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Floydbuster

Hurricane Marco

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3 minutes ago, WxWatcher007 said:

It is too early but that could cause one to shear another and a slower track as they interact? Not sure at this point.

That’s what I figured but definitely an interesting thing to think about. If it did slow the storms down especially TD 14 it may land up interacting less with the trough to the north as it moves deeper into the Gulf thus creating less shear for it but either way it’s unique situation for sure. 

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1 hour ago, WesterlyWx said:

That’s what I figured but definitely an interesting thing to think about. If it did slow the storms down especially TD 14 it may land up interacting less with the trough to the north as it moves deeper into the Gulf thus creating less shear for it but either way it’s unique situation for sure. 

Fantastic illustration of one possibility 

 

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TD14's low-level vortex is fully exposed right now but very clearly defined on visible. If convection can go up over it this afternoon than strengthening will be in order and this can get named. However, if land-induced convection becomes dominate, there is the possibility of CS collapses and outflow boundaries adversely affecting it. We'll have to see how this evolves, but it definitely still needs work before I would expect Marco in the short-term.a9a1dea43add885384efc475ddf114fe.gif

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000
WTNT44 KNHC 211456
TCDAT4

Tropical Depression Fourteen Discussion Number   5
NWS National Hurricane Center Miami FL       AL142020
1100 AM EDT Fri Aug 21 2020

An Air Force Reserve Hurricane Hunter aircraft flew into the
depression a few hours ago, and the plane made two center fixes
that were about 35 n mi apart, indicating that there are likely
multiple low-level swirls rotating around a common center.  A
well-defined swirl coincident with the second center fix has become
apparent in visible satellite imagery, but for now a blend of the
aircraft fixes is being used for the initial position until we can
be sure the satellite feature is in fact the one and only center.
Flight-level and SFMR winds, outside of heavy rainfall, indicate
that the maximum winds remain 30 kt.  Deep convection is still
lacking in organization, with the heaviest activity well to the
north near the Cayman Islands and along the Honduras coast.

The depression is moving northwestward, or 305/12 kt, along the
southwestern periphery of an Atlantic subtropical ridge and toward
a deep-layer trough over the Gulf of Mexico.  This northwestward
motion is expected to persist for the entire 5-day forecast period,
with a decrease in forward speed anticipated while the cyclone
approaches the Yucatan coast.  The track guidance has slowed down a
bit during that time, especially the GFS, and the new NHC forecast
is therefore a little slower than the previous forecast.  After
that time, an increase in forward speed is expected, and the NHC
forecast lies to the west of the TVCN model consensus, closer to
the GFS, ECMWF, and HCCA scenarios.

The structure of the depression aside, the environment still
appears conducive for strengthening while the system approaches the
Yucatan Peninsula.  Vertical shear over the depression is currently
less than 10 kt and is expected to remain low for the next 36-48
hours, and sea surface temperatures will be around 30 degrees
Celsius.  Therefore, steady intensification is shown in the official
forecast through 36 hours, and the NHC prediction lies near the
upper end of the guidance envelope between the HCCA and HWRF
solutions just before the center reaches the Yucatan coast.  After
some weakening while over the Yucatan Peninsula, re-intensification
is likely to occur over the central Gulf of Mexico between days 2
and 3 while vertical shear remains relatively low, and the cyclone
could become a hurricane during that time, as shown by the HCCA,
HWRF, and HMON models.  After day 3, southwesterly vertical shear of
30 kt or more is expected to develop over the northwestern Gulf, and
the official forecast follows the trend of all the intensity
guidance, showing weakening by day 4 as the cyclone approaches the
southeastern Texas or southwestern Louisiana coastline.  This
forecast remains highly uncertain, however, and users are urged to
continue monitoring changes to this forecast over the next couple
of days.


Key Messages:

1.  Heavy rainfall and gusty winds over portions of the coasts of
Nicaragua and Honduras, including the Bay Islands, are expected to
diminish today.

2. Tropical Depression Fourteen is expected to strengthen over the
northwestern Caribbean Sea through Saturday, and it is expected to
be near or at hurricane strength when it reaches the east coast of
the Yucatan Peninsula of Mexico late Saturday.  A Hurricane Watch
and a Tropical Storm Warning are in effect for portions of that
region.

