Belize Tropical Weather Outlook: October 21, 2016

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Area wind information

Belize NMS Forecast

6:00 AM in Belize, October 21, 2016

An area of low pressure centred about 450 miles south-southeast of Cape Hatteras, North Carolina is moving northward. This system is expected to merge with a frontal system tonight and its chances of developing are decreasing.

Elsewhere in the North Atlantic, the Caribbean Sea and the Gulf of Mexico, tropical cyclone formation is not expected during the next 48 hours.

Tropical Atlantic Wide Infrared Satellite Image:

USA National Weather Service Forecast

October 21, 2016

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

A broad area of low pressure centered a little more than 200 miles east-northeast of the northwestern Bahamas is moving slowly northward. Although the thunderstorm activity continues to be limited, there is still an opportunity for this system to become a subtropical or tropical cyclone later today before it merges with an approaching cold front well offshore of the United States East Coast Friday night. Moisture from this system is still causing locally heavy rains along with life-threatening flash floods and mud slides over portions of Hispaniola.
* Formation chance through 48 hours...medium...50 percent
* formation chance through 5 days...medium...50 percent

Tropical Weather Discussion

...Special features...
A broad area of low pressure is centered east of the northern Bahamas. The central pressure of the low is 1002 mb and is located near 27n73w. Scattered moderate convection and isolated tstms are within 150 nm from the low center. However, there is still a medium chance for this system to become a subtropical or tropical cyclone before it merges with an approaching cold front well offshore of the United States East Coast Friday night. To the east of the low center, a rainband supported by a diffluent environment aloft generates numerous heavy showers and tstms from 22n to 30n between 64w and 68w. Showers also continue across Hispaniola, mainly across Dominican Republic, with GOES qpe imagery showing there accumulations of up to 2 inches over the last 6 hours. Life-threatening flash floods and mud slides are possible over portions of Hispaniola.

A tight pressure gradient between a cold front and high pressure building in its wake will generate gale force winds in the Gulf of Mexico Friday night. The front is expected to be along 29n82w to 25n96w to 19n95w and the gale winds S of 24n west of the frontal boundary with seas to 9 ft. Please see the High Seas Forecast under AWIPS/WMO headers miahsfat2/fznt02 knhc for more details.

...Tropical waves...
Tropical wave is in the central Atlantic extending from 06n to 16n with axis near 45w, moving W at 15-20 kt over the past 24 hours. The wave is in a region of unfavorable to neutral deep layer wind shear. Furthermore, CIRA lpw imagery from surface to 850 mb show pockets of dry air in the wave environment while water vapor imagery show dry air in the middle to upper levels. These factors are limiting the convection to scattered showers from 07n to 14n between 38w and 53w.

Caribbean Sea...

Southeasterly flow across the eastern Caribbean continues to advect moisture to the north-Central Basin where upper level divergence support scattered heavy showers N of 15n between 66w and 76w, including Hispaniola. The GOES qpe imagery show rain accumulations of up to 2 inches over the last 6 hours in the Dominican Republic. This may result in life-threatening flash floods and mud slides over portions of Hispaniola. A surface trough extends from eastern Jamaica near 18n76w to NE Nicaragua near 14n83w and support isolated showers within 90 nm either side of its axis. A cold front will reach the NW basin Saturday night. This will allow the continuation of showers across Hispaniola over the weekend.

Weather Underground Caribbean Forecast

Tropical cyclone development is not anticipated across the eastern Pacific or the Atlantic Basin on Saturday. In the Atlantic Basin, an elongated area of low pressure is located a couple hundred nautical miles northeast of the central Bahamas. This system has a medium, 50% chance to develop into a tropical cyclone as it pushes northwestward. In the eastern Pacific, a cluster of thunderstorms associated with a small area of low pressure is located about 608 nautical miles south southwest of the southern tip of Baja California. This area of low pressure has a medium, 40% chance to develop into a tropical cyclone as it moves northward. Additionally, a trough of low pressure is producing disorganized showers near the coasts of Guatemala and El Salvador. This cluster of showers has a low, 10% chance to develop into a tropical cyclone as it drifts west northwestward. Regardless of development, moderate to heavy rain will impact portions of Central America throughout the next 48 hours.

48 Hour Forecast Favorable Environmental Conditions For Tropical Development

Infrared Satellite in Belize City

Invest 99L is trying to become better organized

10/21/2016 6:00:19 AM

Invest 99L is somewhat better organized this morning as compared to yesterday. There is a much more defined low-level center with at least some showers and thunderstorms near the center; but most of the showers and thunderstorms are not focused near the center of circulation.

