Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Medford or
906 am PDT Friday Aug 1 2014
Discussion...instability is present over northern portions of the
area and a couple isolated thunderstorms have developed just to
north in Deschutes County. The best moisture has pushed north with
a drier air mass over much of the area but models continue to show
enough instability and moisture over northern and eastern portions
of the area to develop some isolated thunderstorms this afternoon
into this evening...mainly over Klamath and lake counties and
possibly into the Warner Mountains in Modoc County. The current
forecast remains on track. Have added patchy smoke to some areas
in northern California and into the Rogue Valley and southern
Oregon Cascades to account for smoke from recent fires. Some gusty
winds are also expected today in the afternoon and evening. This
trend for gusty winds will continue into Saturday as a weak
shortwave trough moves inland to the north. Also on
Saturday...expect additional chances for thunderstorms mainly from
the Cascades eastward in southern Oregon.
Aviation...based on the 01/12z tafs...
Along the coast...areas of IFR ceilings will continue until late morning
with mainly MVFR visible. Around sunrise expect local IFR visible at koth. The
lower conditions will return to the same areas this evening.
Inland...VFR conditions will prevail today. Isolated to scattered
afternoon and evening thunderstorms may produce areas of turbulence
with gusty outflow winds and hail. /Fb
Marine...updated 230 am PDT 1 Aug 2014...
The current pattern...with some slight day-to-day variation...will
persist into early next week. Offshore high pressure and a thermal
trough over northern California will combine to maintain steep wind
wave dominated seas and areas of Small Craft Advisory winds into the
weekend...with the strongest winds and steepest seas from Cape
Blanco south in the afternoons and evenings. Winds may increase to
gales with very steep seas this afternoon for areas south of Cape
Blanco. Confidence is moderate on the gales and very steep seas...as
models continue to postpone the period of strongest winds. In any
case...the gales will be low end. /Fb
Previous discussion... /issued 321 am PDT Friday Aug 1 2014/
Discussion...current water vapor image shows a shortwave moving
north along southwest Oregon. Isolated to scattered storms have
developed north of of the forecast area ahead of the shortwave. In
our area, a couple of isolated storms popped up in northern Douglas
County and suspect this is in part due to a weak trigger and slight
cooling aloft indicated by the models. The storms have now since
weakened and do not expect much if anything to happen through this
morning. Steering winds will bring the smoke from The Gulch and
3-7 day wildfires northward bringing patchy to areas of smoke to
the Rogue Valley and parts of Modoc and southern Klamath counties
this morning. Dry conditions are expected through early this
afternoon. The models show most of the instability east of the
Cascades this afternoon. However storms should be isolated at best
with a weak trigger and with increasing middle level drying and
slight warming at 500 mb which should put a cap on the amount of
activity. In addition steering winds will be light, therefore isolated
storms should set up and remain over the higher terrain.
Temperatures will approach triple digit territory in parts of the
rogue and Shasta valleys.
Any isolated storms should fizzle out Friday evening with dry
conditions expected Friday night through Saturday morning. Once
again we'll be under the gun for thunderstorms Saturday. The NAM and
GFS show the greatest threat for storms in northern Klamath and
lake counties Saturday afternoon and evening, but could not rule out
isolated storms in the Shasta Trinity and east of Mount Shasta. Both
models have backed off some on the strength of shortwaves moving
through, but for now did not make any wholesale changes and see if
the models remain consistent.
Not much change in the overall pattern is expected through at least
the first half of next week. Thunderstorms will remain in the
forecast with the greatest chance on the east side with a general
southwest flow aloft. Temperatures will remain hot and will push
near or at triple digits for the rogue and Shasta valleys.
or... Fire Weather Watch from Saturday afternoon through Saturday
evening for orz624-625.
Pacific coastal waters...Small Craft Advisory for hazardous seas until 5 am PDT Monday
Small Craft Advisory for winds until 11 PM PDT Sunday for
Hazardous seas warning until 5 am PDT Monday for pzz356-376.
Gale Warning from 2 PM this afternoon to 11 PM PDT Sunday for