December 18, 2018
Summary: A fairly low cloud deck based at 2,500 feet over Bakersfield is based at between 3,400 and 3,000 between Porterville and Visalia. It continues to regenerate in a northwest flow behind yesterday’s frontal passage. Along the west side and from Madera north, skies are clear to partly cloudy but with wide areas of dense fog. There is a considerable amount of high, thin clouds above the lower clouds, as well. The clouds along the eastern and southern flanks of the valley will be slow to dissipate due to the higher clouds above. Also, upper level high pressure is now taking shape off the southern California coast and is building northward, deflecting the rather robust Pacific storm into the Pacific northwest. The latest freezing level over Vandenberg has already advanced up to 11,400 feet.
The high will dominate our weather into Thursday morning then will sink southward over Baja, allowing a weak trough of low pressure to spread showers over northern California Thursday night and Friday. The question will be whether it will lift the inversion out of here and, thus, the low level moisture with it. Currently, I’m on the fence at about 50/50. Over the weekend, a flat high off shore will create a zonal or westerly flow into California. This will be accompanied by various amounts of cloud cover from time to time as weak impulses move inland to our north. This may actually inhibit fog formation.
The next major change in the pattern should occur Christmas Eve and Christmas Day as what appears to be a relatively strong low pressure system moves into northern and central California. Unlike previous model runs, precipitation is being shown moving all the way down into the valley and even parts of southern California.
Models are still pointing towards a colder weather regime coming up between Christmas and New Year’s. On paper, an upper level high will build into the Pacific Northwest while a low center develops either over southern California or Arizona, depending upon model of choice. This will briefly turn the winds aloft north/south, and just possibly northeast/southwest, which is never good news on the frost front. For now, the off shore high is not expected to build far enough to the north to pick up very cold air, resulting in a freeze. Even so, it’s pretty close and deserves monitoring.
Forecast: Partly to mostly cloudy today with areas of dense fog, mainly in Fresno and Madera Counties. Partly cloudy tonight with widespread fog and/or low clouds developing. Fog and/or low clouds Wednesday through Thursday with a chance of partial afternoon clearing. Areas of fog and low clouds Friday morning, otherwise partly cloudy. Variable cloudiness at times Saturday through Sunday night with patchy night and morning fog. Mostly cloudy Christmas Eve with a small chance of light showers from mainly Fresno County northward. Periods of rain Christmas Day and night.
Short Term:
| Madera 55/38/54/41/54 | Reedley 56/39/56/39/57 | Dinuba 55/38/53/42/54 | |
| Porterville 55/39/56/37/56 | Lindsay 56/38/56/42/54 | Delano 56/41/56/40/58 | |
| Bakersfield 57/45/56/43/59 | Taft 57/45/59/44/61 | Arvin 55/42/57/41/64 | |
| Lamont 56/42/59/42/63 | Pixley 56/40/56/38/55 | Tulare 55/38/54/43/54 | |
| Woodlake 56/38/56/40/57 | Hanford 57/39/56/42/55 | Orosi 56/38/56/42/56 | |
Seven Day Forecast:
| Friday
Patchy fog/mostly cloudy 43/61 |
Saturday
Patchy fog/mostly cloudy 44/57 |
Sunday
Mostly cloudy 43/61 |
Christmas Eve
Slight chance of showers 45/62 |
Christmas Day
Rain likely 44/54 |
Two Week Outlook: Christmas Day-December 31: This model is indicating a colder weather pattern will settle in over the western 2/3 of the U.S. It also indicates there’s an equal chance of dry and wet weather. Other models show generally dry weather between the 26 and January 1. Temperatures would be below seasonal average.
December: It’s been quite some time since this model has actually projected above average precipitation, but the good news is that is the case. It appears the dominant pattern for the month will maintain winds generally out of the west or northwest, which would favor above average temperatures.
December, January, February: It’s been a long time since the 90 day outlook projected above average precipitation for December through February, in other words the winter months. It also continues the better than even chance that over the next three months, temperatures will largely be above average. However, like any winter there will be below average periods as well.
