Marine Weather and Tide Forecast for National City, CA

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

Tonight through Wednesday...

The area of low pressure is continuing to slide slowly southward just off the coast of central California, and will propagate more eastward by later in the day, and eventually exit the region. Until then, there will still be a few lingering light to moderate showers, mainly west of the mountains. A general consensus of the high res models shows the precipitation completely coming to an end by early tomorrow morning. Any remaining showers should not amount to anymore than an additional tenth of an inch or less for the coastal areas to a quarter of an inch for the mountains, with the highest amounts expected for the western-facing coastal slopes and inland foothills. Clearing tonight will allow for temperatures to cool off efficiently, and lead to our coldest night in recent months, with lows dipping down into the upper 40s to lower 50s for some of the higher inland valleys. With antecedent rainfall, there could also be some areas of patchy radiational fog also developing within some of the higher valleys. High pressure will build in over the region through tomorrow, with a gradual warming, although highs will still be running around 10 to 15 degrees below the seasonal average for most locations for this time of year for tomorrow due to the colder air advection behind the low. The marine layer for tonight will fill in slightly overnight, but remain rather broken and dispersed, with a few isolated showers still being possible through the early morning hours tomorrow.
Skies will further clear by tomorrow afternoon as the upper level low pulls away from the region, with drying conditions establishing themselves as we begin to transition into Santa Ana conditions.

Thursday through Monday...

High pressure is going to begin to build in over the Great Basin as the upper level low becomes stalled out over the Four Corners Region. This will begin to establish Santa Ana conditions. By Thursday, highs will still be slightly below average for the mountains and deserts, although around average, and even slightly higher for the coastal locations as offshore winds settle in over the region. By Friday, a strong supergradient jet maxima at the 300 mb level is going to move in from the north over central CONUS, and force the U/L low to cut off and retrograde back towards the southwest. This will help the enhance the offshore winds on Friday into early Saturday, with some of the coastal and inland basins climbing to afternoon temperatures being as much as 15 degrees above average for Friday afternoon, and possible return of Moderate HeatRisk returning to portions of these locations. Winds will also be rather strong and gusty for some of the higher terrain and within mountain canyons and passes, and there might even need to be Wind Advisories issued for a few locations, which will be decided in the next day or two once there is better agreement and confidence as to where these winds will be. RH values will drop on Thursday, but then slightly increase on Friday as the retrograded low taps into some subtropical moisture to the south. However, fire concerns with the strong and gusty easterly winds will remain elevated for both days. These winds will begin to subside going into the upcoming weekend, as max temperatures begin to flatline a bit, with a gradual cooling occurring each day into early next week. There will also be a very slight chance of precipitation for the mountains and deserts during the afternoon hours on Friday as a result of some moisture being introduced, along with a slight increase in instability, yet this will likely remain east of our CWA The return of onshore flow going into late Saturday/early Sunday may result in the onset of some areas of dense fog during the early morning hours. Otherwise, conditions look to be rather tranquil in comparison as weak ridging returns over the region, with the transition back into more zonal flow and troughing upstream becoming the predominant features going into the early part of next week.

AVIATION
121730Z
Coast/Valleys
SCT -SHRA will continue today with cigs 2500-3000 feet MSL in -SHRA, otherwise bases 3500+ feet MSL.
-SHRA tapering off and gradually scattering out after 03Z KSNA/KONT and after 14Z Tuesday at KCRQ/KSAN.

Mountains...SCT -SHRA will continue through 12Z Tue. BKN-OVC MVFR cigs and obscured terrain will linger into Tue AM, with occasional vis 2-5 SM with -SHRA. Clearing north (~07Z) to south (~12Z) tonight.

Deserts...BKN clouds based around 5000-7000 ft MSL through around 22Z. SCT clouds AOA 10000 ft MSL through Mon PM.

MARINE
No hazardous marine conditions are expected through Saturday.

BEACHES
High tides will slowly decrease but remain above 6.5* ft through the Thursday high tide at 12 PM. A persistent south swell from 190 degrees with a period of 16 seconds and a west swell from 290 degrees with a 13 second period will generate surf of 4 to 6 ft, with local sets to 7 ft through Thursday, with highest surf through Tuesday. Minor coastal flooding remains possible through Thursday, becoming more localized after Tuesday. Check the Coastal Flood Advisory for details.

*Tide predictions have been corrected to reflect current trends in actual tide observations.

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



SGX WATCHES/WARNINGS/ADVISORIES
CA...Coastal Flood Advisory until 2 PM PDT Tuesday for Orange County Coastal Areas-San Diego County Coastal Areas.

PZ...None.