February 1, 2020
Summary: Even though upper level high pressure is almost right overhead this afternoon, the high is already flattening out over the Pacific Northwest. Temperatures this afternoon as of 1:00pm were already nearing the 70 degree mark in the warmest locations, so most locations this afternoon will run from 70 to 73 or so.
A rapidly developing low pressure system both at the surface and aloft is currently over southern British Columbia and Washington state. This system has strong dynamics but is moisture starved. By sunrise tomorrow morning, the cold front will have already zipped into the lower Sacramento Valley and will be moving through Kern County by midday.
Behind the front is a very cold air mass with modified arctic air embedded within it. By Monday morning, a deep low pressure system will be centered over Utah and southern Nevada while a big ridge of upper level high pressure builds along the coast of North America, creating a north/south pipeline of modified arctic air right into California.
A hard freeze is now imminent for Tuesday and Wednesday mornings with many locations at or below freezing as early as Monday morning. this is outlined in the frost summary below.
By Tuesday, the trough will have shifted into the Rocky Mountain region with upper level high pressure just off the coast of the Pacific Northwest and northern California. This will continue the northerly flow through Wednesday. by Thursday, the off shore high will begin to shift eastward into California, changing the northerly flow to a northwesterly flow with rising pressures aloft and an end to the overland north/south flow. The high will continue to shift eastward Friday and Saturday, continuing the warming trend.
Medium range models continue to depict a low pressure center dropping from the Pacific Northwest and into northern and central California Sunday. This appears to be a cut off low situation which could result in light showers. This storm will also be an overland system, meaning it will be moisture starved, so whatever precipitation occurs will be light. Models then show the low moving to a position off the southern California coast, meaning dry weather will return perhaps as early as Monday. Of course, these models are spitting out information for more than a week down the road, and no doubt much will change between now and then, but I must admit the trend has been pretty consistent.
Forecast: Mostly clear before midnight. Increasing cloudiness after midnight. Variable cloudiness Sunday through Monday morning with a slight chance of a few light showers later Sunday afternoon and night. expect gusty northwesterly winds to begin later Sunday morning and continuing through Sunday night. much cooler both Sunday and Monday. Mostly clear and cold Monday afternoon through Wednesday. mostly clear Wednesday night through Saturday with a warming trend.
Short Term:
| Madera 43/58/31/50 | Reedley 43/59/32/50 | Dinuba 42/57/31/49 | |
| Porterville 41/59/32/51 | Lindsay 41/58/31/51 | Delano 43/59/33/50 | |
| Bakersfield 47/62/34/50 | Taft 47/61/34/49 | Arvin 43/60/33/49 | |
| Lamont 44/61/33/50 | Pixley 42/58/32/50 | Tulare 42/58/31/49 | |
| Woodlake 41/59/32/51 | Hanford 43/59/32/50 | Orosi 40/58/30/50 | |
Winds: Winds tonight will be generally at or less than 6 MPH with periods of near calm conditions. By mid to late morning, winds will increase out of the northwest at 15 to 30 MPH with gusts to near 40 MPH, mainly in western Fresno and Kings Counties, but locally elsewhere. Winds Sunday night will decrease to 10 to 20 MPH with stronger gusts along the west side. Winds Monday will decrease to around 5 to 15 MPH with the exception of the far west side where winds will be out of the north at 15 to 25 MPH with stronger gusts. Winds Monday night through Tuesday will be generally at or less than 12 MPH with periods of near calm conditions during the early morning hours.
Rain: Models continue to show a fast moving moisture starved cold front moving through central California Sunday morning followed by a cold trough of low pressure aloft. There is a chance of a few light showers along and behind the front, mainly Sunday through Sunday evening. Realistically, most locations will remain dry. Eventually, the snow level will drop down to 2,000 to 3,000 feet with light snow showers along the Sierra Nevada and the Kern County mountains. Otherwise, this upcoming week will be dry. We’ll mention a small chance of light showers next Sunday from a possible cold upper low moving southward from the Pacific Northwest. We’ll adjust this further as we progress through the week.
Frost Discussion: All locations will be above 32 degrees tonight. it is pretty much set in stone now that a hard freeze will occur Tuesday and Wednesday mornings. Very cold air will dive southward into California behind a fast moving cold front which will move through the valley Sunday morning. my feeling is upslope clouds along the Sierra Nevada foothills and the Kern County mountains as well as wind conditions will keep temperatures in the low to mid 30s at most locations Monday morning. however, in low lying locations where skies clear and winds die off, temperatures down into the 27 to 29 degree range cannot be ruled out.
As strong, gusty, northwesterly winds move down the valley Sunday and Sunday night, dew points will plummet. It now appears dew points will rocket down into the low to mid 20s compared to the near 50 degree dew points we have this afternoon. The NAM model paints a low temperature of 24 degrees in Porterville Tuesday morning while the GFS says 29. Models have been very consistent the past several days in indicating the likelihood of mid to upper 20s Tuesday and Wednesday mornings. It’s possible that in low spots, lows could drop to 23 to 25 degrees with most flatland locations generally in the 26 to 29 degree range. On Tuesday morning, coldest locations could dip to 32 degrees by 8 or 9 PM and 28 degrees by midnight to 1:00am, meaning the potential for durations at or below 28 degrees is likely in the coldest locations. Elsewhere, readings at or below 28 are possible around 2:00am, not rising to above freezing until after 8:30am.
The inversion Monday morning will be pretty much nonexistent. On Tuesday morning, expect a weak inversion with temperatures at 34 feet from 2 to 4 degrees warmer with considerable improvement Wednesday morning.
By Thursday morning, some moderation will have begun with coldest locations in the upper 20s and most other locations in the low 30s. by Friday, most locations will range in the mid to upper 30s with additional moderation over the weekend.
Medium range models are showing a cold upper low over northern and central California a week from tomorrow, possibly followed by another round of cold weather. It’s much too soon to speculate on temperature potentials, but all the models are indicating temperatures will remain below average from next Sunday well into the following week.
Next report: February 2/morning