December 15, 2020
Both infrared satellite imagery and ground observations show widespread fog over much of Tulare County up through Merced County with patchy fog elsewhere. Forecasting temperatures for day through Wednesday will be challenging because of the potential burn off time of the fog and low clouds at any given location. Where skies are mostly clear, mid 50s will be a good bet today with possibly upper 40s and lower 50s where fog remains dominant.
We are on the eastern flank of upper level high pressure off shore, putting us under a northwest flow aloft. The freezing level has risen to 9,700 feet, up from 5,900 feet yesterday.
The next change will occur Wednesday night and Thursday as the high migrates further out to sea. A trough of low pressure will begin spreading rain over northern California Wednesday with light showers reaching Merced County around midnight and Fresno County possibly as early as 3:00am Thursday. Light showers will spread over the south valley Thursday as the cold front moves quickly through.
High resolution models which predict precipitation amounts at any given location are not quite as bullish as the previous storm, which is discussed below in the rain section.
The storm will move into the Great Basin Friday with another northwest flow of air behind the exiting system. Upslope clouds will develop along the Sierra Nevada and the Kern County mountains, so it may be Friday afternoon before skies begin to clear out in some areas.
A flat zone of upper level high pressure will cover the eastern Pacific and California, eastward into the Great Basin, Saturday through Tuesday. As a warm air inversion builds above the valley floor, widespread fog and low clouds will develop during the night and morning hours, possibly persisting through the day in some areas. Saturday could be the beginning of a multi-day fog regime…in other words, typical December weather can be expected.
Forecast: Areas of dense fog and low clouds this morning. clearing in most areas this afternoon. Mostly clear tonight through Wednesday morning but with widespread fog and low clouds developing. Increasing higher clouds late Wednesday afternoon. Cloudy Wednesday night with showers developing over Fresno County, spreading over the rest of the valley by 3;00am. Mostly cloudy Thursday night through Friday morning with patchy fog. Becoming mostly clear Friday afternoon through Tuesday with extensive fog and low clouds each morning, possibly persisting through the day in some areas.
Short Term:
| Madera 54/29/55/40/57 | Reedley 54/29/57/41/58 | Dinuba 53/29/57/40/57 |
| Porterville 56/29/58/40/58 | Lindsay 55/28/58/39/58 | Delano 56/30/58/41/58 |
| Bakersfield 56/36/59/42/58 | Taft 56/44/58/46/59 | Arvin 57/33/59/44/57 |
| Lamont 56/32/59/43/57 | Pixley 55/29/57/41/59 | Tulare 53/28/58/39/57 |
| Woodlake 54/29/58/39/57 | Hanford 55/30/58/41/58 | Orosi 54/28/58/39/57 |
Seven Day Forecast:
| Friday
Patchy fog/partly cloudy 39/57 |
Saturday
AM fog/partial clearing 34/55 |
Sunday
AM fog/partial clearing’ 33/53 |
Monday
AM fog/partial clearing 35/52 |
Tuesday
AM fog/partial clearing 34/53 |
Two Week Outlook: December 22 through December 28: This model has central California on the dividing line between dry weather over southern California and potentially wet weather over northern California and the Pacific Northwest. I need to introduce a chance of showers from main Fresno north during this period with above average temperatures.
December: This model shows above average temperatures during the month of December. Southern California should experience below average precipitation. There is some hope for northern and central California, however, as this model spits out equal chances of above or below average rainfall. We’re hoping for the above average side of things.
December, January, February: This model definitely reflects a La Nina pattern, which is when ocean temperatures are below average through the equatorial waters off of Peru, extending into the mid Pacific. Typically, this results in above average temperatures for much of the southern half of the U.S., including California, with unfortunately below average precipitation for California including the valley.
Winds Discussion: Winds afternoons and evenings will be variable to no more than 10 MPH. Winds tonight will be no more than 5 MPH with extended periods of near calm conditions. Late Wednesday night through Thursday evening, winds will be out of the northwest at 8 to 15 MPH with stronger gusts north of Kern County and along the west side. Winds will become light Thursday night and Friday.
Rain Discussion: dry weather will continue through Wednesday evening. The chance of light showers will begin to increase at about 3:00am Thursday from Fresno County north. Light showers will spread over the remainder of the valley Thursday morning, ending by evening. High resolution models are not as bullish on rainfall amounts this go round. The latest projections indicate anywhere from .10 to .25 for eastern Fresno County and Madera County, no more than a tenth of two in Tulare County and probably no more than a few hundredths over the valley portion of Kern County. Western Kings and Fresno Counties can expect .10 or less due to a rain shadow.
Dry weather will return at least through Tuesday. One model placed a closed low over California by the middle of next week, however this feature does not show up on other models, so we’ll go with a dry forecast.
Frost Discussion: Low to mid 30s were widespread through the citrus belt this morning. Only two locations dropped into the upper 20s: Famoso chilled to 28 degrees and Lindsay 29.
Tonight’s forecast will be more of a typical December challenge. With generally clear skies, fog and low clouds will become widespread, especially after midnight. Readings in the fog shrouded areas will be generally in the low to mid 30s. Where skies remain clear, unprotected low spots could drop as low as 26 with most flatland locations between 28 and 30 with hillsides above freezing.
