intensity is set at 105 kt.

Sam continues to move northwest, or 315/8 kt. The hurricane is
expected to continue this northwestward motion around a subtropical
ridge over the next few days. By late Thursday or early Friday a
turn toward the north is anticipated as Sam rounds the western
periphery of the ridge. The cyclone should begin to gradually
accelerate during that time in the increasing flow ahead of a mid-
to upper-level trough emerging off the U.S. east coast later this
week. Model guidance remains in very good agreement on this
scenario and the latest NHC forecast track is little changed from
the previous one, and lies near tightly clustered consensus track
guidance.

The southwesterly winds that brought in some dry air and disrupted
Sam's impressive satellite appearance last night appear to have
abated. As long as environmental winds surrounding the hurricane
remain light, then the dry air surrounding the cyclone should not 
have as much of an impact on the hurricane's strength over the next 
few days. Based on the improving inner-core structure appearance of 
Sam, re-strengthening is forecast over the next 12 h. Thereafter, 
mainly minor fluctuations in intensity are indicated through 72 h. 
Beyond that time, increasing vertical wind shear and decreasing 
sea-surface temperatures should cause Sam to weaken. The latest NHC 
intensity forecast was nudged slightly upward through 36 h and is 
on the high end of the guidance. Thereafter, no changes were made, 
and that portion of the forecast is close to the various multimodel 
consensus solutions.

Key Messages:

1. Large swells generated by Sam are affecting the Leeward Islands 
and will spread to portions of the Virgin Islands, Puerto Rico, 
Hispaniola, the Bahamas, and Bermuda by Thursday or Friday.  
Significant swells will likely reach the east coast of the United 
States and Atlantic Canada by the weekend.  These swells will likely 
cause life-threatening surf and rip current conditions, and 
beachgoers and other interests along these coasts are urged to 
follow the advice of lifeguards and local officials through the 
upcoming weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  27/2100Z 16.3N  52.7W  105 KT 120 MPH
 12H  28/0600Z 17.0N  53.5W  115 KT 130 MPH
 24H  28/1800Z 17.8N  54.6W  115 KT 130 MPH
 36H  29/0600Z 18.8N  55.8W  115 KT 130 MPH
 48H  29/1800Z 19.8N  57.3W  110 KT 125 MPH
 60H  30/0600Z 21.2N  59.0W  110 KT 125 MPH
 72H  30/1800Z 22.9N  60.5W  110 KT 125 MPH
 96H  01/1800Z 27.8N  62.0W  105 KT 120 MPH
120H  02/1800Z 34.7N  59.6W  100 KT 115 MPH

$$
Forecaster Latto
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Gettings spoiled by these reconnaissance radar scans. This needs to become a thing. Bless the meteorology college dude providing these on his own time.


Last scan looks like an ongoing merger to me. But of course there are multiple banding features around the core. Any continued VWS is going to help spur ongoing replacement cycles at this point.
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I didn't save the Tweet, but a couple of days ago someone on Weather Twitter screencapped some news website asking if Sam was going to be the next Sandy.  For the laughs and disappointment someone could hype that much.

 

Now that no model brings it close, out of sight, out of mind.  That and the eye is warming.  Eyewall convection still cold, but the eye itself, pretty meh.

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4 hours ago, StormchaserChuck! said:

When I was in a mental hospital when Cat 5 Micheal was making landfall, it was like a global blackout.. quietest I've ever experienced. 

I’m not sure Michael was actually a 5. 

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7 minutes ago, ncforecaster89 said:

Actually, there’s more evidential data to support 145 kt than 135 kt…much less 140 kt.  SImply put, It was most certainly a Cat 5.   

That “evidential” data is subject to human interpretation and assumptions. SFMR has a high bias and the rest of the data is just hand waving about flight level reductions and stuff. 

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And the debate is getting a bit nasty too. Maybe it is anger that Sam and these two storms to follow will be only for the fishes?
I mean, whatever. I am sure there are plenty that only follow for landfalls. I enjoy tracking them regardless. This has already been a better CV season than last year with Larry (which did landfall) and Sam, the strongest MDR system since Lorenzo. 2020 Paulette was kind of meh. Really, Teddy was the only quality MDR system last year. At any rate, it's far from dead or boring.
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