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Hurricane Nana


yoda
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000
WTNT41 KNHC 012055
TCDAT1

Tropical Storm Nana Discussion Number   3
NWS National Hurricane Center Miami FL       AL162020
500 PM EDT Tue Sep 01 2020

Although convection has waned somewhat since the previous advisory 
due to mid-level dry air entrainment, Nana still has enough deep
convection over and surrounding the low-level center to keep the 
intensity at 45 kt. Upper-level outflow has continued to improve, 
with the associated anticyclone becoming more symmetrical. Another 
reconnaissance mission is scheduled for this evening.

The initial motion estimate is 275/16 kt. There are no significant 
changes to the previous track forecast or reasoning. A pronounced 
deep-layer to the north of Nana is forecast to remain intact and 
even build westward over the next few days, keeping Nana moving in a 
general westward direction for the next 36 hours or so. Thereafter, 
the aforementioned ridge is expected to build west-southwestward 
across southern Mexico, driving the cyclone west-southwestward as 
well across northern Central America. The new NHC forecast track is 
similar to the previous advisory track, and lies close to a blend of 
the simple consensus models TVCN and GFEX, and the corrected- 
consensus models NOAA-HCCA and FSSE.

The current northeasterly 15 kt of vertical wind shear and dry air 
intrusions should inhibit development for next 24 hours or so. 
However, the GFS and ECMWF models both forecast the shear to 
gradually decrease during the next 48 hours, becoming near 5 kt by 
36 hours. The lower vertical shear, coupled with the already 
impressive outflow pattern, sea-surface temperatures of 29.5-30.5 
deg C, and a moistening mid-level environment should allow for 
gradual strengthening for the next 24 hours, followed by more 
significant intensification thereafter, which will continue right up 
until landfall occurs. The NHC official intensity forecast is a 
blend of the simple consensus intensity model IVCN, and the 
corrected-consensus models NOAA-HCCA and FSSE.

A Tropical Storm Warning and Tropical Storm Watch have been issued  
for the southern portion of the Yucatan Peninsula and the 
Caribbean Sea coast of Guatemala, respectively.

KEY MESSAGES:

1. Tropical Storm Nana is now forecast to be a hurricane as it
approaches the coast, and interests in Honduras, Guatemala,
Belize, and Yucatan should closely monitor the progress of this
storm.  Strong winds, dangerous storm surge and very heavy rainfall
causing flash flooding are becoming more likely from Nana.


FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 16.8N  79.3W   45 KT  50 MPH
 12H  02/0600Z 17.1N  81.5W   50 KT  60 MPH
 24H  02/1800Z 17.3N  84.7W   55 KT  65 MPH
 36H  03/0600Z 17.2N  87.3W   65 KT  75 MPH
 48H  03/1800Z 16.9N  89.4W   45 KT  50 MPH...INLAND
 60H  04/0600Z 16.5N  91.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  04/1800Z...DISSIPATED

$$
Forecaster Stewart

 

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26 minutes ago, NorthHillsWx said:

Nice blowup of convection over the COC. Let’s see what happens with it. Still some E, NE shear present. Rapid motion isn’t helping either but system still looks well positioned for strengthening 

I think the rapid speed is one of the only real inhibiting factors at the moment. Looking at the profiles, dry air is still an issue ahead of the system, but generally Nana has created a fairly moist pocket around her with healthy expanding outflow to the east and west. Still some shear to the south of the system, but developing anticyclone in the upper levels will keep the environment favorable until landfall.

Definitely could reach hurricane strength tonight into tomorrow

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43 minutes ago, the ghost of leroy said:

I’ll keep hating. That’s a pretty basic bitch cyan ring. Plus like guru Phil said cayman radar is showing convective anemia. 
 

CAPPI is not the best radar at 240km though. It's missing shallow core convection at that distance. That cyan ring looks concerning even if the SW eyewall has the big CBs right now that are being easterly sheared. At any rate, we'll have recon soon.

