Marine Weather and Tide Forecast for Newport Beach, CA

DISCUSSION
FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

A persistent area of high pressure will remain over the western United States through the weekend. The position of the high through Wednesday will allow for a shallow influx of moisture into the lower deserts, which may taper daytime highs but elevate overnight lows.
The high is expected to strengthen Thursday through Saturday, bringing widespread moderate HeatRisk to the Inland Empire and mountains and areas of major HeatRisk to the deserts.

High temperatures through Wednesday will generally be within a few degrees of average. Thursday through Saturday highs will be above average near the coast to 5 to locally 10 degrees above average for some inland areas. Low temperatures will also run above average, most noticeable in the mountains and deserts where lows will be 10 to 15 degrees above average. For the Inland Empire and mountains, the widespread moderate HeatRisk indicates that folks who are sensitive heat, especially those without consistent cooling/hydration, will be most impacted. In the deserts, major HeatRisk indicates anyone may see negative impacts from the heat if precautions aren't taken. Make sure to stay hydrated and if possible avoid strenuous activity during the hottest parts of the day (10 AM to 4 PM).

For Sunday through Tuesday, the high pressure will begin to slowly weaken with the flow aloft becoming more southeasterly. This would allow for some additional influx of monsoonal moisture into the area and bring a 15 to 20 percent chance of showers and thunderstorms to the mountains each afternoon. Ensemble guidance show precipitable water values and instability peaking Sunday and Monday. Current forecast follows the NBM which has chances each afternoon, with most widespread coverage Sunday and Monday.

AVIATION
041800Z
Coasts/Valleys
Low clouds eventually scattering out along coast by 20Z, but with patches persisting. Low clouds around 1000 feet MSL will redevelop over coastal areas 02-05Z and into western valleys overnight. Inland vis reduced 1-5SM. Scatter out Wednesday 16-17Z.

Mountains/Deserts
Mostly clear skies and unrestricted VIS through Wednesday morning.

MARINE
No hazardous marine conditions are expected through Saturday.

SKYWARN
Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.



SGX WATCHES/WARNINGS/ADVISORIES
CA...Heat Advisory until 8 PM PDT Saturday for Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains.

Extreme Heat Warning until 8 PM PDT Saturday for Apple and Lucerne Valleys-Coachella Valley-San Diego County Deserts- San Gorgonio Pass near Banning.

PZ...None.