AXNT20 KNHC 211659

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1259 PM EDT Mon Aug 21 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 1615 UTC.

...SPECIAL FEATURES... A tropical wave extends from 09N82W to 21N82W moving W-NW at 15-20 kt. The remnant circulation of Harvey continues to be analyzed as a 1008 mb low along the wave axis near 16N82W with scattered to numerous moderate and scattered strong convection occurring from 15N-21N between 80W-87W. Scattered moderate convection is elsewhere from 15N-22N between 79W-88W. Regardless of development...the wave will continue across the NW Caribbean Sea waters and portions of Central America through tonight into early Tuesday morning and move across the Yucatan peninsula Tuesday. Largest impacts at this point will be the expected rainfall and strong convection the wave and low pressure area will generate across interior portions of eastern Honduras... Guatemala...Belize...southern Mexico...and the Yucatan peninsula Monday night into Tuesday. In addition to the expected rainfall...a higher probability of flash flooding and mudslides will be an ongoing hazard across this region early in the week.

...TROPICAL WAVES... A tropical wave extends from 10N26W to 22N24W moving W at 15-20 kt. The wave coincides with an amplified 700 mb trough that has emerged off the West Africa coast between 18W-31W with a maximum in 850 mb relative vorticity along the wave axis. A 1010 mb low precedes the wave centered near 13N29W. Scattered moderate convection is noted from 12N-18N between 19W-23W...and within 90 nm either side of a line from 13N21W to 09N32W.

A tropical wave extends from 06N62W to 16N60W moving W at 20-25 kt. The wave has continued a westward motion after energy fractured to the N and is now associated with a surface trough and upper level low in the vicinity of 25N53W. The wave is expected to move across the Caribbean Sea and portions of Venezuela through Tuesday increasing cloudiness and convective precipitation. Currently no significant deep convection is occurring across the eastern Caribbean Sea...however isolated showers are noted S of 17N between 61W-68W.

A tropical wave extends from 11N93W to 20N83W moving W at 15-20 kt. Most influence associated with the wave is located in the East Pacific waters...however the wave is the focus for isolated showers and tstms across the SW Gulf of Mexico S of 22N W of 94W.

...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N29W to 07N43W. The Intertropical Convergence Zone axis extends from 07N43W to 08N50W. Widely scattered moderate convection is from 03N-09N between 33W-45W.


GULF OF MEXICO... An upper level low is centered over the central Gulf near 26N89W and continues to support isolated showers and tstms occurring primarily N of 22N between 83W-91W. Farther west across the remainder of the basin...a weak surface trough has formed across the SW Gulf analyzed from 20N95W to 25N97W. This troughing is providing focus for isolated showers and tstms from 19N-26N between 93W-98W. Otherwise...ridging to the N across the SE CONUS is providing light to moderate easterly winds. This overall snyoptic pattern is expected to persist until Tuesday night into Wednesday when the special features low pressure area emerges off the coast of the Yucatan peninsula and into the SW Gulf waters.

CARIBBEAN SEA... Two tropical waves continue moving across the basin this afternoon and are highlighted above. One of these waves is the special feature wave containing the remnant circulation of Harvey. Scattered to numerous showers and scattered strong tstms are occurring across the area from 15N-22N between 79W-88W. This wave will cross Central America through tonight and the reach the Yucatan peninsula by late tonight into Tuesday morning. Farther east...another tropical wave is analyzed across the Lesser Antilles and portions of the far eastern Caribbean. Isolated showers associated with this wave and inverted upper level troughing between 72W-75W are occurring generally between 61W-73W. Finally...moderate to occasional fresh trades are expected through Wednesday.

...HISPANIOLA... Daytime heating...local sea breezes...and mountain upslope lifting will combine with an inverted upper level trough extending from over the SE Bahamas to western Hispaniola and produce widely scattered showers and tstms across the island mainly during the afternoon and evening hours this afternoon. An approaching tropical wave currently along 62W is expected to skirt south of the island on Tuesday night into Wednesday.

ATLANTIC OCEAN... The SW North Atlc is under the influence of an inverted upper level trough extending from 28N77W to over the Windward Passage region near 20N74W. The troughing supports a surface trough extending from 23N74W to 29N71W with scattered showers and isolated tstms occurring from 24N-30N between 69W-78W. Otherwise...the remainder of the SW North Atlc falls within the influence of a surface ridge anchored by a pair of 1024 mb highs centered near 31N65W and 32N72W. Farther east...an upper level low is noted on water vapor imagery near 27N57W with a surface trough analyzed from 18N54W to 26N50W. Scattered showers and tstms are occurring from 21N-30N between 48W-55W.

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