Modesto, CA 95358 Weather

Key Messages

- Chance for a shower over the Coastal Range this afternoon/evening.

- Widespread precipitation Tuesday through Thursday, with below normal temperatures, thunderstorm chances, and high elevation snow showers.

- Dry conditions return end of the week and into the weekend, followed by the potential for further unsettled weather.

Discussion

...Today through Thursday...

Current satellite and radar has an area of light showers over the Coastal Range this afternoon as a trough sits off the coast. This trough will continue to deepen and move onshore through Thursday. Today we will continue to see clouds move into the region with a broken cloud deck overnight. Temperatures will be in the upper 60s to lower 70s today and through the remainder of the week.

The main push of precipitation comes Tuesday evening as moisture from the south pushes through California. Snow levels will be above 9000 feet on Tuesday and drop to 8000-9000 feet Wednesday. Tuesday evening, we will see instability increase across the mountains and foothills, with up to 500 J/kg of CAPE and strong speed and directional shear. This fuels the chances for an isolated thunderstorms within the mountains and foothills. A few storms may be on the stronger side with small hail, gusty winds, and frequent lightning possible. As we move through Tuesday night into Wednesday precipitation chances becomes widespread across the forecast area, with increased chances for thunderstorms by Wednesday afternoon in parts of the southern Sacramento Valley, northern San Joaquin Valley, foothills, and mountains. Shear, instability, moisture, and lift are in better positions to initiate and sustain thunderstorms Wednesday afternoon/evening. A few storms may be on the stronger side Wednesday, with small hail, gusty winds, brief heavy rain, and frequently lightning being the main hazards. There is a low chance for a low top supercell to develop within the foothills and/or northern San Joaquin Valley where shear is more elongated and sustainable for supercellular development. We will continue to monitor the latest for thunderstorms Tuesday and Wednesday.

Snow levels start to drop to the 8000-9000 feet Wednesday, and a few inches are possible within the higher peaks of the Sierra predominantly south of Highway 50. Minor impacts are possible in eastern Tuolumne and Alpine counties Wednesday and potentially into Thursday as the system lingers across the area. Thunderstorm chances will again be possible Thursday, but remain in the foothills and Sierra where lift is more sustainable for the growth and development.

...Friday and onward...

The system moves out of the southwestern United States Friday and Saturday, with a return to dry conditions for the area. This doesn't last long as ensemble guidance continues to show an unsettled pattern redeveloping across the western United States bringing the potential for more precipitation to parts of California. Temperatures during this time remain below average for this time of year. Uncertainty arises with the development, timing, and strength of any precipitation end of the weekend and into next week.

Aviation

VFR conditions prevail across the region through the TAF period. There are some brief low clouds around the RBL site this morning, which will continue off and on through 19z. Otherwise, winds will be breezy at times, with a few gusts near the Sacramento sites to 20kts this afternoon/evening. Overnight clouds move in for all sites from the west as a system moves into the region.

Sto Watches

None.