AXPZ20 KNHC 240955

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Jul 24 2017

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 0600 UTC surface analysis and satellite imagery through 0900 UTC.


The Eastern Pacific region remains very active with three tropical cyclones: from east to west, Hurricane Hilary, Tropical Storm Irwin and Tropical Storm Greg. So far in July, five named storms have developed.

Hurricane Hilary is centered about 300 nm S of Manzanillo Mexico near 14.0N 103.8W at 2 am PDT, moving WNW at 7 kt. Estimated minimum central pressure is 990 mb. Maximum sustained winds have increased to 65 kt with gusts to 80 kt. Numerous moderate scattered strong convection is within 120 nm of the center. Conditions are favorable for significant strengthening during the next 24 to 48 hours, and Hilary is forcast to become a major hurricane on Tuesday as it continues on a WNW track about 200 to 250 nm west of the Mexican coast for the next couple of days. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4 WTPZ24 for more details.

Tropical Storm Irwin is centered near 14.8N 117.4W at 2 am PDT, moving W at 4 kt with a minimum central pressure of 1001 mb. Maximum sustained winds remain 45 kt with gusts to 55 kt. Scattered moderate isolated strong convection is from 12N to 17N between 114W and 119W. Irwin will remain in relatively close proximity to Hilary the next few days. Gradual strengthening is expected during the next 48 hours, and Irwin is forecast to become a minimal hurricane in about 24 hours. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5 WTPZ25 for more details.

Tropical Storm Greg is centered near 14.4N 132.1W, moving W at 10 kt. Estimated minimum central pressure is 1003 mb. Maximum sustained winds are 40 kt with gusts to 50 kt. Scattered moderate to strong convection is within 90 nm of the center. Greg is forecast to gradually weaken during the next 24 to 48 hours, becoming a remnant low by Thursday. See the latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2 WTPZ22 for more details.


A tropical wave north of 06N along 90W is moving west at 10 to 15 kt. Scattered moderate isolated strong convection is within 60 nm W and 30 nm E of the wave axis from 06N to 09N.


The monsoon trough is analyzed E of the tropical cyclone activity from 09N85W to 11N100W. The ITCZ extends from 10N135W to beyond 08N140W. Scattered moderate and isolated strong convection is noted within 60 nm either side of the monsoon trough axis between 93W and 100w.



Gentle to moderate NW winds off the Baja California peninsula are expected to continue through mid-week, as high pressure remains centered N of the area. Seas will remain 4 to 7 ft in a mix of long period north and southwesterly swell. Gentle southerly flow will generally prevail in the Gulf of California, except for moderate southerly flow over the northern Gulf.

Moderate E to SE winds are expected across most of the area between just west of Tehuantepec and Acapulco through early Mon. Nocturnal fresh northerly winds are forecast over the Gulf of Tehuantepec Tuesday through Thursday nights. Hilary is expected to impact the offshore waters beyond 200 nm off the coasts of Oaxaca, Guerrero, Michoacan, Colima and Jalisco through Tue, then pass south of the Revillagigedo Islands Wed as a major hurricane.


Across the Gulf of Papagayo, expect fresh winds each night with the assistance of the nocturnal drainage flow through the week, occasionally building max seas to near 8 ft in a mix of east wind waves and long period southwest swell.

Gentle to moderate S to SW winds are expected across the forecast zones. Long period cross-equatorial SW swell creating 5-7 ft seas will continue to propagate into the forecast waters through mid week. Another set of cross-equatorial long period SW swell of 6 to 9 ft will reach the waters between Ecuador and the Galapagos Islands late Wednesday, and the coast of Central America on Thursday.


High pressure is located north of area with a ridge axis that extends across the forecast waters north of 20N. The pressure gradient between this system and an active zone of tropical cyclones between 12N and 20N will maintain fresh N to NE winds W of 125W through mid-week. Seas associated with T.S. Greg are already propagating across the waters N of 20N W of 130W. By Thursday night, cross equatorial southwesterly swell of 8 to 9 ft will spread over the waters south of 10N and east of 110W, persisting into next weekend.

$$ Mundell