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000
AXNT20 KNHC 251804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
204 PM EDT Tue Jul 25 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 1200 UTC surface analysis and satellite imagery through 1745 UTC.


...TROPICAL WAVES...

A tropical wave is in the E Atlc with axis extending from 15N20W to 06N20W, moving W at 5 kt within the last 24 hours. The wave is in a region of favorable to neutral vertical wind shear, and is being affected by Saharan dry air and dust intrusion. Shallow moisture confined to the vicinity of the African monsoon along with upper level diffluence support scattered showers from 05N to 10N between 20W and 30W and isolated showers elsewhere E of 20W.

A tropical wave is in the central Atlc with axis extending from 14N30W to 03N30W, moving W at 5 kt within the last 24 hours. The wave is in a region of favorable vertical wind shear, however it continues to be severely affected by Saharan dry air dust, which is limiting convection to isolated showers in the vicinity of the monsoon trough from 04N to 09N between 30W and 39W.

A tropical wave is in the central Atlc with axis extending from 22N46W to 10N46W, moving W at 20 kt within the last 24 hours. The wave is in a region of unfavorable vertical wind shear, and it continues being severely affected by intrusion of Saharan dry air dust to its environment, which is supporting lack of convection, except from 20N to 24W between 45W and 49W where scattered showers are noted underneath upper level confluent flow.

A tropical wave is just E of the Lesser Antilles with axis extending from 17N58W to 07N59W, moving W at 15-20 kt within the last 24 hours. The wave is in a region of unfavorable to neutral vertical wind shear, however it is underneath middle to upper level diffluent flow that along with shallow moisture support scattered showers from 08N to 14N between 56W and 63W, including the Windward Islands.


...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 13N17W and continues along 09N27W to 06N36W. The ITCZ begins near 06N36W and continues to 06N44W to 10N54W. For information about convection see the tropical waves sections above. Otherwise, scattered showers are in the western end of the ITCZ from 08N to 11N between 51W and 55W.


...DISCUSSION...

GULF OF MEXICO...

An upper level low is situated in the western Gulf near 24N93W with a surface trough underneath along 24N95W to 17N95W. Diffluent wind flow in the S-SE periphery of the upper low along with abundant moisture is supporting scattered heavy showers and isolated tstms in the southwestern Gulf 23N W of 93W. Shallow moisture and middle level diffluent flow is generating isolated heavy showers and tstms N of that area of convection from 23N to 26N W of 90W. Scattered showers and isolated tstms are in the SE basin in the vicinity of a surface trough that extends from 25N83W into the NW Caribben near 15N84W. The general area of this convection is S of 26N E 90W. Some localized fresh to strong winds are possible within this area of convection. Surface high pressure near 28N90W has developed in the north central Gulf with gentle to light anticyclonic flow generaly N of 22N. The overall current synoptic pattern is expected to continue through the next 48 hours.

CARIBBEAN SEA...

A surface trough extends from western Cuba near 22N83W towards eastern Honduras near 15N84W, which is supporting scattered to isolated showers across the western basin W of the trough axis. In the SW part of the sea, the eastern extension of the eastern Pacific monsoon trough moves across Costa Rica and Panama to a 1009 mb low pressure center near 10N76W, which is forecast to move W within the next 24 hours. Scattered to isolated showers associated to these features are S of 12N. In the NE to N-central Caribbean, shallow moisture and the influence of an upper level trough support isolated showers and tstms, including Puerto Rico and Dominican Republic. A tropical wave is just E of the Lesser Antilles and is expected to move into E Caribbean waters late tonight. The wave is already supporting scattered to isolated showers across the Windward Islands and the SE basin S of 13N E of 63W. The pressure gradient across the area will maintain fresh to strong winds across the south-central Caribbean the next two days. Moderate to locally fresh trades will prevail elsewhere across the Caribbean. See tropical waves section for further information about this feature.


...HISPANIOLA...

Shallow moisture, and the influence of an upper level low in the central Atlc with associated trough extending SW across the NE and N-central Caribbean support isolated showers and tstms in the Dominican Republic. This convection will continue and spread to the rest of the Island through tonight. On Wednesday, a tropical wave is forecast to pass just to the south of the Island. Global model guidance indicate the development of showers and thunderstorm through the night hours.

ATLANTIC OCEAN...

An upper level trough just E of the SE CONUS support scattered heavy showers and tstms in the SW basin W of 77W. In the tropical Atlc, there are four waves. Refer to the section above for details. The remainder of the basin is under the influence of a broad surface ridge anchored by a 1030 mb high centered near 34N33W. No major changes expected through next couple of days.

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

$$ Ramos/Tomoff

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