[su_note note_color=”#ffffff”]Updated Sun 12:15 PM — This morning’s models still maintain the possibility of afternoon scattered showers and thundershowers, mostly north and west of the city. [/su_note]

[su_note note_color=”#ffffff”]Updated Sat 10:50 PM — Little change In the Sunday forecast shown below. Fog and clouds break between 9:30 AM and 11AM. High Temp 84.2° sd 1.2°  Afternoon showers much less likely except in northern suburbs. [/su_note]

[su_note note_color=”#ffffff”]Updated Sat 08:29 AM — Most of last night’s models onboard for showers and thunderstorms between 12 PM and 5 PM.   Two probability maxima- about 1-2 PM and about 4-5 PM.   Some cloudiness moves in about noon. These storm’s main threat will be mostly moderate to heavy rain where they occur. [/su_note]

The upper air cyclonic flow will continue to cause instability as warm, increasingly humid air moves in from the south.  Both Saturday and to some extent  Sunday will be similar to Friday, weather-wise, with scattered showers and thunderstorms.

Tonight’s HIRESW just available shows showers and thunderstorms developing as early as 12 PM.

Saturday —

• Sunny in the morning, considerable cloudiness after noon time..
• Scattered showers and thunderstorms develop 12-5 PM.
• High Temp 83.6º sd 2.1º (NBM). 85.3º (GFS)
• Dew points- mid 60s
• Winds very light in the morning, increasing to 10 mph from the south in the afternoon.

Sunday—

• Cloudy/some fog in the morning, becoming sunny
• Lower chance of scattered showers in the afternoon.
• High Temp 82.6º sd 2.5º (NBM) (wide spread)
• Dew points 67º
• Winds very light, increasing to 8 mph from the south late afternoon.

[su_note note_color=”#ffffff”]Updated Fri 05:14 PM — Here’s current radar at 5:09 PM.  Showers usually don’t develop in the exact position predicted by the models.

[/su_note]

Last night’s models continue with the idea that scattered thunderstorms are possible Friday afternoon and early evening. They will be scattered, but more widespread than my earlier forecast had suggested from last night.

Some possibility of very widely scattered (isolated) thunderstorms as early as 2 PM.  A bit more widespread between 5 PM and 10 PM.  Not everyone will get a thunderstorm.

(“Predicting thunderstorms is like trying to guess which spot in a saucepan is going to form the first bubble when heating water to a boil”.)

Here’s another approach to predicting thunderstorms:  Upward Vertical Velocity (dark circles) combined with available energy (CAPE).  The exact location of these areas is never exactly as shown.