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Joined: Oct 1999
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Marty Offline OP
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Current track brings this into our area Tuesday morning as a Cat 1 Hurricane....


Potential Tropical Cyclone Nine is expected to track westward into the Windward Islands Friday. It will still bring heavy rainfall and strong gusty winds to the Windward Islands Friday and Friday night. Interests on those islands should be prepared for localized flooding and perhaps very localized mudslides. Winds might be strong enough to cause some utility disruptions. The system will track westward probably north of the ABC Islands and remain north of South America. The system will move over very warm water and if the shear remains low enough, this system could become a strong tropical cyclone. Computer forecasts show it tracking westward across the southern Caribbean Saturday through early next week. The system could become a strong tropical cyclone before moving very close to and then over Central America next week.



Figure 1. Visible-wavelength GOES-16 satellite image of Potential Tropical Cyclone 9 as of 1515Z (11:15 am EDT) Thursday, August 17, 2017. GOES-16 data are preliminary and non-operational. The RAMMB site also has a "floater" loop zoomed in on PTC 9, offering vivid detail. Image credit: RAMMB/CIRA @ CSU.

Potential Tropical Cyclone 9 heading toward Caribbean

The NOAA/NWS National Hurricane Center launched advisories on Potential Tropical Cyclone 9 (formerly Invest 91) on Thursday morning. As we discussed back in June, the new PTC designation allows for more detailed guidance on systems that are not yet at depression strength but that have a chance of intensifying and bringing tropical storm or hurricane conditions to land areas within 48 hours. Potential tropical cyclones are assigned numbers as part of the same chronological list that includes tropical depressions.

At 11 am EDT Thursday, PTC 9 was located about 365 miles east of Barbados, moving west at about 17 mph. Our top computer models for track forecasting are in very strong agreement that PTC 9 will continue westward, taking it through the Lesser Antilles late Friday, across the eastern and central Caribbean over the weekend, and into the western Caribbean by Monday. There is no reason to doubt the model consensus, especially given that any track interaction between PTC 9 and the system to its east, Invest 92L, would tend to keep PTC 9 moving westward. The official NHC forecast makes PTC 9 a tropical storm by Friday morning. The next name on the Atlantic list is Harvey.

The ASCAT scatterometer has not made a pass directly over PTC 9 for the last few hours, so it has been unable to provide us with recent wind data on the system. A Hurricane Hunter flight will explore the area on Thursday afternoon, at which point we will see if PTC 9 has the closed low-level circulation needed to classify it as a tropical depression (or tropical storm).

Ahead of PTC 9, a tropical storm warning was in effect Thursday morning for Martinique, St. Lucia, Barbados, and St. Vincent and the Grenadines, and a tropical storm watch was in effect for Dominica.

Long-term outlook for PTC 9

PTC 9 has maintained a solid core of moderate to strong showers and thunderstorms (convection) since Wednesday night and has a modest amount of spin. Easterly vertical wind shear of around 15 knots has kept most of the convection focused on PTC 9's west side. This shear is predicted to continue until around Sunday, when it may drop below 10 knots. The wind shear is injecting dry air into PTC 9, with mid-level relative humidities averaging around 50%, but as the shear lessens, the environment around PTC 9 will be moistening from Sunday onward. Sea surface temperatures are more than warm enough for development along PTC 9's path, running at 28-29°C (84-86°F), or about 0.5°C above average for this time of year.

If PTC 9 can keep the ill effects of wind shear and dry air at bay, it should be able to at least hold its own while moving across the eastern Caribbean, a region often hostile to tropical development because of predominant sinking air and strong trade winds. However, ensemble forecasts from Wednesday night suggest that PTC 9 may not make it through the central Caribbean. More than 60% of the European model ensemble members from 0Z Thursday, and more than 90% of the GFS members, bring PTC 9 to tropical storm strength, but the majority of both ensembles call for PTC 9 to weaken or dissipate Monday in the central Caribbean. Of our top three track models, only the UKMET takes PTC 9 into the western Caribbean as a robust tropical cyclone.

