February 15, 2019
Summary: One of the amazing facts about the tremendous atmospheric river event of the past 48 hours is not only the floods in northern and southern California, but the tremendous rain shadow in the San Joaquin Valley. I really credit one forecast model that predicted this, calling for no more than .25 along the west side of the valley, which did pan out, and no more than .50 elsewhere, which also panned out. Precipitation fell by the bucket over the Sierra Nevada, especially over the higher elevations where 3 to 6 inches of rain was recorded in some locations.
The very warm atmospheric river is now gone and is being replaced by a very cold low which is centered just off the Oregon coast this morning. The associated cold front is currently moving down the valley with generally light showers with the exception of the Sierra Nevada from Fresno County northward where heavy snow has begun. The freezing level over Oakland overnight plummeted back down to 4,800 feet, so snow levels today will probably be about 4,000 feet or so. It will continue to fall through the weekend as a north/south flow continues along the east side of high pressure off shore and a modified arctic trough over the interior west. By Sunday, snow levels will be down to near 1,500 feet or so, possibly even lower in heavier showers.
Currently, the cold front from that low to our north is moving down the valley. This will spread precipitation all the way down to Kern County this morning. Following the front will be periods of showers and, if we get some breaks in the overcast, isolated thunderstorms may fire up which will be accompanied by localized heavy rain and small hail.
Two more waves of low pressure will follow. The next will arrive later Saturday with the one after that, the coldest of the group, will arrive Sunday through Sunday night. the bottom line is, we will have periods of showers through Sunday night before the weather finally begins to dry up Monday.
The winds aloft Monday and Tuesday will be out of the north/northeast out of western Canada and into California, leading to the possibility of below freezing temperatures Monday and Tuesday mornings. That is discussed below in the frost section.
The pattern for Wednesday night or Thursday shows a very cold low sliding southward from western Canada. Some models show the low skimming the Sierra Nevada, meaning most of the dynamics would b e just to our east. Nevertheless, I feel it’s necessary to add a slight chance of showers for that time period along with very low snow levels. And guess what? A very large arctic trough is projected to carve itself out over the west and just off shore next weekend, maintaining unsettled weather with low snow levels and well below average temperatures.
Forecast: There will be periods of showers at any given time through Sunday night with snow levels in the surrounding mountains falling below 2,000 feet by Sunday. There will be a chance of isolated thunderstorms this afternoon and again Saturday and Sunday afternoons. Thunderstorms will be accompanied by localized heavy rain and small hail. Partly cloudy Monday through Wednesday morning with cold nights. Increasing cloudiness Wednesday with a small chance of light showers Wednesday night and Thursday. A slight chance of showers Thursday night. becoming partly cloudy Friday.
Short Term:
| Madera 54/40/52/37/50 | Reedley 54/39/53/38/49 | Dinuba 53/38/51/37/48 | |
| Porterville 54/40/52/37/50 | Lindsay 54/39/52/37/50 | Delano 55/41/52/39/49 | |
| Bakersfield 56/43/52/39/49 | Taft 56/43/52/40/50 | Arvin 56/41/52/40/50 | |
| Lamont 56/40/52/39/49 | Pixley 55/39/53/38/48 | Tulare 53/38/51/37/48 | |
| Woodlake 54/40/52/39/50 | Hanford 55/40/52/39/51 | Orosi 54/39/51/37/50 | |
Seven Day Forecast:
| Monday
Partly cloudy 32/51 |
Tuesday
Partly cloudy 30/55 |
Wednesday
PM showers possible 35/54 |
Thursday
Small chance of showers 39/53 |
Friday
Partly cloudy 36/58 |
Two Week Outlook: February 23 through February 28: It’s been a while but this model is now indicating a high chance of dry weather during this time frame. This model does show a consistent northwest flow aloft which would mean a continuation of below average temperatures.
February: This model indicates the eastern Pacific high will be the most dominant feature during the month of February. There will be the usual exceptions, but overall this would result in above average temperatures and drier than average precipitation over much of the west and colder than average temperatures east of the Rockies.
February, March, April: At least this model projects about equal chances for either above or below average precipitation. There is actually a greater possibility of below average rain over the Pacific Northwest. Generally speaking, temperatures should remain at least marginally above average.
Winds: Winds will be generally out of the southeast at 5 to 15 MPH through Sunday with local gusts to near 25 MPH, especially near showers or thunderstorms. Winds Sunday evening and night will be out of the northwest at 10 to 20 MPH, diminishing after midnight and becoming light thereafter with light winds Monday.
Rain: The cold rains are back and so are the showers which have spread down to the Kern County line as of the time of this writing. Precipitation amounts will vary widely from this point on. The first of three waves of low pressure will move through today and tonight with periods of showers and possible isolated thunderstorms this afternoon accompanied by small hail and localized heavy rain. More waves will move from north to south along the area through Monday evening, allowing periods of showers to continue on and off. Isolated thunderstorms will be possible again Saturday and Sunday afternoons with…localized heavy rain and hail.
