000 AXPZ20 KNHC 082205 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Apr 08 2020 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A trough axis extends from A 1008 mb low over northwest Colombia westward to across northern Panama, to the Costa Rican/Panamanian border, then southwestward to 08N90W and to 05N97W, where the latest scatterometer data pass indicates that the ITCZ begins and continues to 05N104W. It is briefly interrupted by a trough that extends from 12N105W to 07N106W and to 01N106W before resuming at 06N109W to 05N120W to 04N130W and to 04N140W. Scattered moderate convection is within 120 nm south of the ITCZ between 124W-127W, and within 60 nm north of the ITCZ between 114W-122W. A trough extends from 12N105W to 07N106W to 01N106W. Scattered moderate to isolated strong convection is within 180 nm east of the trough from 07N to 09N, and also within 60 nm west of the trough from 06N to 08N. Scattered moderate convection is seen within 60 nm of 09N102W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A cold front extends from a 1008 mb low that is located over California/Nevada border, south-southwestward to over the northern Gulf of California and continues to the eastern Pacific waters near 22N120W. An anomalously large and deep upper-level low moving slowly eastward is identified to be just north of the area near 33N120W. The short-wave trough earlier noted within the eastern periphery of the low has lifted. However, plenty of instability and Pacific moisture wrapping around the low is leading to scattered showers over the waters north of 30N and east of 122W to southern California. This activity is expected to last through late Fri as the upper-level low advances inland the southwestern United States. Meanwhile, a high pressure is building southeastward in the wake of the front. The earlier fresh to strong southwest winds that were preceding the front over the northern Gulf of California diminished to moderate to fresh speeds this afternoon. Gentle to mainly moderate northwest to north winds continue from Baja California Sur to near Cabo Corrientes, including the southern Gulf of California. Light to gentle northwest to north winds remain elsewhere across these waters. Over the open waters off Mexico, wave heights are in the 5-6 ft range. Wave height are in the 4-5 ft range over the northern Gulf of California, and 2 ft or less over the remainder of the Gulf of California. The cold front will move inland northwest Mexico tonight and farther inland Mexico through Thu evening while weakening. As the ridge builds toward Baja California, fresh to locally strong northwest winds will develop off the west coast of Baja California Sur and offshore Cabo Corrientes beginning tonight and through Thu. The winds off the west coast of Baja California will diminish to mainly fresh speeds Thu, while the winds offshore Cabo Corrientes change little through late Sat. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The earlier fresh to strong northeast to east winds across the Gulf of Papagayo have diminished to mainly fresh speeds. These winds are again expected to late tonight, with wave heights reaching a peak of 8 ft. This occurrence of these winds will be rather short-lived as they will diminish to fresh speeds early Thu afternoon. Elsewhere light to gentle winds prevail. Outside the Gulf of Papagayo, wave heights are in the 5-6 ft range. Very moist southerly flow is expected to gradually increase south of the trough, while at the same time a large scale upper- level disturbance is forecast to move across the eastern Pacific and the southern section of Central America into the middle of next week. These ingredients appear favorable to possibly promote locally heavy rainfall over sections of southern Costa Rica, Panama, western Colombia and northwest Ecuador during this time period. REMAINDER OF THE AREA... A cold front extends from the northern Gulf of California southwestward to across central Baja California and to near 22N120W. High pressure is building southeastward in the wake of the front. The pressure gradient between the area of high pressure and lower pressure in the vicinity of the ITCZ is creating an area of fresh to strong northeast to east trades from about 12N to 16N and between 122W and 129W as was noted in a recent Ascat pass. Wave heights within this area of winds are in the 8-10 ft range. Moderate to fresh northeast to east trades are elsewhere from 08N to 24N and west of 115W, where wave heights are in the 6-8 ft range. Elsewhere, trade winds are in the gentle to moderate range, with wave heights of 5-7 ft. With the high pressure building southeastward through Fri night, the related gradient will maintain the fresh to strong northeast to east trades until then, but from the latest model guidance it appears the areal coverage will be shrinking. On the Fri, the wave heights to 10 ft are expected to subside to 8 ft in a mixture of northeast, southeast and northwest swell. A trough, supported by a sharp mid to upper-level trough extends from 12N105W to 07N106W to 01N106W. Scattered moderate to isolated strong convection is within 180 nm east of the trough from 07N to 09N, and also within 60 nm west of the trough from 06N to 08N. Scattered moderate convection is seen within 60 nm of 09N102W. Ample deep layer moisture is streaming northeastward with an upper-level jet stream branch that rounds the base of a broad upper trough that found to the north of 30N and east of 122W. This jet stream branch stretches southwest and west from 32N115W to 22N123W to 20N130W and to west of the area at 20N140W. The noted moisture consists of overcast multilayer clouds from 17N to 25N and east off 120W. Similar moisture is observed from 12N to 19N west of 120W. Areas of rain with scattered showers and possible isolated thunderstorms may be underneath these clouds. $$ Aguirre