Assuming that PTC 9 makes it to the moist, low-shear environment of the western Caribbean, there will be a higher chance of more rapid strengthening early next week. The system will encounter higher oceanic heat content as it continues west, adding further credence to the potential for strengthening once wind shear decreases. The official NHC outlook issued at 11 am EDT Thursday brings PTC 9 to minimal hurricane strength by Monday morning into Tuesday. It is certainly possible that PTC 9 will become stronger than that if it survives its weekend trek.

At this point, it is too soon to know which land areas might be affected by PTC 9 next week. Only a slight shift in the overall westward track would make the difference between PTC 9 striking Nicaragua or the Yucatan Peninsula.

Category 6 Weather



For more information, check the daily Tropical Weather Outlook CLICK HERE.


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The reports above are illustrative of how differently the various weather mavens view this system, and of their general lack of specific interest in what happens in our area. Best we stay alert and watch many sources of info.

Joined: Oct 1999
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Marty Offline OP
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Earliest Arrival Time of Tropical Force Winds

[Linked Image]

These times are Atlantic Daylight time, 3 hours ahead of us.
So - 8 AM on that map is 5 AM here in Belize.

Easy to forget that when you're looking at the charts.

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Marty Offline OP
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From Belmopan...

There is certainly the potential for 91L to develop into a storm, and it could come close to Belize.

But it is still a very small area of cloud, and not visibly rotating at present, but it is showing signs of increased vertical activity.

POTENTIAL TROPICAL CYCLONE NINE



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Marty Offline OP
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Regardless of strength, this seems to be the path that Harvey would follow.

All the models are pretty much in agreement on where it will go. It isn't showing rotation as yet and the environment is only mildly favorable for development.

However. It's bound to bring us some weather in some capacity.


NHC has begun issuing advisories on Potential Tropical Cyclone Nine. The disturbance is centered as of 11 a.m. AST (EDT) about 365 miles (585 km) east of Barbados, moving toward the west near 17 mph (28 km/h). This motion is expected to continue for the next couple of days. On the forecast track, the disturbance should move through the Windward Islands and into the eastern Caribbean Sea on Friday.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. The disturbance is expected to become a tropical cyclone later today or tonight, and it could become a tropical storm before reaching the Windward islands. A Tropical Storm Warning is now in effect for Martinique, St. Lucia, Barbados and St. Vincent & the Grenadines. A Tropical Storm Watch is in effect for Dominica.

Tropical storm conditions are expected to first reach the Lesser Antilles within the warning area by early Friday, making outside preparations difficult or dangerous. Tropical storm conditions are possible in the watch area on Friday. Rainfall totals of 2 to 4 inches are expected across portions of the Windward Islands from Martinique southward to Grenada. These rains could cause life-threatening flash floods and mudslides.

An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system this afternoon.

Tropical Storm Force Wind Speed Probablities



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it's Harvey but latest predictions give us a storm arriving in Belize, not a hurricane...... on Tuesday.
A storm -- we can handle that, no problem, but don't trust projections so far out.
Eyes open.

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Marty Offline OP
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Potential Tropical Cyclone Nine is now Tropical Storm Harvey

Potential Tropical Cyclone Nine has been upgraded to tropical storm Harvey about 250 miles east of Barbados in the Windward Islands. Harvey has maximum sustained winds of 40 mph and is moving west at a brisk 18 mph. This westward movement will bring the center of Harvey through the middle of the Windward Islands late tonight and during the day Friday.

The tropical storm will bring heavy rainfall and strong gusty winds to the Windward Islands Friday and Friday night. Interests on those islands should be prepared for localized flooding and perhaps very localized mudslides. Winds might be strong enough to cause some utility disruptions. Harvey will continue westward probably north of the ABC Islands and remain north of South America through the upcoming weekend. The tropical storm will move over very warm water and if the shear remains low enough, this system should continue to strengthen gradually during the next few days. Harvey could become a strong tropical storm and perhaps a hurricane before moving very close to and then over Central America next week.

Accuweather


Tropical Storm Harvey Forms

The Atlantic's eighth named storm of 2017, Tropical Storm Harvey, is en route to the Caribbean. Air Force Hurricane Hunters found that Harvey had gained a closed low-level circulation, with peak winds of around 40 mph, so the former Potential Tropical Cyclone 9 was upgraded to TS Harvey by the NOAA/NWS National Hurricane Center in its 5:00 pm EDT Thursday advisory. During the years 1966-2009, the average arrival date of the eighth storm of the Atlantic season was September 24-more than a month later than this year's formation of Harvey-so 2017 is considerably more active than usual.

