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904
AXNT20 KNHC 160009
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
809 PM EDT Sun Jul 15 2018

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 2315 UTC.


...SPECIAL FEATURES...

Subtropical Storm Beryl is centered near 38.2N 63.8W at 15/2100 UTC or about 356 nm N of Bermuda, moving ENE or 75 degrees at 5 kt. The estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 35 kt with gusts to 45 knots. Latest satellite imagery shows that Beryl has weakened since yesterday as noted by its exposed center that consists of broken to scattered low to mid-level clouds. Beryl should begin to weaken tonight when it moves over colder water, and the cyclone is expected to degenerate into a remnant low pressure system late tonight or on Monday. Please read the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT2/WTNT22 KNHC and high seas forecasts issued by the National Weather Service under AWIPS header NFDHSFAT1 and WMO header FZNT01 for more information.

SW Caribbean Sea gale warning: NE to E minimal gale force winds are near the coast of Colombia from 11N to 13N between 73W and 76W. The gale is forecast to end 16/1500 UTC. Please read the High Seas Forecast, under the AWIPS/WMO headers HSFAT2/FZNT02 KNHC, for more details.


...TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 32W from 07N to 18N, moving westward at 10-15 kt. The wave is depicted on GOES-16 RGB imagery as having a rather broad envelope of broken to overcast mainly stratocumulus clouds. The GOES-16 RGB images along with visible images of the far eastern Atlantic are depicting yet another massive plume of Saharan dry air and associated dust following in behind the wave from 10N-28N.

A eastern Caribbean Sea tropical wave has its axis extending from near 21N59W to 09N62W, moving westward at 15-20 kt. This wave continues to be impacted by Saharan dust, which is not allowing for any deep convection to develop along and near it. Only isolated showers moving quickly westward with the fresh easterly trades are seen within about 300 nm east and 180 west of the wave axis. This wave will move across the eastern Caribbean Sea through Tue night, and the central Caribbean Wed through Thu.

A central Caribbean Sea tropical wave axis is along 79W S of 20N to beyond Panama, moving westward around 15 kt. This wave is ill- defined at the surface. Its position was based on extrapolation from the past 6 to 24 hr analyzed position and from the latest guidance from 700 mb model diagnostics. No deep convection is noted with this wave as it located to the west of an upper level trough as mentioned in the above paragraph.

A Central America tropical wave is along 86W S of 18N, moving westward at 10-15 kt. The combination of this wave with local topography effects has initiated scattered moderate convection over much of the central America to include the Gulf of Honduras. Model guidance indicates that 700 mb troughing is present over much of Central America providing further support for the shower and thunderstorm activity. The wave will move into the eastern Pacific Ocean on Mon.


...MONSOON TROUGH/ITCZ...

The monsoon trough extends from W Africa near 13N16W to 06N40W. The ITCZ begins near 06N40W and continues to South America near 05N52W. Scattered moderate convection is from 05N-07N between 42W-47W.


...DISCUSSION...

GULF OF MEXICO...

High pressure of 1018 mb is the main feature that is influencing the synoptic pattern across the basin. Its associated gradient is allowing for generally light to moderate anticyclonic flow to exist over the gulf waters. Current NWS mosaic radar displays show scattered showers and isolated thunderstorms over much of the eastern gulf waters as well as over the eastern half of the central gulf. This activity is moving westward under moderate upper northeast winds. The activity should continue into the early evening, with some possibility of more activity developing during the overnight hours.

The high pressure will prevail across the northern waters through Thu. A surface trough will move westward off the Yucatan Peninsula each evening through Thu, enhancing nocturnal winds in the SW Gulf.

CARIBBEAN SEA...

Please read the Special Features section for details about gale- force winds near the coast of Colombia.

Aside from the tropical wave features as described above, an upper level trough is noted on water vapor imagery to be anchored from near eastern Cuba to vicinity Jamaica and to near 10N80W. Scattered to broken high clouds streaming northeastward are seen within 600 nm to its southeast. Isolated showers moving rapidly to the west are present over much of the basin, except along the immediate coasts of Central America S of 16N where deeper convective activity is occurring as described above with the inland tropical wave along 83W. This activity should persist through Mon night or so. Otherwise, a tight pressure gradient will allow for NE-E winds to pulse to minimal gale near the coast of Colombia over the next few days as described above under Special Features. Fresh to strong E winds will continue over the central Caribbean Sea through the middle of next week.

ATLANTIC OCEAN...

Please read the Special Features section for details about Subtropical Storm Beryl.

A weak 1018 mb low is near 31N78W with a trough extending southwestward to near Cape Canaveral, Florida. Recent scatterometer data picked up on this feature. Current NWS mosaic radar imagery along with recent satellite imagery show increasing scattered moderate isolated strong convection within 90 nm of the low in the SE and S quadrants. Another surface trough is analyzed from near 32N63W to 27N76W near the N Bahamas. The latter surface trough will slowly weaken through Tue as the upper trough lifts to the NE away from it. High pressure will build in the wake of the trough. Scattered showers and isolated thunderstorms between the Bahamas and southeastern Florida are due to a weak surface.

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

$$ Formosa

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