December 20, 2018
Summary:There are many areas covered with dense fog this morning. Most locations from Merced to Visalia were reporting a visibility of ¼ mile or less, however, Bakersfield and Porterville still have a visibility of over 3 miles each. In most locations, the fog is rather shallow so there is a better chance of afternoon clearing. On the flip side, though, high clouds are streaming in from the southwest which will reduce the solar energy which would make the fog and low clouds burn off later in the day.
A weak wave of low pressure will move through northern and central California Friday, probably breaking up the inversion enough for less fog, especially Saturday through Monday. Over the weekend, a zonal or westerly flow from the eastern Pacific will move variable amounts of mid and high level clouds overhead, but active weather will remain to our north. Current models are showing the Christmas Eve/Christmas Day storm to be a weak one. Light precipitation will spread down to Fresno County, but the term “chance of light showers” is appropriate for the south valley. The best chance of rain appears to be late Christmas Eve night and Christmas morning.
Colder air will wrap around the back side of the Christmas system, lowering temperatures both day and night. a second low pressure system will dive through about 36 hours later, issuing in a colder air mass and dry conditions for the remainder of the year and, if models are correct, the first several days of January.
Models seem to be trending towards upper level high pressure off shore building into the Pacific Northwest, but so far, fortunately it appears the high will not build far enough to the north to allow polar air to spill southward into the valley. Nevertheless, it will be a north/south flow and it will possibly lead to a series of frost nights from the 29th on unless fog and low clouds take over, which is possible.
Forecast: Areas of fog and/or low clouds, possibly burning off during the late morning and afternoon hours, revealing high clouds above the fog. Variable high clouds tonight and Friday with areas of fog possible Friday morning. Variable cloudiness at times Saturday through Monday morning. Increasing clouduiness Christmas Eve, leading to the likelihood of light rain as far south as Fresno County with a slight chance of showers south of Fresno County through Christmas Day. Mostly cloudy Christmas night and Wednesday morning. Partly cloudy Wednesday afternoon through Thursday with patchy night and morning fog. Mostly clear to occasionally partly cloudy Thursday with areas of night and morning fog.
Short Term:
| Madera 58/40/59/41/57 | Reedley 58/41/59/43/57 | Dinuba 57/40/58/42/56 | |
| Porterville 61/41/60/42/58 | Lindsay 61/39/60/41/58 | Delano 59/43/61/44/58 | |
| Bakersfield 63/45/62/46/59 | Taft 62/47/62/47/58 | Arvin 64/40/60/44/59 | |
| Lamont 62/42/62/43/59 | Pixley 59/40/59/43/57 | Tulare 57/40/58/42/57 | |
| Woodlake 59/39/59/42/57 | Hanford 59/41/60/43/58 | Orosi 59/39/60/42/58 | |
Seven Day Forecast:
| Sunday
Mostly cloudy 43/57 |
Monday
PM rain possible 42/61 |
Christmas Day
Light showers likely 44/55 |
Wednesday
Mostly cloudy 37/54 |
Thursday
Partly cloudy 32/54 |
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 Sunday with periods of near calm conditions.
Rain: It seems each set of computer models weakens the Christmas Eve/Christmas Day storm system. Light rain appears fairly likely from Fresno County north but only light showers are possible in the south valley. From Fresno County north, I wouldn’t anticipate more than .10 to .20 and generally less than .10 south of Fresno County. Dry weather will return Tuesday night and will likely prevail through the remainder of this year and into the first few days of the new year.
Frost Discussion: Models this morning are trending in the same direction as they were yesterday. That is, the upper high over the eastern Pacific will not build far enough to the northeast to allow polar air to infiltrate the valley. Still, this bears watching as, beginning the 27, a north/south flow of air will dive into California from the Pacific Northwest which will lead to colder nights and cooler days. It’s also possible fog could become entrenched in the valley which is always our saving grace this time of year. Even so, I anticipate frost nights coming up about the 28th and lasting through the first few days of the new year, unless the fog takes over. I’m still taking a wait and see attitude towards this event as model projections will change as the days go by, but for now, so far so good.
Afternoon Dew Points Today: Upper 40s to the lower 50s. Kern: Upper 40s to the lower 50s.
Humidity: Porterville: 75%/100%, Bakersfield: 70%/95%
Actual Humidity December 19, 2018: Delano, 100%/67% Porterville, 97%/60%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 50%, tomorrow 30% Bakersfield: Today: 60% Tomorrow: 40%
ET Rates Over the Past Seven Days: Stratford .31, Parlier .30, Blackwell .37, Lindcove .27, Arvin .37, Orange Cove .32, Porterville .29, Delano .31 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 51
Record Temperatures: 70/24. Average Temperatures: 54/35
Heating Degree Days this Season: 614 -263
Courtesy of the NWS
Average temperature for December so far: 49.4 +4.5
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 2.27 season. or -.38, Month to Date: .50 -.45
Since Oct 1, 2018, Bakersfield: 1.20, or -.31. Month to Date: .52 -.05
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 279, Parlier, 307 , Arvin, 233 Shafter, 324 Stratford, 281, Delano 299, Lindcove, 410, Porterville, 585
. Hours at 45 or below 45.
Sunrise: 7:08 am Sunset: 4:46 pm. Hours of Daylight: 9:39
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 61 / 41 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 61 / 42 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 63 / 36 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 61 / 37 / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 63 / 55 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 61 / 41 / 0.00 /
ATEC1 : Avenal 787 : DH1552 / 60 / 38 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 63 / 47 / 0.00 /
TFTC1 : Taft 759 : DH1555 / 60 / 44 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 57 / 42 / 0.00 /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.00 5.00 132 0.91 24 3.78 14.06
MODESTO 0.00 4.20 132 0.98 31 3.18 13.11
MERCED 0.00 3.56 130 1.03 38 2.74 12.50
MADERA 0.00 2.85 98 0.32 11 2.91 12.02
FRESNO 0.00 2.27 86 0.37 14 2.65 11.50
HANFORD 0.00 1.80 83 0.37 17 2.18 10.10
BAKERSFIELD 0.00 1.20 79 0.03 2 1.51 6.47
BISHOP 0.00 1.31 107 0.16 13 1.22 5.18
SALINAS 0.00 4.47 145 0.75 24 3.08 12.83
PASO ROBLES 0.00 3.52 129 0.25 9 2.73 12.78
SANTA MARIA 0.00 2.29 74 0.09 3 3.09 13.95
Next report: Thursday afternoon/December 20