, Issued at 1235 PM PDT Mon Oct 19 2026 (This evening through Tuesday night)
Morning marine layer mixed out giving way to mostly sunny skies this afternoon. Despite the increased insolation temperatures are much colder than yesterday. Definitely a far cry from last weeks heat. 24 hour trends this afternoon are 5 to 20 degrees colder with highs still on track to top out in the 60s to 70s (80s interior Central Coast).
Tonight through Tuesday afternoon will be the proverbial calm before the "storm". If we take a broader view of the EPac and West Coast one can see an active pattern with change in our sensible weather literally on the horizon. A robust 150kt upper level jet is diving southward from the Gulf of Alaska and rounding the base of an upper level trough off the PacNW as we speak. The cyclonic curvature of the jet is supporting upper level divergence, which in turn promotes surface cyclongensis. Or in this case, will further enhance the surface low already positioned off the PacNW. This surface low an associated upper level low are all upstream. In the meantime, it's a waiting game. Not expecting a marine layer tonight due to increasing surface pressure gradients and some marginal cold air advection. Don't be surprised to see some radar echoes off the N Bay Coast either today through Tuesday. These radar returns are elevated and tied to the upper jet max rounding the base of the digging trough.
For Tuesday the upper level trough deepens enough and eventually becomes cut-off from the mean flow. Any weather watchers know that upper level lows are tricky and can lead to lower confidence on timing/position since they're cut-off from the mean flow. For this upper low, confidence begins to decrease as some hi-res guidance begins to suggest two upper level vort maxes pivoting/rounding the base of the upper trough. With two vort maxes focus of best lift/dynamics becomes less certain. That being said, will carry a chance of scattered showers over the coastal waters through Tuesday afternoon. As for land locations, dry through Tuesday afternoon with seasonably cool temps: 60s and 70s.
Tuesday night into Wednesday morning, enough moisture and lift will be present with the nearby fully cut-off low to promote showers moving onshore. Still best dynamics remain offshore, but a few scout showers moving inland are plausible.
..issued at 130 PM PDT Mon Oct 19 2026 (Wednesday through next Sunday)
Wednesday will be an active day across the region as the upper level low wobbles off the Central Coast before moving inland late in the day. Solid upper level jet will fuel the main thrust with this system. In fact, one could even argue a little bit of phasing just offshore and through Point Conception during the day. As such, expect precip chc to become more widespread across the forecast area, but still main focus over the Central Coast. We've been advertising a chance (15-20%) of thunderstorms over the Central Coast waters and Central Coast. Current forecast keeps the low chance in the forecast. Taking a closer look at dynamics (still 48hrs out) this could end up being a lower CAPE high shear environment. So what does that mean? Possible low topped cells with some rotation. Given a solid lower level jet (under 850mb) we'll see a higher shear environment for CA standards. Combine the shear with some meager SFC and MU CAPE developed storms may rotate. Predicted hodographs are also elongated implying a deeper layer of shear. Greatest likelihood is near the Big Sur Coast Wednesday from 12-18Z. SPC does at least have this region in a general mention. Given the convective threat we'll be watching the Timber and Plaskett burn areas. If a developed cell moves over the right location it's within the realm of possbilities that a threshold will be met for debris flows. Very low conf high impact scenario, but wanted to at least mention it. The upper level low slowly loses upper level jet support and ultimately becomes an open wave late Wednesday into Thursday. As such, we'll keep precip chances in the forecast through Thursday. Rainfall amounts from Tuesday night through Thursday will generally be 0.05-0.25" and 0.25-0.75" Central Coast.
Drier weather returns by Thursday night as the now open wave moves eastward. Behind the departing system some form of ridging develops with a warming and drying trend heading into the weekend. Not expecting the heat we just had, but a few degrees above normal will be possible.
(18z TAFS) Issued at 1034 AM PDT Mon Oct 19 2026
Currently MVFR-VFR. Stratus is dissipating with VFR expected by the afternoon. High clouds are streaming in from the southwest and will increase in coverage through the TAF period. Onshore winds this morning and this afternoon will back through the TAF period to become southerly. While there's no precipitation in the TAFs, there is a chance for rain showers Tuesday, especially across the coastal waters. The incoming low pressure system will deepen and mix out the marine layer, likely keeping the terminals VFR after this morning.
Vicinity of SFO, Currently MVFR with westerly flow. High confidence in VFR prevailing by this afternoon. Westerly winds will diminish and begin to back this evening, becoming southeasterly overnight and northwesterly tomorrow afternoon.
SFO Bridge Approach, After this morning, the San Mateo Bridge Approach will likely remain clear of clouds below FL070.
Monterey Bay Terminals, Currently MVFR with westerly flow at MRY and MVFR with southerly flow at SNS. High confidence in VFR prevailing by this afternoon. Westerly winds will diminish and begin to back this evening, becoming southeasterly overnight.
(today through Saturday) Issued at 1034 AM PDT Mon Oct 19 2026
Moderate northwesterly breezes will prevail today with hazardous conditions for small craft along the Big Sur Coast through this afternoon and Monterey Bay this afternoon through this evening. Winds will diminish and back to a gentle southerly breeze Tuesday. Moderate northerly breezes will prevail Wednesday, increasing to become fresh to strong Thursday into Friday. Moderate seas will prevail with rough seas across the outer waters Tuesday and Friday. Rain showers with a chance of thunderstorms are expected Tuesday through Thursday, especially south of Pigeon Point.
Ca, None. PZ, Small Craft Advisory until 9 PM PDT this evening for Mry Bay.
Small Craft Advisory until 3 PM PDT this afternoon for Pt Pinos to Pt Piedras Blancas 0-10 nm.
