AXNT20 KNHC 222333

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
733 PM EDT Sat Jul 22 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 1800 UTC surface analysis and satellite imagery through 2330 UTC.

...SPECIAL FEATURES... Please refer to the METEO-FRANCE High Seas Forecast listed under the following links: MARINE...BULLETINS EXPERTISES...GRAND LARGE...METAREA II...or on the website: WWW.METEOFRANCE.COM /PREVISIONS-METEO-MARINE/BULLETIN/ GRANDLARGE/METAREA2. Gale-force winds are forecast for the AGADIR area through tonight.


A tropical wave came off the African coast this morning. It axis extends from 15N19W to 06N19W, moving wet at about 10 kt. At this time, abundant moisture combined with the presence of the monsoon trough are enhancing scattered moderate convection south of 10N between 16W-24W.

A tropical wave is in the central Atlantic with axis extending from 20N35W to 10N35W, moving west at 5-10 kt during the last 24 hours. The wave is in a region of Saharan dry air and dust that is hindering deep convection at the time.

A low amplitude tropical wave is in the central Atlantic with axis extending from 15N45W to 06N46W, moving west at 10-15 kt. Middle to upper-level diffluence is supporting isolated showers from 08N-12N between 45W-48W.

A tropical wave is in the east Caribbean with axis extending from 21N65W to 10N67W, moving west at 10 kt within the last 24 hours. Strong dry air subsidence from aloft seems to be hindering the development of deep convection at this time. Isolated showers are observed along the northern portion of the wave affecting portions of Puerto Rico and adjacent waters north of 18N between 60W-67W.

A tropical wave is in the central Caribbean with axis extending from 20N76W to 09N80W, moving west at 15 kt within the last 24 hours. Shallow moisture over the northern portion of the wave is supporting isolated moderate convection affecting Jamaica, eastern Cuba and adjacent waters north of 17N between 75W-79W.


The monsoon trough extends from 11N15W to 09N22W to 12N35W to 11N43W. The ITCZ begins near 08N48W to 08N61W. Aside from the convection associated with the tropical waves, scattered showers are south of 10N between 50W-60W.



Weak surface ridging continues to dominate the Gulf anchored by a 1021 mb high centered over the west Atlantic. A light to gentle anticyclonic flow prevails across the area. Abundant moisture along with a very unstable environment aloft supports an area of scattered to numerous showers and thunderstorms north of 26N and east of 95W affecting the coastal Gulf states and the Florida Peninsula. Scatterometer data show fresh to near-gale winds within this activity. No significant changes are expected during the rest of the weekend.


The main features across the basin are two tropical waves. Please refer to the section above for details. In the southwest portion of the basin, the monsoon trough supports scattered moderate convection along Panama, Costa Rica and adjacent waters south of 10N between 78W-83W. The remainder basin is under the influence of dry air subsidence, which is supporting fair weather. The high pressure over the Atlantic extends across the basin supporting a pressure gradient strong enough to maintain fresh to strong trades over the south-central Caribbean. These winds are forecast to prevail during the next two days.


Fair weather prevails across the island at this time. A tropical wave has moved across the island this morning, while another one is coming from the east. This wave will allow for the re- development of showers and thunderstorms through the weekend.


Aside from the tropical activity associated with the waves, the remainder basin remains under the influence of a broad surface ridge that is anchored by a stationary 1021 mb high centered near 30N62W. No significant changes are expected during the next few days. See the section above for details about the waves and associated convection.

For additional information please visit http://www.hurricanes.gov/marine