• Member Statistics

    16,061
    Total Members
    7,904
    Most Online
    cheeroip
    Newest Member
    cheeroip
    Joined
yoda

Hurricane Nana

Recommended Posts

BULLETIN
Potential Tropical Cyclone Sixteen Advisory Number   1
NWS National Hurricane Center Miami FL       AL162020
1100 AM EDT Tue Sep 01 2020

...RECONNAISSANCE AIRCRAFT FINDS VIGOROUS TROPICAL DISTURBANCE
SOUTH OF JAMAICA GETTING BETTER ORGANIZED...
...TROPICAL STORM WATCH ISSUED FOR NORTHERN HONDURAS AND THE
OFFSHORE ROATAN ISLANDS...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.1N 77.5W
ABOUT 140 MI...225 KM SSW OF KINGSTON JAMAICA
ABOUT 160 MI...260 KM SSE OF NEGRIL JAMAICA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 285 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES


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

A Tropical Storm Watch has been issued for the northern coast of
Honduras from Punta Patuca westward to the Guatemala-Honduras
border, including Roatan Island and the Bay Islands of Honduras.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Watch is in effect for...
* Northern Honduras
* Roatan Island and the Bay Islands of Honduras

A Tropical Storm Watch may be required for portions of Guatemala,
Belize, and the southern Yucatan Peninsula later today.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

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


DISCUSSION AND OUTLOOK
----------------------
At 1100 AM EDT (1500 UTC), the disturbance was centered near
latitude 16.1 North, longitude 77.5 West. The system is moving
toward the west near 18 mph (30 km/h), and this general motion is 
expected to continue through Thursday.  On the forecast track, the 
system will be moving near but north of the coast of Honduras on 
Wednesday.

Maximum sustained winds are near 40 mph (65 km/h) with higher gusts.
Some strengthening is forecast during the next 48 hours.

Additional development is expected today and on Wednesday, and a 
tropical depression or tropical storm could form at any time.
* Formation chance through 48 hours...high...90 percent
* Formation chance through 5 days...high...90 percent

Tropical-storm-force winds extend outward up to 80 miles (130 km), 
mainly northeast through northwest of the center.

The estimated minimum central pressure is 1005 mb (29.68 inches).


HAZARDS AFFECTING LAND
----------------------
WIND:  Tropical storm conditions are possible within the watch
area by late Wednesday.

RAINFALL:  Rainfall amounts of 2 to 3 inches will be possible over
the northern portions of Honduras beginning late Wednesday.

SURF:  Swells generated by this system are affecting portions of the
southern coast of Jamaica, and will continue into Wednesday morning.
These swells are likely to cause life-threatening surf and rip
current conditions.  Please consult products from your local weather
office.


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

$$
Forecaster Stewart
  • Like 1

Share this post


Link to post
Share on other sites
Potential Tropical Cyclone Sixteen Discussion Number   1
NWS National Hurricane Center Miami FL       AL162020
1100 AM EDT Tue Sep 01 2020

An Air Force Reserve reconnaissance aircraft is currently 
investigating the vigorous tropical disturbance located south of 
Jamaica that the NHC has been tracking the past few days across the 
Caribbean Sea. An earlier report of 35 kt winds this morning from 
ship MAOR4 is the basis for the 35-kt initial intensity on 
Potential Tropical Cyclone Sixteen. (PTC-16)

The initial motion estimate is an uncertain 285/16 kt, based mainly
on past scatterometer surface wind data and passive microwave
satellite fix data. A strong deep-layer to the north of the system
is expected to build slowly westward over the next few days,
keeping the disturbance moving in a general west-northwestward to
westward direction through 48 hours, followed by a turn toward the
west-southwest shortly thereafter when the system will be inland
over Central America. The NHC official forecast track lies close
to a blend of the simple consensus models TVCN and GFEX, and the
corrected-consensus model HCCA.

The disturbance has already developed an upper-level anticyclone, 
with outflow only restricted in the northeastern quadrant due to 
northeasterly shear of about 15 kt. This modest northeasterly to 
easterly vertical wind shear is expected to gradually subside to 
less than 10 kt by 48 hours, which should allow for at least some 
slow but steady strengthening, given that sea-surface temperatures 
(SST) will be 29.5-30.5 deg C along the track. Occasional intrusions 
of dry mid-level air might hinder development for the next 24-36 
hours, but model guidance shows that the atmosphere is expected to 
moisten thereafter and right up until landfall. The official 
intensity forecast is similar to the consensus of the intensity 
guidance through 24 hours, and then is a little above the consensus 
at 36 h and 48 h due to the very warm waters, moistening atmosphere, 
and low shear conditions. The statistical SHIPS guidance suggests 
that the cyclone could reach hurricane strength just prior to 
landfall. This alternate scenario will be evaluated on the next 
advisory cycle.

Due to the system's expected proximity to the north coast of 
Honduras and Roatan Island, a Tropical Storm Watch has been 
issued for those areas. Additional watches and possible warnings 
will likely be required later today for Guatemala, Belize, and the 
southern portion of the Yucatan Peninsula.


FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 16.1N  77.5W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
 12H  02/0000Z 16.4N  79.6W   35 KT  40 MPH...TROPICAL STORM
 24H  02/1200Z 16.6N  82.3W   40 KT  45 MPH
 36H  03/0000Z 16.7N  85.1W   45 KT  50 MPH
 48H  03/1200Z 16.8N  87.4W   50 KT  60 MPH
 60H  04/0000Z 16.5N  89.6W   25 KT  30 MPH...INLAND
 72H  04/1200Z 15.7N  91.7W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  05/1200Z...DISSIPATED

$$
Forecaster Stewart
  • Like 1

Share this post


Link to post
Share on other sites

Recon is finding westerlies. They appear to have missed south of the potential vortex and are still in the process of locating it. They'll need to make another pass but closer to Jamaica.

1fc0a3c3aab28a6a5e05879eeea471f9.jpg&key=446ce0d6d9520d1951e3a94c738bb9f050594d2815a9eb16c8326b32595af079

Share this post


Link to post
Share on other sites

Interesting that the NHC mentions the possibility of this becoming a strong TS or minimal hurricane. That'd be a huge fail for most of the operational guidance if this verified stronger on final approach to land. Para GFS has probably been the best handling this system so far IMO. 

  • Like 3

Share this post


Link to post
Share on other sites
Question is will they send out a special update to name it TS Nana or just wait till the 2pm advisory?

¯\_(ツ)_/¯

 

I do know that with such a small and well defined surface vortex this has likely been a TC for ~12 hours, perhaps yesterday evening. But maybe it was too small to get picked up by the earlier ASCAT, though the most recent scans missed.

Share this post


Link to post
Share on other sites

Yeah this thing likely ends up Hurricane Nana before landfall. Already well-defined core with 60 kt flight level winds and 50 kt SFMR.

  • Like 1

Share this post


Link to post
Share on other sites
15 minutes ago, Windspeed said:

Yeah this thing likely ends up Hurricane Nana before landfall. Already well-defined core with 60 kt flight level winds and 50 kt SFMR.

I didn’t expect it to be this strong this soon, but it was looking good last night and this morning. 

Share this post


Link to post
Share on other sites

There it is... but set at 50mph

Tropical Storm Nana Tropical Cyclone Update
NWS National Hurricane Center Miami FL       AL162020
1205 PM EDT Tue Sep 01 2020

...POTENTIAL TROPICAL CYCLONE STRENGTHENS TO TROPICAL STORM NANA...

Air Force Reserve Hurricane Hunter aircraft data indicate that the 
potential tropical cyclone has become Tropical Storm Nana. The 
maximum winds are estimated to be 50 mph (85 km/h) with higher 
gusts.  A special advisory will be issued to update the forecast 
within the hour.

SUMMARY OF 1205 PM AST...1605 UTC...INFORMATION
----------------------------------------------
LOCATION...16.5N 77.7W
ABOUT 120 MI...195 KM SW OF KINGSTON JAMAICA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES
$$
Forecaster Blake/Stewart
  • Like 1

Share this post


Link to post
Share on other sites

Small core of this system + improving shear conditions until landfall could lead to a quick intensification. These smaller systems can give us some surprises! I like that NHC went above the guidance with the intensity forecast. After seeing what recon found (tight core, high FL wind) this seems like one with the potential to ramp up quickly. I think we’ll be looking at a strong C1 by landfall 

  • Like 1

Share this post


Link to post
Share on other sites

Holy crap there’s an eye

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 1st day of the month at 16:15Z
Agency: United States Air Force 
Aircraft: Lockheed WC-130J Hercules with reg. number AF98-5307 
Mission Purpose: Investigate fifth suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 12 ( See all messages of this type for this mission. )

A. Time of Center Fix: 1st day of the month at 15:36:50Z
B. Center Fix Coordinates: 16.48N 77.60W
B. Center Fix Location: 118 statute miles (191 km) to the SSW (206°) from Kingston, Jamaica.
C. Minimum Height at Standard Level: 720m (2,362ft) at 925mb
D. Minimum Sea Level Pressure: 1004mb (29.65 inHg) - Extrapolated
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Open in the northeast
G. Eye Shape & Diameter: Circular with a diameter of 6 nautical miles
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 45kts (51.8mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 4 nautical miles to the NNW (335°) of center fix at 15:35:30Z
J. Maximum Flight Level Wind Inbound: From 64° at 53kts (From the ENE at 61.0mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 4 nautical miles to the NNW (335°) of center fix at 15:35:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 53kts (61.0mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 8 nautical miles to the ENE (74°) of center fix at 15:40:00Z
N. Maximum Flight Level Wind Outbound: From 171° at 60kts (From the S at 69.0mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 7 nautical miles to the ENE (78°) of center fix at 15:39:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 19°C (66°F) at a pressure alt. of 762m (2,500ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 759m (2,490ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 19°C (66°F)
R. Sea Surface Temp (collected at same location as temp inside eye): 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: 1.25 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 60kts (~ 69.0mph) which was observed 7 nautical miles to the ENE (78°) from the flight level center at 15:39:30Z
Sea Level Pressure Extrapolation From: 925mb

Share this post


Link to post
Share on other sites

I mean that’s quite impressive. We know this region has seen some significant events, and if you follow the only model that really developed this—the Para—there could be intensification close to landfall. That’d continue the trend with our other three hurricanes.

