000 AXNT20 KNHC 181738 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 130 PM EDT SAT JUN 18 2016 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 1715 UTC. ...SPECIAL FEATURE... Surface low pressure has formed along the northwestern coast of the Yucatan peninsula near 20N91W. This low is forecast to move west-northwestward around 5 to 10 kt during the next couple of days across the southwestern Gulf of Mexico. This system has a medium chance of developing into a tropical cyclone during the next 48 hours. Please refer to the Atlantic Tropical Weather Discussion under AWIPS/WMO header TWOAT/ABNT20 for more details. ...TROPICAL WAVES... A tropical wave is in the East tropical Atlc with axis near 22W from 03N-09N, moving W at 15 kt during the last 24 hours. The wave coincides with broad 700 mb troughing between 15W and 30W according to the GFS model. Satellite imagery and GFS initial model wind fields show most of the deep convection associated with this wave is being sheared to W of the wave axis...and may be part of the monsoon trough. A tropical wave is over the W tropical Atlc with axis near 48W from 04N to 12N, moving W at 15 kt during the last 24 hours. The wave coincides with broad 700 mb troughing between 45W and 55W according to the GFS model and low values of deep layer wind shear S of 12N. Satellite imagery indicates the wave is experiencing wind shear at mid to upper levels from the NW to W that is reducing coverage of convection to isolated moderate from 01N to 12N between 48W and 56W. A tropical wave is crossing the Windward Islands into the Caribbean. The axis of the wave is along 59W S of 15N. The wave is moving W at 15 kt during the last 24 hours. The wave coincides with 700 mb troughing between 56W and 62W according to the GFS model. Satellite imagery indicates the wave is situated within a region of strong deep layer wind shear that is inhibiting deep convection. The northern part of the tropical wave that was over the western Yucatan Peninsula has lost definition due to interaction with a surface low along the northeastern coast of the Yucatan Peninsula. The southern part of the wave is continuing to propagate westward over the Pacific Ocean south of Mexico. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N14W to 05N30W. The ITCZ axis continues from 05N30W to 03N37W to 04N46W. Aside from the convection associated with the tropical waves, Scattered moderate to isolated strong convection is located from 03N to 07N between 24W and 29W. ...DISCUSSION... GULF OF MEXICO... The tropical wave that extended southward from the central Bay of Campeche over the Isthmus of Tehuantepec has lost definition. Refer to the tropical waves section for more details. A surface low has formed along the northwestern coast of the Yucatan Peninsula. See the special features section for details. Otherwise...surface troughing reaches southeastward from 21N92W through the low across the Yucatan Peninsula to the Gulf of Honduras. Surface ridging crosses the Gulf from the Straits of Florida to the Texas Coastal Bend. A weak surface trough crosses the northeastern Gulf from the Florida Big Bend to the Mississippi Delta. The only associated deep convection was near the mouth of the Mississippi. CARIBBEAN SEA... Surface low pressure along the NW coast of the Yucatan Peninsula is maintaining scattered showers and isolated tstms across the NW Caribbean SW of a line from northeastern Nicaragua to near Cozumel Island. Isolated showers are evident over the Yucatan Channel. An upper level low is located over Hispaniola. The associated trough extends southward to northwestern Venezuela. Water vapor imagery indicates strong upper-level convergence and sinking at middle levels, which is suppressing deep convection over this area. Otherwise, a tight gradient between low pres over the SW basin and high pres over the N-NE Caribbean prevails. Fresh to strong NE to E winds from 11N to 17N between 65W and 80W. Fresh to strong winds are present S of 18N W of 85W, including the Gulf of Honduras. A new tropical wave is crossing the Windward Islands and is bringing a modest increase in shower coverage to the eastern Caribbean. See the tropical waves section for more details. ...HISPANIOLA... An upper level low is centered just north of the island. However, water vapor imagery shows upper-level convergence and sinking air on both sides of the low. This is favoring fair weather over the entire area. Similar weather will persist for the next several days. ATLANTIC OCEAN... Low pressure to the north of the area supports a cold front extends from 31N73W to the extreme northeastern coast of Florida. Pre-frontal forcing supports scattered thunderstorms from the central Bahamas northward to the cold front. Strong northeasterly winds and increasing seas are north of the front. Middle to upper level troughing remains over the Atlantic from the African coast near 30N10W to the southeastern Bahamas. A broad area of upper-level convergence and sinking air is associated with this feature. Otherwise, besides the tropical waves discussed above, a surface high pressure ridge extends southwestward from SW of the Azores at 32N37W to N of Puerto Rico near 23N65W. For additional information please visit http://www.hurricanes.gov/marine $$ cam