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TROPICAL STORM BRET
06-16-2017, 01:55 PM (This post was last modified: 06-19-2017 03:47 PM by ROLLTIDE.)
Post: #1
TROPICAL STORM BRET
JM

Quote:

92L may threaten the Windward Islands
The NOAA/NWS National Hurricane Center (NHC) designated the central Atlantic wave as Invest 92L on Friday morning, which kicks off the process of tracking and forecasting this wave in greater detail. The wave was located at 8 am EDT Friday near 5°N 33°W, a few hundred miles southwest of the Cabo Verde Islands. Satellite imagery on Friday morning showed that Invest 92L was more organized than on Thursday, with a concentrated area of heavy thunderstorms developing near its core, and a modest amount of upper-level outflow becoming established.

The storm is too close to the equator for the system to leverage Earth's spin to help itself get spinning, which will make development slow to occur. Otherwise, conditions are favorable for development: the SHIPS model predicts that wind shear should remain light to moderate, dry air is expected to stay just to the north, and SSTs of 27-28°C (81-82°F) will be about 0.5°C above the seasonal norm along the wave’s track. In their 8 am EDT Friday Tropical Weather Outlook, the National Hurricane Center (NHC) gave this system 2-day and 5-day odds of tropical cyclone development (at least depression strength) of 20% and 40%, respectively—double the odds given on Thursday.

Of our three top models for predicting tropical cyclone genesis, the European, GFS and UKMET models, only one--the GFS model--predicted in its 0Z Friday run that 92L would develop into a tropical depression over the next four days. Less than 10% of the European ensemble members produce a depression, while about two-thirds of the GFS ensemble members gin up 92L to depression strength, and roughly half bring it to tropical storm strength.

The 0Z Friday models had 92L maintaining a due west to slightly west-northwest track at 15 – 20 mph for the next five days, which would bring the system to the northern coast of Venezuela and into the Southern Lesser Antilles (Windward Islands) on Tuesday morning. The GFS track is slightly north of the ECMWF track, implying a higher chance of potential impacts to the islands of Trinidad and/or Grenada. The 06Z and 12Z Friday runs of the GFS brings the center near Trinidad as a mid-range tropical storm. Only one tropical storm and one hurricane have affected the Windwards or Venezuela prior to July 1 in NHC records going back to 1851.
Even if it becomes a named storm before reaching the Windwards, 92L is very unlikely to make it through the Caribbean Sea. The eastern Caribbean is a notorious “graveyard” for tropical cyclones, especially early in the season, because of persistent divergence at low levels that tends to weaken showers and thunderstorms. This divergence is the result of trade winds that are typically stronger in the central Caribbean than in the eastern Caribbean. system. None of the GFS and ECMWF ensemble members keep 92L as an identifiable
beyond the central Caribbean.

Unquote

Quote: [Image: 20170616.1845.goes13.x.vis1km_high.92LIN....100pc.jpg]
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06-16-2017, 07:03 PM
Post: #2
RE: INVEST 92L
Sudduth update for 6/16 if you're interested...

https://www.youtube.com/watch?v=B_qI8GY6...e=youtu.be
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06-16-2017, 11:07 PM (This post was last modified: 06-16-2017 11:10 PM by Her-icane.)
Post: #3
RE: INVEST 92L
[Image: plot20170616-2111.gif]

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06-17-2017, 07:59 PM (This post was last modified: 06-17-2017 08:14 PM by Her-icane.)
Post: #4
RE: INVEST 92L
JM 6/17

Quote: 92L likely to threaten the southern Windwards early next week

The tropical wave known as Invest 92L continued chugging through the tropical Atlantic on Saturday. There is an increasing amount of spin evident on satellite around 92L, but ASCAT scatterometer data on Saturday afternoon failed to show a closed low-level center of circulation, and showers and thunderstorms (convection) remained scattered and disorganized around 92L. The usual nighttime peak in tropical convection could give 92L a boost tonight and/or Sunday night.

Wind shear over 92L will be light (less than 10 knots) through Monday, and the system will be passing over warm SSTs of around 29°C (84°F) and through a moist atmosphere (mid-level relative humidity around 60 - 70%). All of these signs point toward a good chance of 92L organizing into a depression and perhaps a tropical storm by Monday. As of Saturday afternoon, NHC gave the system a 40% chance of becoming at least a depression by Monday and a 60% chance by Thursday, compared to the 20% and 40% odds given on Friday.

