PM Update by Dave Hovde, KSBY Chief Meteorologist:
New modeling and the new outlooks from the National Hurricane Center take Tropical Storm Kay off to the west faster than prior forecasts.
It also looks to continue to weaken. This track adjustment will impact rain projections. The model trends are down in terms of rain potential. Thus far, I have not adjusted my forecast much...still going with light to .70" for coastal areas with foothills .25-1" and mountain areas having higher potential but mostly across SoCal.
Why is my forecast unchanged? Because I have the low end very low, at light accumulations. Why keep the higher .70" end? Because some of the activity is convective (t-storms) which can cause isolated areas of higher rain rates and accumulation. I also think the amounts will vary a lot across the area because modeling is showing scattered rain and thunderstorms and thundershowers. Scattered means like what it sounds...you get areas of activity bounded by areas where no or almost no activity occurs, and the activity is also quite on and off. Folks often ask, when will it rain exactly? The forecast is for scattered activity Friday into Monday. Saturday should see the most activity but since it is on and off folks need to be ready for activity to pop up during the entire period.
——-the following is from the earlier article———
Our heat wave began on Aug. 31st in the interior and grew to encompass much of the Central Coast in above-average temps. The interior has seen temps 100+ that entire run. The heat remains on into Friday then fades over the weekend but in exchange for some rare tropically-related rain potential.
Today Paso Robles set another daily record topping at 108, the standing record of 106 only stood for 1 year. Elsewhere temps remained above average with 100+ also in New Cuyama and Santa Ynez.
The excessive heat warning that has been in place for the interior since last week is expected to expire tonight at 8pm. However, there is another excessive heat warning posted for Central Coast valleys for Friday. Currently, I expect temps to come up at coastal locations a little but with some offshore winds it is entirely possible that extreme heat could develop in coastal valleys. Currently, beaches are not in the warning but if offshore and downsloping winds develop even beaches could get hot. Right now I have beaches warm in the 70s and 80s.
The heat will abate this weekend. High pressure breaks down a bit but a huge factor are the leftovers of Kay. This afternoon Kay was a hurricane but it is now back to tropical storm strength as it hits some cooler waters less favorable to maintain strength.
There is so much moisture associated with tropical systems that significant impacts can happen even if no landfall takes place, that is the case here. The track will take the tropical storm further north before it turns west then south as it continues to weaken into a tropical depression, then just a post-tropical low.
The track and rain potential are closely related. The last few days have seen rain modeling all over the place. At times rain forecasts have ranged from light to several inches of rain. The current outlooks mostly place the heaviest rains in Southern California and also at higher elevations in SoCal, where inches of rain are possible and flood advisories are already posted for that potential.
The further north you go the less rain potential we see. Locally, I like light to .70" of rain for most of the coast and beaches with more likely in some foothills and inches possible in mountains, but more likely those higher amounts are in mountains out of the area (but can't be ruled out locally). This part of the forecast could still change. Since the storm still has winds of 70+ there is plenty of energy going into the water so the Southcoast will likely see waves of 4-7ft. and a high surf advisory is in place. No rain or flood advisories are currently posted for the Central Coast.
The rain can come in the form of scattered showers, thundershowers, and thunderstorms. In terms of timing, we could see activity as early as Friday and some diminishing activity is still possible Monday. I know folks would like specific times for any rain potential but in this case with the chaotic flow of circulation around Kay (and its remnants) folks should be ready for rain essentially at any time over the weekend even though it will likely not rain for long periods of time.
Temps drop dramatically to normal and even below average due to the system, and clouds. The good news is that milder temps look to linger all of next week.
Thursday is drought and lakes day at KSBY. The US Drought Monitor showed no week-to-week change, which is somewhat interesting in that after a week of excessive heat we didn't see any change. Lakes continue their seasonal drop. Some rain wouldn't hurt but would also be unlikely to make any huge changes in conditions at area lakes.