AXNT20 KNHC 281033

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
633 AM EDT Wed Jun 28 2017

Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through 1030 UTC.


A tropical wave has its axis just off the coast of Africa along 19W from 12N to 20N, moving westward at around 10 kt. Low-level moisture is limited within this wave, therefore, no convection is associated with this feature at this time.

A tropical wave has its axis from 11N36W to 02N37W, moving westward at 10-15 kt. Satellite imagery and TPW data reveals that the wave remains embedded within a very moist environment, except for over its eastern region where Saharan dry air and dust is present. Isolated moderate convection is noted north of 06N between 34W-40W.

A broad tropical wave has its axis tilted from 15N56W to 05N61W, moving westward 15-20 kt. This wave continues to be easily identifiable on satellite imagery as having the typical configuration of waves observed later during the season. It is detected in the model fields, and is further supported by the latest diagnostic model analysis. Scattered moderate convection is observed from 11N-16N between 54W-65W. The wave is forecast to continue moving west affecting the eastern and central Caribbean waters through Thursday.

A tropical wave is moving across the western Caribbean with its axis along 82W from 08N to 21N, moving westward at 10-15 kt. This wave is also evident in satellite imagery, and continues to mark the leading surge of very deep atmospheric moisture, as seen in TPW data. Isolated moderate convection is observed in the vicinity of this wave between 80W-84W. The wave will move across the remainder of the western Caribbean Sea through today, and inland Central America by tonight.


The Monsoon Trough extends from the coast of Africa near 20N16W, and continues southwest to 10N30W. The Intertropical Convergence Zone then extends from 06N39W to 09N56W. Isolated moderate convection is within 100 nm on either side of the ITCZ axis.



A mid to upper-level trough axis is over the far northwest Gulf, while a surface trough is along the Texas coast. The combination of these features along with the presence of diffluent flow aloft east of the mid-upper level trough continues to support isolated showers and thunderstorms mainly north of 24N and west of 90W. A stationary front is analyzed from northeast Florida to near Cross City, Florida and to 29N86W where it becomes diffuse from there to 29N88W. The shower and thunderstorm activity over the western Gulf is forecast to remain active through today, then shift northeast by tonight and Thursday as the mid/upper level trough slides eastward. The stationary frontal boundary is forecast to gradually become diffuse through the morning hours, with the remnants lifting back to the north through tonight.


The main feature presently in the basin is a tropical wave currently over the western Caribbean, and the near-future arrival of another tropical wave which is approaching the Lesser Antilles at this time. These features are discussed in the section above. Aside from the convection related to the tropical waves, fair weather prevails elsewhere. Scatterometer data depicts moderate to fresh trades across the basin. The pressure gradient is forecast to tighten over portions of the far south-central Caribbean beginning tonight and continuing through Thursday night inducing strong to near-gale force east winds over this area, with the near-gale force winds expected across and near the Gulf of Venezuela.


Fair weather prevails across the island at this time. Little change is expected in the present weather pattern through the next 24 hours. Convection is expected once again by the end of the week as a tropical wave approaches.


Three tropical waves are moving across the tropical Atlantic. Refer to the section above for details. A broad mid to upper-level trough extends southwestward from along the eastern seaboard to the far northwest portion of the basin. It supports a stationary front that extends through 33N74W to 30N81W. Scattered showers and thunderstorms are noted north of the Bahamas and west of about 75W. This activity will continue through much of today and tonight as the surface boundary weakens, and the mid to upper trough slides eastward while it broadens out further. A surface trough extends from 32N56W to 24N57W with isolated showers. This trough is a reflection of an upper-level low centered in the same area. A broad high pressure prevails across the remainder of the basin, anchored by a 1028 mb surface high centered near 36N40W.

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