3. The system is expected to move into the south-central Gulf of
Mexico as a tropical storm on Sunday.  Some strengthening is
anticipated while it moves northwestward over the central Gulf of
Mexico early next week, but it is too soon to know exactly how
strong it will get or the location and magnitude of impacts it will
produce along the central or northwestern Gulf Coast. Interests in
that area should continue monitoring the progress of this system
over the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 16.6N  84.1W   30 KT  35 MPH
 12H  22/0000Z 17.4N  85.0W   40 KT  45 MPH
 24H  22/1200Z 18.6N  85.9W   50 KT  60 MPH
 36H  23/0000Z 20.0N  86.9W   60 KT  70 MPH
 48H  23/1200Z 21.5N  88.2W   50 KT  60 MPH...INLAND
 60H  24/0000Z 23.2N  89.7W   55 KT  65 MPH...OVER WATER
 72H  24/1200Z 25.1N  91.4W   65 KT  75 MPH
 96H  25/1200Z 28.7N  94.1W   60 KT  70 MPH
120H  26/1200Z 31.3N  95.5W   40 KT  45 MPH...INLAND

$$
Forecaster Berg

 

145757_5day_cone_no_line_and_wind (1).png

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Really bizarre looking now.  Yesterday it was a large cluster of convection.  Now an exposed LLCC and a large band of convection well-removed to the NE.  This is what you'd expect a TS or min hurricane to look like after it moved over the Yucatan, not before (hollowed out center)!  Also, peripheral convection seems to be driven more by the deep trough to the NW.
 

goes16_ir_gom.gif

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6 minutes ago, vortex95 said:

Really bizarre looking now.  Yesterday it was a large cluster of convection.  Now an exposed LLCC and a large band of convection well-removed to the NE.  This is what you'd expect a TS or min hurricane to look like after it moved over the Yucatan, not before (hollowed out center)!  Also, peripheral convection seems to be driven more by the deep trough to the NW.
 

goes16_ir_gom.gif

What’s causing the mass void in convection all around the western side of the center of circulation? Is it down sloping off the land or is it from the SW shear from the trough to its north or both, or neither?

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Tropical Depression Fourteen Discussion Number   6
NWS National Hurricane Center Miami FL       AL142020
500 PM EDT Fri Aug 21 2020

Since this morning's advisory, the low-level swirl on which the Air 
Force reconnaissance plane made its last fix has apparently become 
the new center of circulation of the depression.  A little bit of 
deep convection has developed over this new center during the past 
few hours, but on the whole there is very little convective activity 
in the central region of the circulation.  The strongest and most 
persistent convection is located within a band that extends across 
the Cayman Islands toward western Cuba.  An ASCAT pass from this 
morning showed winds of 25-30 kt to the northeast of the new center, 
so 30 kt remains the initial intensity on this advisory.

It is a bit of a mystery why the depression has struggled to 
develop much central convection, given a seemingly low-shear 
environment and warm waters.  Since these conditions are expected 
to continue for the next few days, intensification is still 
indicated in the official forecast, although the rate of 
strengthening has been muted a bit while the system approaches 
the Yucatan Peninsula given its current structure.  After the 
center moves over the Gulf of Mexico, many of the models still show 
the cyclone reaching hurricane intensity in about 3 days, including 
the intensity consensus, and that possibility is still shown in the 
NHC forecast.  By day 4, the cyclone is likely to be blasted by 
30-40 kt of southwesterly shear, which would lead to weakening 
while it approaches the northwestern Gulf coast.  The official 
forecast has been reduced at that time, although it's noteworthy to 
mention that it still lies above all the guidance on day 4.

Now that there is more confidence in the initial position, the new 
motion estimate is a little to the right from before, but still 
toward the northwest, or 325/11 kt.  A deep-layer trough over the 
Gulf of Mexico is forecast to be shoved aside by the Atlantic 
subtropical ridge building westward over the next 2 days.  Even 
with this pattern change, the cyclone is expected to move generally 
northwestward for the entire 5-day forecast period.  However, there 
has been a notable westward bend in some of the track models, 
(particularly the GFS and ECMWF) from days 3-5, which is likely 
due those models having a weaker cyclone steered more by the 
low-level ridge at that time.  Since the NHC intensity forecast is 
mirroring this particular model trend, the track forecast has been 
shifted westward from the previous prediction on days 4 and 5 
toward the GFS and ECMWF solutions.  The track forecast is still of 
rather low confidence, with the spread among the model guidance 
being larger than normal at every forecast time period.


