December 27, 2018
Summary: Almost the entire southern half of the San Joaquin Valley is either under a low overcast or dense fog or both. Even despite low clouds, many frost locations are in the low to mid 30s this morning with the exception of a few locations in Tulare County which are still in the lower 40s as of 6:00am as persistent low clouds kept that area comfy. A cold low is now driving southeastward through the Great Basin. The current flow both at the surface and aloft is out of the northwest. As barometric pressure rapidly falls over the interior, gusty winds will blow down mainly the west side of the valley. As the low dives southward into southern California and Arizona, the winds aloft by Friday morning will be out of the north then northeast by Friday evening. This is stacking up well with recent computer model data which leaves the valley with a complex forecast. As we’ve been discussing, there are two possible scenarios as far as frost concerns go over the next several days.
The first scenario is the northeast flow will remain aloft, leaving the lower few thousand feet undisturbed. Fog and low clouds and higher dew points would keep temperatures generally in the low to mid 30s.
Scenario number two is that colder and drier air drives down the west side, eventually mixing out lower level clouds in the south valley and along the east side. This would leave relatively clear skies and lower dew points. This seems to be the more likely forecast as of now
Some fog and low clouds may remain through Friday morning, but by Saturday and Sunday mornings, winds will have calmed down and skies would be relatively clear for well below freezing temperatures. This is all discussed in the frost section below.
For New Year’s Eve and Day, high pressure will remain just off shore. Latest model information this morning continue to indicate an arctic air mass will plunge into the interior west, just missing California. Winter is finally arriving over portions of the country that were very mild for the month of December. Once we get past January 3, projections indicate possible precipitation around the sixth or seventh. That’s low confidence for now. But at least the winds aloft will turn westerly, cutting off any potential cold air masses.
Forecast: Fog and/or low clouds this morning. Clearing along the west side this afternoon. Mainly low clouds will persist along the eastern and southern portions of the valley through part of the night and, if we’re lucky, into Friday morning. Mostly clear Friday afternoon through Sunday with patchy fog possible. Mostly clear to occasionally partly cloudy New Year’s Eve and Day. Mostly clear to occasionally partly cloudy Tuesday night through Thursday.
Short Term:
| Madera 53/30/53/27/54 | Reedley 52/32/52/27/53 | Dinuba 52/29/53/26/54 | |
| Porterville 51/31/53/27/54 | Lindsay 51/29/52/26/54 | Delano 53/32/53/29/55 | |
| Bakersfield 52/35/54/32/54 | Taft 55/35/54/33/56 | Arvin 51/34/54/30/54 | |
| Lamont 53/34/54/30/53 | Pixley 53/30/53/27/54 | Tulare 52/29/53/26/53 | |
| Woodlake 52/30/53/27/54 | Hanford 52/31/53/27/54 | Orosi 52/29/53/26/53 | |
Seven Day Forecast:
| Sunday
Mostly clear 27/54 |
Monday
Partly cloudy 31/56 |
Tuesday
Partly cloudy 30/55 |
Wednesday
Mostly clear 29/57 |
Thursday
Mostly clear 31/59 |
Two Week Outlook: January 2 through January 8: This model shows a persistent ridge of upper level high pressure over the eastern Pacific and at least the western one-fourth of the U.S. This means rain is unlikely during this period with above average daytime temperatures.
January: This model shows generally above average temperatures for January over the western one-third of the United States while near to below average temperatures will prevail east of the Rockies. There is no firm indicator of really above or below average precipitation although it does forecast below average rain in the Pacific Northwest.
January, February, March: The western half of the United States is projected in a very general sense to have above average temperatures for the next 90 days. Like the 30 day outlook, it seems to want to project near average precipitation, which would be nice.
Winds: Winds will be generally light for a time this morning then will increase out of the northwest at 10 to 20 MPH this afternoon along the west side with local gusts to 35 MPH possible. Elsewhere, winds will be out of the northwest at 5 to 15 MPH. winds tonight will continue at 10 to 20 MPH along the west side but will become light elsewhere after midnight. Winds Friday will be generally less than 10 MPH with periods of near calm conditions. There will still be the possibility of localized gusty winds out of the north or northeast at 10 to 20 MPH along the west side. Winds Saturday through Sunday will be generally less than 7 MPH with periods of near calm conditions.
Rain: Expect dry conditions for the remainder of the year and quite possibly for the first five days of January.
Frost Discussion: Coldest locations this morning have dropped to 30 degrees so no doubt there were some riverbottom locations out there that dipped to 28 to 29 or so. Tonight’s forecast will be complex as we will be dealing with potential lower level clouds along the eastern and southern flanks of the valley and also variable wind conditions.
Along the west side, breezy conditions may very well last all night long, maintaining above freezing temperatures. Along the eastern and southern flanks of the valley, especially in Tulare and Kern Counties, the main question will be whether upslope clouds will cause clouds and fog to dissipate as drier air moves down the west side and tries to infiltrate the remainder of the valley. Also, local wind conditions may be a factor.
My feeling is, under ideal frost conditions, frost pockets could lower down to 27 to 30 tonight with most locations ranging from 29 to 33 or so. If clouds hang in there, low to mid 30s will be more prevalent.
The current northwest flow will become northerly late tonight and Friday morning and out of the northeast Friday night and Saturday. Pressure gradients will be such that drier air will move down, theoretically mixing out any cloud cover in the valley.