Winds: Winds will be generally at or below 6 MPH through Friday with periods of near calm conditions.
Rain: Expect dry weather through Friday night. there’s a very low chance of a few sprinkles over the weekend with a low risk of rain, mainly from Fresno County north, Christmas Eve. On Christmas Day, most models are now indicating a rather robust Pacific storm will move through. Rain would be likely throughout the valley with heavy amounts, as usual, from Fresno County north. Most of the models show things drying out between Christmas and New Year’s, although that’s far enough away where much could change.
Frost Discussion: All locations will be above freezing tonight and each night for the remainder of the week and more than likely through the 26 or 27. However, beyond the 27, most models are pointing towards a colder weather pattern, one which could result in below freezing nights. What we have on paper for now is a ridge of high pressure building northeastward into the Pacific Northwest with a low center somewhere over southern California or the Desert Southwest. This would generate a north/south upper wind pattern down the west coast and possibly northeastward which would mean part of the flow would be overland without the tempering influence of the ocean. The good news, however, is that the off shore high for now does not build into Alaska or the Yukon Territory which would mean a freeze event would be likely. For now, we’ll just call for colder weather with possible frosty mornings after Christmas and tweak this forecast as we move forward.
Afternoon Dew Points Today: Upper 40s to the lower 50s. Kern: Upper 40s to the lower 50s.
Humidity: Porterville: 75%/100%, Bakersfield: 75%/95%
Actual Humidity December 17, 2018: Delano, NA Porterville, 95%/72%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 30%, tomorrow 50% Bakersfield: Today: 20% Tomorrow: 50%
ET Rates Over the Past Seven Days: Stratford .26, Parlier .27, Blackwell .34, Lindcove .25, Arvin .35, Orange Cove .29, Porterville .26, Delano .28 Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 55, Parlier 52, Blackwell 54, Lindcove, 58, Arvin, 53, Orange Cove 54, Porterville 52, Delano 50
Record Temperatures: 71/26. Average Temperatures: 54/35
Heating Degree Days this Season: 574 -244
Courtesy of the NWS
Average temperature for December so far: 49.3 +4.2
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 2.27 season. or -.26, Month to Date: .50 -.33
Since Oct 1, 2018, Bakersfield: 1.20, or -.24. Month to Date: .52 +.02
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 270, Parlier, 293 , Arvin, 228 Shafter, 309 Stratford, 264, Delano 287, Lindcove, 397, Porterville, 551
. Hours at 45 or below 45.
Sunrise: 7:07 am Sunset: 4:45 pm. Hours of Daylight: 9:40
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 62 / 54 / 0.43 /
FAT : Fresno Airport 333 : DH1600 / 60 / 52 / 0.35 /
HJO : Hanford Airport 242 : DH1600 / 60 / 50 / 0.06 /
NLC : Lemoore Naval AS 234 : DH1600 / 59 / 50 / 0.01 /
BFL : Bakersfield Airport 496 : DH1600 / 64 / 54 / T /
ATEC1 : Avenal 787 : DH1556 / 56 / 49 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 60 / 50 / 0.06 /
TFTC1 : Taft 759 : DH1556 / 60 / 52 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 60 / 50 / M /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.48 5.00 138 0.91 25 3.62 14.06
MODESTO 0.52 4.20 138 0.98 32 3.04 13.11
MERCED 0.45 3.56 136 1.03 39 2.62 12.50
MADERA 0.29 2.85 102 0.32 11 2.79 12.02
FRESNO 0.34 2.27 90 0.37 15 2.53 11.50
HANFORD 0.06 1.77 86 0.37 18 2.05 10.10
BAKERSFIELD T 1.20 83 0.03 2 1.44 6.47
BISHOP 0.00 1.31 112 0.16 14 1.17 5.18
SALINAS 0.05 4.47 152 0.75 25 2.95 12.83
PASO ROBLES 0.31 3.51 136 0.25 10 2.59 12.78
SANTA MARIA 0.27 2.29 78 0.09 3 2.95 13.95
Next report: Tuesday afternoon/December 18