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1 minute ago, Windspeed said:

C APPI is not the best radar at 240nm though. It's missing the core convection at that distance. That cyan ring looks concerning even if the SW eyewall has the big CBs right now that are being easterly sheared. At any rate, we'll have recon soon.

That caymans radar definitely helps paint the shear picture however. Weak northern convection coupled with a lopsided eyewall. It won’t rapidly intensify unless that stuff gets worked out, regardless of a wisp of a cyan ring. 

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3 minutes ago, the ghost of leroy said:

That caymans radar definitely helps paint the shear picture however. Weak northern convection coupled with a lopsided eyewall. It won’t rapidly intensify unless that stuff gets worked out, regardless of a wisp of a cyan ring. 

That should have been km not nm. But yeah.. I don't necessarily disagree. It has an intact core though. Shear will lessen as time goes on. If anything, the vorticity maximum may be larger than what recon found earlier. The sheared CBs may be stretching the vortex and expanding it some.

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Gone in 72 hours lol

Tropical Storm Nana Discussion Number   4
NWS National Hurricane Center Miami FL       AL162020
1100 PM EDT Tue Sep 01 2020

Deep convection redeveloped over the center of Nana during the late
afternoon and recent microwave imagery has revealed a small,
well-defined low-level eye-like feature, and convective banding
around the southwestern portion of the circulation.  An Air Force
Reserve hurricane hunter aircraft that has provided a couple of 
center fixes within the past hour or two has measured a peak 
850-mb flight-level wind of 62 kt, and believable SFMR winds of 
around 50 kt, which supports an initial intensity of 50 kt. 
Data from aircraft indicated that the minimum pressure is around
999 mb. 

Nana is moving westward or 275/16 kt. A strong deep-layer ridge to
the north of the tropical cyclone should steer it westward over the 
next day or so.  After that time, the ridge is forecast to build 
west-southwestward and the dynamical models indicate that this will 
cause Nana to turn west-southwestward by Thursday.  On this track,  
Nana is expected to approach the coast of Belize late Wednesday 
night or early Thursday, and move inland over Belize and Guatemala 
later that day.  The track guidance is in good agreement on this 
scenario but has trended slightly southward, which seems reasonable 
given that Nana is vertically deep and is more likely to feel the 
deep-layered east-northeasterly flow.  The new NHC track forecast is 
close to the FSU Superensemble and the HFIP corrected consensus 
model. 

The tropical storm is currently within an environment of light to 
moderate northeasterly shear.  This shear does not seem to be strong 
enough to prevent strengthening during the next 12-24 hours, and 
the NHC intensity forecast shows a slightly faster rate of 
intensification during that time.  This is in agreement with the 
latest SHIPS model output and the HCCA and HWRF models, and calls 
for Nana to become a hurricane within 24 hours.  The shear is 
forecast to become more northerly just before landfall, and this 
is likely to slow the intensification process.  Rapid weakening is 
expected after landfall, and the low-level circulation is expected 
to dissipate over Guatemala or southeastern Mexico by day 3.

KEY MESSAGES:

1. Tropical Storm Nana is forecast to be a hurricane as it
approaches the coast, and interests in Honduras, Guatemala,
Belize, and Yucatan should closely monitor the progress of this
storm.  Strong winds, dangerous storm surge and very heavy rainfall
causing flash flooding are becoming more likely from Nana.


FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 17.0N  80.9W   50 KT  60 MPH
 12H  02/1200Z 17.1N  83.5W   60 KT  70 MPH
 24H  03/0000Z 17.0N  86.3W   65 KT  75 MPH
 36H  03/1200Z 16.8N  88.6W   65 KT  75 MPH...INLAND
 48H  04/0000Z 16.5N  90.7W   35 KT  40 MPH...INLAND
 60H  04/1200Z 16.2N  93.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  05/0000Z...DISSIPATED
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BULLETIN
Tropical Storm Nana Intermediate Advisory Number 4A
NWS National Hurricane Center Miami FL       AL162020
200 AM EDT Wed Sep 02 2020

...NANA EXPECTED TO BECOME A HURRICANE BY TONIGHT...


