A very weak May-like system brought some sprinkles and light showers to NorCal this morning…nothing of any real singificance. Outside of isolated thundershowers in the far north, today’s weather was rather unexciting. Tomorrow will be mostly dry in most places, but another disturbance diving down west side of the Gulf of Alaska trough will renew showerÂ chances across the northern 2/3 of the state late Thursday into Friday. Rainfall amounts will be a bit higherÂ than the precious system, but still on the light side (generally 0.15 to 0.35 in.Â at best). ThereÂ is the outside chance of an isolated thunderstorm, mainly in the Central Valley, but convective chancesÂ really willÂ be minimal with this system. AfterÂ Friday, strong high pressure builds back into the region and 850 mb tempsÂ rise significantly going into the weekend and beyond, when inland highsÂ could climb back into the 90s.
The most recent snow survey forÂ California drainage basins paints an even drier picture thanÂ the April 1st survey did. Statewide, snowpackÂ water content averaged an abysmal 27% ofÂ the May 1st average.Â More northern basins faredÂ decidedly better than thoseÂ in the Southern Sierras; the Northern Sacramento River basin scored a positivelyÂ drenching 52% of normal while the San Joaquin RiverÂ drainage had a spectacularly low 8% of average snowpack water content. All hydrologic regions, however, scored a collective 30% or lower. We’ll make it through this summer…as reservior levels are still near average for thisÂ time of year thanks to a series of good snow accumulations in NorCal the past few years previous to this one…but peak flowsÂ on snow-fed rivers andÂ streams will occur in just a couple of weeks and there will be very little water to replentish reserviorsÂ once June comes around. Reservoir level percent of normal values will start to drop rapidly once summer sets in…and we may begin to see some concerned water managers by the end of August. Everything, at this point, hinges onÂ 2007-2008 precipitation: ifÂ it’s not above average, we’re going toÂ have water shortages. AÂ unusually hot summer wouldn’t help, either…Â