Share this post


Link to post
Share on other sites
Tropical Storm Nana Special Discussion Number   2
NWS National Hurricane Center Miami FL       AL162020
100 PM EDT Tue Sep 01 2020

An Air Force Reserve reconnaissance aircraft investigating the 
vigorous disturbance south of Jamaica this morning has found that 
the system has a well-defined, closed circulation center. The 
aircraft also measured 60 kt at 925 mb in the northeastern quadrant 
and reliable SFMR surface winds of 45 kt. Based on these data, the 
system has been upgraded to Tropical Storm Nana, the 14th named 
tropical storm of the 2020 Atlantic hurricane season.

The initial motion estimate is an uncertain 280/14 kt, No 
significant changes were made to the previous track forecast. A 
strong deep-layer to the north of the system is expected to build 
slowly westward over the next few days, keeping the disturbance 
moving in a general west-northwestward to westward direction through 
48 hours, followed by a turn toward the west-southwest shortly 
thereafter when the system will be inland over Central America. The 
NHC official forecast track lies close to a blend of the simple 
consensus models TVCN and GFEX, and the corrected-consensus model 
HCCA.

Nana has developed a well-defined upper-level anticyclone, with 
outflow gradually improving in all quadrants. Modest northeasterly 
to easterly vertical wind shear is expected to gradually subside to 
less than 10 kt by 48 hours, which should allow for at least some 
slow but steady strengthening, given that sea-surface temperatures 
(SST) will be 29.5-30.5 deg C along the track. Some dry air 
intrusions might hinder development for the next 24 hours or so, but 
the global and regional models still indicate that the atmosphere 
will moisten thereafter, and continue to moisten right up until 
landfall. Based on the higher initial intensity and the mostly 
favorable environmental conditions expected after 24 hours, the peak 
forecast intensity has been increased to 65 kt at 48 hours, just 
prior to landfall. 

Due to the Nana's expected proximity to Belize in 48 hours, a 
Tropical Storm Watch has been issued for that country. Additional 
watches and possible warnings will likely be required later today 
for Guatemala and the southern portion of the Yucatan Peninsula.

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  01/1700Z 16.6N  77.9W   45 KT  50 MPH
 12H  02/0000Z 16.6N  79.5W   50 KT  60 MPH
 24H  02/1200Z 16.7N  82.3W   55 KT  65 MPH
 36H  03/0000Z 16.8N  85.1W   60 KT  70 MPH
 48H  03/1200Z 16.8N  87.4W   65 KT  75 MPH
 60H  04/0000Z 16.5N  89.6W   30 KT  35 MPH...INLAND
 72H  04/1200Z 15.7N  91.7W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  05/1200Z...DISSIPATED

$$
Forecaster Stewart
  • Like 1

Share this post


Link to post
Share on other sites
2 minutes ago, yoda said:

I would have thought higher in teh wind forecast with the eye report in the VDM.... guess we shall see then

It’s still open, so it’s possible that shear or dry air can disrupt organization in the next 24 hours or so. I think we’d want to see convection begin wrapping around fully and some banding features to be more confident in a quickening intensification pace. I think 75 mph works for now. 

  • Like 2

Share this post


Link to post
Share on other sites
44 minutes ago, Windspeed said:

lol.. 6nm. This reminds me of Iris back in 2001.

Iris is a favorite of mine for sure. It really put dank microcanes into the consciousness of a generation of early 2000s tropical weenies. 

  • Like 1

Share this post


Link to post
Share on other sites
8 minutes ago, Superstorm93 said:

Recon now reports that the eye is closed and only 6nm wide 

I thought AF307 was finished with their mission? You sure that isn't an old VDM?

Share this post


Link to post
Share on other sites
20 minutes ago, the ghost of leroy said:

Iris is a favorite of mine for sure. It really put dank microcanes into the consciousness of a generation of early 2000s tropical weenies. 

 

irisir.jpeg

Share this post


Link to post
Share on other sites
4 minutes ago, Windspeed said:

I thought AF307 was finished with their mission? You sure that isn't an old VDM?

URNT12 KNHC 011719
VORTEX DATA MESSAGE   AL162020
A. 01/16:32:20Z
B. 16.59 deg N 077.82 deg W
C. 850 mb 1455 m
D. 1004 mb
E. 290 deg 15 kt
F. CLOSED
G. C6
H. 42 kt
I. 119 deg 10 nm 16:24:00Z
J. 076 deg 58 kt
K. 343 deg 6 nm 16:30:30Z
L. 48 kt
M. 295 deg 34 nm 16:47:00Z
N. 052 deg 54 kt
O. 316 deg 7 nm 16:39:30Z
P. 17 C / 1522 m
Q. 20 C / 1540 m
R. 14 C / NA
S. 12345 / 8
T. 0.02 / 1.25 nm
U. AF307 01FFA INVEST OB 16
MAX FL WIND 60 KT 078 / 7 NM 15:39:30Z
;
  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.