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| August 20 Lightning Map: 3,458 down strikes recorded in the past 24 hours |
Numerous new fire starts were reported yesterday, with some developing into major incidents. New starts are likely throughout the next week, with lightning activity predicted to intensify today. On many National Forests the lightning alert level (LAL) is at 4 out of a possible 5, with resources beginning to be stretched thin. (A definition of LAL levels can be found here.>)
Red flag warning in effect until Wednesday night.
The National Weather Service in Sacramento posted the following update: Upper level low off the Central California coast is drifting west overnight. Precipitable water values around 1.25 inches across the area which is about 175% of normal for this time of year. Isolated showers have developed over the Sierra and across the Northern Sacramento valley and Northern San Joaquin valley overnight. Mild night with temperatures mainly in the 70s except in the mid to upper 60s over the ridges and near the Delta due to cloud cover and warm air mass. A few record high minimums were tied or broken yesterday. Some locations are nearing their record high minimum at 4 am this morning but should cool a little this morning and may be even cooler tonight. As of 4 am Stockton had dropped to 72 which approaches the record high minimum of 71 set in 1961 for august 20. At Modesto 75 with a record of 72 in 1961, at downtown Sacramento 70 with a record of 69 in 1995 at Sacramento Executive 69 with a record high min of 68 in 1964, at Red Bluff 82 with a record of 77 in 1964, at Redding 79 with an old record hi min of 78 in 1919.
The low is expected to gradually move to the northeast this afternoon and be off the Bay Area coast on Wednesday and move inland across Northern California on Thursday bringing instability and moisture over interior Northern California. Isolated to scattered showers are expected to continue through Thursday especially in the afternoons and evenings with daytime heating. The threat will diminish from south to north as the low moves off to the northeast Wednesday into Thursday. Although the gfs is slower in the bringing the low inland and a little further west with the track compared to the ecmwf and nam. So there is some uncertainty in how quickly the thunderstorm threat will linger in interior Northern California on Thursday. The current forecast slows the timing a little and lingers a chance of showers and thunderstorms over the northern mountains into Thursday evening. The red flag warning for possible abundant lightning and gusty winds over the foothills and mountains continues into Wednesday night/Thursday morning at this time. My need to extend it over the Shasta Trinity Forest during the day Thursday if the low is slower. The thunderstorms may also bring heavy rain and small hail. Mostly sunny skies and warmer temperatures along with southwesterly flow are expected on Friday as the low continues off to the northeast.
The low is expected to gradually move to the northeast this afternoon and be off the Bay Area coast on Wednesday and move inland across Northern California on Thursday bringing instability and moisture over interior Northern California. Isolated to scattered showers are expected to continue through Thursday especially in the afternoons and evenings with daytime heating. The threat will diminish from south to north as the low moves off to the northeast Wednesday into Thursday. Although the gfs is slower in the bringing the low inland and a little further west with the track compared to the ecmwf and nam. So there is some uncertainty in how quickly the thunderstorm threat will linger in interior Northern California on Thursday. The current forecast slows the timing a little and lingers a chance of showers and thunderstorms over the northern mountains into Thursday evening. The red flag warning for possible abundant lightning and gusty winds over the foothills and mountains continues into Wednesday night/Thursday morning at this time. My need to extend it over the Shasta Trinity Forest during the day Thursday if the low is slower. The thunderstorms may also bring heavy rain and small hail. Mostly sunny skies and warmer temperatures along with southwesterly flow are expected on Friday as the low continues off to the northeast.
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