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TROPICAL STORM DON - Her-icane - 07-16-2017 07:49 PM

[Image: two_atl_2d0.png]
[Image: two_atl_5d0.png]



ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sun Jul 16 2017

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

1. A weak area of low pressure located about 900 miles east-southeast
of the Windward Islands continues to produce disorganized showers
and thunderstorms. Environmental conditions are marginally
conducive for some development of this system before it reaches the
Lesser Antilles in two to three days. After that time, less
favorable upper-level winds are expected to hinder additional
development. An Air Force Reserve reconnaissance aircraft is
scheduled to investigate the disturbance Monday afternoon, if
necessary.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...40 percent.

Forecaster Pasch







JM


Quote: Watching 95L in the Atlantic and Cat 4 Fernanda in the Pacific
Dr. Jeff Masters

A tropical wave located at 8 am EDT Sunday near 11°N, 44°W, about 1000 miles east-southeast of the Lesser Antilles Islands, was headed west to west-northwest at about 15 mph, and was designated 95L by NHC on Sunday morning. This system has the potential to develop into a tropical depression or weak tropical storm by the time it arrives in the Lesser Antilles Islands on Wednesday.


Satellite images on Sunday morning showed that 95L was very disorganized, with little spin and only a modest amount of heavy thunderstorm activity. Development was being retarded by dry air, thanks to a presence of the Saharan Air Layer (SAL) just to the north (Figure 1.) Wind shear was low to moderate, 5 – 15 knots, and sea surface temperatures (SSTs) were warm enough for development, near 27.5°C (82°F)--about 1°F above the seasonal norm.



[Image: sal-jul16.jpeg]Figure 1: The Saharan Air Layer (SAL) analysis from 11 am EDT Sunday, July 16, 2017, showed a large area of dry Saharan air in the tropical Atlantic north of Invest 95L. Image credit: University of Wisconsin CIMSS/NOAA Hurricane Research Division.


Forecast for 95L


The main impediment for development over the next three days will be the presence of the dry air to the system’s north. Also, the Madden-Julian Oscillation (MJO), a periodic pulse of thunderstorm activity that circles equatorial regions of the globe every few weeks, is not in a phase that will help development of Atlantic tropical cyclones this week. Otherwise, conditions are favorable for development: wind shear should be light to moderate, and SSTs will be 27.5 - 28°C (82°F). In their 8 am EDT Sunday Tropical Weather Outlook, the National Hurricane Center (NHC) gave 95L 2-day and 5-day odds of tropical cyclone development of 20% and 40%, respectively.


The operational versions of our three top models for predicting tropical cyclone genesis--the European, GFS and UKMET--did not show development of the system over the next five days. However, 65% of the 20 members of the 0Z Sunday GFS ensemble forecast did predict development. Only about 10% of the 50 members of the 0Z Sunday European model ensemble forecast did so, though. None of these forecasts had 95L becoming a hurricane, and the vast majority of the forecasts showed the storm only becoming a tropical depression or weak tropical storm by mid-week, then dying out in the Eastern Caribbean late in the week. At that time, the 12Z Sunday run of the SHIPS model was predicting that 95L would see very high wind shear of 25 – 40 knots, and the Eastern Caribbean is notoriously hostile to tropical cyclones, especially this early in the season.


The models had a strong ridge of high pressure steering the system west to west-northwest at about 15 mph for the next five days, which would bring the storm to the Lesser Antilles Islands on Wednesday and into the Eastern Caribbean by Thursday. The next name of the Atlantic list of storms is Don.

[Image: 2017AL95_MPSATWND_201707161800_SWHR.GIF]

[Image: clark5latest.png]

[Image: clarki5latest.png]

Recon

000
NOUS42 KNHC 161445
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT SUN 16 JULY 2017
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 17/1100Z TO 18/1100Z JULY 2017
TCPOD NUMBER.....17-046

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (EAST OF WINDWARD ISLANDS)
FLIGHT ONE -- TEAL 74 FLIGHT TWO -- TEAL 75
A. 17/1800Z A. 18/1130Z, 1730Z
B. AFXXX 01BBA INVEST B. AFXXX 0205A CYCLONE
C. 17/1500Z C. 18/0930Z
D. 11.5N 52.5W D. 12.0N 57.0W
E. 17/1800Z TO 17/2200Z E. 18/1100Z TO 18/1730Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY: 12-HRLY FIXES BEGINNING
AT 19/0530Z IF SYSTEM DEVELOPS AND REMAINS A THREAT.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.

$$
WJM


RE: Invest 95L - Her-icane - 07-17-2017 01:38 PM

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Mon Jul 17 2017

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

1. An area of low pressure located about 525 miles east-southeast of
Barbados is moving westward at 15 to 20 mph. The associated
shower and thunderstorm activity has changed little in organization
since this morning and the system still appears to lack a
well-defined center. Environmental conditions are conducive for
some development before the system reaches the Lesser Antilles late
Tuesday or early Wednesday. After that time, less favorable
upper-level winds are expected to hinder additional development.
Regardless of development, this system is expected to bring locally
heavy rainfall and gusty winds to portions of the Lesser Antilles
beginning Tuesday. An Air Force Reserve reconnaissance aircraft is
currently en route to investigate the disturbance.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...medium...50 percent.

