High temperatures for inland areas of around 4 to 8 degrees above average through Friday will cool slightly to a few to around 5 degrees above average for early next week. Greater monsoonal moisture on Thursday and Friday and again around Monday of next week will bring a chance of afternoon showers and thunderstorms for the mountains and deserts. Night and morning low clouds will continue for the coastal waters into coastal areas.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
This afternoon, clear skies are prevailing across the region. The ridge is at its maximum westward reach today, yielding the hottest temperatures for the inland valleys this week. Widespread 100F to 105F readings are anticipated across the Inland Empire with mid to upper 90s in the interior valleys.
Highs Thursday may back off a degree or two, then remain very steady through early next week, only fluctuating by a degree or two each day. Today through early next week, highs will hover around 109-113F in the lower deserts with persistent areas of Major HeatRisk as a result of overnight lows only falling to the mid/upper 80s, about 5- 8 degrees above average.
The center of the ridge retracts slightly eastward, spinning around the Four Corners region and opening the door for monsoonal moisture. Around a 15-25% chance for afternoon isolated showers and a t-storm Thursday and Friday over the mountains, with lesser chances over the weekend as the ridge axis moves south and PWAT's decrease. Chances for more scattered shower/t-storm activity increase again early next week as the GFS shows the ridge access rotating and potentially re- opening the door to more mid-level moisture.
Throughout the forecast period, the marine layer will be fairly shallow, between 1,000-2000 feet deep, as the influence of the ridge continues. Low clouds should develop and push up to 20 miles inland as they typically do in the evening, except for nights with greater high cloud coverage, which could delay the formation of low clouds.
191130z. Coast, Low clouds with bases near 700-1200 ft MSL will be patchier this tonight. Some clouds will move inland after 06Z Thu. with a more uniform cloud coverage pattern in San Diego county after 10Z. Cigs scattering after 14Z Thu.
Otherwise, mostly clear today and tonight.
No hazardous marine conditions are expected through Sunday.
Ca, Heat Advisory until 8 PM PDT Thursday for San Bernardino and Riverside County Valleys-The Inland Empire.
Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
