Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Sacramento California
300 am PDT Sat may 27 2017
warming up this weekend. Isolated afternoon showers or
thunderstorms possible over the central Sierra into early next
Discussion (today through monday)...
marine layer not as deep this morning (around 2000 feet) with
stratus remaining mostly across the Bay area. Could see a few
clouds into the Delta this morning, but not expecting a widespread
intrusion like previous few mornings with weaker onshore flow.
Ridging will build across the area today into Sunday, resulting in
warming temperatures. Highs today will top out near normal, in
the 80s across the valley, and 60s-70s in the mountains. An
isolated thunderstorm is possible this afternoon/evening in the
higher elevations of Tuolumne County, but forcing is limited so
not expecting much.
Temperatures warm several degrees for Sunday with plenty of
sunshine around. Again, cannot rule out an isolated PM
thunderstorm across Tuolumne County but forcing remains weak.
Ridging shifts off to the east for Memorial Day in advance of
trough approaching the West Coast. Models have trended cooler over
past several runs for Monday and Tuesday and have nudged
temperatures down again. Monday's highs will be similar to
sunday's readings. As onshore flow increases by Tuesday, expect
cooling trend to begin with valley highs back down into the 80s.
Better chances for PM thunderstorms across the mountains, but not
expecting widespread activity at this time. Delta breeze will also pick
up on Tuesday with gusts to 35 mph and a more substantial
cooldown across Solano County.
Extended discussion (wednesday through saturday)
an upper trough pushing on to the West Coast Wednesday will bring
more cooling with daytime highs expected to come in just a little
above normal. GFS and European model (ecmwf) in fairly good agreement in bringing
a chance of light showers to the northern most state in the
morning and a chance of thunderstorms over the mountains in the
afternoon and evening hours. A second weaker shortwave is forecast
to clip the north state on Thursday bringing a slight threat of
thunderstorms over the Shasta County mountains. The rest of the
forecast area will see generally fair skies and a little warmer
temperatures. Model consistency drops towards the end of the week
as models diverge on timing of next upstream shortwave system to
move into the Pacific northwest. GFS brings light precipitation to
the far north state on Friday while European model (ecmwf) holds the precip
farther north and a day later on Saturday. For now, have kept the
forecast area dry waiting for better consistency. Heights do climb
a bit for Friday and Saturday so daytime temperatures warm a bit
however, upper ridge over southwest U.S. Will remain suppressed so
temperatures should remain within about 10 degrees of normal.
VFR conditions expected next 24 hours. Winds generally 10 kts or
less for taf sites with gusts to around 25 knots in vicinity of