Key Messages:

1. Tropical Depression Fourteen is expected to strengthen over the
northwestern Caribbean Sea through Saturday, and it could still be
near hurricane strength when it reaches the east coast of the 
Yucatan Peninsula of Mexico late Saturday.  A Hurricane Watch
and a Tropical Storm Warning are in effect for portions of that
region.

2. The system is expected to move into the south-central Gulf of
Mexico as a tropical storm on Sunday.  Although some strengthening 
is anticipated Sunday and Monday, weakening is forecast as the 
system approaches the northwestern Gulf coast on Tuesday.  It is 
still too soon to know exactly the location and magnitude of impacts 
the system will produce along the central or northwestern Gulf 
Coast, and interests in that area should continue monitoring the 
progress of this system over the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 17.7N  84.3W   30 KT  35 MPH
 12H  22/0600Z 18.6N  85.0W   35 KT  40 MPH
 24H  22/1800Z 19.8N  85.9W   45 KT  50 MPH
 36H  23/0600Z 21.2N  87.1W   55 KT  65 MPH...INLAND
 48H  23/1800Z 22.9N  88.7W   55 KT  65 MPH...OVER WATER
 60H  24/0600Z 24.6N  90.4W   60 KT  70 MPH
 72H  24/1800Z 26.2N  92.2W   65 KT  75 MPH
 96H  25/1800Z 28.5N  95.0W   50 KT  60 MPH
120H  26/1800Z 30.0N  97.5W   30 KT  35 MPH...INLAND

$$
Forecaster Berg

 

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The center did look pretty tight on visible earlier today. 

  Some convection around the center now. 

Hurricane models are showing  a 25-30mb pressure drop before it hits the Yucatan.  

I take these models more seriously in the near term with storms  over warm water in low shear, with a small core.   

Ernesto, Micheal and Harvey all experienced these kind of deepening rates when they were  near the Yucatan.  

Watch closely the next few hours if the burst over the center continues to grow, it could be an impressive 6-18hr RI event.

 

 

 

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I think it's in the final stages of mixing out dry air that's been prevalent to it's N and NW the last couple of days..  I would venture to guess that we see some fairly significant sustained convection during DMAX overnight.  If it misses the peninsula altogether there's not a lot in it's way until it hits potential forecasted shear in a few days.  Not saying RI or anything but I do think it will be Marco by 5am at the latest.  It sure is in a historical area to blow up :weenie: 

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FWIW, forecasted shear among dynamical models is generally in the 20-30 kt range upon entry into the gulf. 

2020al14_diagplot_202008220000.png

 

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1005.3 mb extrapolated on that center pass, so we do have both a gradual pressure drop and increasing winds. Not a lot of convection elsewhere, but it’s solid where it matters.

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Just now, WxWatcher007 said:

1005.3 mb extrapolated on that center pass, so we do have both a gradual pressure drop and increasing winds. Not a lot of convection elsewhere, but it’s solid where it matters.

4mb drop from the last pass. 

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Vortex message shows an extrapolated pressure of 1003mb. 39kt maximum SFMR.
 

 

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 22nd day of the month at 1:46Z
Agency: United States Air Force 
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5305 
Tropical Depression: Fourteen (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 06 ( See all messages of this type for this mission. )

A. Time of Center Fix: 22nd day of the month at 1:19:30Z
B. Center Fix Coordinates: 18.59N 84.69W
B. Center Fix Location: 227 statute miles (365 km) to the SE (142°) from Cancún, Quintana Roo, Mexico.
C. Minimum Height at Standard Level: 731m (2,398ft) at 925mb
D. Minimum Sea Level Pressure: 1003mb (29.62 inHg) - Extrapolated
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Not Available
G. Eye Shape: Not Available
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 39kts (44.9mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 20 nautical miles (23 statute miles) to the NE (42°) of center fix at 1:13:00Z
J. Maximum Flight Level Wind Inbound: From 133° at 35kts (From the SE at 40.3mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 10 nautical miles (12 statute miles) to the NE (39°) of center fix at 1:16:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 23kts (26.5mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 18 nautical miles (21 statute miles) to the SW (223°) of center fix at 1:26:00Z
N. Maximum Flight Level Wind Outbound: From 255° at 17kts (From the WSW at 19.6mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 4 nautical miles to the SSW (198°) of center fix at 1:21:00Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 761m (2,497ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 761m (2,497ft)
R. Dewpoint Temp & Sea Surface Temp: Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Level: 925mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 4 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 38kts (~ 43.7mph) which was observed 82 nautical miles (94 statute miles) to the ENE (71°) from the flight level center at 0:33:30Z
Sea Level Pressure Extrapolation From: 925mb