The inversion tonight will be decent with temperatures at 34 feet generally 4 to 8 degrees warmer. Expect above freezing conditions on Thursday and Friday mornings as a weather system moves through. Saturday through the middle of next week will see lows determined by the amount of fog and low clouds. It appears the pattern will be ideal for a multi-day fog regime. Generally speaking, any night that sees clear skies would see coldest locations in the upper 20s to the lower 30s. if a full—fledged fog regime develops, when the fog lifts into a low overcast with only partial afternoon clearing-temperatures will remain above freezing.
For now, there’s nothing on paper suggesting a cold pattern on the horizon.
Lows Tonight:
| Terra Bella
29 |
Porterville
28 |
Ivanhoe
27 |
Woodlake
29 |
| Strathmore
28 |
McFarland
27 |
Ducor
29 |
Tea Pot Dome
28 |
| Lindsay
27 |
Exeter
28 |
Famoso
27 |
Madera
29 |
| Belridge
28 |
Delano
29 |
North Bakersfield
29 |
Orosi
27 |
| Orange Cove
28 |
Lindcove
28 |
Lindcove Hillside
Af |
Sanger River Bottom
25 |
| Root Creek
27 |
Venice Hill
28 |
Rosedale
29 |
Jasmine
29 |
| Arvin
31 |
Lamont
32 |
Plainview
28 |
Mettler
Af |
| Edison
32 |
Maricopa
27 |
Holland Creek
31 |
Tivy Valley
28 |
| Kite Road South
31 |
Kite Road North
28 |
AF=Above Freezing
Air Quality Expectations: The San Joaquin Valley Air Pollution Control District has issued the following warning(s) for December 15, 2020:
Today’s air quality is listed as Good for Merced County. The air quality for the remainder of the valley is Moderate.
The District’s Real-time Air Advisory Network (RAAN) can be used to track air quality at any Valley location by visiting myRAAN.com. The option to use a specific address is available.
In addition, anyone can follow air quality conditions by downloading the free “Valley Air” app on their mobile device
Afternoon Dew Points Today: Low to mid 40s. Kern, low to mid 40s.
Actual Humidity Range Yesterday: Delano, 99%/65% Porterville, NA
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 80%, tomorrow 60%. Bakersfield: Today: 80% Tomorrow: 70%
ET Rates Over the Past Seven Days: Stratford .35, Parlier .29, Blackwell Corners .NA, Arvin .37, Orange Cove .28, Porterville .NA, Delano .32. Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 54, Parlier 50, Blackwell 55, Arvin, 52, Orange Cove 54, Porterville 51, Delano 45
Record Temperatures: 76/25. Average Temperatures: 55/35
Heating Degree Days This Season: 615, -157
Courtesy of the NWS
Average Temperature for this month So Far: 48.2 +2,9
Precipitation: Seasonal total for Fresno, 1.07, or -1.29, Month to Date: .79, or +.13
Precipitation for Bakersfield, Season, .40, +or- -.94. Month to date .01, or -.39
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 324, Parlier, 402, Arvin, 319, Belridge, 380, Shafter, 353, Stratford, 373, Delano, 410, Porterville, 458
Hours at 45 or below 45. Courtesy UC Davis
Sunrise: 7:05 am Sunset: 4:44 pm Hours of Daylight: 9:39
Yesterday’s Weather
MCE : Merced 153 : DH1600 / 55 / 50 / 0.07 /
MAE : Madera 253 : DH1600 / 56 / 47 / 0.01 /
FAT : Fresno Airport 333 : DH1600 / 55 / 43 / 0.20 /
HJO : Hanford Airport 242 : DH1600 / 56 / 50 / T /
NLC : Lemoore Naval AS 234 : DH1600 / 50 / 35 / 0.01 /
BFL : Bakersfield Airport 496 : DHM / 57 / 44 / 0.01 /
VIS : Visalia Airport 292 : DH1600 / 51 / 43 / 0.01 /
ATEC1 : Avenal 787 : DH1542 / 54 / 38 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 54 / 41 / 0.01 /
TFTC1 : Taft 759 : DHM / M / M / M /
LOSC1 : Los Banos 120 : DH1600 / 56 / 38 / 0.23 /
Rainfall: 24hr W.Y. % Last Y. % Ave. Year ave.
STOCKTON 0.00 1.38 40 4.05 119 3.41 14.06
MODESTO 0.00 1.20 42 2.79 98 2.84 13.11
MERCED 0.00 1.91 77 0.00 0 2.47 12.50
MADERA 0.00 0.55 21 0.00 0 2.60 12.02
FRESNO 0.00 1.07 45 0.00 0 2.36 11.50
HANFORD 0.00 0.49 26 0.00 0 1.89 10.10
BAKERSFIELD 0.01 0.40 30 0.00 0 1.34 6.47
BISHOP 0.00 0.01 1 1.06 96 1.10 5.18
SALINAS 0.00 0.66 24 4.12 149 2.76 12.83
PASO ROBLES 0.00 0.30 13 4.70 197 2.39 12.78
SANTA MARIA 0.03 0.30 11 2.68 97 2.75 13.95
Next report: December 15/pm