Overall, the prognosis for Harvey has changed little since our last post midday Thursday. There is very high confidence in a westward track through the Caribbean during the weekend. By Monday afternoon, Harvey is forecast by NHC to be very close to the north coast of Honduras, with a landfall projected by NHC for Tuesday along the Belize coast. Even though models agree strongly on Harvey's general westward track, it would take only a slight departure north or south to change the landfall location significantly.

Harvey is expected to intensify only gradually over the next several days, as it is fighting off persistent easterly wind shear of 10-20 knots that's been injecting dry air into the storm. By Sunday, the wind shear is predicted to weaken to less than 10 knots, and midlevel relative humidity in the vicinity of Harvey will rise from around 50% to the range of 65-70%. Sea surface temperatures (SSTs) will be in the range of 28-29°C (82-84°F) along Harvey's track through the Caribbean-more than adequate for development-so the key to Harvey's ultimate strength will be the timing of the expect drop in wind shear. If the shear decreases more quickly and/or more dramatically than expected, a period of rapid intensification cannot be ruled out. A more southerly-angled track would limit the time frame of this risk, since it would bring Harvey ashore sooner (over Nicaragua).

Category 6/ Jeff Masters

For more information, check the daily Tropical Weather Outlook CLICK HERE.


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Marty Offline OP
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The NAVY track this morning.... no change... predicted to arrive Tuesday morning as Cat 1 Hurricane


Not Another Tropical Storm!

About a week and a half ago, stores, banks and businesses countrywide closed down early in preparation for Tropical Storm Franklin. Fortunately for us, Franklin veered north, and his rains and winds had very little effect on Northern Belize.

But before you can properly say, "Farewell Franklin", it may already be time to say "Hello Harvey!" - with a clear sense of dread!

That's right, today, a weather system that formed off the coast of Africa has made its way into the Caribbean, and as of 3:00 this afternoon, has been upgraded to a tropical storm, and its projected path has it coming straight to Belize by early next week. Now, we stress this is just a projection, but we spoke to the Deputy Chief Meteorologist, Catherine Cumberbatch, to get a clearer idea of where this storm may be heading...

Catherine Cumberbatch - Deputy Chief Meteorologist
"As I, Alex, earlier today one of the hurricane hunters went in to investigate the system that was east of Barbados and they came back with information, their observation and it's shown that the area of disturbed weather that is out there has been upgraded to tropical storm Harvey, Which makes it the 8th tropical system for the 2017 Atlantic Hurricane Season."

"Let me just give you a quick where the system is exactly located right now. At 3 pm time the center of tropical storm Harvey was located at Latitude 13.0 N and Longitude 55.8 W, that makes it about 251 miles East of Barbados. The system is moving West near 18 mph and that motion is expected in the next couple of days. Now, with TS Harvey, is being steered by a ridge pattern, a deep layer ridge that is steering the TS Harvey. And with that motion it is expected that TS Harvey will be in the Eastern Caribbean in the next 12-24 hours, in the Central Caribbean by 48-72 hours and in the Western Caribbean, which is out area, by 96-120 hours. That is like on Tuesday we expect on that motion and that forecast track that the system should be in our area at that time."

Cumberbatch warned against listening to rumors about potentially threatening storms circulating around the internet and social media, and urges people to always refer to the latest advisories issued by NEMO and the Met. Office.

Channel 7


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Marty Offline OP
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Harvey Will Push Into The Eastern Caribbean Later Today & Will Head For The Western Caribbean With Hurricane Impacts Possible For Honduras, Belize & The Yucatan Peninsula From Monday Into Tuesday

Tropical Storm Harvey:
11 am EDT/10 am CDT Statistics:
Location: 13.1 North Latitude, 61.3 West Longitude or about 15 miles to the south-southwest of St. Vincent.
Maximum Winds: 40 mph.
Minimum Central Pressure: 1005 Millibars or 29.68 Inches.
Forward Movement: West at a forward speed of 21 mph.

