December 19, 2020
Summary: Upper level high pressure continues to shift eastward over California as a warm air inversion tightens up over the valley floor. As of 1:30, the sun was shining in most areas of the valley with temperatures approaching the 60 degree mark. Both Madera and Merced were still under a low overcast with temperatures of 48. Today is a good example of the way things will be until Tuesday. Extensive fog during the later night and morning hours with clearing in at least some areas during the afternoons. Locations that are generally fog and low cloud free will see highs in the upper 50s to the lower 60s while locations locked under the low overcast will only be in the upper 40s.
Beginning Tuesday night, the pattern will become more complex. Models are trending towards a weak upper low approaching the central and southern California coast late Tuesday night through Christmas Eve. Some models actually call for a few sprinkles out of this system, but that remains to be seen. In the meantime, a strong low pressure system will move into the Pacific Northwest, carving out a vicious winter storm over the Rocky Mountain region and the northern Midwest Christmas Eve and Day. Behind this system, a sharp ridge of upper level high pressure will build Wednesday all the way into Alaska and northwest Canada.
The flow along the back side of that winter storm will have the winds aloft over California out of the north/northwest which should ensure none of that arctic air spills into central California. By Friday night, models are trending towards the high breaking down, allowing the possibility of two winter storms to affect central California.
The first could potentially spread showers as far south as the Kern County mountains and, for the second day in a row, a vigorous low pressure system shows up off the northern California coast with possibly a significant trail of energy sweeping in underneath the low and into northern and central California a week from Monday.
Forecast: Widespread fog and low clouds redeveloping later tonight. Widespread fog and low clouds during the night and morning hours with partial clearing in the afternoons through Tuesday. Areas of fog and low clouds nights and mornings Wednesday through Christmas Eve with variable clouds above the fog. Areas of fog and low clouds Christmas morning with increasing cloudiness during the afternoon. Mostly cloudy with a slight chance of showers Friday night with an increasing possibility of rain Saturday.
Short Term:
| Madera 29/53/29/52 | Reedley 28/53/29/52 | Dinuba 28/55/29/55 | |
| Porterville 28/57/29/58 | Lindsay 27/56/28/55 | Delano 29/56/30/57 | |
| Bakersfield 36/58/37/61 | Taft 44/58/45/62 | Arvin 34/58/34/59 | |
| Lamont 34/57/34/60 | Pixley 29/55/29/55 | Tulare 28/52/29/52 | |
| Woodlake 28/54/29/54 | Hanford 30/53/30/52 | Orosi 28/54/29/54 | |
Winds: Winds through Tuesday will be generally less than 10 MPH late mornings and afternoons and at or less than 5 MPH during the night and early morning hours with extended periods of near calm conditions.
Rain: Expect dry weather through at least Tuesday night. models are showing a weak upper low approaching the central and southern California coast Wednesday and Christmas Eve. This little system is by no means impressive, but a few sprinkles would not be an entire shock, especially in the south valley. From Friday night through Monday, models continue to trend towards an active pattern. The eastern Pacific high is projected to drop well south, allowing two potential storms to affect central California. The first is from late Friday night through Saturday night, with rain possibly spreading as far south as the Kern County mountains. Instead of a trough of low pressure, the second system shows up as a deep low off the northern California coast a week from Monday with potentially a fairly rich feed of moisture underneath the low, moving through northern and central California. Of course, this far out it’s a shaky forecast at best, but it does look pretty on paper.
Frost: Today is probably a good illustration of what each day will be like, at least through Tuesday. In other words: extensive fog nights and mornings with cat and mouse clearing afternoons. As of 1:30, most of the valley was enjoying hazy sunshine with a few remaining pockets of low clouds over Madera and Merced Counties where readings were only in the upper 40s. Dew points this afternoon are generally running in the lower 40s. with generally clear skies for most of the night, radiational cooling will be strong again for widespread upper 20s and lower 30s with generally low to mid 30s in portions of Kern County.
Coldest unprotected river bottom and other low spots will drop down to 26 to 27 degrees, that’s in those fog free locations. Most flat land locations will range between 28 and 32 with hillsides coming in above freezing.
The inversion tonight will be good with temperatures at 34 feet generally 5 to 8 degrees warmer at most locations.
If fog and low clouds form early enough, conditions will be somewhat milder. Again, this will be the same rule of thumb through Tuesday.
Beginning Wednesday, a weak upper low will approach the central and southern California coast. In theory, this feature should spread enough cloud cover overhead to nudge temperatures upward. From Friday night through the weekend, the first of two storms will sweep through for above freezing conditions. Fortunately for now, there’s nothing on models to suggest a particularly cold weather pattern on the horizon. As a note: the time frame from now through mid January is historically the coldest of the year.
Lows Tonight:
| Terra Bella
28 |
Porterville
28 |
Ivanhoe
27 |
Woodlake
28 |
| Strathmore
28 |
Mcfarland
27 |
Ducor
29 |
Tea Pot Dome
28 |
| Lindsay
27 |
Exeter
27 |
Famoso
28 |
Madera
29 |
| Belridge
27 |
Delano
28 |
North Bakersfield
29 |
Orosi
28 |
| Orange Cove
28 |
Lindcove
27 |
Lindcove Hillside
Af |
Sanger River Bottom
26 |
| Root Creek
28 |
Venice Hill
29 |
Rosedale
29 |
Jasmin
29 |
| Arvin
Af |
Lamont
Af |
Plainview
29 |
Mettler
Af |
| Edison
Af |
Maricopa
29 |
Holland Creek
31 |
Tivy Valley
28 |
| Kite Road South
31 |
Kite Road North
28 |
AF=Above Freezing
Next update: December 20/am