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  Area forecast discussionArea forecast discussion
This national weather service
Product is intended to provide a
Well-reasoned discussion of the
Meteorological thinking which went
Into the preparation of the zone
Forecast product. The forecaster
Will try to focus on the most
Particular challenges of the
Forecast. The text will be written
In plain language or in proper
Contractions. At the end of the
Discussion, there will be a list of
All advisor...
Click for more......updated 
  National weather serviceNational weather service
An agency of the federal government
Within the department of commerce,
National oceanic and atmospheric
Click for more... pendleton or 
  320 pm PstPst
Pacific standard time
Click for more... mon nov 23 2009 
   
  updated aviation discussion  
   
  .Short term...tonight through Wednesday night. Low pressure entering  
  the pacnw will continue to spread clouds into the area tonight.  
  showers will also develop along the east slopes of the Washington  
  cascades and then spread east into portions of the Washington  
  columbia BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more... and northern blue mountains overnight. The PcpnPcpn
Precipitation
Click for more...  
  should be mostly liquid but across the higher elevations this could  
  be some snow as well. As the system sags south and east the PcpnPcpn
Precipitation
Click for more...  
  will migrate into the Oregon portions of the BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more... and blue MtnsMtns
Mountains
Click for more... and  
  surrounding area overnight. MoistureMoisture
Refers to the water vapor content
In the atmosphere, or the total
Water, liquid, solid or vapor, in a
Given volume of air.
Click for more... lingers over the blue/wallowa  
  MtnsMtns
Mountains
Click for more... and along the east slopes of the wa cascades tomorrow with  
  showers continuing. With the clearing skies some FogFog
(abbrev. F) fog is water droplets
Suspended in the air at the earth's
Surface. Fog is often hazardous
When the visibility is reduced to ¼
Mile or less.
Click for more... may develop  
  over the lower columbia BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more... Tuesday night. A RidgeRidge
An elongated area of relatively
High atmospheric pressure; the
Opposite of trough.
Click for more... of high  
  pressure moves into the region Wednesday shoving another StormStorm
Any disturbed state of the
Atmosphere, especially affecting
The earth's surface, and strongly
Implying destructive and otherwise
Unpleasant weather. Storms range in
Scale from tornadoes and
Thunderstorms to tropical cyclones
To synoptic-scale extratropical
Cyclones.
Click for more...  
  system north and away from our area. However enough MoistureMoisture
Refers to the water vapor content
In the atmosphere, or the total
Water, liquid, solid or vapor, in a
Given volume of air.
Click for more... will  
  skirt the far NwNw
Northwest
Click for more... and some showers will develop over the east slopes  
  of the wa cascades Wednesday and Wednesday night. Further east FogFog
(abbrev. F) fog is water droplets
Suspended in the air at the earth's
Surface. Fog is often hazardous
When the visibility is reduced to ¼
Mile or less.
Click for more...  
  should develop and expand in coverage to not only include the lower  
  columbia BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more... but also into portions of the blue MtnMtn
Mountain
Click for more... foothills and  
  perhaps the gorge as well Wednesday night.  
   