Even though the center of Harvey is difficult to find on satellite imagery, reconnaissance aircraft have found that the storm has a broad low-level center. There is about 10 to 15 knots of northeasterly wind shear that is pushing most of the thunderstorm activity to the west of the center of the storm. With that said, Harvey has 40-45 mph winds according to reconnaissance reports and has drenched the southern Lesser Antilles from Martinique to Barbados with very heavy rainfall and flooding since last night. Weather conditions are expected to gradually improve this afternoon across the southern Lesser Antilles as Harvey moves into the eastern Caribbean.

The wind shear over Harvey is expected to increase to about 15-20 knots late tonight through Saturday and this will likely put either a cap on strengthening, but may also lead to weakening of the storm as it pushes westward across the eastern Caribbean. By Sunday and Monday, Harvey is expected to reach the western Caribbean where the wind shear values are forecast to decrease to 10 knots or less leading to a favorable environment for strengthening. Harvey has the potential to be a hurricane when it reaches the area around Honduras, Belize and the Yucatan Peninsula on Monday night and Tuesday.

With all of that said, let’s not get ahead of ourselves as Harvey does a pose a threat to Honduras, Belize and the Yucatan Peninsula starting on Monday and continuing into Tuesday and I do think it will be a hurricane by that point. So, everyone across the Yucatan Peninsula, Belize and Honduras should keep very close tabs on the progress of Harvey and be prepared to take your hurricane precautions for Monday into Tuesday.

Crown Weather



Navy Track



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Marty Offline OP
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Wind shear has kept Harvey's strongest showers and thunderstorms (convection) displaced to the west of the storm center, so most of the heaviest rains preceded the arrival of Harvey's center. The storm is moving west at a fairly rapid clip, about 21 mph, and conditions across the Windward Islands were improving rapidly by midday Friday. Meanwhile, Harvey was continuing to expand its upper-level outflow and its shield of strong convection, an impressive sign of strength in the face of persistently strong wind shear and midlevel dry air (see below).

Outlook for Harvey

Harvey should steer clear of land areas for the next couple of days as it charges quickly westward.  Computer models are in strong agreement that Harvey will traverse the entire Caribbean through the weekend. The major track question is how far north or south Harvey will be by the time it reaches land.

  • If the track remains on the south side of model guidance (as suggested by the 0Z Friday UKMET run and most members of the GFS ensemble run), then Harvey will likely track along or near the Honduras coast on Monday and arrive in Belize around Tuesday.
  • If Harvey stays toward the north side of guidance (as indicated by most members of the European model ensemble from 0Z Friday, and by the operational GFS run from 12Z Friday), it would remain just north of Honduras and would make landfall late Monday or Tuesday in Belize, or perhaps the Yucatan coast of Mexico.

Harvey will continue to battle strong wind shear of 15-20 knots from the northeast and north through Saturday. This will keep the storm's convection somewhat asymmetric and inject dry air into the storm, so it is unlikely Harvey will strengthen dramatically, although some intensification is quite possible. Around Sunday, models indicate a brief window of reduced wind shear, and midlevel relative humidities should jump from around 45-50% to 70% or more. Together with very warm waters (sea surface temperatures of 29-30°C, or 84-86°F), this will give Harvey a window of potential for more rapid strengthening before it reaches Central America. None of the GFS or European ensemble members from 0Z Friday made Harvey a hurricane before landfall-nor did the 0Z and 6Z Friday runs of the HWRF, our top intensity model. Nevertheless, Harvey bears close watching for any signs of strengthening more quickly than models expect, especially on Sunday.

Harvey's post-landfall future depends greatly on the angle of its track early next week. The more northerly European model solutions-including the 0Z Friday operational run-indicate that Harvey could get pulled northwestward through the western Gulf of Mexico, while the 0Z Friday GFS ensemble members and operational run keep Harvey moving west-northwest across the southern Bay of Campeche and into the east coast of central Mexico, similar to the track of Hurricane Franklin earlier this month. The more northward solutions would give Harvey a better chance of intensifying in the Gulf, and potentially affecting the western Gulf Coast a week or more from now; the southward solutions imply very heavy rainfall across parts of southern Mexico and Central America.

Category 6/ Jeff Masters

For more information, check the daily Tropical Weather Outlook CLICK HERE.


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