16/1218 AM.
A significant heat wave will continue to affect the region this week, peaking Wednesday through Friday for most areas. There is a HIGH risk for heat illness this week, with conditions remaining warm overnight adding to the heat risk.
(tdy-Wed), 16/247 AM.
THE HEAT EVENT THIS WEEK IS FORECAST TO BE A HISTORIC MARCH EVENT, LIKELY BREAKING MANY DAILY AND EVEN MONTHLY TEMPERATURE RECORDS.
There will be a high risk for heat illness for everyone - especially locations away from the coast. If you or someone you know is at risk for heat-related problems, please make cooling plans now for the rest of this week. Locate where the nearest cooling center is near you, make sure to have plenty of hydrating liquids nearby to consume through the week, and check in on neighbors and loved ones. Stay inside air- conditioned rooms if possible, and avoid going outside or working outdoors, especially between the hours of 10am and 5pm. NEVER leave any person or pet inside a car without air conditioning, as temperatures inside a car without adequate cooling can turn deadly within minutes. Know the signs of heat illness, heat stroke, heat exhaustion.
As previously expressed, the long duration heat wave continues across the region through this week, peaking Tuesday through Friday, with warm overnight temperatures providing little relief.
Why are we having this heat event? Very strong high pressure will be camping out over the region (while ever-so-slowly drifting southeastward), strengthening from 588 dam heights today to 590-594 dam through Friday. At the surface, weak diurnal flow (offshore night/morning and onshore afternoon/evening) is forecast.
What makes it historic? 590-594 dam heights are extremely rare for March. Based on the local LOX Temp Study (going back to 2006), 500 mb heights have previously topped out around 586 dam, which current projections for 500 mb heights are expecting to exceed these heights by 4-8 dam. Remember, higher pressure typically leads to warmer temperatures (at least away from the coasts or when surface pressure gradients are on the weak side). Temperatures will be 20-35 degrees above normal by Thursday and Friday. Locations across the region are forecast to break daily records, and potentially even all- time March records (any day in March).
Today, temperatures will climb into the 80s to mid 90s for all areas. These temperatures will be 15-30 degrees above normal for this time of year. Based on Heat Risk calculations, HEAT ADVISORIES still look good for all coastal and coastal valleys as well as the mountains.
For Tuesday and Wednesday, the heat will continue to build as the upper level high pressure strengthens. For areas away from the coast, temperatures will climb into the mid 90s to low 100s. However, across immediate coastal areas, high temperatures are a bit more uncertain due to their dependence on the surface pressure gradients and are currently forecast to be in the mid 80s to mid 90s. With this in mind, EXTREME HEAT WARNINGs will go into effect Tuesday morning through Friday for all coastal valley zones (except the Santa Ynez Valley), the mountains as well as the interior LA coast. For the remainder of the coastal zones, as well as the Santa Ynez Valley, HEAT ADVISORIES will continue through Friday. However, if the offshore gradients are a bit stronger than forecast, some of these coastal zones could be pushed into warning levels.
As previously mentioned, overnight lows will continue to be on the warmer side, also increasing in temperature each night, like the high temperatures, adding to the heat stress.
(Thu-Sun), 16/247 AM.
You guessed it (or read it above), the heat will continue through Friday, due to the very strong upper level high pressure continuing to slowly drift southeast. There will be a few degrees of warming on Thursday compared to Wednesday, but the overall range of 90-103 degrees remains the same, with 80s and 90s at the coasts and Santa Ynez Valley. Overnight temperatures will peak Wednesday night through Friday night, with the risk of heat illness remaining high. Thus, Extreme Heat Warnings and Heat Advisories will continue through Friday. Again, as mentioned in the short term discussion, depending on the strength of the surface pressure gradients, some coastal zones could bump up to warning levels on Thursday and Friday. So, will continue to monitor that potential very closely.
Saturday and Sunday, models suggest that the high pressure will start to flatten out, and temperatures will finally start to decrease again. For Saturday, there is a 50% chance that some heat products will need to extended through the evening hours, mainly inland from the beaches. However by Sunday, things should cool down rather noticeably. Therefore, no heat products are anticipated.
As for rain chances, deterministic models (and their respective ensembles) indicate some possibility of light showers after the 25th. However, no significant storms are indicated for Southern California through the end of the month.
16/0613z.
At 0533Z at KLAX, the marine layer was 500 ft deep. The top of the inversion was at 2000 ft with a temperature of 25 C.
Overall, moderate confidence in 06Z TAF Package. Timing of CIG/VSBY restrictions may be off +/- 2 hours and flight minimums by one cat.
KLAX, Moderate confidence in TAF. Arrival and clearing times of CIGs may be off +/- 2 hours. CIGs: 003-008 with 2-4SM expected. 20% chance of VLIFR conditions: 001 & 1/4 SM. High confidence that any east wind component will be below 7 kts.
KBUR, High confidence in VFR TAF.
16/216 AM.
Conditions are expected to remain benign through at least mid- week across all waters. The only exception could be offshore gusty winds at times across nearshore favored locations. These winds will likely remain below Small Craft Advisory (SCA) levels. Moderate chances for SCA level winds starting either Thursday or Friday across the northernmost outer waters.
Dense fog is possible at times this week.
Ca, Heat Advisory remains in effect from 10 AM this morning to 10 AM PDT Tuesday for zones 87-88-340>342-345>358-362-366>376-378>380-548. (See LAXNPWLOX). Heat Advisory now in effect from 10 AM Tuesday to 8 PM PDT Friday for zones 87-340-341-346>350-354-355-362-366-367-549-550. (See LAXNPWLOX). Extreme Heat Warning in effect from 10 AM Tuesday to 8 PM PDT Friday for zones 88-342-345-351>353-356>358-368>376-378>380-548. (See LAXNPWLOX). Beach Hazards Statement in effect through Wednesday evening for zones 354-362-366. (See LAXCFWLOX). PZ, Small Craft Advisory in effect until 3 AM PDT early this morning for zones 670-673. (See LAXMWWLOX).
