textproduct: San Joaquin Valley

KEY MESSAGES

1. A Wind Advisory will be in effect this afternoon through tomorrow morning in the Mojave Desert slopes with a 55 to 75% chance of gusts exceeding 40 mph in that area.

2. Below to near normal temperatures continue for the next several days before a potential warm up this coming weekend.

3. There will be isolated rainfall and snowfall this afternoon through this evening mostly confined to the mountains; a few spotty showers can not be ruled out in the valley.

DISCUSSION

A shortwave trough is currently influencing our weather pattern resulting in potentially light to moderate precipitation this afternoon and evening. While most of the precipitation will remain north of our region, there will be some minor rainfall and snowfall accumulations mostly in the northern San Joaquin Valley and along the Sierra Nevada. The probability of exceeding (POE) .01 inches is around 50 to 65% from Merced to Mariposa, with higher probabilities further north and lower probabilities further south. From Fresno to points south in the valley, no accumulation due to rainfall is expected. In addition to rainfall, snow is expected in the mountains, generally above 8,000 feet in elevation. The POE 1 inch of snow is 35 to 50%. The worst case scenario, or the largest amount of snow possible in the mountains for this event is 3 inches. Given that this disturbance will remain mostly to our north, there will not be significant rain or snow accumulations in our area. This disturbance is expected to move out of the area tonight, and after that there will not be a chance for any rain or snow in our area at least for several days.

In addition to the precipitation, localized wind gusts are expected along the Mojave Desert slopes. The POE 40 mph is 55 to 75%. A Wind Advisory has therefore been issued from 4 PM this afternoon until 6 AM tomorrow morning. Be cautious when driving along the Mojave Desert slopes, given that these strong wind gusts could potentially make driving conditions more difficult. The worst case scenario, with only a 10% chance of this happening, would be wind gusts exceeding 50 mph in localized areas. Wind gusts will luckily recede by tomorrow morning.

Temperatures are expected to warm today from the cooler conditions the last couple of days; with the POE 70 degrees above 70 percent from Fresno and points south in the valley. From Madera to points north the POE 70 degrees is below 55%. Temperatures will cool slightly tomorrow due to the influence of the shortwave trough that is currently over our region today, with only a 10 to 25% chance of exceeding 70 degrees through much of the valley. A ridge of high pressure is expected to influence our area this weekend resulting in potentially above normal temperatures. The POE 75 degrees is 65 to 85% on Saturday and Sunday. The ridge pattern will likely weaken and temperatures will decrease next week. By Tuesday, the POE 75 degrees is only 30 to 50% across the valley.

Some model runs indicate that a deep trough and area of low pressure could potentially influence our area by mid-week next week. There is a lot of inconsistency however with regards to the exact timeframe and positioning of this trough. In addition, a potential disturbance could influence the California coast by Thursday of next week. The track of that system is very uncertain at this point, and more details with regards to whether the system will influence our area or remain to our north will be determined as we progress closer towards next week.

AVIATION

VFR conditions will prevail for the next 24 hours, except KVIS where haze could potentially reduce visibility to 4 SM prior to 17Z tomorrow morning.

AIR QUALITY ISSUES

None.

CERTAINTY

The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 4 PM this afternoon to 6 AM PST Wednesday for CAZ338.