Summary: North of Kern County is like an icebox this afternoon by valley standards. As of 1:00pm, Visalia was reporting 39 degrees, Madera 41, Fresno and Lemoore 43, Porterville 47, with Bakersfield having hazy sunshine and a high of 54. Skies had cleared at Porterville with a visibility of 3 miles. Visalia, Lemoore, and Fresno were each reporting the base of the overcast at 500 feet and 700 feet above Hanford. These locations now have better than a mile visibility.
Where it has cleared this afternoon, fog will likely rapidly reform during the night with the low overcast or ground fog widespread by sunrise. I’ve changed my mind a bit in the frost report below, so please read.
Upper level high pressure will begin to weaken tonight and will be suppressed southward. A mammoth upper high stretches from off shore California northward along the Pacific coast all the way into Alaska while an impressive winter storm is centered over the Montana/North Dakota border. Along the back side of that storm is a Canadian air mass which will dive into the Rockies over the next 24 hours and into the Midwest Wednesday night through Christmas Eve. Thank heavens for the Sierra Nevada which usually blocks arctic air masses from moving into the valley.
A surface high over the Great Basin by Wednesday will reach 1044.4 millibars, which is very high. This will generate a strong off shore flow. This is an extremely dry air mass and I’ll have to watch very closely to see whether any of this dry air mixes down to the valley floor, thus dissipating the low cloud deck. For now, that appears doubtful but worth watching.
An upper low off the southern California coast will begin to spread increasing higher clouds above Wednesday. as this feature moves across central and southern California Christmas Eve and Day, it’s possible a few sprinkles could occur. Just as soon as this system heads into the interior west, a trough of low pressure will move through central and southern California late Friday night and Saturday. this system will simply lose its upper air support as it moves inland with just light, scattered showers at best, and mainly from Fresno County north from Saturday through Saturday evening.
About 36 hours later, or Sunday night, clouds will begin to increase ahead of a polar low moving southeastward from the Gulf of Alaska. This storm is still projected to move right through central and southern California Monday, and possibly even into Tuesday morning. I will have to watch the potential for gusty winds in the extreme south valley late Sunday and Monday. Latest models indicate there’s less of a risk of this occurring, but I’m still cautious.
After Tuesday, unfortunately it looks like a blocking ridge pattern will redevelop. We may also see a northerly develop aloft behind the Sunday through Tuesday storm, resulting in below average temperatures as we wind down the year. It will be nice to get this 2020 business behind us.
Forecast: Widespread dense fog tonight in some areas, fog and/or low clouds elsewhere with some clearing in the afternoon, mainly in Kern County and along the foothills, through Wednesday night. variable cloudiness Christmas Eve through Christmas Day with a slight chance of a few sprinkles. Areas of fog and low clouds can be expected Thursday morning. mostly cloudy Friday night through Saturday night with a chance of scattered light showers from mainly Fresno County north Saturday through Saturday evening. Partly cloudy Sunday. Increasing clouds later in the day. Mostly cloudy Sunday night with a chance of rain from Fresno County north after midnight. Periods of rain Monday and Monday night with a chance of showers into Tuesday morning. partly to mostly cloudy Tuesday afternoon.
Short Term:
| Madera 32/47/35/55 | Reedley 33/48/35/56 | Dinuba 34/47/35/54 | |
| Porterville 28/54/34/58 | Lindsay 28/53/33/55 | Delano 31/50/35/58 | |
| Bakersfield 36/59/41/62 | Taft 44/57/48/61 | Arvin 32/59/35/62 | |
| Lamont 32/59/35/61 | Pixley 33/50/35/57 | Tulare 35/46/35/55 | |
| Woodlake 29/51/35/56 | Hanford 35/48/35/57 | Orosi 28/51/34/56 | |
Winds: Winds through Christmas Day 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. Forecast models are less bullish this afternoon about the possibility of strong, gusty, southeast winds in the extreme south valley late Sunday into Monday. Still, the difference in pressure between the high deserts and off shore San Francisco is pretty significant. This far out, it’s just wise to mention the possibility of this occurring, but it isn’t in cement.
Rain: A few sprinkles will be possible Christmas Eve through Christmas Day from a weak upper low which will be meandering through central and southern California. If any rain reaches the valley floor, I’d be surprised if it was measurable. Just as soon as this little system scoots eastward, a weakening trough of low pressure will move through northern and central California late Friday night through Saturday evening. There’s nothing to suggest this will be much of an event with only light scattered showers mainly on Saturday and mainly from Fresno County north. If enough precipitation to measure does occur, expect less than .10. our best shot at rain and mountain snow will begin later Sunday night , lasting into Tuesday morning as a colder winter storm drops out of the Gulf of Alaska. Most models place it just west of the Bay Area by Monday morning then moving slowly south/southeast through central and southern California Monday through Tuesday morning. so far, the trend looks good on this storm. I have seen systems like this suddenly change their minds and move southward off shore, robbing us of potential precipitation. So far, that isn’t showing up. We’ll keep you posted. For now, a blocking ridge pattern shows up after this storm moves through for at least several days of dry weather.
Frost: I am changing my thinking a bit from this morning. the lion’s share of my brain says that the fog, which has lifted into a low overcast north of Kern County, will remain locked in. Areas that have enjoyed some hazy sunshine this afternoon will fill in with dense ground fog and the night moves on.
What has me a little nervous is a very robust off shore flow that will develop later tonight through Thursday. It’s possible this very dry air mass could mix down to the valley floor, possibly dissipating the low clouds in some areas, especially in Kern County. Even though I believe most, if not all locations, will be at or slightly above freezing tonight, I’m going to throw some numbers at you anyway just in case the fog does mix out.
By Wednesday night, higher clouds will begin to increase ahead of a low off the south coast. This will continue through Christmas Day. That, in conjunction with stubborn fog and low clouds on the valley floor, should keep readings in at least the low to mid 30s Christmas Eve morning and just plain above freezing Christmas morning. Merry Christmas!
An active weather pattern will prevail Saturday into Tuesday which will result in plenty of cloud cover maintaining above freezing conditions more than likely through Tuesday morning. a northerly flow aloft shows up behind the Monday/Tuesday system, so frost will be possible beginning Wednesday morning and beyond, but I don’t see anything serious on the horizon.
Lows Tonight:
| Terra Bella
28 |
Porterville
28 |
Ivanhoe
27 |
Woodlake
29 |
| Strathmore
29 |
Mcfarland
28 |
Ducor
29 |
Tea Pot Dome
28 |
| Lindsay
27 |
Exeter
28 |
Famoso
29 |
Madera
31 |
| Belridge
27 |
Delano
30 |
North Bakersfield
29 |
Orosi
28 |
| Orange Cove
29 |
Lindcove
28 |
Lindcove Hillside
Af |
Sanger River Bottom
30 |
| Root Creek
28 |
Venice Hill
29 |
Rosedale
29 |
Jasmine
30 |
| Arvin
32 |
Lamont
32 |
Plainview
29 |
Mettler
Af |
| Edison
33 |
Maricopa
29 |
Holland Creek
31 |
Tivy Valley
28 |
| Kite Road South
31 |
Kite Road North
28 |
AF=Above Freezing
Next update: December 23/am