  .Long term...Thursday through Monday...an Upper levelUpper level
In weather observing, the term
Applies to the portion of the
Atmosphere that is above the lower
Troposphere, generally 850 hpa and
Above.
Click for more... RidgeRidge
An elongated area of relatively
High atmospheric pressure; the
Opposite of trough.
Click for more... will  
  move east of the area Thursday. Lingering effects of the RidgeRidge
An elongated area of relatively
High atmospheric pressure; the
Opposite of trough.
Click for more... will  
  keep patchy FogFog
(abbrev. F) fog is water droplets
Suspended in the air at the earth's
Surface. Fog is often hazardous
When the visibility is reduced to ¼
Mile or less.
Click for more... in the lower columbia BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more.... A splitting Upper levelUpper level
In weather observing, the term
Applies to the portion of the
Atmosphere that is above the lower
Troposphere, generally 850 hpa and
Above.
Click for more...  
  low and FrontFront
A boundary or transition zone
Between two air masses of different
Density, and thus (usually) of
Different temperature. A moving
Front is named according to the
Advancing air mass, e.G., cold
Front if colder air is advancing.
Click for more... will approach the cascades Thursday afternoon...and  
  move over eastern Washington and Oregon Thursday night and Friday.  
  this system will bring some PrecipitationPrecipitation
The process where water vapor
Condenses in the atmosphere to form
Water droplets that fall to the
Earth as rain, sleet, snow, hail,
Etc.
Click for more... and winds to the area.  
  Saturday the EnsemblesEnsembles
Reference to a set of computer
Models run under the concept of
Ensemble forecasting: multiple
Predictions from an ensemble of
Models with slightly different
Initial conditions used as input
And/or slightly different versions
Of models. The objectives are to
Improve the accuracy of the
Forecast through averaging the
Various forecasts, which eliminates
Non-predictable components, and to
Provide reli...
Click for more... start to diverge indicating more uncertainty  
  in the forecast. Both the GfsGfs
Global forecast system - one of the
Operational forecast models run at
Ncep. The gfs is run four times
Daily, with forecast output out to
384 hours.
Click for more... and EcmwfEcmwf
European center for medium-range
Weather forecasts. Operational
References in forecast discussions
Typically refer to the ecmwf's
Medium-range numerical forecast
Model, which runs out to 10 days.
Click for more... indicate a building RidgeRidge
An elongated area of relatively
High atmospheric pressure; the
Opposite of trough.
Click for more...  
  Saturday night...but this pattern does not have any run to run  
  consistency. Trended forecast to drier ridge-like pattern...but did  
  keep some low PopsPops
Probability of precipitation
Click for more... in the mountains due to low confidence. Added  
  fog/freezing FogFog
(abbrev. F) fog is water droplets
Suspended in the air at the earth's
Surface. Fog is often hazardous
When the visibility is reduced to ¼
Mile or less.
Click for more... to the lower columbia BasinBasin
An area having a common outlet for
Its surface runoff. Also called a
"drainage basin."
Click for more... Saturday night through  
  Monday night with spreading pattern through time.  coonfield 
   
  && 
   
  .Aviation...0z tafs...VfrVfr
Visual flight rules - usually
Denotes clear skies or ceilings
Greater than 3000 ft and
Visibilities greater than 6 statute
Miles.
Click for more... conditions will prevail through tonight   
  with increasing MidMid
Middle
Click for more... and High cloudsHigh clouds
These clouds have bases between
16,500 and 45,000 feet in the mid
Latitudes. At this
Click for more.... Another weather disturbance  
  will move into the area overnight with another chance of rain and  
  mountain snow.  krdm in central Oregon will likely not see any  
  PrecipitationPrecipitation
The process where water vapor
Condenses in the atmosphere to form
Water droplets that fall to the
Earth as rain, sleet, snow, hail,
Etc.
Click for more... from this system. There may be brief periods of MvfrMvfr
Marginal visual flight rules -
Usually refers to ceilings between
1000 and 3000 feet and/or
Visibilities between 3 and 5
Statute miles.
Click for more...  
  overnight in rain/snow showers...especially at kdls and kykm...and  
  to a lesser degree at kpdt and kalw. Winds mainly less than 15  
  KtsKts
Knots
Click for more......but perhaps 10 to 20 KtsKts
Knots
Click for more... at times near showers.  76 
   
  && 
   
  .Preliminary point temps/pops... 
  pdt  35  48  33  44 /  30  20   0   0  
  alw  37  47  35  41 /  30  20   0   0  
  psc  34  50  32  46 /  30  10   0   0  
  ykm  31  48  30  45 /  40  20   0   0  
  hri  33  48  31  45 /  30  10   0   0  
  eln  31  47  31  44 /  40  20  10   0  
  rdm  28  52  25  50 /  10  10   0   0  
  lgd  29  44  27  43 /  20  30  10   0  
  gcd  28  47  27  52 /  10  10   0   0  
  dls  36  51  37  52 /  40  20   0   0  
   
  && 
   
  .Pdt watches/warnings/advisories... 
  or...none. 
  wa...none. 
  && 
   
  threat index 
  Tuesday : green 
  Wednesday : green 
  Thursday : green 
   
  green: none or limited need for watches, warnings, or advisories. 
  yellow: a few watches, warnings, or advisories possible or in effect. 
  red: numerous watches, warnings, or advisories possible or in effect. 
   
  for additional weather information, check our web site at... 
  Www.Weather.Gov/pendleton 
   
  
 
   
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