Southwest shear will be relatively low over the next 12 hours and this will provide a window when 99L could become even better organized and strengthen. It is still possible this could become a subtropical, hybrid storm or a more purely tropical one and obtain the name Otto. Heavy surf continues around the Bahama Islands and other northern Caribbean Islands along with areas of showers and thunderstorms.

A strong cold front entering the Eastern States today and tonight will begin to impact the low. 99L will accelerate to the north and northeast tonight into Saturday, passing west of Bermuda late tonight and then moving into Atlantic Canada on Saturday. Whether a named or unnamed storm it will bring rough surf and some showers and thunderstorms and gusty winds to Bermuda for a time and will likely enhance rainfall over Atlantic Canada later Saturday and Saturday night.

All interest in the Bahamas, Bermuda and Atlantic Canada should continue to monitor this feature.

Elsewhere, development is not expected in the Atlantic Basin.

120 Hour Forecast Favorable Environmental Conditions For Tropical Development

Invest 99-L Will Move Northward & Combine With A Coastal Storm To Produce Heavy Rainfall Across The Northeastern United States & Heavy Snowfall Across The Mountains Of Northern New York & Northern New England From Friday To Sunday
Rob Lightbown of Crown Weather Services

October 20, 2016

Invest 99-L Located To The Northeast Of The Bahamas: An area of low pressure, Invest 99-L, seems to be slowly becoming better organized this morning, however, it is still fairly disorganized with most of the shower and thunderstorm activity occurring away from the low pressure center. This says to me that if Invest 99-L continues to become better organized that it probably will become a sub-tropical storm rather than a true tropical storm.

Invest 99-L is forecast to move in a northerly direction today through Friday and should be located about halfway between the North Carolina coast and Bermuda by Friday evening. From there, this system is forecast to combine or become absorbed within a developing storm system that will be located over New England on Saturday. All indications are that this is forecast to be a very strong storm system over New England this weekend that is likely to produce heavy rainfall across much of the northeastern United States and the potential for heavy snow across the mountains of northern New York and northern New England this weekend.

Forecast Impacts Across New England & New York State:
Heavy Rainfall Potential: Heavy rain with embedded thunderstorms are forecast to overspread much of New York State tonight and then overspread much of New England from west to east during the day on Friday. Heavy rain is expected to continue across mainly central and northern New England during Friday night and Saturday before it changes over to snow on Saturday night across the mountains of northern Vermont, northern New Hampshire and western Maine.

Total rainfall amounts from tonight through Friday and Saturday will range from 1 to 2 inches across much of eastern and southeastern New York State, all of southern New England, southern Vermont, southern New Hampshire and southern and central Maine to as much as 3 to 5 inches of rain possible across western and northern Pennsylvania, western and northern New York State, northern Vermont, northern New Hampshire and western and northwestern Maine. Some guidance is showing the potential for 6 to 8 inches of rain across northeastern New York State and northwestern Vermont.

Even though the rainfall is very much needed across New England and New York State, some flooding is possible across western and northern New York State and parts of northern New England due to the fact that the 3 to 6 inches of rain is expected to fall in a very short amount of time.

Heavy Snowfall Potential Across The Mountains Of Northern New England & Northern New York State: Heavy rain is forecast to change to heavy snow on Saturday night across northern New York State and across the higher elevations and mountains of northern Vermont, northern New Hampshire and western Maine. The snow is likely to continue throughout Sunday across northern parts of New York State, northern Vermont, northern New Hampshire and western Maine.

There is the potential for upwards of 4 to 8 inches of snowfall across the higher elevations of northeastern New York State, northern Vermont, northern New Hampshire and western Maine. In fact, some of the higher mountain tops of northern New England could see 10 or more inches of snow from Saturday night into Sunday.

We will be monitoring Invest 99-L to see if it does become a sub-tropical system over the next couple of days and then see how much of an impact it has on the northeastern United States and the Canadian Maritimes.

Starting This Monday, Barring Any Additional Tropical Development Threats, We Will Begin Writing Weather Updates Detailing Potential Weather Threats To The United States & Caribbean. If by this Monday, we do not see any compelling evidence of tropical development threats across the Atlantic, Caribbean or Gulf of Mexico, we will begin sending out weather updates that detail potential weather threats across the United States and Caribbean. These alerts will include severe weather and tornado threats, heavy rain/flood threats, heavy snow threats and marine weather threats.

If it does look like we will see additional tropical development in early November, then we will delay these weather updates until mid or late November and instead concentrate on our tropical weather updates.

Finally, just to let you know that these weather updates will be sent out throughout this winter and into the spring of 2017. We hope that these significant/severe weather updates will give you advanced notice upwards of 5 to 7 days in advance of any severe weather that may impact you, your family or your business interests.

