December 15, 2018
Summary: Skies cleared overnight, allowing radiational cooling to lower temperatures at frost stations into the low to mid 30s. The back side of the trough of low pressure is now into the interior west, allowing a very temporary ridge of high pressure to move overhead today and tonight. The high, however, will quickly move eastward. Satellite imagery shows a mammoth low pressure system west of the British Columbia coast with a strong cold front just off the coast of the Pacific Northwest. It is this front which will bring precipitation back to central California Sunday night and Monday morning. This will be one of those situations where the northern part of the valley should get a good soaking, but models indicate the upper air support will weaken rapidly as the front moves southeastward through valley. I still feel .25 or so is possible over Fresno and Madera Counties, sloping off to .10 or less in Kern County.
Rain should begin later Sunday evening north of Fresno and spread rapidly southward during the night. this will be a relatively fast moving system, so the precipitation should end by about noon Monday with only a minimal chance of a few showers in Kern County during the afternoon.
Beginning Monday night, a high center will develop off the coast of southern California. This upper high will be quite strong, driving temperatures well above average with the possible exception of the valley floor which will be dealing with increasing amounts of night and morning valley fog, possibly lasting through the day once we get to mid week.
Another very weak trough will move through Thursday night and Friday with no precipitation. Upper level high pressure will quickly bounce back, keeping conditions dry through next weekend and well into the following week.
For the second day in a row, there are some hints suggesting a change in the pattern after Christmas which could bring rain back to central California. For now, it’s just pretty on paper. We’ll go with a dry forecast at this time from Monday afternoon through at least early the following week.
Forecast: Mostly clear with patchy fog this morning. Partly cloudy later this afternoon and tonight. Increasing cloudiness Sunday. Rain likely as far south as Fresno County before midnight Sunday night with lighter showers spreading over the rest of the valley later Sunday night and Monday morning. Partly to mostly cloudy Monday afternoon through Tuesday morning. Clearing Tuesday afternoon. Mostly clear Wednesday with widespread night and morning fog. Widespread night and morning fog with partial afternoon clear Thursday through Saturday.
Short Term:
| Madera 62/35/63/48/58 | Reedley 63/36/63/48/59 | Dinuba 61/34/62/47/58 | |
| Porterville 63/35/63/48/59 | Lindsay 63/34/63/47/59 | Delano 64/46/65/49/60 | |
| Bakersfield 66/43/68/51/61 | Taft 64/45/66/50/60 | Arvin 66/38/67/48/60 | |
| Lamont 65/37/67/49/60 | Pixley 63/35/65/48/59 | Tulare 62/34/63/47/58 | |
| Woodlake 62/34/63/47/58 | Hanford 63/36/63/47/59 | Orosi 62/35/63/46/59 | |
Seven Day Forecast:
| Tuesday
Mostly cloudy 42/57 |
Wednesday
AM fog/PM sun 37/55 |
Thursday
AM fog/PM sun 42/54 |
Friday
AM fog/PM sun 43/53 |
Saturday
AM fog/PM sun 44/54 |
Two Week Outlook: December 22 through December 28: This model now shows a blocking pattern as a high pressure system parks itself off the California coast, driving the storm track into British Columbia and the Pacific Northwest. The chance of rain will be low with temperatures above the valley floor running above average. Temperatures on the valley floor will be determined by the amount of fog and low clouds.
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 less than 6 MPH with periods of near calm conditions through Sunday morning then will be out of the southeast at 5 to 10 MPH Sunday afternoon. Winds will increase to 5 to 15 MPH Sunday night and early Monday. Winds later Monday will be out of the northwest at 5 to 15 MPH, becoming light again Monday night and Tuesday.
