SoCal Wx Update (4th of July)


#1

Overall as of the 4th of July, everything still looks pretty much on track for the SoCal Heat this weekend.

Strong ridge of high pressure will build over the desert Southwest the next few days, squashing the marine layer and bringing some very hot temperatures to the area. The warmup will begin in earnest tomorrow (Thursday) with weakening onshore gradients. Highs on Thursday will climb into the mid 90s to around 100 across the coastal valleys to the deserts. For Friday and Saturday, things will be even warmer with an increase in northerly offshore flow. For Friday, highs will range between 102 and 112 across the coastal valleys and out to the deserts. Even along the coast, highs on Friday will be in the 90s to around 100. On Saturday, temperatures west of the mountains may be a few degrees cooler as models indicate some developing low-level southeasterly flow. However inland areas will still warm an additional couple of degrees on Saturday. For Sunday into early next week, temperatures will being to cool off, but still remain noticeably above seasonal normals.

As for winds, we still are expecting some pretty gusty northerly winds to develop as the surface pressure gradients tighten. For Thursday night/Friday morning, Sundowner winds gusting between 35 and 45 MPH will be likely across southern Santa Barbara county while comparable northerly wind gusts through the I-5 Corridor. For Friday through Saturday morning, the northerly winds are expected to be bit stronger across southern Santa Barbara county and the I-5 corridor with some of the gusty north winds filtering down through the Santa Clarita and San Fernando Valleys as well as the Santa Monica Mountains. The winds should start to weaken through the day on Saturday.

Finally, just to add to the Fire Wx mix, there will be some increasing mid-level moisture across the area this weekend as the upper high is centered over the 4-Corners area. The threat of TSTMs will begin over the mountains and deserts on Saturday and will continue through Monday. The best chances of TSTMs will be during the afternoon and evening hours. At this time, models do not spit out much precipitation over the area with the potential convective activity. So, I would anticipate that any TSTMs that develop would be on the dry side, especially Saturday and Sunday.

Needless to say, this is shaping up to be a very interesting few days of Fire Wx. With the hot temperatures and northerly winds, widespread single digit RH will occur on Friday with some slight increase in RH on Saturday and Sunday. So, critical fire weather conditions will be possible in some areas of SoCal and FIRE WEATHER WATCHES remain in effect for southern Santa Barbara county as well as the LA/Ventura mountains and even the Santa Monica Mountains and Santa Clarita Valley. Additionally, any dry thunderstorms that develop could further exacerbate the situation. If any fires do develop, plume-dominated fire behavior will be likely, given the hot and unstable conditions.

Keep a heads up on the latest forecasts from the NWS and GACC.

Stay safe out there!!!

Wx_Guy


#2

Red Flag Warning now in effect for parts of SoCal…Heads up everyone!!!

…RED FLAG WARNING REMAINS IN EFFECT FROM 3 AM FRIDAY TO 6 PM
PDT SATURDAY FOR GUSTY NORTH WINDS, HOT TEMPERATURES, AND VERY
LOW RELATIVE HUMIDITY FOR THE SANTA MONICA MOUNTAINS AND SANTA
CLARITA VALLEY…

Winds…Areas of north winds 15 to 25 mph with gusts to 35 mph
except isolated gusts over 40 mph across the Santa Monica
mountains. Peak winds expected Friday morning into Saturday
morning.

Relative Humidity…Minimum humidities 2 to 6 percent on Friday
rising to 7 to 12 percent on Saturday. Very poor humidity
recovery Friday night.

  • Temperatures…Highs 102 to 112 degrees on Friday, 98 to 108 on
    Saturday. Lows Friday night 75 to 88.

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=sgx&wwa=red flag warning