[su_note note_color=”#d9f2da”]Fri 10:45 pm. Minor forecast updates highlighted below for Saturday.[/su_note]

The forecast for this weekend continues to evolve and has changed since I posted my “Weekend Outlook” yesterday. A dip in the jet stream, a stalled front to our south and a secondary coastal low will make for a less than stellar weekend.

A front will move through this evening with some showers. Most of the dynamics are moving to our north and the showers are not expected to be very heavy.

After the frontal passage which hangs to our south, skies had been expected to clear. However today’s NAM and GFS have upper air disturbances moving through our area that will cause significant cloudiness for Saturday, [su_highlight]mostly in the afternoon.[/su_highlight]  A northerly wind will bring cooler temperatures and the much of the day will be somewhat windy, [su_highlight]breezy[/su_highlight] with winds diminishing later in the afternoon. High temperatures 66-68.

For Sunday, there is still disagreement between the GFS and NAM regarding the timing and amounts of rain during the daytime hours.

It’s based on the uncertainty regarding low pressure developing along the stalled front to our south and the transfer of energy to a coastal low expected to develop.

The NAM has been consistent forecasting heavy rain for much of Sunday. It is supported by the European model (ECMWF).

The GFS and the new FV3-GFS have the rain moving in before daybreak with a hiatus during the late morning and afternoon hours.  So if the GFS and FV3-GFS are correct, Sunday mid-day won’t be a washout.  Impossible to say which is correct, but it’s something to hope for.  All models have it cloudy with an easterly cold wind and temperatures in the mid 50s!

[su_note note_color=”#d9f2da”]Thurs 7PM: Still uncertainty with Sunday’s forecast, with the NAM predicting rain for much of the day, while the GFS and FV3-GFS have the rain now later in the day. [/su_note]

I often post an “outlook” forecast on Tuesdays or Wednesdays. I’m glad I waited – the forecast for the weekend has changed significantly over the past few days.

Following a cold front passage on Friday night, skies will clear on Saturday.  Saturday looks to be a nice day with sunny skies and high temps near 70.  (Details Friday evening)

Sunday had initially looked to be another nice day, BUT the latest models, (NAM, FV3-GFS, EKDMOS) have the front that moved through Saturday stalling to our south with low pressure moving along the front.  An easterly flow will bring cooler temps (high in the low 60s) and rain is looking likely, especially for Sunday morning.

The GFS is an outlier this time around, with it holding off the rain until later in the day on Sunday.  Last week, the FV3-GFS had the correct forecast and I suspect its rainier forecast is correct for Sunday.

[su_note note_color=”#d9f2da”]Speaking of the FV3-GFS, the NWS will be upgrading the current GFS model (known as GFS v14) to the FV3-GFS (to be known as GFS v15.1)  on June 12th.  This is a major upgrade to the principal US weather model.

The FV3-GFS has been in development for many years and in comparison testing for over 3 years.  Its forecasts have been shown to be equal or better than the current GFS.[/su_note]

I’ll update the weekend forecast on Friday evening as usual.