2. An area of disturbed weather is located about 875 miles west-
southwest of the Cabo Verde Islands. Some gradual development of
this system is possible over the next few days while it moves slowly
toward the west-northwest or northwest over the open Atlantic Ocean.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...30 percent.

Forecaster Brown

[Image: clark5latest.png]

[Image: clarki5latest.png]

[Image: 2017AL95_MPSATWND_201707171800_SWHR.GIF]

000
NOUS42 KNHC 171500
REPRPD
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1100 AM EDT MON 17 JULY 2017
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 18/1100Z TO 19/1100Z JULY 2017
TCPOD NUMBER.....17-047

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (EAST OF WINDWARD ISLANDS)
FLIGHT ONE -- TEAL 74 FLIGHT TWO -- TEAL 75
A. 18/2330Z A. 19/1130Z
B. AFXXX 0305A CYCLONE B. AFXXX 0405A CYCLONE
C. 18/2130Z C. 19/0930Z
D. 11.5N 60.5W D. 12.0N 64.5W
E. 18/2300Z TO 19/0200Z E. 19/1100Z TO 19/1400Z
F. SFC TO 10,000 FT F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY...NEGATIVE.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.

$$
WJM


RE: Invest 95L - ROLLTIDE - 07-17-2017 04:59 PM

Tropical Don !!! Wow where the heck did that come from ?


RE: TROPICAL STORM DON - Her-icane - 07-18-2017 06:58 AM

JM


Quote: [Image: don-jul17.jpg] Tropical Storm Don Forms Near the Lesser Antilles Islands
Dr. Jeff Masters · July 18, 2017, 00:09

Share:
Above: Tropical Storm Don as seen by the MODIS instrument on NASA’s Aqua satellite on Monday afternoon, July 17, 2017. Image credit: NASA.

A Tropical Storm Warning is up for the island of Grenada, and Tropical Storm Watches are posted for Barbados, St. Vincent and the Grenadines, and St. Lucia as Tropical Storm Don cruises west at 17 mph towards the Lesser Antilles. On Monday afternoon, an Air Force hurricane hunter aircraft found a tight closed circulation and surface winds of 40 mph, prompting the National Hurricane Center to begin issuing advisories for the fourth named storm of the 2017 Atlantic hurricane season. By 8 pm EDT Monday, these winds were up to 45 mph.
On Monday evening, Don was enjoying light wind shear of 5 - 10 knots and warm sea surface temperatures (SSTs) near 28.5°C (83°F)--about 1°F above the seasonal norm. However, development was being slowed by dry air, thanks to a presence of the Saharan Air Layer (SAL) just to the north. The relative humidity at mid-levels of the atmosphere was a marginal 65%. Satellite images showed that Don was small storm, with only a modest amount of heavy thunderstorms.
Forecast for Don
Don will continue to move west to west-northwest at 15 – 20 mph through Wednesday, which will bring the core of the storm over the southern Lesser Antilles Islands on Tuesday evening through Wednesday morning. Dry air will continue to interfere with development, and the 18Z Monday run of the SHIPS model predicted that relative humidity at mid-levels of the atmosphere would drop to 55 – 60% by Wednesday. With wind shear expected to remain low to moderate through Wednesday, there is the potential that Don could strengthen to have top winds in the 55 – 60 mph range as it moves through the Lesser Antilles. On Thursday, when Don will be in the Eastern Caribbean, wind shear will rise to a high 25 knots, and the 70 members of the 12Z Monday European and GFS model forecasts predict that Don will weaken and meet its demise by Friday. However, Don could potentially affect the ABC Islands and make landfall in northwestern Venezuela late in the week before dying.

[Image of probabilities of 34-kt winds]

[Image: 115433_5day_cone_no_line_and_wind.png]


RE: TROPICAL STORM DON - Her-icane - 07-18-2017 08:06 PM

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Tue Jul 18 2017

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

The National Hurricane Center is issuing advisories on Tropical
Storm Don, located just to the east-southeast of Grenada.

1. Showers and thunderstorms remain limited in association with a low
pressure system located over 1000 miles west-southwest of the Cabo
Verde Islands. Some slow development of this system is possible
during the next day or two while it moves toward the west-northwest
or northwest at 10 to 15 mph. After that time, environmental
conditions are forecast to become unfavorable for development.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...low...30 percent.

Forecaster Roberts

000
WTNT35 KNHC 182355
TCPAT5

BULLETIN
Tropical Storm Don Intermediate Advisory Number 5A
NWS National Hurricane Center Miami FL AL052017
800 PM AST Tue Jul 18 2017

...DON ACCELERATING WESTWARD AS IT APPROACHES GRENADA...


