Summary: A strong surface high has now set up shop over the Great Basin with the center of circulation in southern Idaho and northeast Nevada. With a weak upper low off the southern California coast, a strong off shore flow is underway. Winds at Sandburg at the 4,100 foot elevation are out of the northeast at 35 MPH, gusting to 48. This is an extremely dry air mass that’s invading southern California. Dew points have fallen to near 0 over the Tehachapi Mountains. I’ve been watching the low overcast dissipate from south to north over the valley. Skies have cleared out over the southern half of Tulare County down to Kern County while a low overcast remains intact from the northern half of Tulare County north where temperatures are in the mid to upper 40s.
The overcast has risen somewhat, as well, ranging from 900 feet above Madera to 1,700 feet over Porterville. Typically, when it gets this far off the deck, the warm air inversion has weakened at least some which will make frost forecasting tonight a nightmare. This is all explained below.
That weak low off the southern California coast has already spread high, thin clouds over central California. These clouds will continue to thicken and lower somewhat with even a slight chance of a few sprinkles Christmas Eve and Day.
As this system moves eastward, high pressure will give way over the western states and will be suppressed southward as a weakening trough of low pressure moves through northern and central California Friday night through Saturday. models this afternoon are even more skeptical. It’s entirely possible the south valley may not record measurable rain at all, and even from Fresno County north, if measurable rain does occur, it will be nothing to write home about. This system will move quickly eastward Saturday night.
We then will turn our attention to the northwest as a colder and stronger low drops southward just off the northern California coast Sunday night. even though this storm will be weakening as it moves south/southeast through central and southern California, the entire valley should receive precipitation with snow in the mountains. This system will shift into the Desert Southwest by early Tuesday, allowing upper level high pressure over the eastern Pacific to build into California with a north/northwest flow aloft. Even though this air mass will be relatively cold, it appears to be nothing unusual for late December.
The first week of January will see chances of rain in northern California. For now, though, it looks like central and southern California will remain dry.
Forecast: Widespread night and morning fog through Thursday morning with increasing higher clouds above the fog. Variable cloudiness Christmas eve through Christmas Day with a slight chance of sprinkles. Increasing cloudiness Friday night with a chance of light showers late Friday night through Saturday, mainly from Fresno County north. Mostly cloudy Saturday night. partly cloudy Sunday morning. increasing cloudiness later Sunday afternoon. A chance of rain Sunday night, especially after midnight. Periods of rain Monday through Monday evening. Mostly cloudy later Monday night and Tuesday morning, clearing during the afternoon. Mostly clear Tuesday afternoon through Wednesday with areas of night and morning fog and low clouds.
Short Term:
| Madera 32/55/37/60 | Reedley 30/54/37/61 | Dinuba 30/54/37/60 | |
| Porterville 30/57/36/62 | Lindsay 29/54/36/62 | Delano 31/59/38/63 | |
| Bakersfield 40/62/43/63 | Taft 46/57/46/62 | Arvin 35/61/40/64 | |
| Lamont 35/60/37/63 | Pixley 30/58/37/61 | Tulare 30/53/37/60 | |
| Woodlake 30/55/35/61 | Hanford 32/58/36/61 | Orosi 29/55/35/60 | |
Winds: A very strong surface off shore flow is underway. Strong gusty winds out of the east to northeast are buffeting the Tehachapi Mountains. There is a slight chance of localized gusty winds near the base of the Tehachapi tonight and for a time Thursday. Otherwise, winds will be generally light and variable with periods of near calm conditions through Saturday night. there’s also a small chance of some gusty southeast winds again near the base of the Tehachapi Mountains later Sunday into Monday, although I must admit models this afternoon aren’t as strong on this. Nevertheless, I do want to keep that chance in the forecast.
Rain: There is a slight chance of a few sprinkles Christmas Eve into Christmas Day as a weak upper low passes to our south Another weakening system will move through central California later Friday night through Saturday. models this afternoon show this to be even weaker than before with a chance of light showers Saturday through Saturday evening. The next low pressure system to mess with my mind will move southeastward out of the Gulf of Alaska. Even though this storm is weakening, it will track right across central California late Sunday night through Monday evening. Rain appears likely with this system over the entire valley with snow over the higher elevations. Dry weather will return by Tuesday. Models continue to trend towards a dry weather pattern through the first several days of January with the storm track again parading through the Pacific Northwest, clipping northern California from time to time.
Frost: Like last night, tonight will be a tricky one. The main wild card is a very strong off shore flow now underway. I’ve been watching the low cloud deck vanish from south to north. As of the time of this writing, skies have generally cleared out from the southern half of Tulare County south, but remain locked in further north. Add to that, high clouds are increasing from a weak upper low off the southern California coast. With the off shore flow underway, it’s possible skies may remain clear tonight over portions of the valley, possibly reforming as ground fog unless the higher clouds are dense enough to slow the radiational cooling process. It’s entirely possible most locations may remain at or just above freezing tonight. however, it’s also possible enough dry air may mix down, inhibiting fog formation.
With this in mind, I’ll go ahead and place some numbers at various locations and hope the fog and low clouds reform or that the higher clouds begin to thicken enough to moderate the situation a bit.
For Friday morning, most locations will drop into the low to mid 30s, although cloud cover may be dense enough to maintain above freezing conditions. Saturday through Monday, an active pattern will develo9p, keeping temperatures above freezing. For Tuesday and Monday, low to mid 30s will be possible as a dry pattern sets up with possibly another cat and mouse game with the fog and low clouds. Fortunately, there’s nothing on medium range models suggesting a pattern that would be conducive for worrisome temperatures.
Lows Tonight:
| Terra Bella
29 |
Porterville
30 |
Ivanhoe
29 |
Woodlake
30 |
| Strathmore
29 |
Mcfarland
29 |
Ducor
30 |
Tea Pot Dome
29 |
| Lindsay
28 |
Exeter
29 |
Famoso
30 |
Madera
32 |
| Belridge
29 |
Delano
31 |
North Bakersfield
30 |
Orosi
29 |
| Orange Cove
29 |
Lindcove
29 |
Lindcove Hillside
Af |
Sanger River Bottom
28 |
| Root Creek
30 |
Venice Hill
29 |
Rosedale
31 |
Jasmine
31 |
| Arvin
Af |
Lamont
Af |
Plainview
29 |
Mettler
Af |
| Edison
Af |
Maricopa
30 |
Holland Creek
33 |
Tivy Valley
29 |
| Kite Road South
33 |
Kite Road North
29 |
AF=Above Freezing
Next update: December 24/am