December 31, 2018
Summary: A very cold low has raced southward from western Canada and is now centered over Nevada. It will drop into Arizona by tonight. Gusty winds are picking up along the west side of the valley. Gusts to 31 MPH have been reported along Panoche road and 22 MPH at Kettleman Hills. These winds, both at the surface and aloft, formed a wide area of lower level clouds over a good portion of the valley during the overnight hours. This will pose interesting questions on whether or not they mix out and any effects on overnight lows tonight. Models show the clouds mixing out later this afternoon and evening, but experience has taught me models have a poor time dealing with these upslope situations. I wouldn’t rule out cloud cover all night long in portions of Tulare and Kern Counties. But we’ll study these winds as the day progresses and see what the drier air moving in does to it.
Strong downslope winds are also blowing along the western slopes of the Sierra Nevada. Several locations are reporting winds topping 30 MPH. This may increase during the afternoon and nighttime hours and could also help cause the cloud cover to dissipate. The cloud cover is based at between 3,100 and 4,000 feet.
A north/south flow from western Canada is already moving into California. As the low drops into Arizona later this afternoon and tonight, the upper winds will wrap around the west side of the low, creating a northeast flow. This air mass’s potential is at least marginally colder than the present one. Wednesday and Thursday mornings are the time frame of most concern. Widespread mid to upper 20s is a given with a possibility of low 20s in river bottom and like locations.
As we’ve been discussing, this will be a short lived pattern. As early as late Wednesday a flat zone of upper level high pressure will take shape over the eastern Pacific, expanding eastward into the western U.S. This will create a westerly flow which will move much milder air into California, ending subfreezing temperatures possibly as early as Friday.
Models for the coming weekend are quite interesting. Some show a low from the mid Pacific moving to a position off the southern California coast Friday and into northern Baja Saturday night and Sunday. This would give southern California an excellent chance of rain. How far north the precipitation progresses is speculative but at least a chance of showers should be added to the forecast for Saturday night and Sunday. Most models look dry after Sunday, but much could change between now and then.
Forecast: Overcast this morning. Clearing along the west side this afternoon and much of elsewhere. Clearing tonight. Becoming mostly clear New Year’s Day and New Year’s night, turning colder. Mostly clear to occasionally partly cloudy Wednesday through Friday. Partly cloudy Friday night. increasing cloudiness Saturday with a chance of rain Saturday night through Sunday night. becoming partly cloudy Monday.
Short Term:
| Madera 51/29/53/26/53 | Reedley 52/28/53/25/53 | Dinuba 51/28/52/25/53 | |
| Porterville 50/28/52/25/54 | Lindsay 51/28/51/24/54 | Delano 50/29/51/26/53 | |
| Bakersfield 48/31/52/29/53 | Taft 50/40/52/33/52 | Arvin 48/31/52/27/53 | |
| Lamont 49/30/51/27/53 | Pixley 50/29/51/25/52 | Tulare 50/28/51/24/52 | |
| Woodlake 49/29/51/25/52 | Hanford 51/29/52/26/53 | Orosi 49/29/51/24/52 | |
Seven Day Forecast:
| Thursday
Mostly clear 26/55 |
Friday
Mostly clear 31/58 |
Saturday
Pm showers possible 41/62 |
Sunday
Chance of rain 41/57 |
Monday
Mostly cloudy 42/57 |
Two Week Outlook: January 7 through January 13: This model indicates a higher potential for rain during this time frame. It’s possible lower latitude storms could affect the area. With generally a westerly flow, expect temperatures to run above average.
January: This model shows generally above average temperatures for January over the western one-third of the United States while near to below average temperatures will prevail east of the Rockies. There is no firm indicator of really above or below average precipitation although it does forecast below average rain in the Pacific Northwest.
January, February, March: The western half of the United States is projected in a very general sense to have above average temperatures for the next 90 days. Like the 30 day outlook, it seems to want to project near average precipitation, which would be nice.
Winds: Along the west side, winds are already gusting in excess of 30 MPH along the Interstate 5 corridor. This will continue through tonight. Winds will then be northeast at 10 to 20 MPh with stronger gusts, mainly along the Interstate 5 corridor. Elsewhere, winds will be out of the northwest at 10 to 15 MPH with stronger gusts, mainly from Fresno County north. On Tuesday afternoon, winds will be generally light, generally less than 8 MPH, with periods of near calm conditions through Thursday.
Rain: Expect dry weather more than likely through Saturday morning. Southern California has an excellent chance of rain Saturday afternoon through Sunday as a storm drops from the mid Pacific to off the southern California coast. As of now it appears will storm will move through northern Baja, giving a chance of rain as far north as Fresno. After Sunday night, models show dry weather again for a while.
