December 1, 2020
A trough of low pressure has moved into the northern Rockies. This is allowing a massive ridge of high pressure to cover the eastern Pacific Ocean and the western ¼ of the U.S. The ridge juts as far north as the southern Yukon Territory of Canada. Warmer ais has moved in aloft. The freezing level this morning above Vandenburg jumped all the way up to 14,100 feet while at Oakland the freezing level was 13,700 feet.
At the surface, high pressure is once again building over the Great basin and will strengthen a great deal Wednesday and Thursday. A colder, drier air mass will invade the interior west including the deserts of southern California. Models are back to showing the possibility of Santa Ana winds in the south valley Wednesday night and Thursday. One model indicated these winds could move as far north as Bakersfield. if this occurs, temperatures could rise into the 70s over the valley portion of Kern County as downslope heating takes place off the Kern County mountains and the extreme southern Sierra Nevada.
As we’ve been discussing, this would no doubt inject another round of drier air onto the valley floor with colder nights coming up Friday and Saturday. For now, it doesn’t appear to be a critical situation as the overall air mass will not be that cold. Again, though, the drier the air, the greater the ability of the air to cool during the overnight hours.
A trough of low pressure will stretch from the western U.S. into the Desert Southwest, contributing to the off shore flow.
Over the weekend, a very weak upper low may develop over northern California then drift southward. If this feature does form, no active weather would be associated with it.
I keep looking at projections for the 11 and 12 of December. They show a deep low forming possibly over southern California with a southwest to northeast ridge of high pressure into Canada. Theoretically, this would be a freeze pattern, however there’s so much time between now and then that much would no doubt change. There has been a bit of a trend over the past couple of days, so we’ll watch this.
Forecast: Other than occasional high clouds, it will be mostly clear through Saturday. Mostly clear skies will continue Saturday night through Tuesday.
Short Term:
| Madera 28/63/30/64 | Reedley 63/39/63/30/65 | Dinuba 62/28/61/29/63 |
| Porterville 64/29/62/29/67 | Lindsay 63/29/61/30/65 | Delano 65/29/66/31/67 |
| Bakersfield 64/38/65/41/72 | Taft 64/46/65/47/70 | Arvin 64/35/66/37/71 |
| Lamont 65/35/66/37/70 | Pixley 63/29/61/30/64 | Tulare 62/28/61/29/63 |
| Woodlake 63/29/61/30/64 | Hanford 63/30/62/31/65 | Orosi 62/28/61/29/64 |
Seven Day Forecast:
| Friday
Mostly clear 28/62 |
Saturday
Mostly clear 27/62 |
Sunday
Mostly clear 28/63 |
Monday
Mostly clear 28/64 |
Tuesday
Mostly clear 29/65 |
Two Week Outlook: December 6 through December 12: This model gives absolutely no hope for precipitation. It is simply a variation of the blocking ridge pattern we’ve been under through the fall season so expect little chance of rain with above average daytime 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 through Wednesday during the late mornings and afternoons will be at or less than 10 MPH and variable in nature. We’re back to a tricky forecast for Kern County later Wednesday night and Thursday. A strong Santa Ana wind event will commence, including over the Kern County mountains. I’m back to rolling the dice to determine whether or not these winds will make it to the valley floor. One model even suggests these winds will make it as far north as Bakersfield. We’ll put a chance of winds in the 20 to 35 MPH in the extreme south valley with stronger gusts with gusts possibly as high as 20 MPH as far north as Bakersfield. the remainder of the valley will continue to have light winds through Friday.
Rain Discussion: Expect dry conditions for the next 7 to possibly 10 days.
Frost Discussion: There was some minor modifications in temperatures this morning. most locations were 1 to2 degrees warmer than yesterday. The coldest I could find as of 6:30am was 26 at Famoso, and 27 at McFarland and Ivanhoe. Most other locations were between 28 and 31 with readings generally in the mid to upper 30s in Kern County. We should see slight moderation tonight with the very coldest unprotected frost pockets chilling down to 26 to 27 with most flatland locations between 29 and 32 with above freezing conditions continuing on hillsides and in portions of Kern County.
The inversion tonight will be similar with temperatures at 34 feet generally from 4 to 8 degrees warmer at most locations.
