December 27, 2020
A cold winter storm has dropped south/southeast from the Gulf of Alaska to a position off the coast of Oregon and northern California. This system will continue to track south/southeast, centering near Monterey by midnight tonight. rain will pinwheel around the low and into central California from time to time tonight and Monday. This is a cold system with snow levels dropping to 3,500 to 4,000 feet in the surrounding mountains. Most models peg the center of circulation over Kern County by midday Monday with a cold pool of unstable air above the valley floor. If we get breaks in the cloud deck, warm air currents will spiral skyward, interacting with the cold air above. This may trigger a few thunderstorms Monday afternoon. The low will track inland through southern California Monday night and into the Desert Southwest Tuesday. Precipitation amounts could potentially be decent with this system. This is discussed in the rain summary below.
Upper level high pressure will begin building in from the west Tuesday. The flow behind this system will be out of the north, meaning it will be fairly cold, but nothing unusual. Considering we’re into what on average are the coldest weeks of the year anyway.
The next system of note will race through the Pacific Northwest New Years Eve then will drop into the Great Basin as an inside slider. It’s possible light showers could occur over the high Sierra with the valley remaining dry
Models for the first week in January show a strong zonal flow with wet conditions over the Pacific Northwest and northern California. As we progress later in the week, some models drop the jet stream further south, possibly spreading precipitation back into southern California around Tuesday of next week. In the meantime, from Wednesday through next weekend, areas of fog and low clouds will develop. How widespread it ultimately becomes is difficult to discern right now.
Forecast: Mostly cloudy this morning. increasing cloudiness this afternoon with a chance of rain in western Fresno County by mid to late afternoon. Rain likely at times tonight and Monday morning. showers Monday afternoon with a small chance of isolated thunderstorms. A chance of showers Monday evening. Becoming mostly cloudy Monday night and Tuesday morning. Mostly clear to occasionally partly cloudy Tuesday afternoon through Wednesday night with areas of night and morning fog and low clouds. Partly cloudy Thursday and New Year’s Day with areas of night and morning fog and low clouds. Mostly clear to occasionally partly cloudy Friday night through Sunday.
Short Term:
Madera 57/41/54/33/52 | Reedley 57/42/54/34/51 | Dinuba 56/41/53/33/50 |
Porterville 59/42/54/34/51 | Lindsay 58/41/54/33/51 | Delano 59/43/54/35/52 |
Bakersfield 61/45/54/40/50 | Taft 60/47/54/41/50 | Arvin 61/43/54/39/52 |
Lamont 60/42/54/37/50 | Pixley 59/41/54/35/51 | Tulare 57/40/54/33/51 |
Woodlake 58/40/54/34/50 | Hanford 58/42/54/34/52 | Orosi 5 7/40/54/33/51 |
Seven Day Forecast:
Wednesday
AM fog/partly cloudy 32/53 |
Thursday
AM fog/partly cloudy 34/53 |
Friday
Am fog/mostly cloudy 37/53 |
Saturday
AM fog/mostly clear 32/56 |
Sunday
AM fog/partly cloudy 33/55 |
Two Week Outlook: January 3 through January 9: This is the most encouraging two week model forecast I’ve seen for a while. It projects above average precipitation for all of California as the storm track migrates southward. Temperatures will be near to marginally above 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 later today will be out of the east to southeast at 10 to 15 MPH with gusts to 25 MPH possible, mainly along the west side and from Fresno County north. There’s still a chance of gusty east to southeast winds in the extreme south valley later this afternoon and tonight. if these winds do make it to the valley floor, gusts to45 or 50 will be possible in places like the bottom of the Grapevine and locally elsewhere. Winds Monday will be variable to15 MPH in the morning then will be out of the northwest at 8 to 15 MPH Monday afternoon and evening. Winds late Monday night through Wednesday will be light to near calm.
Rain Discussion: The chance of rain will begin to increase as early as late this afternoon in western Fresno County. The counterclockwise circulation around the low will pinwheel bands of rain over the valley tonight through Monday morning. the center of the storm’s circulation is projected to be somewhere near Kern County by Monday morning which means a cold pool of air will be overhead during the period of maximum daytime heating. If this were March or April, the chance of thunderstorms would be high. With the low sun angle, the chance is reduced, but there will still be a chance of isolated thunderstorms Monday afternoon. Showers will taper off Monday evening.
