Quick Update: Inside Slider Sunday/Monday

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Northern California is once again in a pattern that disfavors much precipitation, with ridging from northern California throughout the Pacific Northwest & eastern Pacific. Late this weekend into early next week, though, an upper-level low will split off from a very stretched out trough expanding from the Rockies eastward into the eastern U.S., and become trapped under the ridge in the Pacific Northwest, slowly traveling southward over California from the north-central part of the state during the day Sunday into the southern part of the state by later Monday, and on into the Desert Southwest by Tuesday onward. Sunday into Monday, as the low travels overhead and just south of northern & north-central California, some showers will be likely… mainly from Sacramento southward, as precipitation generally has a hard time developing on the north side of a low given less lift and a dryer/offshore flow behind it.

This upper low will be fairly cool, with a core of 850mb temperatures ranging from 2 to -2c overhead by late Sunday into Monday, equating to snow levels around 4000 – 5000ft. This cool air, combined with pockets of clearing (sunshine) given the broken up/showery nature of precipitation will lead to the potential for some thunderstorms from Sacramento southward as well, Sunday and Monday afternoons… though the best chance will likely be from around Sonora southward. Precipitation shouldn’t be very significant generally, with a tenth to a quarter inch across the foothills and mountains south of Sacramento, with perhaps a few hundredths to a tenth or two in the San Joaquin valley – more perhaps between Bakersfield and Merced given the low may travel directly overhead of this area late Sunday into Monday.

Precipitation forecast for Sunday - Tuesday, track of darker green is generally the path the low will take as it heads inland, and thus where its likely to dump more precipitation.

Precipitation forecast for Sunday – Tuesday, track of darker green is generally the path the low will take as it heads inland, and thus where its likely to dump more precipitation.

It appears quite unlikely there’ll be any severe storms given the low will take a fairly inland track, limiting moisture availability, even though there’ll be some decently cool air aloft. That said, some storms/showers could be capable of some hail, gusty winds, and locally higher precipitation totals of course.

Behind the low, periods of gusty winds over the course of the week will be possible as surface high pressure off the west coast grinds against a surface low in the Four Corners region. Otherwise, it doesn’t look like we’ll see any significant changes/storms in the next week or so or outside of this relatively minor split off upper low this weekend/Monday, as strong ridging dominates the eastern Pacific, playing goalie against storms.

500mb height anomaly valid late this coming week via the 12z GFS ensemble('s) mean. While there are lower than "normal" heights progged for the interior western U.S., the ridging offshore in the eastern Pacific would block any significant/heavy-precipitation systems.

500mb height anomaly valid late this coming week via the 12z GFS ensemble(‘s) mean. While there are lower than “normal” heights progged for the interior western U.S., the ridging offshore in the eastern Pacific would block any significant/heavy-precipitation systems.

Long range models suggest there may be potential for some real storms returning in March – but given the history of this dry pattern and that models have been pretty sketchy when it comes to the pattern in the west, it’s most certainly a wait and see type deal here.

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