000 AXPZ20 KNHC 151605 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Mon Jul 15 2019 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 140W. The following information is based on satellite imagery, weather observations, radar, and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...TROPICAL WAVES... A tropical wave with axis along 87W and north of 05N to inland the central section of Nicaragua and the eastern part of Honduras is moving westward at about 15 kt. First visible satellite imagery shows a mid-level cyclonic circulation along the wave axis near 09N87W. Both latest TPW imagery animation and satellite imagery depicts this wave within a very moist and unstable pocket of atmospheric moisture. The overall cloud envelop surrounding this wave is becoming quite symmetrical with time. Scattered moderate isolated strong convection is seen within 180 nm to the west of the wave axis from 08N to 10N, and also from 10N to 13N between 87W and 90W. The convection appears to be exhibiting signs of a developing banding pattern. Per the latest NHC Tropical Weather Outlook, low pressure is likely to form in association with this system during the next few days several hundred miles south of the southern coast of Mexico. Computer model guidance suggest that conditions appear favorable for gradual development of this system by late week and over the upcoming weekend while it moves in a westward to west-northwestward motion. A tropical wave with axis along 97W from 03N to 17N is moving westward at an estimated 24 hour motion of 10 kt. Latest satellite imagery reveals what appears to be a mid-level cyclonic circulation near 07N97W. The imagery indicated scattered moderate convection within 180 nm west of the wave axis from 05N to 09N. Isolated showers and thunderstorms are noted elsewhere from 05N to 10N between 95W and 100W. A tropical wave with axis along 105W from 03N to 17N is moving westward near 15 kt. This wave is moving through a very moist and unstable atmospheric environment. Latest satellite imagery shows scattered moderate to isolated strong convection west of the wave axis to 109W from 07N to 10N, and within 180 nm east of the wave axis from 05N to 08N. Some of these convective activity may contain strong gusty winds. A tropical wave with axis along 126W from 03N to 16N is moving westward at 10-15 kt. Per TPW imagery animation, this wave marks the leading edge of a large area of atmospheric moisture, that is gradually advecting westward. Latest satellite imagery shows scattered moderate to isolated strong convection within 120 nm east of the wave axis from 09N to 10N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1010 mb low over northern Colombia near 10N75W to southern Panama and westward to 09N79W to 09N90W and northwestward to 11N100W to 13N120W, then southwestward to 10N123W and to 09N136W, where overnight scatterometer data indicated that it transitions to the ITCZ and continues to 09N136W and to beyond the area at 09N140W. Scattered moderate to isolated strong convection exists within 120 nm north of the trough between 120W-124W, and within 90 nm north of the trough between 127W-130W. Scattered moderate convection is from 04N to 08N between 77W and 80W, within 60 nm south of the trough between 127W-129W, within 60 nm south of the trough between 108W and 111W, and also within 30 nm of a line from 09N111W to 10N114W. Additional convection is described above under the Tropical Waves section. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A weak pressure pattern over the forecast waters is allowing for generally light to gentle variable winds over these waters, except for gentle east to southeast winds south of 15N between 95W and 105W. Long-period southwest swell propagating through these waters is resulting in wave heights in the range of 5-7 ft. Long-period swell will gradually subside through the end of the week. Low pressure over the Great Basin area of the U.S. will deepen some on Tue providing impetus to the thermal Baja California trough. At the same time, high pressure ridging west of Baja California strengthens while it builds further to the southeast. The tightening gradient, will develop moderate to fresh southeast winds across the central Gulf of California early on Tue, and increasing to fresh to strong intensity over the northern part of the Gulf on Tue afternoon into Tue night. Southeast winds will increase to strong speeds across the remainder of the Gulf late on Tue night, then to north of 28N by Wed afternoon. These winds will then be confined to the extreme northern part of the Gulf late on Wed night before diminishing to fresh speeds early Thu and to moderate speeds Thu afternoon. Wave heights are expected to peak to or near 7 ft with these winds. Northwest swell will begin to propagate into the waters off Baja California Norte by early Tue afternoon and begin to mix with a southwest swell component, building waveheights to 8 ft. By Tue evening, the swell will consist of mainly a northwest component with wave heights of 8-9 ft. The swell will then begin to decay late Tue night, with wave heights expected to peak to 8 ft north of 27N and between 117W and 122W. By early Wed, the waveheights over this are will subside to just below 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough is located roughly along 09N-10N across the Central American offshore waters. Overnight scatterometer data indicated moderate southwest flow south of the monsoon trough, and moderate to fresh northeast winds to the north of the trough. Fresh to strong northeast to east winds began to pulse through the Gulf of Papagayo last night as the pressure gradient tightened some over the western Caribbean Sea. These winds will diminish to fresh speeds early this afternoon, then pulse back up to fresh to speeds early this evening and through Tue morning before diminishing back to fresh speeds early Tue afternoon. The pulsing of these winds will repeat through the rest of the week. Wave heights will peak to 8 ft with these winds. Long-period southwest swell continues to impact the forecast waters, with peak wave heights of 8 to 9 ft continuing over the Colombian and Panamanian offshore waters. These wave heights will gradually subside through this evening as the swell energy decays. REMAINDER OF THE AREA... The remnant low pressure of former Tropical Depression Four-E, is centered near 19N119W, with a pressure of 1011 mb. Ascat data from 0506 UTC last night revealed north to northeast moderate winds roughly within 240 nm of the low in the NW quadrant and northeast to east winds within 210 nm of the low in the NE quadrant. Wave heights in the range of 5-7 ft are occurring within these quadrants of the low. The low is forecast to open to a trough today and dissipate by early Tue afternoon. High pressure is centered north of the forecast area near 33N140W, with a pressure of 1025 mb. A ridge extends from this high center to 32N130W and to near 22N123.5W. The pressure gradient between the area of high pressure and lower pressure in the vicinity of the monsoon/ITCZ is supporting moderate to fresh trades north of the monsoon/ITCZ to 22N and west of 122W. Wave heights over this area are in the range of 6-8 ft. Long-period southwest swell continues across much of the southern waters. Altimeter data passes from this morning showed wave heights of 8-9 ft over much of the area south of 15N and to the east of 120W. These wave heights will slowly subside through Tue. $$ Aguirre