Above average temperatures will prevail through much of the forecast period. The warmest conditions are expected Monday, with a gradual cooling to within a few degrees of normal Tuesday through Friday. Night and morning low clouds and fog will be present each day along the coast and into portions of the valleys. A gradual warming trend is possible next weekend.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, New Aviation Discussion for 00z TAF Package,
High temperatures today are expected to be a few degrees warmer than yesterday along the coast and up to 10 degrees warmer further inland. Warming will continue into Monday with an additional 3 to 7 degree increase compared to today. This will bring high temperatures 10 to 20 degrees above average for inland locations Monday and 5 to 8 degrees above average along the coast. Areas of widespread moderate HeatRisk are expected in the Inland Empire and High Desert with major HeatRisk in the low deserts through Monday. Make sure to stay hydrated and seek shade when possible if working outdoors.
Temperatures on Tuesday will cool 5 to 12 degrees compared to Monday as the ridge aloft weakens and is pushed east by a shortwave trough passing from our southwest. The passing shortwave will strengthen onshore flow for Tuesday and Wednesday, increasing south to southeast winds in the deserts on Tuesday and westerly winds from the mountain slopes into the deserts on Wednesday. This passing feature is not expected to have moisture associated with it so dry conditions will prevail.
For Wednesday through Friday, most ensemble clusters are showing a weak troughing pattern prevailing over the US West Coast. This will maintain marine layer low clouds and fog for the coast and valleys and take high temperatures back to within a few degrees of normal. For next weekend, the majority of ensemble clusters keep the upper level pattern weakly troughy to zonal, with only 10 percent of solutions showing weak ridging developing by next Sunday. The forecast for next weekend follows the NBM which indicates a gradual warm up for Saturday and Sunday. There remains low confidence in just how warm it will get with the deterministic NBM again representing the highest percentiles of most other ensemble guidance.
110000z, Coast/Valleys, Satellite shows low clouds hanging along the coastline, poised to move up to 10-15 miles inland beginning 01- 03z. Bases near 1000-1300ft MSL, will slowly fall through the night closer to 700-900ft MSL by 09-12z. Lower confidence in clouds reaching KONT (20%) compared to this morning, TEMPO in for brief FG. VIS reductions 4-6SM in BR for higher coastal terrain, with locally 1-3SM for interior valleys. Bases likely lifting back above 1000ft MSL by 14-15z, with full scattering back offshore by 16-17z.
Mountains/Deserts, SKC and VFR through Monday. Gusts 20 to 30 kts along desert slopes (up to 40 kts through the Banning Pass) through 06z Mon.
No hazardous marine conditions are expected through Thursday.
Ca, Heat Advisory from 10 AM to 8 PM PDT Monday for San Bernardino and Riverside County Valleys-The Inland Empire.
Extreme Heat Warning until 8 PM PDT Monday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
