[willamette-fcst] Forecast - Monday, May 12th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon May 12 08:00:34 PDT 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.
Monday, May 12th, 2008 at 9:00am.
Agricultural burning is not recommended.
Stack burning is not allowed.
A weak cold front moved across Oregon Saturday with onshore
flow and scattered sprinkles across the state. Willamette
Valley temperatures were near normal Saturday with highs in
the low to mid 60s. A cool upper-level trough brought
scattered light showers and cooler temperatures to the state
Sunday. Highs Sunday were only in the mid to upper 50s
along the Oregon Coast and in the Willamette Valley. Southwest,
Central, and Eastern Oregon temperatures Sunday ranged from
the mid 50s to the mid 60s.
The upper-level trough had moved to over Idaho by this morning
with northwesterly flow aloft over Oregon. A few showers
will still circulating around this system into Eastern
Washington and Eastern Oregon. West of the Cascades, a fair
amount of low cloudiness was persisting in the Northern
Willamette Valley with a few light showers. The south
valley had partly sunny skies. The ODA surface analysis
showed high pressure over Western Oregon with weak pressure
gradients across the Willamette Valley. Gradients were stronger
from the Cascades to the Idaho Border with westerly winds gusting
to about 25 mph in the Columbia Basin near Pendleton.
The air mass over Oregon is quite cool with the freezing
levels measured over Salem and Medford early this morning at
just 3800 feet and 4600 feet respectively. Partial clearing
allowed Willamette Valley temperatures to locally drop into
the upper 30s overnight. McMinnville, Salem, and Corvallis
all dropped to at least 38 degrees early this morning and
Hillsboro dipped to at least 37. Many areas east of the
Cascades fell below the freezing mark. Redmond was the cool
spot in the state this morning at 23 degrees.
The showers will end today, as the upper-level trough pushes
into the Northern Rockies and high pressure begins building
over Oregon. Partly sunnny skies will help temperatures
recover into the low 60s across the Willamette Valley this
afternoon. Weak surface pressure gradients and light
transport winds will make for poor ventilation conditions
over the Willamette Valley today, in spite of relatively
high mixing heights this afternoon.
As an upper-level ridge of high pressure continues to push
onshore Tuesday, a warm front is forecast to bring some
light rain to Western Washington. Considerable mid and high
clouds will cover Oregon with a chance of light rain over the
northern half of the state. Even with warming aloft, cloudy
skies will keep surface temperatues near or below normal across
Western Oregon Tuesday. It still appears as if we will get a
taste of summer during the second half of the week...
Var 0-4 this morning, N 5 this afternoon.
Var 3 this morning, NNW 5 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 5000 feet. Ventilation index 25.
Salem\'s high temperature today will be near 62.
Minimum relative humidity will be near 46%.
Salem sunset tonight: 8:32pm; sunrise tomorrow: 5:45am.
An unseasonably strong upper-level ridge is forecast to
bring sunny and much warmer weather to all of Oregon later this week.
Onshore flow Tuesday will turn northerly Wednesday and offshore by Thursday
afternoon. Temperatures will become progressively warmer each day.
Willamette Valley highs may shoot well into the 80s by Thursday.
The warmest day, west of the Cascades, appears to be Friday, with
strong offshore flow helping temperatures climb to near record values
across much of Western Oregon.
The upper-level ridge, and associated surface thermal
trough, are forecast to push east of the Cascades Saturday.
That would shift the warmest weather to Central and Eastern
Oregon with cooling onshore winds moving back into Western Oregon.
The cooling trend should progress eastward, across
Central and Eastern Oregon, Sunday, with increasing onshore flow
west of the Cascades. A strong westerly jet stream is forcast
to return more typical weather to the region by Monday.
Tue (13 May): Mostly Cloudy North...Slight Chance of Rain. Partly Cloudy South. 42/65
Wed (14 May): Becoming Mostly Sunny and Warmer. 49/74
Thu (15 May): Sunny and Unseasonably Warm. 50/84
Fri (16 May): Sunny with Possible Record High Temperatures. 54/91
Sat (17 May): Sunny and Very Warm. 55/83
Sun (18 May): Mostly Cloudy and Much Cooler. 48/68
Mon (19 May): Mostly Cloudy. 46/66
weather at oda.state.or.us
The following is the forecast page from the latest montly update of the ODA
Seasonal Climate Forecast. The complete forecast is available on the ODA
website at http://oregon.gov/ODA/NRD/weather.shtml#Weather_forecasts
Seasonal Climate Forecast
May through August, 2008
Issued: May 7, 2008
Purpose: To provide Oregon farmers and growers with a seasonal climate
outlook that is more accurate than assuming average conditions will prevail.
Basis of Forecast: Changes in Sea-Surface Temperatures (SST) in the
Tropical Pacific Ocean have been closely linked with subsequent changes in
world-wide weather patterns. Modern technology makes it possible to accurately
track changes in ocean temperatures. I compare the current tropical SST structure
(including the evolution since the previous winter) with former years to find the
best matches (analogs). Using historical data from these analogs, I am able to
construct a climate forecast for the upcoming season.
Accuracy: Over the past decade, using historical records, from analog years,
to create a climate forecast has proven more accurate than simply forecasting average
conditions. The accuracy of the forecast increases during El Nino and La Nina events,
because the resultant weather pattern changes are more identifiable and affect the
local climate in fairly consistent ways.
Limitations of Forecast: Long-range climate forecasts are fundamentally
different from short-term weather forecasts derived from dynamic computer models.
Rather than getting specific, the goal of this product is to forecast general trends
in the local climate during the upcoming season.
Forecast: La Nina conditions, in the Tropical Pacific, have been weakening
since mid-February. La Nina is expected to continue to weaken with El Nino-Southern
Oscillation (ENSO) neutral conditions possible by July. It should be noted that the
link between ENSO and the Pacific Northwest Climate is not as pronounced in the
summer as it is during the other seasons.
The following May through August climate predictions are based on historical weather
data from the top three analog years (1971, 1974, and 1989) with extra weight given
to the top analog year of 1971:
Below normal temperatures in May that will trend to near normal in June and July
(above normal eastern zones). Above normal temperatures in August, especially eastern zones.
Precipitation generally near or slightly below normal. The best chance for above normal
precipitation is in June. The coastal zone may stay slightly damp.
Increased chance of late-season frost damage to crops east of the Cascades.
Your feedback is encouraged to help us maximize the utility of this service.
Pete Parsons - Meteorologist - Oregon Department of Agriculture
(503) 986-4701, pparsons at oda.state.or.us
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