SUMMARY OF 800 PM AST...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...11.9N 61.4W
ABOUT 25 MI...40 KM SE OF GRENADA
ABOUT 100 MI...155 KM S OF ST. VINCENT
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...W OR 275 DEGREES AT 23 MPH...37 KM/H
MINIMUM CENTRAL PRESSURE...1011 MB...29.85 INCHES


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

The government of the Netherlands has discontinued the Tropical
Storm Watch for Bonaire.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

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

Interests in Trinidad and Tobago, Bonaire, Curacao, and Aruba should
continue to monitor the progress of Don.

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 center of Tropical Storm Don was
located near latitude 11.9 North, longitude 61.4 West. Don is
moving toward the west near 23 mph (37 km/h). This general motion
is expected through Wednesday. On the forecast track, the center of
Don will move across the Windward Islands within the next few hours,
and then move westward across the southeastern Caribbean Sea late
tonight and Wednesday.

Maximum sustained winds are near 40 mph (65 km/h) with higher
gusts. Little change in strength is forecast during the next 24
hours. The system is forecast to degenerate into a trough of low
pressure tonight or Wednesday
.

Tropical-storm-force winds extend outward up to 35 miles (55 km)
from the center.

The estimated minimum central pressure is 1011 mb (29.85 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Tropical storm conditions are expected to spread across the
Windward Islands within the warning area during the next several
hours.

RAINFALL: Don is expected to produce total rain accumulations of
3 to 6 inches, with isolated higher amounts, across Trinidad and
Tobago and the southern Windward Islands through Wednesday. These
rains could produce life-threatening flash floods and mudslides,
especially in mountainous areas.


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

$$
Forecaster Berg

JM


Quote: [Image: don-ir-1445Z-7.18.17-835px.jpg] Tropical Storm Don Approaching the Windward Islands
Bob Henson · July 18, 2017, 16:34

Share:
Tropical storm warnings were in effect for Grenada and for St. Vincent and the Grenadines at midday Tuesday as Tropical Storm Don chugged westward toward the Windward Islands. A Hurricane Hunter aircraft found a closed circulation and tropical-storm-strength winds in a western Atlantic wave on Monday afternoon, which led to Don’s immediate christening.
As of 11 am EDT Tuesday, Don was located about 155 miles southeast of Barbados and about 255 miles east of Grenada, moving nearly due west at 20 mph. Don’s top sustained winds were at minimal tropical-storm strength of 40 mph, down from 50 mph overnight. Relatively dry air (mid-level humidities of 55-60%) is not helping Don, and wind shear will be increasing to around 15 knots by Tuesday night as Don moves west.
Satellite imagery from Don at midday Tuesday showed an unimpressive cluster of showers and thunderstorms (see image above), and Hurricane Hunter observations on Tuesday morning found a weakening system that may have already lost its closed surface circulation. If the next flight confirms this, Don may be downgraded later on Tuesday to a tropical depression or a remnant low, perhaps just before Don reaches Grenada.
[Image: don-radar-jul18.jpg]Figure 1. Radar image of Tropical Storm Don taken at 10:45 am EDT July 18, 2017, from the Trinidad and Tobago radar.
Tropical-storm-force winds extend just 35 miles from Don’s center (mainly on the north side), and that may be generous. The impacts from Don on the Windwards will likely be little more than some heavy showers and thunderstorms and gale-force squalls. It's worth noting that the HWRF and new HMON models have been consistent in calling for Don to strengthen somewhat as it approaches the islands, so residents in the warned areas should not let their guard down just yet.



RE: TROPICAL STORM DON - Her-icane - 07-18-2017 10:49 PM

000
WTNT45 KNHC 190249
TCDAT5


Remnants Of Don

Discussion Number 6
NWS National Hurricane Center Miami FL AL052017
1100 PM AST Tue Jul 18 2017



An Air Force Reserve reconnaissance aircraft made several passes
through the system this evening and was only able to find a sharp
wind shift--but no winds with a westerly component. Pressures have
also risen, and it appears that Don no longer has a center of
circulation. Therefore, Don is being declared an open wave, and
this is the last advisory on this system
.

Based on the aircraft
data, the wave is still producing maximum winds of 35 kt west of
the Windward Islands over the far southeastern Caribbean Sea.

The wave is moving westward at about 22 kt, and it should continue
moving quickly westward across the Caribbean Sea during the next
couple of days. Due to the system's fast motion, as well as
unfavorable atmospheric conditions over the Caribbean Sea,
regeneration into a tropical cyclone is not expected at this time.
However, the wave is expected to continue producing gales through
early Wednesday, and then winds just below gale force for the next
couple of days.



This is the last advisory on Don, and additional information on this
system can be found in High Seas Forecasts issued by the National
Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and available on the Web at
http://www.opc.ncep.noaa.gov/shtml/NFDHSFAT1.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 11.9N 62.5W 35 KT 40 MPH...REMNANTS OF DON
12H 19/1200Z...DISSIPATED

$$
Forecaster Berg






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