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000
AXNT20 KNHC 241803
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
203 PM EDT Mon Jul 24 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 came off the W coast of Africa earlier this morning. Its axis extends from 16N17W to 06N17W and according to global model guidance is forecast to move at 10 kt within the next 24 hours. The wave is in a region of favorable to neutral vertical wind shear, and is being engulfed by Saharan dry air and dust. Abundant moisture confined to the vicinity of the African monsoon along with middle to upper level diffluence support scattered heavy showers from 07N to 10N E of 20W.

A tropical wave is in the E Atlc with axis extending from 15N27W to 02N27W, moving W at 15 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 from 03N to 09N between 23W and 35W.

A tropical wave is in the central Atlc with axis extending from 22N39W to 10N39W, moving W at 10 kt within the last 24 hours. The wave is in a region of favorable to neutral vertical wind shear, however it continues being severely affected by intrusion of Saharan dry air dust to its environment, which is supporting lack of convection at the time.

A tropical wave is in the central Atlc with axis extending from 17N53W to 06N54W, moving W at 10 kt within the last 24 hours. The wave is in a region of unfavorable to neutral vertical wind shear that along with prevailing intrusion of Saharan dry air dust to its environment support lack of deep convection at the time. Shallow moisture support isolated showers from 11N to 14N between 52W and 58W.


...ITCZ/MONSOON TROUGH...

The monsoon trough axis extends from 11N15W and continues along 06N28W to 07N39W. The ITCZ begins near 07N39W and continues to 06N45W to 05N52W. For information about convection see the tropical waves sections above.


...DISCUSSION...

GULF OF MEXICO...

Weak surface ridging prevails across the Gulf waters with gentle to light variable winds E of 91W and moderate easterly to southeasterly flow elsewhere. Instability aloft continues in the form of middle level diffluence and a broad upper level low centered NW of the Yucatan Peninsula. In the north-central and NE Gulf, the remnants of a former surface trough support scattered showers and isolated tstms N of 27N E of 90W. Similar convection is within 120 nm off the northern Yucatan Peninsula and in the SW basin S of 24N due in part to the passage of a tropical wave with axis approximately along 94W. CIRA LPW and water vapor imagery show very dry air elsewhere, which support fair weather. No major changes expected during the next two to three days.

CARIBBEAN SEA...

Except for a portion of the NW Caribbean and the SW basin, the remainder basin is under dry air subsidence and unfavorable vertical wind shear, which is supporting fair weather at the time. In the NW Caribbean, instability associated with the passage of a tropical wave currently moving across EPAC waters and the SW Gulf of Mexico along with upper level diffluence support scattered showers and isolated tstms W of 76W. In the SW basin, the eastern extension of the E Pacific monsoon trough support scattered heavy showers and tstms S of 11N W of 80W. Otherwise, strong high pressure over the Atlc extending a ridge along the northern basin increase the pressure gradient enough to maintain the continuation of fresh to near gale-force winds in the south-central Caribbean. These winds are forecast to prevail the next two days.


...HISPANIOLA...

With dry sinking air aloft advecting westward across the island, only isolated showers and thunderstorms are possible to develop with daytime heating combining with local island effects today and again on Tuesday.

ATLANTIC OCEAN...

Upper level divergence between an upper level high centered along the Georgia coast and the SW periphery of a broad upper level high centered near 34N54W support scattered heavy showers and tstms in the SW basin W of 70W. In the tropical Atlc, three waves are in the central basin while one last one is just off the W African coast. Refer to the section above for details. The remainder of the basin is under the influence of a broad surface ridge anchored by a 1033 mb high centered near the Azores and a 1023 mb high near 28N61W. No major changes expected through next couple of days.

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

$$ Ramos

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