Low temperatures Saturday and Sunday mornings in the very coldest areas could chill down to 24 to 25 or so with most flat terrain locations dipping down to 26 to 29 with hillsides in the low to mid 30s. it’s still possible that these drying winds may blow over the top of the valley, leaving the lower few thousand feet unscathed and with dew points remaining up. Low clouds and fog would remain in place. If this occurs, temperatures would dip into the upper 20s to the low to mid 30s, but that’s less likely to occur. If all the cloud cover does mix out, a series of frost nights will continue for the first few days of the new year and possibly longer. If this cold, dry air mass remains stuck on the valley floor, daytime times would begin to slowly moderate, but overnight lows would moderate much more slowly.
From January 1 through the 2, an arctic air mass will plunge southward over mainly the Rocky Mountain region and the Midwest with some of this air moving over the Great Basin. As of now, from the Sierra Nevada westward, there should not be an affect.
Lows Tonight:
| Terra Bella
30 |
Porterville
29 |
Ivanhoe
29 |
Woodlake
29 |
| Strathmore
28 |
McFarland
28 |
Ducor
31 |
Tea Pot Dome
29 |
| Lindsay
28 |
Exeter
28 |
Famoso
31 |
Madera
28 |
| Belridge
28 |
Delano
31 |
North Bakersfield
31 |
Orosi
28 |
| Orange Cove
29 |
Lindcove
27 |
Lindcove Hillside
32 |
Sanger River Bottom
26 |
| Root Creek
28 |
Venice Hill
28 |
Rosedale
30 |
Jasmine
30 |
| Arvin
31 |
Lamont
31 |
Plainview
29 |
Mettler
33 |
| Edison
30 |
Maricopa
29 |
Holland creek
33 |
Tivy Valley
30 |
| Kite Road South
32 |
Kite Road North
29 |
AF=Above Freezing
Afternoon Dew Points Today: Low to mid 40s. Kern: Low to mid 40s.
Humidity: Porterville: 70%/95%, Bakersfield: 65%/95%
Actual Humidity December 26, 2018: Delano, 99%/62% Porterville, 97%/59%
Percentage of Sunshine Today/Tomorrow: Visalia: Today: 30%, tomorrow 60% Bakersfield: Today: 20% Tomorrow: 50%
ET Rates Over the Past Seven Days: Stratford .20, Parlier .17, Blackwell .24, Lindcove .16, Arvin .31, Orange Cove .19, Porterville .20, Delano .23 Courtesy University of California *=estimate, NA=not available.
Seven Day Soil Temperatures: Stratford 55, Parlier 54, Blackwell 55, Lindcove, 59, Arvin, 54, Orange Cove 57, Porterville 54, Delano 52
Record Temperatures: 72/23. Average Temperatures: 53/35
Heating Degree Days this Season: 712 -312
Courtesy of the NWS
Average temperature for December so far: 49.8 +5.1
Precipitation: Seasonal total/average/above or below average:
Since Oct 1, 2018 Fresno: 2.33 season. or -.80, Month to Date: .56 -.87
Since Oct 1, 2018, Bakersfield: 1.30, or -.47. Month to Date: .62 -.21
Water year season is from October 1st through September.
Chilling Hours November 1st through February 28: Orange Cove, 305, Parlier, 334 , Arvin, 259 Shafter, 354 Stratford, 318, Delano 326, Lindcove, 505, Porterville, 704
. Hours at 45 or below 45.
Sunrise: 7:11 am Sunset: 4:51 pm. Hours of Daylight: 9:40
Yesterday’s Weather:
MAE : Madera 253 : DH1600 / 60 / 36 / 0.00 /
FAT : Fresno Airport 333 : DH1600 / 57 / 40 / T /
HJO : Hanford Airport 242 : DH1600 / 57 / 38 / 0.00 /
NLC : Lemoore Naval AS 234 : DH1600 / 56 / 34 / 0.00 /
BFL : Bakersfield Airport 496 : DH1600 / 48 / 40 / 0.00 /
VIS : Visalia Airport 292 : DH1600 / 56 / 36 / M /
ATEC1 : Avenal 787 : DH1555 / 55 / 38 / 0.00 /
PTV : Porterville Airport 442 : DH1600 / 55 / 38 / 0.00 /
TFTC1 : Taft 759 : DHM / 53 / 45 / 0.00 /
LOSC1 : Los Banos 120 : DH1600 / 57 / 38 / 0.00 /
Rainfall: Water year Oct 1st through September 30th
24hr Season % L.Y. % Ave. Ave. yearly total
STOCKTON 0.00 5.88 135 0.96 22 4.34 14.06
MODESTO 0.00 4.49 121 1.03 28 3.71 13.11
MERCED 0.00 3.87 122 1.11 35 3.16 12.50
MADERA 0.00 2.99 89 0.41 12 3.37 12.02
FRESNO 0.00 2.33 74 0.41 13 3.13 11.50
HANFORD 0.00 1.87 70 0.41 15 2.69 10.10
BAKERSFIELD 0.00 1.30 73 0.07 4 1.77 6.47
BISHOP 0.00 1.57 109 0.16 11 1.44 5.18
SALINAS 0.00 4.77 134 0.78 22 3.56 12.83
PASO ROBLES 0.00 3.60 110 0.27 8 3.26 12.78
SANTA MARIA 0.00 2.74 75 0.12 3 3.63 13.95
Next report: Thursday afternoon/December 27