Rain: Rain should begin over Madera and Fresno Counties late Sunday evening and then break off into light showers which will spread over the south valley later in the night. most of the precipitation will end by noon Monday with the possible exception of a few lingering showers in mainly Kern County. This will be a fast mover and it will weaken quickly as it moves southward through the valley. Rainfall amounts of about .25 is possible in Fresno and Madera Counties with locally higher amounts in primarily Madera County. I would anticipate .10 to .20 in Kings and Tulare Counties and .10 or less over the valley portion of Kern County. Once the rain ends Monday, a prolonged period of dry weather will set up, lasting through next week and quite possibly into the following week. A couple of models are holding onto the idea of the storm track moving further south beginning about the 27th. For now it’s just conjecture. After Monday, we’ll go with a dry forecast.
Frost Discussion: As skies cleared overnight, many locations dropped into the low to mid 30s with mid to upper 30s in Kern County. Lows tonight will be determined by the arrival of higher level clouds advancing ahead of a Pacific cold front. Currently, I’m expecting at least some cloud cover during the early morning hours, but even so, it’s possible lower 30s could occur before the cloud cover arrives. Above freezing conditions can be expected Monday and beyond as a strong ridge of high pressure caps the valley with increasing amounts of fog and low clouds nights and mornings. We could see some partial afternoon clearing. On any given night that for whatever reason is clear, mid to upper 30s will be possible. The air next week above the valley floor will be quite warm, topping the 70 degree mark in the foothills. But, here we are, deep in December and in the heart of the fog season, so I’m betting fog will maintain above freezing conditions at night with cool conditions during the day.
Afternoon Dew Points Today: Mid to upper 40s. Kern: Low to mid 40s.
Humidity: Porterville: 70%/95%, Bakersfield: 55%/65%
Actual Humidity December 14, 2018: Delano, 99%/60%, Porterville, 98%/51%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 80% tomorrow 30% Bakersfield: Today: 90% Tomorrow: 50%
ET Rates Over the Past Seven Days: Stratford .13, Parlier .15, Blackwell .20, Lindcove .15, Arvin .26, Orange Cove .19, Porterville .16, Delano .19 Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 56, Parlier 53, Blackwell 55, Lindcove, 59, Arvin, 54, Orange Cove 54, Porterville 53, Delano 52
Record Temperatures: 76/25. Average Temperatures: 55/35
Heating Degree Days this Season: 544 -228
Courtesy of the NWS
Average temperature for December so far: 48.9 +3.6
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 1.92 season. or -.44, Month to Date: .15 -.51
Since Oct 1, 2018, Bakersfield: 1.20, or -.14. Month to Date: .52 +.12
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 251, Parlier, 273 , Arvin, 209 Shafter, 289 Stratford, 243, Delano 265, Lindcove, 374, Porterville, 524
. Hours at 45 or below 45.
Sunrise: 7:04 am Sunset: 4:44 pm. Hours of Daylight: 9:41
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 61 / 44 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 60 / 43 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 59 / 38 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 55 / 39 / 0.00 /
BFL : Bakersfield Airport 496 : DHM / 60 / 45 / 0.00 /
VIS : Visalia Airport 292 : DH1500 / 52 / 39 / 0.00 /
ATEC1 : Avenal 787 : DH1549 / 65 / 40 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 61 / 39 / 0.00 /
TFTC1 : Taft 759 : DH1554 / 61 / 47 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 63 / 37 / 0.00 /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.00 3.87 113 0.91 27 3.41 14.06
MODESTO 0.00 3.05 107 0.98 35 2.84 13.11
MERCED 0.00 2.69 109 1.03 42 2.47 12.50
MADERA 0.00 2.42 93 0.32 12 2.60 12.02
FRESNO 0.00 1.92 81 0.37 16 2.36 11.50
HANFORD 0.00 1.71 90 0.37 20 1.89 10.10
BAKERSFIELD 0.00 1.20 90 0.03 2 1.34 6.47
BISHOP 0.00 1.31 119 0.16 15 1.10 5.18
SALINAS 0.00 3.87 140 0.75 27 2.76 12.83
PASO ROBLES 0.00 2.84 119 0.25 10 2.39 12.78
SANTA MARIA 0.00 1.95 71 0.09 3 2.75 13.95
Next report: Saturday December 15/pm