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December 12, 2020/report

December 12, 2020

We received some decent amounts of precipitation north of Kern County overnight.  More than .33 has been measured in parts of Fresno and Madera Counties and as much as .66 up in Merced County.  More below in the rain discussion.


The low pressure system has now moved into the Great Basin.  As of the time of this writing, there was still some light precipitation moving through eastern Tulare County, but that will be out of here shortly.  With a northwest flow moving down the valley, a low upslope cloud deck will develop against the  north facing slopes of the Tehachapi an the west facing slopes of the Sierra Nevada tonight.


We next turn our attention to storm number 2 which is approaching the coast of the pacific Northwest.  Rain will spread over northern California tonight with showers spreading over central California Sunday into Sunday night.  it appears now the precipitation pattern will be similar to the current system with heavier amounts from Fresno County north to generally trace amounts over the valley portion of Kern County.


The eastern Pacific high is now quite a ways west of its more typical winter position, creating a northwest flow aloft.  That high will begin to approach the California coast on Monday for at least a temporary return to dry weather through at least  Wednesday evening.


Models are back in showing low pressure moving through northern and central California Thursday into Friday for another chance of showers.  Models yesterday had begun to back off on this possibility but are again flipping.  I feel at least a chance of showers needs to be in the forecast for this timeframe.


Models do indicate the storm track next weekend will continue to move through the Pacific Northwest, affecting parts of northern California from time to time.  At least these models give some hope for additional opportunities for rain as we progress deeper into December.  One element we will have to monitor now that we actually have moisture on the ground is night and morning valley fog which may begin as early as Monday morning if skies clear but more so Tuesday and Wednesday.


Forecast:  Showers for a time in the south valley this morning.  mostly to partly cloudy this afternoon.  Mostly cloudy tonight through Monday morning.  showers will spread from northwest to southeast down the valley Sunday into Sunday night.  Becoming partly cloudy Monday afternoon.  Mostly clear to occasionally partly cloudy Monday night through Wednesday with areas of night and morning fog and low clouds.  Increasing cloudiness Wednesday night leading to a chance of showers Thursday into Friday, mainly from Fresno County north.  Partly cloudy Friday night and Saturday with areas of night and morning fog and low clouds.


Short Term:                                                                        

Madera 56/39/58/40/55 Reedley 57/41/58/41/55 Dinuba 56/39/57/40/54
Porterville 57/40/58/40/56 Lindsay 57/39/54/41/55 Delano 57/41/58/41/55
Bakersfield 56/42/60/44/52 Taft 56/45/59/46/54 Arvin 57/42/60/44/54
Lamont 57/41/60/43/54 Pixley 57/40/58/41/55 Tulare 56/39/57/40/55
Woodlake 56/39/59/39/55 Hanford 57/41/58/41/54 Orosi 56/39/57/40/54


Seven Day Forecast:


AM fog/ partly cloudy



AM fog/partly cloudy



PM showers possible



Chance of showers



AM fog/partly cloudy



Two Week Outlook:  December 19 through Christmas:  This model has central California on the dividing line between dry weather over southern California and potentially wet weather over northern California and the Pacific Northwest.  I need to introduce a chance of showers from main Fresno north during this period with above average 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 Tuesday during the later morning through afternoon hours will be generally no more than 10 MPH with locally stronger gusts near showers.  Winds during the night and morning hours will be generally at or less than 7 MPH with periods of near calm conditions.


Rain Discussion: The following are storm totals as of 6:00am today.  Delano .01, Porterville .08, Tulare .11, Stratford .07, Lemoore .20, Hanford .14, Visalia .15, Exeter .18, Madera .32, Fresno .34, Orange Cove .28, Del Rey .28, Merced .65,


As you can see, from Fresno County northward this storm exceeded expectations.  The last showers will be moving out during the next few hours, mainly in the south valley.  Showers will then spread from northwest to southeast over the valley Sunday and Sunday evening.  Precipitation estimates are roughly the same as the current system with heaviest amounts from Fresno County north dropping off to a few hundreds in Kern County.


Dry weather will return later Sunday night and Monday, although it’s possible light rain drizzle could continue for a time near the base of the Tehachapi Mountains due to upslope conditions.

Dry weather will continue through Wednesday night.  Models have flipped again and are now indicating the next trough of low pressure will move through the northern half of California Thursday into Friday.  Models are inconclusive for next weekend and beyond. If there is any consensus, it’s that precipitation will continue over the Pacific Northwest, clipping northern California from time to time.