Models are in close agreement on a fairly straightforward track for 92L, which should pass near the coast of Venezuela or the southern Windward Island on Tuesday or Wednesday. The ECMWF ensemble continues to lean toward 92L being a depression moving very close to South America, while the GFS ensemble members predict a tropical storm slightly to the north. The 12Z run of the HWRF model—among the most reliable for intensity—makes 92L a minimal hurricane as it passes the islands, although we should wait for the system to develop a closed circulation before we trust any model's intensity forecast. Islanders as far north as St. Lucia and Barbardos should keep an eye on 92L, as it may end up with a compact circulation that could intensify more quickly than models expect it to, especially if it takes a more west-northwest tack.

Models continue to agree that 92L will very likely degenerate on its trek across the Caribbean, as increasing wind shear and diverging surface winds—hallmarks of the early-summer eastern Caribbean “graveyard”—take their toll on the system.

[Image: plot20170617-2111.gif]
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06-17-2017, 11:17 PM
Post: #5
RE: INVEST 92L
ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sat Jun 17 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. A tropical wave located about 1300 miles east-southeast of the
southern Windward Islands is producing disorganized cloudiness and
showers. Some development of this system is possible during the
next few days before environmental conditions become less favorable
for tropical cyclone formation. This system is forecast to move
to the west or west-northwest at 15 to 20 mph toward the Windward
Islands and northeastern South America during the next several days.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

2. A broad area of low pressure located over the northwestern Caribbean
Sea is producing a large area of disorganized showers and
thunderstorms. Gradual development of this system is expected while
it moves slowly northwestward across the Yucatan Peninsula on Sunday
and over the southern or central Gulf of Mexico early next week,
where a tropical or subtropical cyclone is likely to form.
Regardless of development, heavy rains are expected over portions of
Central America, the Yucatan Peninsula, Jamaica, the Cayman Islands,
and western Cuba during the next several days. An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate this system on
Sunday, if necessary.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...80 percent.

Forecaster Cangialosi

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06-18-2017, 06:41 AM
Post: #6
RE: INVEST 92L
2am

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Jun 18 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

1. Showers and thunderstorms have changed little in organization
during the past several hours in association with a tropical wave
located about 1200 miles east-southeast of the southern Windward
Islands. Some development of this system is possible during the
next two to three days before environmental conditions become
less favorable for tropical cyclone formation. This system is
forecast to move to the west or west-northwest at 15 to 20 mph
toward the Windward Islands and northeastern South America during
the next few days.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...50 percent.

2. A broad area of low pressure located over the northwestern Caribbean
Sea continues to produce a large area of disorganized showers and
thunderstorms. Gradual development of this system is expected while
it moves slowly northwestward across the Yucatan Peninsula on Sunday
and over the southern or central Gulf of Mexico early next week,
where a tropical or subtropical cyclone is likely to form.
Regardless of development, heavy rains are expected over portions of
Central America, the Yucatan Peninsula, Jamaica, the Cayman Islands,
and western Cuba during the next several days. An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate this system on
Sunday, if necessary.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...80 percent.

Forecaster Landsea

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06-18-2017, 02:55 PM
Post: #7
RE: INVEST 92L
000
NOUS42 KNHC 181717
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0115 PM EDT SUN 18 JUNE 2017
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 19/1100Z TO 20/1100Z JUNE 2017
TCPOD NUMBER.....17-018

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (EAST OF TRINIDAD)
FLIGHT ONE -- TEAL 74 FLIGHT TWO -- TEAL 75
A. 19/1800Z A. 20/0530Z,1130Z
B. AFXXX 01AAA INVEST B. AFXXX 0202A CYCLONE
C. 19/1500Z C. 20/0300Z
D. 9.0N 56.0W D. 10.5N 60.0W
E. 19/1730Z TO 19/2130Z E. 20/0500Z TO 20/1130Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT

2. SUSPECT AREA (NEAR YUCATAN PENINSULA)
FLIGHT ONE -- TEAL 71 FLIGHT TWO -- TEAL 72
A. 19/2000Z A. 20/1130Z,1730Z
B. AFXXX 01BBA INVEST B. AFXXX 0203A CYCLONE
C. 19/1800Z C. 20/0930Z
D. 23.0N 88.5W D. 24.5N 90.0W
E. 19/1930Z TO 19/2330Z E. 20/1100Z TO 20/1730Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT

3. OUTLOOK FOR SUCCEEDING DAY:
A. CONTINUE 6-HRLY FIXES ON FIRST SYSTEM IF IT DEVELOPS AND
REMAINS A THREAT.
B. CONTINUE 6-HRLY FIXES ON SECOND SYSTEM IF IT DEVELOPS.
4. REMARK: ALL MISSIONS TASKED IN TCPOD 17-017 CANCELED BY
NHC AT 18/1335Z.
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06-18-2017, 07:40 PM
Post: #8
RE: INVEST 92L
BULLETIN
Potential Tropical Cyclone Two Intermediate Advisory Number 1A
NWS National Hurricane Center Miami FL AL022017
800 PM AST Sun Jun 18 2017

...TROPICAL STORM WARNING ISSUED FOR PORTIONS OF THE SOUTHERN
WINDWARD ISLANDS...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...7.7N 51.4W
ABOUT 690 MI...1110 KM ESE OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 23 MPH...37 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES


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

The government of Trinidad and Tobago has issued a Tropical Storm
Warning for Trinidad, Tobago, and Grenada.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Barbados
* St. Vincent and the Grenadines
* Trinidad
* Tobago
* Grenada

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 800 PM AST (0000 UTC), the disturbance was centered near latitude
7.7 North, longitude 51.4 West. The system is moving toward the
west near 23 mph (37 km/h). A fast motion toward the west-
northwest is expected for the next 48 hours. On the forecast track,
the disturbance is expected to move through the Windward Islands
Monday night and Tuesday.

Maximum sustained winds are near 35 mph (55 km/h) with higher
gusts. Some strengthening is forecast during the next 48 hours, and
the disturbance is expected to reach tropical storm intensity later
tonight or on Monday before it reaches the Windward Islands.

Shower and thunderstorm activity associated with the disturbance is
gradually becoming better organized, and additional development is
likely during the next couple of days.
* Formation chance through 48 hours...high...90 percent
* Formation chance through 5 days...high...90 percent

The estimated minimum central pressure is 1007 mb (29.74 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Tropical storm conditions are expected to first reach the
warning area overnight Monday and Tuesday morning, making outside
preparations difficult or dangerous.

RAINFALL: The disturbance is expected to produce total rain
accumulations of 2 to 4 inches over the Windward Islands Monday
through Tuesday.


NEXT ADVISORY
-------------
Next complete advisory at 1100 PM AST.

$$
Forecaster Stewart/Cangialosi

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06-19-2017, 03:48 PM
Post: #9
RE: TROPICAL STORM BRET
WTNT42 KNHC 192042
TCDAT2

Tropical Storm Bret Discussion Number 5
NWS National Hurricane Center Miami FL AL022017
500 PM AST Mon Jun 19 2017

An Air Force WC-130 invest mission this afternoon into the
disturbance was able - after much effort - to find a well-defined
closed circulation. The location of the center was substantially
farther west than anticipated, as the system is now moving toward
the west-northwest at a very quick 26 kt. Because the system
has developed a well-defined center, it is now considered a tropical
storm and has been named Bret.

Convection continues to display robust bands on the northwestern
and southeastern quadrants of the disturbance, as seen in the
geostationary satellite and Trinidad radar imagery. The Hurricane
Hunter mission also found maximum surface winds of about 35 kt,
which agrees with the Dvorak 2.5 CI number from TAFB. These winds
are only occurring in the northern semicircle due to the very quick
translational velocity of the system.

While the convective structure has been impressive today, it
appears that the window of opportunity for the system to
further develop is closing. Between interaction with the landmass
of Venezuela and increasing vertical shear beginning in about a day,
the intensity model guidance does not show any significant
intensification. The official intensity forecast is steady state
for about a day, followed by gradual weakening until dissipation in
about three days. An alternative scenario - given that the
disturbance has tracked left, or equatorward, of the guidance thus
far - is that it could remain south of the forecast track and
dissipate over Venezuela and never reach the Caribbean Sea.

The system is anticipated to slow somewhat, but still move at a
rapid rate toward the west-northwest until dissipation, steered by
strong trade winds south of the Bermuda high. The official track
forecast is based upon the HCCA corrected consensus technique and is
faster compared with the previous advisory, due to the farther west
initial position.


FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 9.4N 59.8W 35 KT 40 MPH
12H 20/0600Z 10.1N 62.1W 35 KT 40 MPH
24H 20/1800Z 11.3N 65.3W 35 KT 40 MPH
36H 21/0600Z 12.2N 68.5W 30 KT 35 MPH
48H 21/1800Z 13.0N 73.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 22/1800Z...DISSIPATED

$$
Forecaster Landsea

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