The rain will begin to taper off Sunday night, but before then snow will fall down to 1,500 feet in the surrounding mountains, including the Coast Range. Monday through most of Wednesday looks dry then the next very cold low will arrive Wednesday night and Thursday. For now, this system looks moisture starved, but a chance of light showers with snow in the foothills again is a good bet for the forecast for Wednesday afternoon through Thursday.
Dry weather will return Friday, then a large modified arctic trough of low pressure will carve itself out over the western U.S. and off shore for an increasing chance of showers, especially for the second half of next weekend.
Frost Discussion: All locations will be above freezing Saturday and Sunday mornings. A very cold modified arctic air mass will become entrenched in the valley as the weekend progresses with snow down to very low elevations. The flow behind the last weather system to move through Sunday evening will be out of the north/northeast. This air’s origins will be out of western Canada, so where it clears Monday morning, the chance of readings from 27 to 31 is possible, but only under ideal conditions which are clear skies and no rain.
The risk factor is a little higher for Tuesday morning. Again, there will be much to consider with potential cloud cover on and off through the night, but again lows down to 27 to 31 are possible area wide.
It now appears we’ll only have to deal with this for two nights as we’ll hopefully begin to observe increasing clouds ahead of the next modified arctic system which will be here Wednesday through Thursday. Assuming clouds arrive on ti me, they would help maintain above freezing conditions Wednesday morning, possibly through Friday morning.
Latest models are indicating a large, modified arctic trough will develop next weekend over the western U.S. and off shore. The bottom side of this trough will be overwater, swinging in from the west over central California. So even though temperatures will be well below average, the chance of below freezing conditions seems low at this time.
Afternoon Dew Points Today: Low to mid 40s. Low to mid 40s. Humidity values ranging from 80%/95% at Hanford. Bakersfield 75%/95%
Actual Humidity February 14, 2019: Delano, NA Porterville, 87%/57%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 20%, tomorrow 20% Bakersfield: Today: 30% Tomorrow: 20%
ET Rates Over the Past Seven Days: Stratford .40, Parlier .44, Blackwell .48, Lindcove .38, Arvin .56, Orange Cove .41, Porterville .41, Delano .NA Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 52, Parlier 49, Blackwell 50, Lindcove, 54, Arvin, 50, Orange Cove 51, Porterville 49, Delano NA
Record Temperatures: 79/24. Average Temperatures: 62/40
Heating Degree Days this Season: 1509 -461
Courtesy of the NWS
Average temperature for February so far: 48.2 -0.6
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 6.82 season. or +.15. Month to Date: 2.26 +1.25
Since Oct 1, 2018, Bakersfield: 3.46, or -.17. Month to Date: .61 +.17
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 728, Parlier, 715 , Arvin, 649 Shafter, 706 Stratford, 718, Delano NA, Lindcove, 1019, Porterville, 1447
Hours at 45 or below 45.
Sunrise: 6:46 am Sunset: 5:40 pm. Hours of Daylight: 10:50
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 71 / 58 / 0.02 /
FAT : Fresno Airport 333 : DH1600 / 67 / 58 / 0.14 /
HJO : Hanford Airport 242 : DH1500 / 66 / 59 / 0.06 /
NLC : Lemoore Naval AS 234 : DH1600 / 65 / 57 / 0.04 /
BFL : Bakersfield Airport 496 : DH1600 / 67 / 60 / 0.26 /
VIS : Visalia Airport 292 : DH1600 / 66 / 58 / M /
ATEC1 : Avenal 787 : DH1556 / 62 / 54 / 0.19 /
PTV : Porterville Airport 442 : DH1600 / 66 / 57 / 0.09 /
TFTC1 : Taft 759 : DH1555 / 68 / 58 / 0.13 /
LOSC1 : Los Banos 120 : DH1600 / 63 / 48 / M /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.08 11.29 129 3.99 45 8.77 14.06
MODESTO 0.25 8.73 110 3.55 45 7.91 13.11
MERCED 0.41 8.73 121 2.29 32 7.22 12.50
MADERA 0.02 6.38 90 1.55 22 7.12 12.02
FRESNO 0.12 6.82 102 1.64 25 6.67 11.50
HANFORD 0.04 5.38 90 1.78 30 5.95 10.10
BAKERSFIELD 0.26 3.46 93 1.10 29 3.73 6.47
BISHOP 1.06 5.63 183 0.20 7 3.07 5.18
SALINAS 0.10 9.48 122 2.51 32 7.76 12.83
PASO ROBLES 0.66 10.90 142 2.30 30 7.65 12.78
SANTA MARIA 0.40 10.03 122 2.02 24 8.25 13.95
Next report: Friday afternoon/February 15