March 1, 2019
Summary: There is almost a mini atmospheric river of air which begins about 1,500 miles to our southwest with a fairly narrow band of clouds coming on shore between roughly Cambria and Santa Barbara. Doppler radar is actually indicating showers moving through southern San Luis Obispo County which will move into the San Joaquin Valley in the next couple of hours, assuming a rain shadow doesn’t chew it up. In the meantime, the actual low is roughly 1,000 miles to the west of Monterey this afternoon and is moving quickly to the east. Showers will become widespread late tonight, continuing through Saturday night. even though this is not the storm of the century, it does have the potential for significant rains over portions of the valley and the Sierra Nevada.
The main area of low pressure will move through about mid to late morning Saturday. Another weak disturbance will follow later Saturday night through Sunday morning, keeping the chance of showers going through until about midday Sunday.
A fast moving, narrow ridge of upper level high pressure will fill in behind this system Sunday afternoon through Monday for a brief respite from the very active pattern we’re under. Where will the AR, or atmospheric river of air or pineapple connection, come on shore Tuesday through Wednesday? That is the big question on model information. My best estimate at this hour would be central San Luis Obispo County and possibly Kings and Tulare Counties southward to Kern County.
For the second day in a row, the best chance for heavy rain appears to be the south valley and from Sequoia Park southward, not to mention the Kern County mountains. This is a moisture laden storm, so even areas that are not necessarily under the AR will pick up significant precipitation, especially over the mountain areas. Initially, this will be a very warm event with snow levels possibly rising to near 9,000 feet, so only the highest peaks will reap the benefits of snow.
A weaker disturbance will move through Thursday, keeping the chance of showers going then a weak ridge will build in from the west Thursday night and Friday. After that, it looks like a weak trough will move through Saturday for another chance of showers, mainly over the Sierra Nevada this time around.
Weak after next, or beyond next weekend, models are now hinting at a broad area of low pressure stretching from the Gulf of Alaska into California for significantly colder weather with potential storms from the Gulf of Alaska.
Forecast: A chance of showers before midnight. Showers likely after midnight and at times through Saturday night. showers for a time Sunday morning. Becoming mostly to partly cloudy Sunday afternoon through Monday. A chance of showers before midnight Monday night. showers becoming likely after Monday night, heavy at times. Rain, possibly heavy at times, Tuesday through Wednesday. Showers Wednesday night with a chance of showers Thursday. Partly cloudy Thursday night and Friday.
Short Term:
Madera 55/65/54/64 | Reedley 56/66/54/65 | Dinuba 54/64/54/63 | |
Porterville 55/67/54/65 | Lindsay 54/67/54/65 | Delano 56/68/54/66 | |
Bakersfield 56/70/54/67 | Taft 57/69/55/66 | Arvin 56/70/55/66 | |
Lamont 55/69/55/66 | Pixley 55/65/54/64 | Tulare 54/64/54/64 | |
Woodlake 53/65/53/64 | Hanford 55/67/54/65 | Orosi 53/64/53/64 |
Winds: Winds lalter tonight will be out of the east to southeast at 5 to 15 MPH, increasing to 10 to 20 MPH after midnight with stronger gusts, mainly along the west side and from Fresno County north. Local gusts to near 40 MPH are possible near the base of the Tehachapi Mountains later tonight and Saturday. Winds Sunday through Monday will generally be in the 5 to 12 MPH range with locally stronger gusts possible, mainly Sunday morning.
Rain: Light showers are spreading over the Coast Range and I not the west side of the valley at this hour. It’s unclear whether these showers will make it all the way across the south valley before they get chewed up by a rain shadow. There will be a continuing risk of light showers before about 2:00am then numerous showers will spread over the valley after that time, continuing on and off through Saturday night. the typical havoc in rainfall totals due to rain shadows will be prevalent. Even so, higher resolution models are indications .33 to .50 is possible along the east side north of the Kern County line. Along the west side, about .25 can be expected with less than .25 over the valley portion of Kern County. There’s a reasonable chance of light showers Sunday morning then a narrow slot of dry weather will arrive Sunday afternoon through Monday. Models are still trying to nail down the exact real estate to be affected by the coming of an atmospheric river of air. Currently, my best guesstimate would be from southern Monterey County southward to Santa Barbara County along the coast and Kings and Tulare Counties southward in the valley. It’s possible with this event that the south valley may actually pick up more rain than points northward. But, this is a moisture lade storm and locations outside of the AR will likely pick up significant amounts of rain, especially over the mountain areas. The rain will taper off into showers Wednesday night with a good chance of showers Thursday. Rainfall amounts from this event have the potential of being considerable. From Monday night through Wednesday night, between 1.0 and 2.00 cannot be ruled out along the east side north of Kern County and upwards of 1.00 along the west side. Kern County may be right under the AR, so .50 to 1.00 totals cannot be ruled out over the valley portion of Kern County. As we progress closer to the event, we’ll tweak these figures. Dry weather will return Thursday night and Friday. A weak wave of low pressure will move through Saturday for more light showers, mainly over the mountain areas. Sunday and Monday appear dry with possibly a chance to colder weather the following week.
Frost Discussion: All locations will be above freezing for the foreseeable future.
Next report: Saturday morning/March 2