Frost Discussion: I was surprised last night to see how much upslope clouds developed in a short period of time due to a strong push of northwesterly winds above the valley floor. These clouds are based between 3,500 and 4,000 feet and it will certainly be interesting to see how quickly they burn off this afternoon or possibly even tonight. The winds both at the surface and aloft are off shore and are generating some impressive winds over the west facing slopes of the Sierra, mainly from Fresno County north. I have seen situations where these winds just blow over the top of the valley floor, leaving lower level upslope clouds alone. This time, however, with a considerable amount of colder and drier air moving into central California, these clouds will clear along the west side this afternoon and probably erode elsewhere with time, leaving clear skies later tonight. The combination of wind conditions, mixing, and possibly a small chance of cloud cover should keep temperatures in the 27 to 32 degree range tonight. This will be one of those nights where there will be a great deal of variance in temperatures from place to place. So, for now this forecast will lower temperatures tonight to between 27 and 32 degrees with a weak inversion. Temperatures at 34 feet will be from 2 to 5 degrees warmer.
On Wednesday morning, I definitely have more concern. By that time, the modified arctic air mass will have settled onto the valley floor. One model places Porterville at 27 and another forecast says 25. The possibility of the coldest locations will be in the lower 20s is certainly there with only small modification Thursday morning.
A great deal of warming will be taking place aloft Friday as the westerlies break through. Even so, temperatures of 29 to 32 will be possible. Increasing clouds over the weekend and a much milder air mass will keep temperatures well above freezing after that. Nothing on medium range models suggests a cold air episode longer term.
Lows Tonight:
| Terra Bella
29 |
Porterville
29 |
Ivanhoe
27 |
Woodlake
29 |
| Strathmore
28 |
McFarland
28 |
Ducor
30 |
Tea Pot Dome
29 |
| Lindsay
27 |
Exeter
27 |
Famoso
28 |
Madera
29 |
| Belridge
31 |
Delano
30 |
North Bakersfield
31 |
Orosi
28 |
| Orange Cove
29 |
Lindcove
27 |
Lindcove Hillside
31 |
Sanger River Bottom
26 |
| Root Creek
27 |
Venice Hill
29 |
Rosedale
31 |
Jasmine
29 |
| Arvin
31 |
Lamont
30 |
Plainview
29 |
Mettler
Af |
| Edison
32 |
Maricopa
28 |
Holland Creek
33 |
Tivy Valley
30 |
| Kite Road South
34 |
Kite Road North
30 |
AF=Above Freezing
Afternoon Dew Points Today: Mid to upper 30s. Kern: Mid to upper 30s.
Humidity: Porterville: 60%/95%, Bakersfield: 60%/90%
Actual Humidity December 30, 2018: Delano, 96%/43% Porterville, NA
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 30%, tomorrow 80% Bakersfield: Today: 20% Tomorrow: 80%
ET Rates Over the Past Seven Days: Stratford .35, Parlier .29, Blackwell .38, Lindcove .24, Arvin .34, Orange Cove .28, Porterville .NA, Delano .33 Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 53, Parlier 51, Blackwell 52, Lindcove, 58, Arvin, 51, Orange Cove 56, Porterville NA, Delano 49
Record Temperatures: 69/23. Average Temperatures: 53/35
Heating Degree Days this Season: 800 -308
Courtesy of the NWS
Average temperature for December so far: 48.9 +4.2
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 2.33 season. or -1.07, Month to Date: .56 -1.14
Since Oct 1, 2018, Bakersfield: 1.30, or -.62. Month to Date: .62 -.36
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 372, Parlier, 400 , Arvin, 329 Shafter, 420 Stratford, 382, Delano 394, Lindcove, 585, Porterville, 763
. Hours at 45 or below 45.
Sunrise: 7:11 am Sunset: 4:53 pm. Hours of Daylight: 9:42
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 57 / 34 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 55 / 34 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 56 / 30 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 55 / 28 / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 57 / 33 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 56 / 29 / 0.00 /
ATEC1 : Avenal 787 : DH1554 / 55 / 30 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 57 / 29 / 0.00 /
TFTC1 : Taft 759 : DH1555 / 55 / 37 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 53 / M / 0.00 /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.00 5.88 126 0.96 21 4.65 14.06
MODESTO 0.00 4.49 112 1.03 26 4.01 13.11
MERCED 0.00 3.87 113 1.11 32 3.44 12.50
MADERA 0.00 2.99 81 0.41 11 3.67 12.02
FRESNO 0.00 2.33 69 0.41 12 3.40 11.50
HANFORD 0.00 1.87 62 0.41 13 3.04 10.10
BAKERSFIELD 0.00 1.30 68 0.07 4 1.92 6.47
BISHOP 0.00 1.57 99 0.16 10 1.58 5.18
SALINAS 0.00 4.77 124 0.78 20 3.84 12.83
PASO ROBLES 0.00 3.60 101 0.27 8 3.58 12.78
SANTA MARIA 0.00 2.74 69 0.12 3 3.97 13.95
Next report: Monday afternoon/January 31