Frost Discussion: All locations will be above 32 Sunday and again Monday morning.  It’s possible readings will dip into the low to mid 30s Tuesday and Wednesday mornings.  However, with the moisture we’ve received in the soil, areas of fog will become more and  more prevalent Tuesday and Wednesday morning along with possible residual cloud cover left behind by the system moving through Sunday and Sunday night.  Thursday and Friday of next week will more than likely be above freezing due to the next system moving in.  generally speaking, for the next week to ten days there will be either a west or northwest flow which will preclude any chance of especially cold weather.


Air Quality Expectations: The San Joaquin Valley Air Pollution Control District has issued the following warning(s) for December 10, 2020:


Today’s air quality is listed as moderate for Merced County north.  The air quality for the remainder of the valley is Unsafe for Sensitive Groups. 


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:  Upper 40s to the lower 50s.  Kern, Upper 40s to the lower 50s.

Actual Humidity Range Yesterday: Delano, 99%/41% Porterville, NA


Percentage of Sunshine Today/Tomorrow: Visalia: Today: 20%, tomorrow 10%.  Bakersfield: Today: 0% Tomorrow: 10%


ET Rates Over the Past Seven Days: Stratford .46, Parlier .42, Blackwell Corners .NA, Arvin .47, Orange Cove .43, Porterville .NA, Delano .39. Courtesy University of California *=estimate, NA=not available


Seven Day Soil Temperatures: Stratford 54, Parlier 48rew21, Blackwell 56, Arvin, 52, Orange Cove 55, Porterville 51, Delano NA

Record Temperatures: 69/18. Average Temperatures: 55/35

Heating Degree Days This Season: 565, -145


Courtesy of the NWS

Average Temperature for this month So Far: 48.2 +2.5

Precipitation:  Seasonal total for Fresno,  .36,  or -1.85,  Month to Date: .08, or -.43

Precipitation for Bakersfield,  Season,  .39, +or-  -.86.   Month to date .00,  or -.31

Water year season is from October 1st through September.

Chilling Hours November 1st through February 28: Orange Cove, 317, Parlier, 388,  Arvin, 302, Shafter, 332, Stratford, 361, Delano, 387, Lindcove, NA, Porterville, 429

Hours at 45 or below 45.  Courtesy UC Davis

Sunrise: 7:03 am   Sunset: 4:43 pm   Hours of Daylight:  9:41



Yesterday’s Weather

MCE   : Merced               153 : DH1600 /  60 /  30 / 0.00 /

MAE   : Madera               253 : DH1600 /  60 /  31 / 0.00 /

FAT   : Fresno Airport       333 : DH1600 /  59 /  37 / 0.00 /

HJO   : Hanford Airport      242 : DH1600 /  60 /  30 / 0.00 /

NLC   : Lemoore Naval AS     234 : DH1600 /  62 /  26 / 0.00 /

BFL   : Bakersfield Airport  496 : DH1600 /  61 /  37 / 0.00 /

+VIS  : Visalia Airport      292 : DH1600 /  60 /  30 / 0.00 /

ATEC1 : Avenal               787 : DHM    /  54 /  35 / 0.00 /

PTV   : Porterville Airport  442 : DH1600 /  61 /  33 / 0.00 /

TFTC1 : Taft                 759 : DHM    /   M /   M /    M /

LOSC1 : Los Banos            120 : DH1600 /  57 /  37 / 0.00 /

Rainfall:                     24hr    W.Y.    %    Last Y.  %     Ave.     Year ave.

STOCKTON                         T    0.09     3    4.00   125     3.21    14.06

MODESTO                       0.00    0.10     4    2.78   105     2.66    13.11

MERCED                        0.00    1.08    46    0.00     0     2.35    12.50

MADERA                        0.00    0.16     7    0.00     0     2.45    12.02

FRESNO                        0.00    0.28    13    0.00     0     2.21    11.50

HANFORD                       0.00    0.13     7    0.00     0     1.78    10.10

BAKERSFIELD                   0.00    0.39    31    0.00     0     1.25     6.47

BISHOP                        0.00       T     0    1.06   103     1.03     5.18

SALINAS                       0.00    0.37    14    4.09   157     2.60    12.83

PASO ROBLES                   0.00    0.28    13    4.70   213     2.21    12.78

SANTA MARIA                   0.00    0.25    10    2.68   105     2.56    13.95


Next report: December 12/pm