April 1, 2017 – Breezy northerly wind continues today, but not as strong as Friday. Dry and warm continues this weekend except for a slight chance of light showers over portions of the Sierra Nevada Sunday night. Continued drying early next week with increasing northerly winds Monday, then a threat of precipitation Wednesday into the weekend.
Short Term Discussion (Today through Tuesday)
Upper ridging along the West Coast, combined with strong surface high pressure from eastern Pacific extending through Oregon into the Great Basin, is producing gusty offshore wind over Interior NorCal. N-S surface pressure gradient has decreased overnight as decoupling occurred, but radar VAD profilers showing 2000-5000 ft MSL wind remaining steady.
Northerly winds increase again tomorrow morning with breezy conditions into the afternoon. However, wind speeds look less than what occurred Friday and will likely remain below advisory criteria. Warm temperatures forecast for today with afternoon highs upwards of 10 to 15 degrees above normal.
Short wave moves through PacNW Sunday followed by secondary wave that takes a more southern route across Interior NorCal Sunday night. System looks weak and moisture starved leading to only a slight chance of showers over portions of the Sierra Nevada. The upper ridging re-amplifies behind this wave Monday returning gusty northerly wind to Interior NorCal. Wind advisories may be needed again on Monday. Downslope warming will be offset by stronger low level cold air advection, leading to some minor cooling over the area Monday.
Extended discussion (Wednesday through Saturday)
Extended period starts out warm and dry under an upper level ridge. Upper ridge axis forecast to shift inland by Wednesday however which will likely allow increasing high cloudiness to spill over much of the forecast area.
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A shortwave trough riding over the ridge is forecast by the models to bring a chance of rain to most of the forecast area by Thursday afternoon. Upper ridge will take most of the energy out of this system so precipitation amounts will likely be fairly minimal. Upper ridge axis continues to shift eastward on Friday allowing a stronger Pacific system to move onshore Thursday night and Friday. Models in fairly good agreement at this time showing this system as at least a moderate precipitation producer.
Wet pattern continues going into next weekend, but models still somewhat discrepant on precipitation amounts. This is shaping up to be an atmospheric river event so will likely see increasing QPF amounts as models progress.