Belize Tropical Weather Outlook: July 24, 2017

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Belize NMS Forecast

6:00 AM in Belize, July 24, 2017

Tropical cyclone formation is not expected during the next 48 hours.

USA National Weather Service Forecast

July 24, 2017

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

Tropical cyclone formation is not expected during the next 5 days.

Tropical Weather Discussion

...Tropical waves...

An eastern Atlantic tropical wave has its axis extending from 17N26W to 05N25.5W, moving westward at 15 kt. Both CIRA LPW and SSMI TPW imagery confirms the extensive presence of dry air mainly in the northern wave's environment. Convection associated with this wave remains at a minimum as dry air to the north of the wave has filtered some into its environment. Only scattered moderate convection is seen within 120 nm either side of the wave along and near the monsoon trough from 05N-08N.

A central Atlantic tropical wave has its axis extending from 21N40W to 15N39W to 09N39W, moving westward at 15 kt. This wave has a broad low-level cloud field associated with it, and is depicted in a somewhat inverted-V shape pattern as seen in the first visible satellite images. No deep convection is noted with this wave as the Saharan Air Layer (SAL) and associated dust has also mixed in with this wave's environment. Only isolated showers and weak isolated thunderstorms are noted east of the wave within 30 nm of 17N39W.

Another tropical wave has its axis extending from 17N52W to 06N53W, moving westward at 15-20 kt. Moisture has increased during the overnight hours mainly west of the wave as upper level dynamics provided by an upper trough that extends east to west across the wave is providing additional instability and lift to the environment around the wave south of 14N. Latest satellite imagery shows increasing scattered moderate convection within 45 nm either side of line from 12N52W to 12N56W to 12N58W. Similar activity is east of the wave within 30 nm either side of line from 13N50W to 12N53W. A swath of Saharan dry air and dust is present over and around this wave north of 14N.

The northern portion of an eastern Pacific tropical wave has moved inland central America to over Guatemala and the far south-central part of the Yucatan Peninsula. It is moving westward at 10-15 kt. The Total Precipitable Water (TPW) imagery animation continues to display abundant deep atmospheric moisture within the environment of this wave. This moisture is seen in infra-red satellite imagery as mainly broken to overcast mid to high level debris cloudiness from previous deep convective activity. Scattered strong convection has recently developed over far southeastern Belize and far northwestern Honduras. Scattered moderate convection is just offshore the northeast part of the Yucatan Peninsula within 30 nm of a line from 20N85W to 21N87W. Isolated showers and thunderstorms are over some areas of the Yucatan Peninsula. This activity is likely to become scattered to locally numerous this afternoon and into this evening.

...The Caribbean Sea...

A tropical wave has moved further inland central America this morning. Refer to the section above for details. A very moist and unstable atmosphere over the western portion of the Caribbean is leading to clusters of scattered moderate convection there, and over the waters between eastern Cuba and Jamaica. In addition, the eastern Pacific monsoon trough extends along 10N to NW Colombia. This continues to enhance scattered shower and thunderstorm activity over the far SW Caribbean south of 13N and west of 80W to near the coasts of Costa Rica and Panama. All of this activity is expected to remain active over the next 48 hours or so. Elsewhere, a broad high pressure over the Atlantic stretches across the basin supporting fair weather and maintaining a pressure gradient to support fresh to near gale-force winds in the south-central Caribbean through early this morning and again late tonight.

48 Hour Forecast – Favorable Environmental Conditions For Tropical Development

Infrared Satellite in Belize City

Tropical Atlantic basin to remain benign
Accuweather

7/24/2017

The Atlantic basin remains very quiet, and tropical development is not expected over the next several days. There are currently several disorganized waves moving across the Atlantic and through Central America. These waves will continue on a westward trajectory and will move at 5-7 degrees longitude per day.

Strong wind shear and dry air will continue to inhibit tropical development from occurring across the Atlantic Basin and there are large areas of Saharan dust which also works against tropical development. There is some indication that wind shear will weaken across the Central Atlantic by the middle of this week, but there is no indication of any possible tropical development at this time.

July 24, 2017

The Atlantic, Caribbean and Gulf of Mexico are very quiet and tropical development is not expected this week. The reason why it is quiet is because there is quite a bit of dry air across a large part of the Atlantic and this dry air is suppressing convection. In addition, there is a downward motion pulse of the Madden Julian Oscillation across the Atlantic Basin and this is contributing to the suppression of convection.

You can see the next upward motion pulse of the Madden Julian Oscillation doing its work in the Pacific with 2 tropical storms and 1 hurricane now occurring in the eastern Pacific. This upward motion pulse of the Madden Julian Oscillation is forecast to move eastward reaching the Atlantic Basin by the first week of August. The map below is a way to represent where there is downward and upward motion pulses associated with the Madden Julian Oscillation. The rust colored areas represent downward motion and these downward motion pulses suppress convection and tropical development is unlikely in these areas. This is what is occurring this week across the Atlantic Basin.