We continue to monitor the development of an off shore flow which will begin today then substantially increase Wednesday and Thursday. In Kern County, there’s a chance these winds could reach the extreme south valley which could warm the valley portion of Kern County into the lower 70s Thursday. These winds also, though, inject very dry air into Kern County and the off shore flow ultimately mixes dry air down to the valley floor as well. So Thursday morning’s forecast will be a tough one with Friday and Saturday’s temperatures being perhaps a bit colder, depending on dew points.
I do see the possibility of those low cold spots Friday morning being in the 24 to 26 degree range with flatland locations bottoming out between 27 and 29.
Air Quality Expectations: The San Joaquin Valley Air Pollution Control District has issued the following warning(s) for December 1, 2020:
Today’s air quality is listed as unsafe for sensitive groups in Fresno, Kern, and Kings Counties. The air quality in the remainder of the growing area 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.
For more information on wildfires affecting the Valley’s air, visit: http://www.valleyair.org/wildfires
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 30s, Kern, Low to mid 30s.
Actual Humidity Range Yesterday: Delano, 84%/32% Porterville, 93%/28%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 90%, tomorrow 90%. Bakersfield: Today: 90% Tomorrow: 90%
ET Rates Over the Past Seven Days: Stratford .55, Parlier .47, Blackwell Corners .54, Arvin .55, Orange Cove .48, Porterville .48, Delano .49. Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 56, Parlier 52, Blackwell 58, Arvin, 55, Orange Cove 57, Porterville 53, Delano 47
Record Temperatures: 77/29. Average Temperatures: 59/37
Heating Degree Days This Season: 394, -85
Courtesy of the NWS
Average Temperature for this month So Far: 52.7 +.0.6
Precipitation: Seasonal total for Fresno, .28, -1.38, Month to Date: .28, -.75
Precipitation for Bakersfield, Season, .39, +or- -.53. Month to date .39, -.23
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 194, Parlier, 234, Arvin, 171, Shafter, 178, Stratford, 216, Delano, 219, Lindcove, 228, Porterville, 275
Hours at 45 or below 45.
Sunrise: 6:53 am Sunset: 4:43 pm Hours of Daylight: 9:50
Yesterday’s Weather
MCE : Merced 153 : DH1600 / 65 / 29 / 0.00 /
MAE : Madera 253 : DH1600 / 66 / 29 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 66 / 34 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 66 / 28 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 66 / 27 / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 64 / 34 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 66 / 29 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 66 / 32 / 0.00 /
Rainfall: 24hr W.Y. % Last Y. % Ave. Year ave.
STOCKTON 0.00 0.09 4 0.77 31 2.45 14.06
MODESTO 0.00 0.10 5 0.50 25 1.99 13.11
MERCED 0.00 1.08 55 0.18 9 1.95 12.50
MADERA 0.00 0.16 8 0.28 14 1.99 12.02
FRESNO 0.00 0.28 17 0.50 30 1.66 11.50
HANFORD 0.00 0.13 9 0.58 39 1.48 10.10
BAKERSFIELD 0.00 0.39 42 1.03 112 0.92 6.47
BISHOP 0.00 T 0 0.91 114 0.80 5.18
SALINAS 0.00 0.37 19 0.85 44 1.92 12.83
PASO ROBLES 0.00 0.28 17 1.01 63 1.61 12.78
SANTA MARIA 0.00 0.25 13 1.47 78 1.88 13.95
Lows Tonight:
| Terra Bella
29 |
Porterville
30 |
Ivanhoe
28 |
Woodlake
29 |
| Strathmore
29 |
McFarland
28 |
Ducor
30 |
Tea Pot Dome
29 |
| Lindsay
28 |
Exeter
29 |
Famoso
28 |
Madera
30 |
| Belridge
28 |
Delano
30 |
North Bakersfield
32 |
Orosi
28 |
| Orange Cove
29 |
Lindcove
29 |
Lindcove Hillside
Af |
Sanger River Bottom
26 |
| Root Creek
28 |
Venice Hill
29 |
Rosedale
30 |
Jasmine
30 |
| Arvin
Af |
Lamont
Af |
Plainview
29 |
Mettler
Af |
| Edison
AF |
Maricopa
30 |
Holland Creek
32 |
Tivy Valley
29 |
| Kite Road South
32 |
Kite Road North
29 |
AF=Above Freezing
Next report: December 1/pm