000 AXPZ20 KNHC 091603 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Jul 09 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 93W north of 03N to 16N is moving westward at 15-20 kt. A 1011 mb low is located along the wave near 10N93W. The wave is embedded within a very moist atmospheric environment as depicted by the total precipitable water satellite animation (TPW) and by conventional satellite imagery. This wave has a good track history as it moved across the Caribbean Sea and into the eastern Pacific waters. Scattered and disorganized moderate to isolated strong convection is observed within 180 nm east of the wave axis from 10N to 14N and within 120 nm west of the wave axis from 11N to 14N. Scattered showers and thunderstorms are within 180 nm west and 60 nm east of the wave axis from 05N to 08N. This activity is under favorable deep-layer shear and under rather pronounced upper- level divergence. The 1011 mb low accompanying this wave is forecast by the NWP models to acquire some gradual development as it tracks in a general west-northwest motion Thu through late Fri before it weakens to a trough afterwards. A tropical wave with axis along 116W from 01N to 14N is moving westward around 15 kt. This wave is moving through an environment of decreasing atmospheric moisture. Scattered showers and isolated thunderstorms are seen within 120 nm either side of the wave axis from 07N to 11N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northern Colombia near 09N75W to low pressure near 09N93W 1011 mb and to 08N115W, where latest scatterometer data indicated that it transitions to the ITCZ and continues to 07N110W to just east of the wave tropical that is along 116W at 08N115W. It resumes just west of the same wave at 08N118W and continues to 09N130W and to beyond 09N140W. Numerous strong convection is within 120 nm north of the ITCZ west of 138W. Scattered moderate isolated strong convection is within 180 nm north of the monsoon trough between 97W and 102W, and within 120 nm north of the ITCZ between 133W and 138W. Scattered moderate convection is within 120 nm north of the ITCZ between 102W and 106W, within 120 nm south of the ITCZ between 110W and 114W, and within 60 nm south of the ITCZ between 134W and 138W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad and relatively weak high pressure ridge remains to the west of Baja California. Overnight scatterometer data highlighted light to gentle northwest to north winds over these waters, with a few small pockets of moderate winds from 21N to 24N between 111W and 112W. Little change in the overall synoptic pattern is expected through Wed night. The ridge will strengthen slightly across the area Thu through Fri, with the associated gradient leading to northwest winds to the W of the Baja California increasing to fresh speeds. Gulf of California: The earlier fresh southwest gap winds over the northern part of the Gulf have diminished to mainly moderate speeds during the morning, with waveheights in the range of 3-4 ft. Over the southern portions, gentle to moderate west to northwest winds will shift to the southeast Thu and Fri as a surface trough deepens near Baja California. Gulf of Tehuantepec: Generally light and variable winds over the Gulf will continue through the remainder of the week, with waveheights in the range of 4-6 ft. Scattered to numerous showers and thunderstorms are moving across the eastern section of the corresponding offshore waters. This activity will continue to spread westward across these waters through Wed night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Scattered to numerous showers and thunderstorms across the offshore waters west of 88W are forecast to shift to the west of these waters Wed as the tropical wave currently along 93W pulls away from the region. Another set of long-period south to southwest swell currently will begin reach the equator on Thu, and continue to propagate through the Central American waters Fri and Sat, with seas building to 10 ft between Ecuador and the Galapagos Islands. REMAINDER OF THE AREA... The weakening post-tropical remnant low of Cosme is centered near 22N121W with a pressure of 1011 mb. Satellite imagery depicts the low as a 7 deg wide swirl of low and mid-level clouds. Isolated showers and/or patches of rain are possible within these clouds. Overnight scatterometer data showed 15-20 kt winds within 120 nm of the low center in the northwest quadrant. The earlier noted waveheights that peaked to 8 ft near the low have subsided to just below 8 ft. The low will continue on a northwest motion through Wed as it gradually opens up to a trough. The waveheights around the low will continue to subside through Wed night. The pressure gradient across the high seas domain remains weak. A persistent broad ridge centered just north of the area will shift slightly southeastward through the end of the week, and while a tropical wave continues on westward west of 120W. The resultant pressure gradient is expected to increase the northeast to east trades to mainly the moderate to fresh range across the trade wind belt. Waveheights may peak to 8 ft Thu through Fri west of about 120W from the combination of the increasing trades and prevailing predominate southwest long-period swell propagating through these waters. $$ Aguirre