Because of the storm’s path, just about any location, including Kern County, could potentially pick up some significant amounts. Generally .25 to .33 seems likely, but I wouldn’t rule out a few locations picking up more than .50. dry weather will return later Monday night and will continue through the remainder of the week. Medium range models show a wet zonal flow sagging south to affect seven central and southern California beginning around Tuesday of next week.
Frost Discussion: All locations will be above 32 degrees tonight and possibly Tuesday morning as well. On Tuesday morning, any location that does clear out with calm winds could potentially dip into the lower 30s. the air mass behind Monday’s storm system is relatively cold, but nothing unusual for late December/early January. Any clear night from Wednesday on will have the potential of upper 20s and lower 30s. fog and low clouds may begin to play a central role as the week progresses. However, storms moving inland to our north could mix out the inversion from time to time. Medium range models for the weekend and next week show a westerly flow of mild air with precipitation possibly re-entering the picture by Wednesday of next week. Still nothing on projections to indicate a problem with a hard freeze in the future.
Air Quality Expectations: The San Joaquin Valley Air Pollution Control District has issued the following warning(s) for December 27, 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, 90%/55% Porterville, NA
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 10%, tomorrow 10%. Bakersfield: Today: 0% Tomorrow: 20%
ET Rates Over the Past Seven Days: Stratford .24, Parlier .32, Blackwell Corners .NA, Arvin .40, Orange Cove .23, Porterville .NA, Delano .26. 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: 72/23. Average Temperatures: 53/35
Heating Degree Days This Season: 851 courtesy of the NWS
Average Temperature for this month So Far: 46.8 +2.1 courtesy of the NWS
Precipitation: Seasonal total for Fresno, 1.11, or -2.02, Month to Date: .83, or -.60
Precipitation for Bakersfield, Season, .40, +or- -1.37 Month to date .01, or -.82
Water year season is from October 1st through September 30.
Chilling Hours November 1st through February 28: Orange Cove, 485, Parlier, 574, Arvin, 463, Belridge, 533, Shafter, 532, Stratford, 550, Delano, 594, Porterville, 645
Hours at 45 or below 45. Courtesy UC Davis
Sunrise: 7:11 am Sunset: 4:51 pm Hours of Daylight: 9:40
Yesterday’s Weather
MCE : Merced 153 : DH1600 / 62 / 45 / 0.05 /
MAE : Madera 253 : DH1600 / 63 / 46 / 0.01 /
FAT : Fresno Airport 333 : DH1600 / 61 / 49 / 0.03 /
HJO : Hanford Airport 242 : DH1600 / 64 / 44 / 0.02 /
NLC : Lemoore Naval AS 234 : DH1600 / 66 / 57 / 0.00 /
BFL : Bakersfield Airport 496 : DH1500 / 61 / 44 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 64 / 47 / T /
ATEC1 : Avenal 787 : DH1551 / 61 / 50 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 61 / 41 / T /
TFTC1 : Taft 759 : DH1600 / 59 / 51 / 0.01 /
Rainfall: 24hr W.Y. % Last Y. % Ave. Year ave.
STOCKTON 0.11 1.83 42 4.19 97 4.34 14.06
MODESTO 0.05 1.50 40 3.22 87 3.71 13.11
MERCED 0.05 2.15 68 0.00 0 3.16 12.50
MADERA T 0.70 21 0.00 0 3.37 12.02
FRESNO 0.03 1.11 35 0.00 0 3.13 11.50
HANFORD 0.02 0.51 19 0.00 0 2.69 10.10
BAKERSFIELD 0.00 0.40 23 0.00 0 1.77 6.47
BISHOP 0.00 0.01 1 1.10 76 1.44 5.18
SALINAS 0.03 0.86 24 4.76 134 3.56 12.83
PASO ROBLES 0.04 0.34 10 5.78 177 3.26 12.78
SANTA MARIA T 0.31 9 3.86 106 3.63 13.95
Next report: December 28/am