December 20, 2017
Summary: The cold front which early this morning was moving through Merced County is now quickly moving through Kern County. As of the time of this writing, skies had cleared from a Visalia/Lemoore line northward. South of that line, there were still some light showers occurring which will come to a rapid end by early this evening. As the front weakens, the parent low is driving southeastward into the northern Great Basin and will dive into southern Nevada and Utah on Thursday. Meanwhile, upper level high pressure is again building northward off shore far to the north into western Canada. The squeeze play between the off shore high and the developing low to our east will create a northerly flow which will pump colder and drier air down the valley. Currently, temperatures are anywhere from 7 to 16 degrees colder than 24 hours ago.
Forecasting lows tonight will be a challenge due to a number of factors. This is discussed below in the frost section. Suffice it to say Friday and Saturday mornings will be very cold as the atmosphere settles down with clear skies and light winds.
A ridge will build inland as we head towards Christmas for dry weather with daytime highs finally rising above average once we get into the second half of the weekend. After Christmas, high temperatures are projected to move into the mid to upper 60s which will hopefully begin the process of dragging up overnight low temperatures. One model does place a low center off the central coast Christmas day, but current thinking is that it will remain too far off shore to have much impact.
Medium range models going out through early January continue to show a blocking ridge which more than likely will mean dry weather for the rest of the year and into the first few days of 2018.
Forecast: Mostly cloudy for a time in Kern and southeastern Tulare County with clearing overnight. Some upslope clouds may remain in portions of Kern County and southeastern Tulare County. Mostly clear Thursday through Friday night. mostly clear to possibly occasionally partly cloudy Saturday through Wednesday with cold nights.
Short Term:
| Madera 26/52/23/55 | Reedley 26/52/23/56 | Dinuba 25/53/22/55 | |
| Porterville 26/53/23/56 | Lindsay 25/52/22/55 | Delano 28/53/24/56 | |
| Bakersfield 30/54/27/57 | Arvin 28/55/25/58 | Taft 34/54/28/58 | |
| Lamont 28/53/23/55 | Pixley 26/52/22/56 | Tulare 25/53/22/55 | |
| Woodlake 26/53/22/55 | Hanford 26/53/23/56 | Orosi 26/54/23/55 | |
Winds: Winds will be generally less than 15 MPH tonight, generally east of Hwy 99, but will continue out of the north to northwest at 10 to 15 MPH along the west side, especially along the Interstate 5 corridor. Winds Thursday through Saturday will be generally less than 10 MPH with periods of near calm conditions.
Rain: As of the time of this writing, a few light showers were falling in southern Tulare County and Kern County. This activity will come to a rapid conclusion early this evening as a cold front shifts into southern California. For now, models point to dry weather through early January although one model does show a low off the central coast Christmas Day. However, I don’t have much faith in it come in close enough to result in precipitation.
Frost Information: Temperatures this afternoon are running anywhere from 7 to 16 degrees colder than 24 hours ago. Dew points from Fresno County south have actually risen into the low to mid 40s, but from Madera County north dew points are falling into the mid to upper 30s and no doubt will dip even more so during the course of the night.
Tonight’s forecast will be difficult due to possible upslope clouds in the south valley. Those clouds are by no means guaranteed. Wind conditions, especially along the west side, may keep some locations above freezing, if those winds hold up through to the early morning hours.
The greatest risk of mid 20s will be on the east side, especially closer to the foothills where winds are more likely to be calm. My feeling is most locations will be in the mid 20s to possibly even the low to mid 30s where mixing and local wind conditions keep things active. Possible lingering cloud cover could play a role in the extreme south valley.
The potential for tonight, under ideal frost conditions, would be lows between 23 and 25 with most locations between 26 and 30, possibly milder along the west side.
The inversion tonight will be weak with temperatures at 34 feet being 2 to 4 degrees warmer at most locations.
Friday and Saturday mornings could be dangerous in unprotected low spots. One model places Porterville at 28 degrees Friday morning while others show a temperature closer to 24 with similar conditions Saturday. Using the colder models as a guide, low lying unprotected frost pockets could dip down to 20 to 23 with potentially long durations with most other locations between 23 and 27.
Slight modification may occur Christmas Eve morning with additional modification possible Christmas morning, but even so, assuming skies remain relatively clear, mid to upper 20s are likely.
Once we get past Christmas Day, daytime highs will actually rise into the mid to upper 60s under strong upper level high pressure. This should drag up overnight lows some, but as what has so often been the case this month, daytime highs don’t necessarily mean modification in overnight lows. Subfreezing temperatures are still likely if skies remain clear.
Lows Tonight:
| Terra Bella
25 |
Porterville
27 |
Ivanhoe
26 |
Woodlake
27 |
| Strathmore
26 |
McFarland
25 |
Ducor
27 |
Tea Pot Dome
27 |
| Lindsay
26 |
Exeter
25 |
Famoso
28 |
Madera
26 |
| Belridge
30 |
Delano
28 |
North Bakersfield
27 |
Orosi
25 |
| Orange Cove
26 |
Lindcove
25 |
Lindcove hillside
31 |
Sanger River Bottom
23 |
| Root Creek
26 |
Venice Hill
27 |
Rosedale
28 |
Jasmine
28 |
| Arvin
27 |
Lamont
26 |
Plainview
26 |
Mettler
30 |
| Edison
28 |
Maricopa
27 |
Holland Creek
30 |
Tivy Valley
26 |
| Kite Road South
29 |
Kite Road North
26 |
Next Report: Thursday morning, December 21