Quote
Dave
Showers for Mariposa on the 19th. That could fizzle as have the past few 10 day predictions.
A large scale pattern change for the north pacific and from northern
California up into the pacific northwest will begin to develop this
Weekend, although it does not appear to be a large precipitation
Producing pattern for our region quite yet (not through day 7). The
Big change will revolve around the fact that the trough over alaska
Will be replaced by an amplified upper ridge which was previously
Located near the west coast. This will open the door, at least
Temporarily, for cold upper trough energy to drop into the pacific
Northwest. Meanwhile, our region will remain on the southern end of
The cold trough energy through early next week with a fairly dry but
Significant cold front possible.
Model discrepancies begin to pop up already by sunday which is not
Surprising given that we are going to experience a shift in the
Large scale pattern. The 12z ecmwf/gem drag a strong cold front into
The region early monday while the gfs keeps it over oregon. The
Ecmwf and gem and at least half of their ensembles support the idea
Of a further south extent to the pacific northwest trough (and thus
Further south cold front), with the gefs showing support as well
With a -1.5 to -2 standard deviation bullseye in the pac nw trough.
Meanwhile, the outlier 12z gfs keeps the trough restricted further
North with a warmer more westerly flow aloft than the ec/gem.
With support seeming to lean towards getting a cold front through
Here early monday per the ec/gem, i have introduced a slight chance
Of showers to the northern half of the cwa sunday night and monday.
As far as possible precipitation amounts with the front, they look
Light at this time as models send the main cold pool aloft to the
North of our region with just a brief window of upper forcing near
Fropa sunday night and monday. Temperature wise monday, i have
Lowered highs a bit with the expectation that we will get
Significant cooling aloft with the fropa. However, keep in mind that
If the ec/gem are right we will be colder still but i did not want
To go hog wild quite yet with some ensembles a bit further north and
The 12z gfs still holding the cold front north of the cwa.
Tuesday and beyond, models come back in line with the large scale
Flow concepts as they quickly undercut the amplified ridge over the
Bering sea and bring fast and moist zonal flow into the northwest
Conus. This is bound to be a good precipitation producer for at
Least the pacific northwest. However, for our region is is difficult
To ascertain how much precip we could get (most likely days 8-10 or
Mid to late next week) as we remain on the southern periphery of the
Moist zonal flow and smaller scale details are indeterminate at this
Time.