Invest 99L Information:

Model Track Forecast:

Courtesy of Weather Underground

Satellite Imagery:

Atlantic Quiets Down
Jeff Masters

October 21, 2016

Potential tropical cyclones are having a tough go of it during these waning days of the 2016 Atlantic hurricane season. Forecasters have been watching Invest 99L for most of this week east of the Bahamas. 99Ls showers and thunderstorms (convection) have never consolidated around a single closed center of low pressure. On Friday morning, 99L consisted of a small pocket of convection near its center and weak showers and storms ringing 99Ls very broad area of low pressure. The entire system will soon accelerate north and get pulled into a midlatitude storm expected to intensify over New England on Friday night and Saturday. In its 8 am EDT Friday Tropical Weather Outlook, the National Hurricane Center gave 99L only a 40% chance of developing into a tropical or subtropical cyclone before it loses its identity, and that may be generous. Moisture feeding from 99L into the midlatitude cyclone and an associated front will produce heavy, drought-easing rains this weekend from Pennsylvania to New England, with 3 - 5 expected from central New York across much of New Hampshire and Maine.

Figure 1. A broad loop of showers and thunderstorms is spiraling into 99L, shown here in a visible satellite image from 10:45 am EDT Friday, October 21, 2016.

Another wave to watch in the tropical Atlantic
Its very late in the season to look for any development in the central Atlantic, but a tropical wave centered around 11N and 44W on Friday morning bears watching. Strong wind shear is now pushing dry air into the wave, limiting the amount of convection present. The shear over the wave may lessen over the next couple of days, and sea-surface temperatures of around 28 - 29C (82 - 84F), about 0.5C above average, are more than adequate to support development. All 20 of the GFS ensemble members from Thursday night (00Z Friday), and almost half of the 50 ECWMF ensemble members, develop this wave over the next 2 to 5 days into at least a tropical depression, with some support for tropical storm formation. A weak upper low east of the Lesser Antilles may interact with this wave, complicating any potential development. If the wave does develop, it would most likely move north or northwest and remain far from land, perhaps stalling in the open central Atlantic later next week.

The next name on the Atlantic list is Otto, and getting to that point would be noteworthy. Since regular naming of Atlantic tropical cyclones began in the early 1950s, we have had only 10 O storms, all of them developing during the active period of Atlantic hurricane activity that began in 1995:

Opal, 1995
Olga, 2001
Odette, 2003
Otto, 2004
Ophelia, 2005
Olga, 2007
Omar, 2008
Otto, 2010
Ophelia, 2011
Oscar, 2012

Figure 2. Forecasts for the total number of hurricanes in the 2016 Atlantic season, issued by the groups shown along the bottom legend. For groups that issue more than one outlook per season, the most recent outlook is shown here. The average forecast across groups was for 8 hurricanes, as compared to the 6 that have occurred through October 21. Image credit: Colorado State University/XL Catlin/Barcelona Supercomputing Center.

The Atlantic season to date
This years predictions of a near-average to slightly above-average 2016 Atlantic hurricane season are looking quite close to the mark as the season begins to wind down. As of October 21, the Atlantic has seen 14 named storms, 6 hurricanes, and 3 major hurricanes. This compares to the 1981-2010 average of 12.1 named storms, 6.4 hurricanes, and 2.7 major hurricanes.

The outlooks from most forecast groups (see Figure 2 above) leaned toward a higher number of hurricanes than we've actually seen. However, in terms of accumulated cyclone energy (ACE)--which integrates the lifespan and wind-speed intensity of each tropical cyclones--its been a more active year than one might expect from hurricane counts alone. This is mainly a result of the strength and duration of the years three major hurricanes: Gaston, Matthew, and Nicole. As of October 21, the 2016 Atlantic season had racked up an ACE total of 133, which is 144% of the typical ACE for the year to date and 128% of the typical total ACE for a season.

[Monday] Subtropical Development Possible this Week Between Bahamas and Bermuda No Immediate Threat

An upper-level trough east of Florida is generating a region of disturbed weather near and east of the southeastern Bahamas. Such a system could gradually organize into a subtropical low between the Bahamas and Bermuda during the course of this week, but development would be slow to occur. The system poses no immediate threat, but wet weather could continue to impact portions of the Bahamas over the next few days. The National Hurricane Center gives this disturbance a 20% chance of developing into a subtropical or tropical storm over the next 2 days, and 50% over the next 5 days.

CLICK HERE for the website for Belize National Emergency Management Organization (NEMO)

Tropical Atlantic Wide Visible Satellite Image

Edited by Marty (Yesterday at 01:53 PM)