KPIX 5 Morning Weather Anchor Roberta Gonzales answers the questions you never get to ask on-air.

Q: Hey Roberta! I heard you on KCBS Radio today and you were talking about how the computer models are “differing” in their projection of this week’s rainfall. Why? -Bill from San Rafael.

A: GREAT question!

Here at KPIX 5, we tap into a variety of different computer models, but when I am forecasting rain, I depend on two projections. The first is called the: WRF-NAM (Weather and Research Forecast Model)and the other is: GFS (Global Forecast System). The WRF-NAM produces a forecast out for 3.5 days, four times a day. The GFS produces a forecast out to 16 days, four times a day.

While there are other sources of Computer Models, those are the two I prefer. Sometimes, just as I may see the timing and the amount of rain differently than a fellow Meteorologist, these Computer Models can disagree or offer differing solutions as well!

As of now, here is what I am going with (this could change as things get closer):

Rain begins North Bay Late Thursday far North Bay and continues in waves through the weekend. Expect periods of heavy rain and gusty winds Friday.

While the bulls eye may change between now and Thursday, it appears as if the bulk of the heavy rain and gusty winds will be North Bay Coastal Range and higher elevations of our Mountains. There have been some differences on timing and exact location of heaviest precipitation. One computer models says 5 inches of rain in the North Bay between Thursday and Saturday with an additional 1 to 2 inches on Sunday.

There is the potential for hydro issues. The possibility of urban and small stream flood advisory issued. The winds will be problematic too with the possibility of downed trees and power lines.

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I would love to hear from you! Please send weather questions, observations and photos to me, and I look forward to hearing from you!

Now, go find your umbrella!