 

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No doubt in my mind based on the data that this is a TS. Looks to be on a NW heading still, though the motion between the first and second passes was more northward. Quite possible this center misses land. As it stands the NHC has a brief clip. 

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BULLETIN
Tropical Storm Marco Advisory Number   7
NWS National Hurricane Center Miami FL       AL142020
1100 PM EDT Fri Aug 21 2020

...TROPICAL STORM MARCO FORMS OVER THE NORTHWESTERN CARIBBEAN...
...FORECAST TO MOVE NEAR THE YUCATAN PENINSULA ON SATURDAY...


SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...18.7N 84.9W
ABOUT 180 MI...290 KM SE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Watch is in effect for...
* Punta Herrero to Cancun Mexico

A Tropical Storm Warning is in effect for...
* Punta Herrero to Dzilam Mexico

A Hurricane Watch means that hurricane conditions are possible
within the watch area, in this case within 24.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case within 24
hours.

For storm information specific to your area, please monitor
products issued by your national meteorological service.


DISCUSSION AND OUTLOOK
----------------------
At 1100 PM EDT (0300 UTC), the center of Tropical Storm Marco was
located near latitude 18.7 North, longitude 84.9 West. Marco is
moving toward the north-northwest near 13 mph (20 km/h). A slightly
slower northwestward motion is expected for the next day or so,
followed by an increase in forward speed by early next week. On the
forecast track, the center of Marco will approach the east coast of
the Yucatan Peninsula of Mexico on Saturday. The center will then
cross the northeastern part of the Yucatan Peninsula Saturday night
and move over the central Gulf of Mexico toward the northwestern
Gulf on Sunday and Monday.

Maximum sustained winds have increased to near 40 mph (65 km/h)
with higher gusts. Additional strengthening is forecast during the
next couple of days as the system approaches the Yucatan peninsula
and Marco could be near hurricane strength when it moves over the
central Gulf of Mexico on Sunday.

Tropical-storm-force winds extend outward up to 90 miles (150 km)
from the center.

The estimated minimum central pressure is 1003 mb (29.62 inches) 
based on reports from the Hurricane Hunter plane.


HAZARDS AFFECTING LAND
----------------------
WIND:  Tropical storm conditions are expected to first reach the
eastern Yucatan coast within the warning area by Saturday afternoon
and will spread northward and westward within the warning area
Saturday night, making outside preparations difficult or dangerous.
Hurricane conditions are also possible within the hurricane watch
area by late Saturday.

RAINFALL:  Marco is expected to produce the following rainfall
accumulations through Sunday:

Eastern portions of the Mexican states of Quintana Roo and Yucatan:
3 to 6 inches, isolated maximum totals of 10 inches. This rainfall
may result in areas of flash flooding.

Northeast Nicaragua and the Cayman Islands: 1 to 2 inches.


NEXT ADVISORY
-------------
Next intermediate advisory at 200 AM EDT.
Next complete advisory at 500 AM EDT.

$$
Forecaster Zelinsky

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Tropical Storm Marco Discussion Number   7
NWS National Hurricane Center Miami FL       AL142020
1100 PM EDT Fri Aug 21 2020

An Air Force Reserve Hurricane Hunter aircraft has investigated the 
system over the northwest Caribbean during the past few hours. The 
plane reported a number of unflagged SFMR winds between 35 and 40 kt 
and max flight level winds of 41 kt. A blend of these data supports 
an intensity of 35 kt, and therefore, this system has been 
designated as Tropical Storm Marco. Deep convection has increased 
near and to the east of Marco's center during the past few hours. 
Although there still isn't much evidence of inner-core banding, the 
data from the plane does indicate that the center of Marco has 
become better defined since the afternoon and that the minimum 
pressure has dropped.

