| Day | Date | High/Low | Forecast |
| Mon | 9th | 77/59 | Mostly cloudy through the evening with high clouds. |
| Tue | 10th | 67/52 | Mostly cloudy through the evening. Chance of showers early evening; Rain likely by late evening. |
| Wed | 11th | 63/50 | Mostly cloudy day with a chance of showers, mainly morning. Becoming partly cloudy in the evening. |
| Thu | 12th | 64/50 | Partly cloudy day. Mostly clear evening. |
| Fri | 13th | 69/51 | Sunny day. Mostly clear evening. |
Synopsis
Although low level, off-shore flow prevails today (reason for one more day of warmer than normal weather), at upper levels, a sub-tropical jet stream is directing considerable high clouds to California. By tomorrow, the high pressure aloft that has promoted the off-shore flow will get depressed to the south (low level transition back to more typical, on-shore flow). In addition, a large, upper level trough will approach from the west. Cloud cover should get thicker as the day progresses (on-shore flow should help promote return of marine layer, low clouds too). At some point tomorrow, light showers (marine layer induced) may develop (not expected in L.A. County before the evening hours).
The various, computer models have trended a little wetter and slower with the approaching trough. Last week, the model consensus favored a Monday night-Tuesday morning precipitation. Now, this looks to be delayed to Tuesday evening (probably late hours). A period of steady rain in the L.A.Basin is expected in the overnight hours (pre-dawn hours Wednesday). There is a chance for brief duration moderate to heavy intensity rain as a cold front passes through (moving from west to east). Predicted, atmospheric instability looks marginal for isolated, brief-lived thunderstorms. By sunrise Wednesday, the steady precipitation should have moved to the east of L.A. County. However, the upper level, trough axis should remain to the west of the Southland, and that should permit instability showers to occur (most numerous near/over the mountains). If the storm doesn’t move eastward too slowly, the threat of showers should end by Wednesday evening (including mountain areas in L.A. County).
Storm totals in lowlands away from the mountains should be in the 0.30-0.75 inch range (up to twice as much for around some coastal facing, mountain slopes). Snow levels should lower to 6000 feet or slightly lower by Wednesday. A few to several inches of snow could fall at higher elevations, depending on how numerous instability showers end up being.
A second disturbance following the first storm should head toward southern Baja California. So, Thursday should be no worse than partly cloudy (temperatures still a little cooler than normal though). Friday is currently predicted to the sunniest day this week. Daytime temperatures should get slightly warmer than normal that day, assuming a marginal off-shore flow develops as most models predict.
Cloudier weather is anticipated on Saturday (Valentine’s Day), but the current model consensus keeps the Southland dry (at one time, a chance for showers existed for the evening hours). A chance for wet weather may return for Sunday, but a number of model solutions have delayed any onset of wet weather to Sunday evening or even Monday morning (Presidents’ Day). At the very least, cooler and cloudier weather should develop over the holiday weekend.
Based on the latest model forecasts, multiple days of wet weather in southern California looks probable next week (starting Monday at the latest). A large, cold trough is forecast to set up just off the state coast. Multiple disturbances should promote periods of showers Monday through at least Wednesday (16th-18th). A day or two of dry weather may prevail, but more wet weather could follow toward the end of next week. Details of the predicted storms remain to be hammered out, but a good soaking is expected for most of the state. This includes plenty of snowfall for the state mountains (includes the local resorts).
Next issued forecast/synopsis should be on Friday, 13 February.