SUMMARY OF 200 AM EDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...17.0N 81.8W
ABOUT 265 MI...425 KM ENE OF LIMON HONDURAS
ABOUT 425 MI...680 KM E OF BELIZE CITY
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES
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5 hours ago, WxWatcher007 said:

You said it earlier. It might be too much to ask. It might be time to upgrade the recon fleet.

We could go without a couple new F-22 Raptors, right?

A family member i have works on those. The mechanics nicknamed those. "The Craptors" cause they always in the shop.

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BULLETIN
Tropical Storm Nana Advisory Number   5
NWS National Hurricane Center Miami FL       AL162020
500 AM EDT Wed Sep 02 2020

...NANA CONTINUES WESTWARD...
...LIKELY TO BECOME A HURRICANE BY TONIGHT...


SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...17.0N 82.7W
ABOUT 210 MI...335 KM ENE OF LIMON HONDURAS
ABOUT 365 MI...585 KM E OF BELIZE CITY
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES
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Tropical Storm Nana Discussion Number   5
NWS National Hurricane Center Miami FL       AL162020
500 AM EDT Wed Sep 02 2020

Nana's Central Dense Overcast has become a little better defined, 
with cloud tops to -80 deg C or colder.  Upper-level outflow 
continues to be somewhat inhibited over the northern portion of the 
circulation.  SFMR-observed surface winds and adjusted flight-level 
winds from an Air Force Hurricane Hunter aircraft indicated an 
intensity of 50 kt.  Although northerly shear is likely to limit 
intensification, the environment is conducive enough for Nana to 
strengthen into a hurricane later today.  The official intensity 
forecast is close to the Decay-SHIPS prediction based on the ECMWF 
global model forecast fields.

Center fixes from the aircraft indicate that the motion continues 
to be generally westward, or 270/16 kt, to the south of a strong 
mid-level high pressure area.  Over the next couple of days, the 
ridge is expected to be maintained or to build a little more to the 
west.  This should keep Nana on a westward or slightly south-of-west 
track until it moves into Central America.  The official track 
forecast is close to the previous one and also very close to the 
latest Florida State University Superensemble prediction.

Observations from the aircraft and NOAA data buoy 42057 indicate 
that Nana is a rather small tropical cyclone, with 
tropical-storm-force winds extending 60 n mi or less from the 
center.

KEY MESSAGES:

1. Tropical Storm Nana is forecast to be a hurricane as it
approaches the coast, and interests in Honduras, Guatemala,
Belize, and the Yucatan Peninsula should closely monitor the 
progress of this storm.  Strong winds, dangerous storm surge and 
very heavy rainfall causing flash flooding are becoming more likely 
from Nana.


FORECAST POSITIONS AND MAX WINDS

INIT  02/0900Z 17.0N  82.7W   50 KT  60 MPH
 12H  02/1800Z 16.9N  85.0W   60 KT  70 MPH
 24H  03/0600Z 16.8N  87.6W   65 KT  75 MPH
 36H  03/1800Z 16.5N  89.8W   50 KT  60 MPH...INLAND
 48H  04/0600Z 16.4N  92.1W   30 KT  35 MPH...INLAND
 60H  04/1800Z 16.1N  93.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  05/0600Z...DISSIPATED

$$
Forecaster Pasch
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Last recon showed northerly shear had encroached and broken down Nana's core. New strong convection is going up over the center, but it will have to rebuild a new core against the ongoing shear for intensification to occur. The shear is forecast to drop this afternoon and the system still does have time to stack prior to landfall, but it would need to pull of some impressive restructuring to be anything stronger than a minimal hurricane at landfall.
cb97d967ddbbec8cac116ec12ac4ecf7.gif

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