[willamette-fcst] Forecast - Friday, December 26th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Dec 26 11:59:59 PST 2008
Daily Smoke Management Forecast
Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.
NOON UPDATE
...Next update scheduled for Monday, January 5th, 2008...
Issued:
Friday, December 26th, 2008 at 12:00pm.
Burn Advisory:
Agricultural burning is allowed. Suggested burn times are from now until 2:30pm.
Straw stack burning is allowed from now until 2:30pm.
Weather Discussion:
Christmas 2008 set snowfall records in the northern
Willamette Valley. It was the snowiest in Portland history,
with 10 inches on the ground at the Portland National
Weather Service office, in northeast Portland. In addition,
December 2008 will go into the record books as the snowiest
December, in Portland, since records started at the Portland
Airport (1940), with 18.9 inches, and one of the snowiest of
all time.
More on this record-setting snowy month can be found at:
http://www.wrh.noaa.gov/total_forecast/getprod.php?wfo=pqr&pil=PNS&sid=PQR
Historical information regarding Willamette Valley snow on
Christmas is available at:
http://www.wrh.noaa.gov/pqr/info/2008_December_Christmas.txt
More snow showers fell in the northern Willamette Valley on
Christmas, with eight-tenths of an inch falling at the
Portland National Weather Service. A cold upper-level
trough was responsible for the rain and snow showers
Christmas Day, with valley high temperatures only climbing
into the mid to upper 30s. There was not much melting of
snow on the ground. Partial clearing overnight allowed
areas of icy fog to form in the valley with low temperatures
generally falling below freezing. That allowed slushy
streets to refreeze in many areas, with visibilities locally
less than one-half mile. That made for difficult travel
conditions again this morning.
A major warming trend will begin, across Washington and
Oregon, later today. The first in a long seris of warmer
weather systems will move onshore this afternoon. A warm
front was already spreading rain onto the northern and
central Oregon Coast late this morning. As precipitation
moves inland this afternoon, the air mass over the wetern
valleys may be cold enough for snow to fall at very low
elevations. No accumulation is expected below 1000 feet.
Increasing warm southerly winds should lift the snow level
to around 2500 feet by this evening.
Cold air remains trapped in the Columbia Gorge, so
precipitation there will begin as snow or freezing rain.
The National Weather Service has issued a Winter Storm
Warning, valid later this afternoon and tonight, for the
Columbia Gorge and the upper Hood River Valley. Snow in the
Gorge, and in the upper Hood River Valley, should change to
rain overnight, with possible areas of freezing rain. Snow
levels will quickly lift above the coastal range passes this
afternoon, but increasing snow is expected in the Cascades
through this evening, where Winter Storm Warnings have been issued.
The incoming storm will also produce strong southerly winds
along the coast, so the National Weather Service has issues
a High Wind Warning for the northern and central Oregon
Coast for later this afternoon and tnight. Southerly winds
may gust to 60 mph late this afternoon and tonight. Rain
and southerly winds will also increase in the Willamette
Valley later today with temperatures climbing into the low
40s by this evening. South winds may gust to near 30 mph by
tonight in the valley.
Temperatures will remain steady or slowly rise overnight
with the cold front not coming onshore until Saturday
morning. The combination of warm southerly winds,
increasing rain, and melting snow will make for local
ponding of water on north-valley and coastal range roadways,
in addition to large quantities of slush. That will make
for locally hazardous travel...especially on less traveled roads.
Surface Winds:
S 10-20 G25 this afternoon.
Transport Winds:
S 25 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 2000 feet. Ventilation index 50.
High Temperature:
Salem\'s high temperature today will be near 42.
Humidities:
Minimum relative humidity will be near 89%.
Sunrise/Sunset:
Salem sunset tonight: 4:37pm; sunrise tomorrow: 7:50am.
Extended Outlook:
A strong westerly jet stream is forecast for this weekend
and much of next week with rain in the valleys and snow for
the mountains. Snow levels will briefly rise to near 5000
feet early Saturday, before dropping back to between 3-4000
feet for most of next week. Coastal and western valley
temperatures will return to near seasonal normals. Run-off
from rain, combined with the significant melting of
low-elevation snow, raises the concern for flooding. At
this time, major flooding is not expected, but rivers and
streams will need to be closely monitored.
The latest weather warnings, advisories, and forecasts, from
the Portland National Weather Service, are available at:
http://www.wrh.noaa.gov/pqr/
River and stream information is avaiable from the Nortwest
River Forecast Center:
http://www.nwrfc.noaa.gov/
Tomorrow (27 Dec): Rain at Times. Snow Levels Rising to 5000 Feet. 40/46
Sun (28 Dec): Rain at Times. Snow Levels 3-4000 Feet. 40/46
Mon (29 Dec): Rain at Times. Snow levels 2-3000 Feet. 39/43
Tue (30 Dec): Rain at Times. Snow Level 2-4000 Feet. 36/44
Wed (31 Dec): Rain at Times. Snow Level 3-4000 Feet. 36/45
Thu (01 Jan): Rain at Times. Snow Level 2-3000 Feet. 37/44
Fri (02 Jan): Rain at Times. Snow Level 3-5000 Feet. 38/48
ODA Meteorologist
weather at oda.state.or.us
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