Hurricane Hilary Impact Warning

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Date: Aug 17 , 2023

Hazardous Condition Warning

Hilary will bring numerous hazards to SoCal starting this weekend with rogue waves possible during the day Saturday the 19th, and heavy surf that will follow. Rip currents will be a concern, as will rain, lightning, waterspouts, and wind effects. Warnings are not just for the coast and mariners, but inland areas could be severely impacted by Hilary as well. Caution is highly advised this weekend into early next week, especially for mariners, beachgoers, and anyone attempting the surf-zone. For inland areas, high winds and heavy rains warrant preparation now.

Water Contact Advisory

Rain is expected from Hilary starting this weekend into early next week. This will increase the risk of bacterial contamination in the surf zone from runoff. As a reminder, there is a risk of increased bacteria levels for at least 72 hours following any measurable rain-event (usually 0.1" or more) during which time water contact should be avoided.

Surf Forecast

Hilary is rapidly intensifying, and models have converged quite well with consensus on a path that will take her across Baja, through inland SoCal, and up into Nevada.  Strong winds should persist when Hilary reaches the US/MX border and heavy rain would ensue. Although the centMap

Description automatically generateder of Hurricane Hilary would house 45' seas, it will be angled from a steep SE angle, sparing much of the SoCal coastline from damage, but Baja will take a direct hit. This course will also make for a significant difference in wave size depending on the varying exposure of south facing beaches. the initial major impact from Hilary's swell should hit SD late in the day Saturday the 19th (by early evening) and spread northward overnight. All areas should see major swell from Hilary Sunday the 20th. At Hilary's peak on Sunday the 20th, beaches with SE exposure would see sets running double overhead, with some triple overhead waves possible (16' face heights). However, west facing beaches (Del Mar to Encinitas) should be much smaller. Nevertheless, there is the strong potential for larger rogue waves at times everywhere. The swell from Hilary should continue in the morning Monday the 21st and back off later in the day. Conditions may be less than favorable from Hilary as we will face weather and wind issues. San Diego should see the brunt of the winds, but all of Southern California will be affected. This could make for very stormy weather Sunday the 20th into Monday the 21st, trashing conditions, and increasing other hazards in the surf zone.
 

Weather Outlook

A cut-off low continues to meander off Southern California as high pressure moves east. This is enhancing the onshore wind flow, which will strengthen further Friday the 18th. At the coast, today and Friday look for AM marine layer, heavy fog in some spots. Saturday the 19th looks like a transition day Map

Description automatically generatedas Hilary approaches clouds will increase from south to north. By the afternoon the first of three bands of rain should take a swipe at San Diego and Orange County. A second band of rain is expected sometime overnight that would reach SD and OC after midnight. The bulk of the rain is expected to reach all of SoCal overnight Sunday into Monday, with rain being very heavy at times, lasting through most of the day Monday the 21st. Here are the totals once again starting Saturday the 19th through Monday the 21st: SD, OC, and LA coasts are looking at 2-3" of rain; Inland deserts and mountains could see upwards of 8" of rain. Thunderstorms are highly likely during this time, which could produce very high rain rates at times. Waterspouts (and inland tornadoes) are not out of the question. The rain should clear late Monday the 21st into the morning Tuesday the 22nd. Sunday the 20th should see winds pick up early as Hilary hits SoCal. Her counterclockwise spin around SoCal will bring in a variety of N, NE, E, and SE winds. Wind speeds could easily reach 25 mph Sunday morning. Monday the 21st should see southerly winds from Hilary, running 15-20 mph in most spots in the morning, lasting for most of the day. Winds should calm Tuesday the 22nd but still hold a southerly element.)