[willamette-fcst] Forecast - Monday, March 29th, 2010
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon Mar 29 08:17:54 PST 2010
Daily Smoke Management Forecast
Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.
Monday, March 29th, 2010 at 9:00am.
Recommended burn times for agricultural burning are from now until 5:30pm.
Straw stack burning is allowed from now until 5:00pm.
The moderate to strong El Nino, in the eqatorial Pacific
Ocean, is weakening but expected to last at least through
this spring. Typical of El Nino, our early spring weather
looks more wintry than spring-like. 6-10 inches of snow fell
over the Cascades passses late last week, with about
one-half inch of rain in the Willamette Valley. After a
brief break, with some sunshine on Saturday, rain spread
back across western Oregon on Sunday.
It seems more like November or December overnight, with
southerly winds, gusting to over 80 mph along the coast and
to nearly 50 mph in the Willamette Valley, accompanied by
heavy rain. The National Weather Service wind tower, at
Garibaldi, recorded a wind gust early this morning of 85
mph. 77 mph winds were clocked at the Yaquina Bay Bridge,
in Newport. Mt. Hebo, in the northern coastal range,
recorded a peak gust of 96 mph. In the Willamette Valley,
southerly winds gusted to 46 mph in Salem and to 38 mph in
Portland. Rainfall totals of more that one-half inch were
common along the coast and across the Willamette Valley,
during the past 24 hours. Troutdale, Hood River, Newport,
and Brookings all picked up around an inch of rain.
The mid-morning ODA surface analysis showed southerly
pressure gradients beginning to relax across western Oregon,
while strengthening slightly east of the Cascades.
South-southwesterly winds were still gusting to around 30
mph across western Oregon, with local gusts to about 35 mph
in the Willamette Valley and to over 40 mph along the coast.
Southerly winds had increased across central and eastern
Oregon, with 25-40 mph gusts. The strongest winds, east of
the Cascades, were from Klamath Falls to Rome.
The strong cold front, responsible for the stormy weather,
was just moving onto the Oregon coast at mid-morning.
Satellite imagery showed solid cloud-cover across the entire
state, with a back edge to the overcast skies nearing the
coast. Doppler radar and surface reports showed locally
heavy rain falling across all of western Oregon, with only a
few areas of light rain making it east of the Cascades. The
freezing level jumped to 6-7000 feet, ahead of the cold
front, Sunday afternoon and was holding there this morning.
ODOT road cameras showed wet pavement over Cascade passes,
where temperatures were several degrees above freezing.
The cold front is forecast to slowly progress eastward,
across western Oregon, this morning and push east of the
Cascades this afternoon. In its wake, the steady rain will
turn showery, with colder air aloft rapidly dropping the
snow levels in the Cascades. Satellite imagery shows
impressive cumulus cloud development approaching the
coastline, so scattered thunderstorms are likely to move
onshore later this afternoon. With lowering snow levels
today, the National Weather Service has issued a Winter
Storm Warning, for elevations above 4000 feet, where more
than foot of new possible is possible later this afternoon
and tonight. That is much-needed snowfall but could cause
serious travel delays over the Cascade passes.
Thunderstorms will likely produce bursts of small hail along
the coast and across the western valleys later this
afternoon and this evening.
Stormy conditions held overnight temperatures mostly in the
mid to upper 40s across western Oregon. Mid-morning
readings ranged from the upper 40s to the low 50s. Highs
this afternoon should only warm into the 50-55 degrees
range. Pressure gradients are forecast to turn more
southwesterly, in the wake of the cold front, this
afternoon. Continued blustery southwesterly winds and
cooling air aloft will provide excellent ventilation
conditions today for agricultural and stack burning.
SW 15-25 G35 this morning, SW 10-20 G30 this afternoon.
SW 35 this morning, SW 30 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3000 feet. Ventilation index 105.
Salem\'s high temperature today will be near 54.
Minimum relative humidity will be near 61%.
Salem sunset tonight: 7:36pm; sunrise tomorrow: 6:56am.
A cold and unstable air mass will move over Oregon Tuesday
and Wednesday, with frequent showers and likely some
afternoon thunderstorms. Coastal and valley locations will
likely see more bursts of small hail. Snow levels will
remain well below the Cascade passes and could drop as low
as the coastal range passes by Tuesday night. The main jet
stream energy will sag southward, to over California, by
Wednesday. However, plenty of cold air aloft will combine
with daytime heating to trigger plenty of showers across Oregon,
with the mountains continuing to pick up much-needed snowfall.
A transitory ridge of high pressure is forecast to move
onshore Thursday and warm the air aloft enough to stabilize
the atmosphere and decrease the showers across the state.
Clearing skies could allow temperatures to approach the
freezing mark across the Willamette Valley Thursday morning.
Partly sunny skies and warmer air aloft will help daytime
highs climb closer to normal Thursday afternoon, with only a
slight chance of a shower.
Another cool Pacific storm is forecast to bring more valley
rain and mountain snow on Friday, with snow levels staying
below the Cascade passes. Showers will follow the cold
front on Saturday, with more snow expected in the mountains.
The next system may take aim more at California, on Easter
Sunday, but that is getting too far out to call.
Tue (30 Mar): Showers and T-storms with Small Hail. Snow Level Dropping to 2500 Feet. 40/51
Wed (31 Mar): Showers and T-storms with Small Hail. Snow Level Dropping to 1500 Feet. 36/50
Thu (01 Apr): Decreasing Showers. Becoming Partly Sunny. Snow Level 2500 Feet. 34/54
Fri (02 Apr): Rain and Mountain Snow. Snow Level 3-4000 Feet. 40/53
Sat (03 Apr): Showers. Snow Level 3000 Feet. 40/55
Sun (04 Apr): Chance of Rain...Mainly South. Snow Level 4000 Feet. 40/55
Mon (05 Apr): Chance of Rain. Snow Level 3-4000 Feet. 39/55
weather at oda.state.or.us
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