Next week and certainly the following week (week of August 6th), an upward motion pulse of the Madden Julian Oscillation, represented in the green area in the map below, is forecast to push into the Atlantic Basin. This upward motion pulse, when it reaches the Atlantic Basin, will likely encourage and enhance the formation of convection and improve the environmental conditions that can assist in tropical storm and hurricane formation.

The extremely long range models like the 46 day European EPS model and the 85 day CFS model continue to strongly suggest that the period from mid and late August into September could be very busy across the Atlantic, Caribbean and Gulf of Mexico in terms of tropical storm and hurricane formation. In fact, the European EPS model is forecasting the formation of up to 6 tropical cyclones between August 13th and September 3rd. Whether we see that many tropical systems form in such a short time period remains to be seen, but it is a signal from the more reliable model guidance that things are likely to get very busy very quickly across the Atlantic Basin by the first and second week of August.

So, My Thinking Continues To Be That we will remain relatively “quiet” in terms of tropical development throughout this week and possibly even into part or most of next week. At some point next week and certainly by the following week (week of August 6th), we will start to see the first rumblings of renewed tropical activity across the Atlantic Basin.

The period from August 7th through the end of August into the beginning of September is forecast to be very, very busy in terms of tropical storm and hurricane activity across the Atlantic, Caribbean and Gulf of Mexico.

What continues to trouble me is the overall weather pattern which will eventually dictate where a tropical storm or hurricane will track. Even though we are likely to see a strong trough of low pressure over the eastern United States through much of this week, I think that we will see the western Atlantic ridge of high pressure fight back and push westward as we get into early August. In addition, that 46 day European EPS model forecasts indicates that the western Atlantic ridge could be a mainstay rather than a mean eastern US trough. If, and this is a big if, this happens then a ridge of high pressure close to the eastern United States could guide any developing/intensifying tropical cyclones into the Caribbean, Bahamas, eastern United States and even the Gulf of Mexico. This is something that is just a possibility right now, but it is something that is being watched very closely.

One clue of many that determines how busy the Atlantic hurricane season may be is the amount of rainfall that occurs over the western Sahel in Africa. When this area is very dry, it leads to a much quieter hurricane season because the tropical waves that push off of Africa have much less energy and moisture and are much less robust. On the other hand, when the western Sahel is very wet, it can lead to an active to very active hurricane season in the Atlantic because the tropical waves that push off of Africa have much more energy and encounter much less dry air. So, right now the rainfall over the western Sahel has been above average and this is a sign that the Atlantic hurricane season could be active to very active.

Finally, history has shown that when tropical storms or hurricanes form in the area between the Lesser Antilles and the coast of Africa during June and July, like we have seen this year, it usually leads to an active hurricane season. The reason why is because this early season activity indicates that the environmental conditions will be favorable for tropical disturbances to develop as they push off of the coast of Africa during the peak of the hurricane season from August 15th to October 15th. So, as of now, we have had two tropical storms form already in the area between the Lesser Antilles and the coast of Africa and this indicates to me that we are in for a more active than average Atlantic Hurricane season.

So, please take this “quiet” time and get prepared now for the rest of the 2017 Atlantic Hurricane Season. If you haven’t restocked your hurricane preparedness kit, do it this week and don’t wait until a hurricane is knocking on your door.

The next tropical weather discussion will be issued between 9 and 11 am EDT/8 and 10 am CDT Thursday Morning. No tropical weather discussions will be issued on Tuesday or Wednesday.

The Atlantic: July may go out like a lamb—but what about August?
Jeff Masters, Category 6

July 24, 2017

Figure 3.  A model-generated forecast, extending in five-day increments from July 24 to September 2, of where upward and downward motion across the tropics at the 200-mb level (about 39,000 feet) is expected to predominate. The forecast is based on a simple technique of propagating wavelike atmospheric features related to the Madden-Julian Oscillation eastward over time. Over the Atlantic tropics, sinking air (warm colors), which now predominates, is predicted to be replaced by a tendency toward rising air during August, which would be more favorable for the development of tropical cyclones. Image credit:  NOAA/NWS Climate Prediction Center, via CPC’s MJO website.

It’s been five days since Tropical Storm Don dissipated near the Windward Islands, and it looks like it will be at least another five days before the tropical Atlantic sees another system with the potential to develop into a tropical depression, according to the 2 pm Monday Tropical Weather Outlook from the National Hurricane Center (NHC).

The 0Z Monday runs of the GFS and European model ensembles predict that the next potential for Atlantic tropical cyclone development will occur in the Friday – Sunday time frame, from a tropical wave that will be midway between the Lesser Antilles Islands and coast of Africa.

The Madden-Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, and which can increase the odds of tropical cyclone formation when it is strong and located in the proper location, is currently weak and in an unfavorable location, and will not favor tropical cyclone formation in the Atlantic over the coming week. However, the MJO is predicted to intensify in August, as it moves into a location that would be more supportive of tropical cyclones downstream in the Atlantic.

The Saharan Air Layer (SAL), which can infiltrate and weaken tropical waves moving across the Atlantic, typically weakens and shifts as we approach late summer, and sea-surface temperatures should be continuing to warm toward their seasonal peak, so it appears multiple factors are coming together for a potentially active August in the Atlantic.

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