December 23, 2019
Summary: We have an odd weather pattern with this storm. There are two surface lows. One is just west of LA with the second near Reno, Nevada with a stationary front running north to south right through the San Joaquin Valley. Batches of showers continue to run from south to north up the valley from time to time. This will continue through the night and possibly even into Tuesday morning.
Rainfall amounts from this storm have so far ranged from .15 on the low side to just under .50 on the high side. The freezing level, both over Oakland and Vandenberg, is just under 6,300 feet, putting snow levels at about 5,500 feet or so.
This first storm will finally shift inland late Tuesday morning for a brief end to the active weather. The chance for showers will begin to increase again Christmas Day, especially during the afternoon, as a cold low slides southward right along the central coast by Wednesday evening. Most models place the center of circulation just to the southwest of Santa Barbara by sunrise Thursday. Rainfall amounts from this storm will be light and generally no more than .10 to .20 at most locations with another significant round of precipitation over southern California where already one to three inches of rain has fallen from Santa Barbara all the way down to San Diego Counties.
The low will be tracking across southeast California Thursday night, putting an end to precipitation over the valley. Upper level high pressure over the eastern Pacific will build north/northeast along the coast, eventually creating a chilly north/northeast flow aloft. Surface high pressure will also build over the Great Basin, generating an off shore flow. This typically is an ideal pattern for increasing amounts of night and morning fog.
The air mass settling into the valley behind the Wednesday/Thursday storm is relatively cold. With the very long nights of late December, subfreezing conditions can be expected on any clear night from Friday through the end of the year. One model, though, is showing a closed low a few hundred miles west of the central coast New Year’s eve. Current modeling information show the precipitation remaining off shore, but that could change.
Forecast: Periods of rain tonight. a chance of showers for a time Tuesday morning, mainly south of Fresno. Partly cloudy later Tuesday morning through Christmas Eve night. showers spreading over the valley Christmas Day with periods of showers Wednesday night and Thursday. Mostly to partly cloudy Thursday night and Friday morning. mostly clear to occasionally partly cloudy Friday afternoon through Monday with increasing amounts of night and morning fog and low clouds.
Short Term:
Madera 42/54/38/53 | Reedley 42/53/39/53 | Dinuba 41/53/38/52 | |
Porterville 41/54/39/54 | Lindsay 41/53/38/53 | Delano 43/54/39/53 | |
Bakersfield 43/54/42/54 | Taft 41/52/40/53 | Arvin 43/53/41/54 | |
Lamont 43/55/41/54 | Pixley 41/53/40/54 | Tulare 41/52/39/53 | |
Woodlake 40/53/38/53 | Hanford 41/53/38/53 | Orosi 41/53/38/52 |
Winds: Winds tonight and Tuesday will be mainly out of the east to southeast at 5 to 10 MPH with stronger gusts in the vicinity of showers. Winds Tuesday night will be generally at or less than 8 MPH. Winds Wednesday will be out of the southeast at 10 to 15 MPH with stronger gusts. Winds Wednesday night and Thursday will be out of the northwest at 8 to 15 MPH. It’s possible some locally gusty easterly winds could develop near the base of the Tehachapi Mountains late Tuesday night and Wednesday morning, subsiding later Wednesday afternoon.
Rain: The following are storm totals as of 1:00pm. Bakersfield .13, Delano .17, Shafter .19, Buttonwillow .29, Taft .24, Lamont .11, Porterville .14, Stratford .25, Huron .26, Five Points .44, Lemoore .33, Hanford .15, Tulare .27, Visalia .30, Exeter .17, Fresno .22, Del Rey .20, Madera .23.
Showers will continue to move from south to north across the valley from time to time, possibly into Tuesday morning with dry weather later Tuesday morning into early Wednesday. the next system is colder and will move southward right off the central coast, spreading light showers over the valley later Wednesday morning and continuing well into Thursday. The potential for heaviest precipitation will be in the south valley as the low moves across southern California late Wednesday night and Thursday morning.
It still appears we’ll see dry weather from Thursday night through the end of the year.
Frost Discussion: All locations will be above 32 degrees through Thursday morning. on Friday morning, behind the exiting storm system, a relatively cold air mass will move in as a northeasterly flow aloft sets up and a surface off shore flow develops. It appears the character of the air mass on the valley floor on any clear night from Friday and beyond will range in the upper 20s to the lower 30s. However, this does seem to be a weather pattern which would be conducive for night and morning fog and low clouds, especially considering more moisture has accumulated on the valley floor. At any rate, this is not a classic freeze pattern, but one which may be a typical late December frost event, assuming fog and low clouds don’t take over.
Next report: Christmas Eve morning/December 24