Unfortunately the intensity forecast has not become any clearer and 
confidence in that aspect of the forecast is quite low. Marco is 
embedded within an environment that could support a fast rate of 
strengthening. However, recent microwave data does not indicate that 
the system has developed an inner-core, and only gradual 
strengthening is likely until it does. The intensity guidance spread 
is quite high, with the GFS and ECMWF global models both showing 
little further strengthening, while the HMON regional model rapidly 
makes Marco a hurricane before it reaches the northeast tip of the 
Yucatan peninsula. That possibility can not be ruled out, but a 
majority of the intensity guidance favors the weaker solution of the 
global models. Even with the HMON outlier included, the NHC 
intensity forecast is above the model consensus. Once Marco moves 
over the central Gulf of Mexico, a rapid increase in wind shear 
associated with an upper-level trough should limit the potential for 
further strengthening, and weakening is still anticipated before 
Marco nears the northern Gulf Coast, as shown in the previous 
official forecast.

Confidence in the track forecast is also lower than normal, as the 
models spread remains quite high. Only small adjustments were made 
to the NHC forecast which heavily favors the GFS and ECMWF solutions 
on the left side of the track guidance. It is worth noting that the 
NHC track forecast is near middle of the GFS and ECMWF ensembles. 
Marco is currently forecast to move northwestward toward a weakness 
in the subtropical ridge over the central Gulf of Mexico for the 
next day or two, before the ridge builds and turns the tropical 
cyclone farther west. Near the end of the period, Marco's track and 
intensity could be also influenced by Tropical Storm Laura which is 
also forecast to be over the Gulf of Mexico, however the details of 
that interaction are highly uncertain at this time. Given the high 
uncertainty in the forecast, larger than normal changes could be 
required to future advisories.


Key Messages:

1. Marco is forecast to strengthen over the northwestern Caribbean 
Sea through Saturday as it approaches the northeast coast of the 
Yucatan Peninsula. A Hurricane Watch and a Tropical Storm Warning 
are in effect for portions of that region.

2. The system is expected to move into the south-central Gulf of
Mexico as a tropical storm on Sunday. Although some strengthening
is anticipated on Sunday, weakening is forecast as the system
approaches the northwestern Gulf coast on Tuesday. It is still too
soon to know exactly the location and magnitude of impacts the
system will produce along the central or northwestern Gulf Coast,
and interests in that area should continue monitoring the progress
of this system over the next few days.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 18.7N  84.9W   35 KT  40 MPH
 12H  22/1200Z 19.7N  85.7W   45 KT  50 MPH
 24H  23/0000Z 21.1N  86.7W   50 KT  60 MPH
 36H  23/1200Z 22.7N  88.0W   55 KT  65 MPH
 48H  24/0000Z 24.4N  89.5W   60 KT  70 MPH
 60H  24/1200Z 25.9N  91.0W   60 KT  70 MPH
 72H  25/0000Z 27.5N  92.8W   60 KT  70 MPH
 96H  26/0000Z 29.0N  95.4W   45 KT  50 MPH...INLAND
120H  27/0000Z 30.0N  97.4W   30 KT  35 MPH...INLAND

$$
Forecaster Zelinsky

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Never seen a TC with a 500mb vorticity field like this.

1KWgiCo.png

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As the NHC states in their discussion, there is convection firing near the center but no evidence yet of banding within the center. As a result, intensification is more gradual. That said, the convection is nice. We have to watch and see if this can get its act together and organize tonight. 

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32 minutes ago, Amped said:

Never seen a TC with a 500mb vorticity field like this.

1KWgiCo.png

It is a model in the future  and yes it's a bit strange.  The Euro shows something similar but not as vigorous.  My take would be it's a signal of rising air riding the western side of maybe a mid level ridge.  Pretty stale winds off to the east so could induce some vorticity along that line.  200mb winds are from the SW almost on top of that and maybe stretching the latent vorticity NE?  Might be a feature in the models that prevents some big dog strengthening.  I'm sitting in a recliner with my dog watching Shipping Wars, what the hell do I know lol.

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