000 AXNT20 KNHC 090605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT Sun Jul 9 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...TROPICAL WAVES... A tropical wave extends from along the coast of Africa near 16N17W to just offshore the coast to 12N17W and to near 07N17W. It is moving westward at about 10 kt. Both water vapor imagery and the Total Precipitable Water (TPW) imagery animation confirm that deep tropical moisture continues to increase over and near the environment of this wave, mainly attributed to it being entrenched within a very pronounced monsoonal flow that has set up along and off the coast of W Africa. With this moisture in place, deep convection near the wave increased since 24 hours ago. Scattered moderate to strong convection is seen west of the wave axis from 09N-11N between 18W-20W. Scattered moderate isolated strong convection is within 30 nm of 13N24W. Another tropical wave is over the far eastern Atlantic with axis extending from 18N26W to 12N30W to 09N31W, moving westward at 10-15 kt. This wave marks the leading edge of deep atmospheric moisture that has increased between it and the wave just offshore the coast of Africa. This is clearly evident on latest satellite imagery, and further supported by the Total Precipitable Water (TPW) loop animation. The wave has a very good signal at the 700 mb level as indicated in the GFS model guidance. The Meteosat 9 imagery continues to depict an extensive area of African Saharan dry air and dust to its west. Deep convection directly associated with this wave is very limited. Only weak isolated showers and thunderstorms are within 90 nm east and 60 nm west of the wave just north of where it intersects the monsoon trough axis. A tropical wave, remnants of Tropical Depression Four, is over the central Atlantic with its axis extending from 24N58W to 18N60W and to 12N59W, and is moving west-northwestward at 15-20 kt. The northern portion of the wave is under an upper trough axis that extends from an upper low (TUTT) located near 29N56W. The combination of diffluence aloft over this portion of the wave and the availability of very deep moisture atmospheric environment surrounding the wave as observed in the TPW loop animation is supporting a large burst of deep convection consisting of the strong type intensity from 20N-24N between 56W- 60W. Scattered showers and thunderstorms have recently developed ahead of the wave within 60 nm of a line from 19N60W to 19N65W. The 0052Z Ascat pass from last night revealed quite an impressive area of 20-25 kt within 90 nm east of the wave axis from 20N-22N, and within 120 nm west of the wave axis from 20N-23N. The wave is forecast to move across the Leeward Islands this morning, pass north of Puerto Rico this afternoon and tonight and move in the general direction of the SE Bahamas Monday through Tuesday. Expect scattered showers and thunderstorms with gusty winds to affect mainly the NE Caribbean today and tonight, with the majority of the activity shifting west-northwest towards the general vicinity of the SE Bahamas and that of the northern and eastern portions of Hispaniola Monday through Tuesday. A tropical wave is over the central Caribbean Sea with axis extending from near 21N72W to 15N74W to inland NW Colombia at 11N74W, moving westward at about 13 kt. The latest water vapor imagery shows subsidence and associated dry air over and around the wave's environment, except south of 12N where moisture becomes evident. Scattered moderate isolated strong convection has recently developed just west of Haiti within 30 nm of 19N73W. Scattered strong convection is over Colombia near the southern extent of the wave. Otherwise, the subsidence aloft is allowing for only isolated showers to exist within 180 nm either side of the wave axis. The northern portion of an eastern Pacific tropical wave reaches to the far western portion of the SW Gulf. It is moving westward at 10-15 kt. The wave is embedded in a very moist and unstable atmospheric environment present to the east of sharp upper trough axis located over central Mexico. Clusters of scattered moderate isolated strong convection persist over much of the SW Gulf of Mexico from 19N-23N between 95W-98W. The wave is forecast to move inland Mexico this morning. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from 11N15W to 10N24W to 08N38W. The Intertropical Convergence Zone extends from 08N38W to 04N52W. Aside from the convection related to the tropical waves over the far eastern Atlantic, scattered strong convection is south of the axis within 30 nm either side of line from 05N32W to 06N36W and within 90 nm north of the axis between 50W-52W. Scattered moderate isolated strong convection is noted within 180 nm south of the axis between 26W-30W. ...DISCUSSION... GULF OF MEXICO... A tropical wave is over the far western portion of the SW Gulf. See above for details. In the upper levels, a small upper level high is centered over the western Bay of Campeche near 20N94W, with the associated anticyclonic flow covering the western half of the Gulf. An upper level low is noted just north of NW Cuba, with a trough extending N to near 28N86W. At the surface, a 1019 mb high is centered over the north-central Gulf near 27N91W. The associated anticyclonic wind flow consists of light to gentle winds covers the area north of about 24N. The thermal trough that moved offshore the Yucatan Peninsula on Saturday evening in combination with upper level anticyclonic flow and a very moist and unstable atmosphere has resulted in recently formed large clusters of strong convection over the Bay of Campeche. Latest mosaic radar imagery shows scattered showers and isolated thunderstorms over the extreme SE Gulf and Straits of Florida moving westward around 10 kt. The tropical wave will move inland by this afternoon. Little change is expected in the present weather pattern through late Monday. CARIBBEAN SEA... A tropical wave is moving across the central Caribbean. See above for details. Scattered moderate convection is over W Cuba. Scattered moderate to isolated strong convection is over the SW Caribbean, Panama, Costa Rica, and S Nicaragua. 10-15 kt tradewinds are over most of the Caribbean. Stronger winds of 20-25 kt are near the coast of Colombia. Expect the central Caribbean tropical wave to move W over the next 24 hours with convection. Also expect convection over the northern Leeward Islands due to another tropical wave, the remnants of Tropical Depression Four, within the next 24 hours. ...HISPANIOLA... Scattered showers and thunderstorms recently developed over the waters just west of Haiti due to the combination of an upper level cyclonic shear axis extending east to west over the vicinity of the island, and a tropical wave axis just west of Haiti as mentioned above. Expect scattered showers and isolated thunderstorms to affect some sections of the eastern and southern portions of the island through Monday in moist easterly flow in the wake of the wave. Also, expect the typical diurnal scattered shower and thunderstorm activity over some of the interior sections through early next week. ATLANTIC OCEAN... Three tropical waves are analyzed over the tropical Atlantic. See above for details. Nearly stationary high pressure of 1030 mb is centered well north of the area at 36N42W, with a ridge stretching southwestward to 32N55W and to central Florida. An upper level low (TUTT) is observed to be near 29N56W, with a trough reaching south to 23N55W, then west-southwest as a cyclonic shear axis to 21N68W and to 21N77W. Scattered showers and isolated thunderstorms are seen from 24N-28N between 55W-57W and north of 26N between 51W- 55W. Scattered showers and isolated thunderstorms moving west- northwest are over much of the western half of the area. The ridge will begin to lift north on Monday. An extensive area of African Saharan dust is situated over the eastern and central Atlantic E of 55W, and is gradually shifting westward. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre