We will be out of the office this afternoon to spend a belated Christmas with our family. Reports will resume December 27. Thank you!
December 26, 2020
Temperatures this morning are running anywhere from 12 to 20 degrees warmer than 24 hours ago. A much warmer air mass moved in ahead of today’s weak frontal passage. Currently, Doppler radar is showing only light scattered showers over the valley. Most of this action will be over by midday.
A westerly flow will reside aloft behind this system tonight and early Sunday as a weak ridge of upper level high pressure moves through.
The next storm upstream has its origins in the Gulf of Alaska and will center just west of the Bay Area Sunday night. there are fairly significant differences in surface pressure between the low and higher pressure over southern California. There is a chance that downslope winds could affect the extreme south valley Sunday afternoon and night.
Models have been unusually consistent in showing the center of the cold low’s circulation right overhead Monday. Even though the sun angle is now at its lowest of the year, daytime heating may be strong enough to trigger some isolated thunderstorms Monday afternoon. If this occurs, localized heavy rain and small hail would be the result. Freezing levels are projected to lower to around 4,200 feet or so, lowering the snow level to roughly 3,500 feet in the surrounding mountains.
The precipitation will taper off Monday evening as the low tracks through southern California and into the Desert Southwest. Behind this system will be a northerly flow which will generate upslope clouds against the Kern County mountains later Monday night and Tuesday morning with clearing skies north of Tulare County.
A flat zone of upper level high pressure will begin to push in from the west Tuesday and Wednesday, turning the winds aloft westerly. The next system will move through the Pacific Northwest then will become an inside slider as it dumps into the Great Basin, New Year’s Eve night. models for the first week of January continue to show a parade of storms moving into the Pacific Northwest, affecting northern California from time to time. However, the new two week model is projecting above average precipitation from roughly Kern County northward.
Forecast: Scattered light showers this morning. Partly to mostly cloudy this afternoon through Sunday morning. increasing cloudiness Sunday afternoon. A chance of rain by mid to late afternoon from Fresno County south. Rain at times Sunday night through Monday with a chance of isolated thunderstorms Monday afternoon. Any thunderstorms that do develop will be accompanied by brief heavy rain and small hail. A chance of showers Monday evening, becoming mostly to partly cloudy Monday night and Tuesday morning. becoming mostly clear Tuesday afternoon. Mostly clear to occasionally partly cloudy with increasing amounts of night and morning fog Wednesday through Saturday.
Short Term:
| Madera 61/38/57/41/53 | Reedley 61/39/56/40/54 | Dinuba 60./38/55/40/52 |
| Porterville 61/40/55/41/52 | Lindsay 61/39/56/41/53 | Delano 60/40/55/41/52 |
| Bakersfield 60/44/59/43/54 | Taft 57/47/57/46/51 | Arvin 59/42/59/42/55 |
| Lamont 60/42/57/42/54 | Pixley 60/39/56/40/53 | Tulare 60/39/55/40/52 |
| Woodlake 61/39/56/41/51 | Hanford 61/39/55/41/52 | Orosi 60/39/55/40/52 |
Seven Day Forecast:
| Tuesday
Partly cloudy 35/53 |
Wednesday
AM fog/partly cloudy 32/53 |
Thursday
AM fog/partly cloudy 33/54 |
Friday
Am fog/partly cloudy 33/55 |
Saturday
AM fog/partly cloudy 34/54 |
Two Week Outlook: January 2 through January 8: This model actually projects above average precipitation from roughly the Kern County mountains through northern California with below average rain over southern California. Temperatures during this period are projected to run marginally below average.
January: This model doesn’t really show a trend for temperatures at all. We’ll call it near average this time around. Not surprisingly, it does indicate January will have below average precipitation, as has been the case this La Nina year.
January, February, March: This model does not really offer much hope for a decent rainy season as below average precipitation is indicated over the Golden State. Temperatures over this 90 day period will be generally above seasonal average.
Winds Discussion: Winds today will be generally out of the west to northwest at around 5 to 12 MPH, becoming light overnight. Winds Sunday will begin to increase out of the east to southeast at around 10 to 20 MPH, mainly from Fresno County north and along the west side. Local gusts to 30 MPH will be possible, especially along the Interstate 5 corridor. The chance of downslope winds off the Tehachapi Mountains and into the Kern County portion of the valley floor remains low, even so, that chance remains. If these winds do develop, they would begin Sunday afternoon and continue through Sunday night, ending Monday as pressure differences equalize. Winds Monday through Monday evening will be mainly out of the northwest at 10 to 15 MPH with stronger gusts. Light winds will return later Monday night through Tuesday.
We will be out of the office this afternoon to spend a belated Christmas with our family. Reports will resume December 27. Thank you!
Rain Discussion: As of the time of this writing, scattered light showers were moving through the valley. This activity will end by midday with dry weather returning this afternoon through Sunday morning. this next system should turn out to be the most significant of the winter season so far. The center of the storm’s circulation will be virtually right overhead Monday. With some breaks in the overcast, we could potentially see some sun heated air spiraling skyward to form showers and even some possible thunderstorms. Any thunderstorm that does develop would be accompanied by brief heavy rain and small hail. The chance of rain will begin to increase by midafternoon Sunday, spreading over the rest of the valley Sunday night. showers may continue into Monday evening before ending Monday night. Rainfall amounts should range anywhere from.25 to .33, possibly locally more and especially if thunderstorms occur. Even in Kern County, as much as .25 could be measured with locally more.
Dry weather will begin Tuesday and, if models have their say, will last through the first week in January. However, there is conflicting model information. For example, the two week model is indicating an above average chance of precipitation. Still, we will revert back to the winter pattern of the storm track moving into Washington and Oregon and, from time to time, southern California.
Frost Discussion: All locations will be above 32 degrees Sunday and Monday mornings and more than likely Tuesday, as well. Heavy cloud cover, precipitation, etc. will maintain above freezing conditions. The air mass swinging in behind Monday’s storm passage is cold, but not exceptionally so. Any clear night from Wednesday on has the potential for colder locations to drop into the upper 20s to the lower 30s. I’m anticipating a good soaking from this storm. A wet valley floor is certainly more conducive for widespread fog and low clouds beginning Wednesday morning.
The storm track will be just to our north from time to time, which could bring higher level clouds in off and on during the week. Even so, we should have enough of a warm air inversion for widespread fog and low clouds as the week wears on. For now, medium range models do not indicate a pattern that would allow for threatening weather.
Air Quality Expectations: The San Joaquin Valley Air Pollution Control District has issued the following warning(s) for December 25, 2020:
The air quality for Merced County is good. 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: Mid to upper 40s. Mid to upper 40s
Actual Humidity Range Yesterday: Delano, 99%/27% Porterville, NA
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 40%, tomorrow 40%. Bakersfield: Today: 20% Tomorrow: 50%
ET Rates Over the Past Seven Days: Stratford .23, Parlier .29, Blackwell Corners .NA, Arvin .41, Orange Cove .21, Porterville .NA, Delano .25. Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 52, Parlier 48, Blackwell 55, Arvin, 51, Orange Cove 51, Porterville 51, Delano 44
Record Temperatures: 70/21. Average Temperatures: 53/35
Heating Degree Days This Season: 839 -164 courtesy of the NWS
Average Temperature for this month So Far: 46.5 +1.8 courtesy of the NWS
Precipitation: Seasonal total for Fresno, 1.08, or -1.98, Month to Date: .80, or -.56
Precipitation for Bakersfield, Season, .40, +or- -1.33 Month to date .01, or -.78
Water year season is from October 1st through September 30.
Chilling Hours November 1st through February 28: Orange Cove, 482, Parlier, 572, Arvin, 457, Belridge, 533, Shafter, 523, Stratford, 547, Delano, 587, Porterville, 634
Hours at 45 or below 45. Courtesy UC Davis
Sunrise: 7:10 am Sunset: 4:50 pm Hours of Daylight: 9:40
Yesterday’s Weather
MCE : Merced 153 : DH1600 / 61 / 32 / 0.00 /
MAE : Madera 253 : DH1600 / 61 / 31 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 59 / 36 / 0.00 /
HJO : Hanford Airport 242 : DH1600 / 63 / 31 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 66 / M / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 67 / 37 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 63 / 29 / 0.00 /
ATEC1 : Avenal 787 : DH1600 / 59 / 34 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 67 / 30 / 0.00 /
Rainfall: 24hr W.Y. % Last Y. % Ave. Year ave.
STOCKTON T 1.70 40 4.19 98 4.26 14.06
MODESTO T 1.45 40 3.22 89 3.63 13.11
MERCED 0.00 2.10 68 0.00 0 3.09 12.50
MADERA 0.00 0.69 21 0.00 0 3.31 12.02
FRESNO 0.00 1.08 35 0.00 0 3.06 11.50
HANFORD 0.00 0.49 19 0.00 0 2.61 10.10
BAKERSFIELD 0.00 0.40 23 0.00 0 1.73 6.47
BISHOP 0.00 0.01 1 1.10 79 1.40 5.18
SALINAS T 0.83 24 4.76 136 3.49 12.83
PASO ROBLES 0.00 0.30 9 5.77 181 3.18 12.78
SANTA MARIA 0.00 0.31 9 3.85 108 3.56 13.95
Next report: December 27/am