AgWeatherNet Weekly Weather Outlook for October 13 to October 19, 2012

Heavy Rain in Western Washington as Very Active Weather Arrives This Weekend

Nic Loyd, Meteorologist, 509-786-9357
Gerrit Hoogenboom, Director, 509-786-9371

A series of weather systems will impact Washington through at least early next week, as the state experiences the stormiest period since June. Western Washington and the mountains will see heavy rain at times this weekend and into early next week, as a strong jet stream sends a subtropical feed of moisture into the region. Generally, northern areas will receive more rainfall than the south, and the heaviest should fall from Sunday into Monday. By Tuesday, the heavy rain will have ended. A concern for flooding would normally arise from the expected very wet conditions, were it not for the exceedingly dry weather and low river levels that have preceded this event. Increased winds and large scale air mass exchange will improve air quality in areas with lingering smoke, while rain, clouds, and higher dew points will place a welcome damper on the still active wildfires.

Although this type of pattern is far from unprecedented for autumn, it will be a drastic change from the weather of the last several months. Several inches of rain could fall in western Washington by Tuesday, while the mountains could see 4 or more inches. Even areas of central Washington that do not experience much rain will observe clouds, breezes, and moist conditions at times. While temperatures have been varying largely from day to night, the clouds and wind will suppress diurnal ranges significantly, especially in rainy areas. While highs will be near to slightly above average, especially in drier areas, lows will be well above average as a result of the lack of overnight inversions. Highs will generally be in the 60s, while lows will fall into the 40s to low 50s. High pressure may attempt to build in from the south and push the jet stream north of the region around the middle of next week. This could potentially dry out southern areas at times. While most of next week will not be as wet as Monday, periodic rainfall cannot be ruled out as weaker systems brush the region. Although the details remain uncertain, it is clear that we are entering a more unsettled and volatile period, with changeable weather likely for the near future.

Temperatures
  • Slightly above normal highs.
  • Above normal lows.

Rainfall
  • Areas of rain on Saturday in western Washington.
  • Heavy rain likely in western Washington and the mountains on Sunday and Monday.
  • A chance of rain later in the week in western Washington.
  • A chance of rain in central Washington, especially on Monday morning.
  • Rain likely in eastern Washington from late Sunday night into Monday.

Wind
  • Breezy to windy at times.

Frost Risk Summary
  • Generally low risk throughout the outlook period.

Important Points about Next Week's Weather

South Central Washington
  • Normal conditions for this time of the year would be highs in the mid 60s and lows in the mid 30s to low 40s.
Weekend
  • A chance of rain on Sunday and breezy.
  • Highs in the mid 60s to low 70s.
  • Lows in the mid 40s to low 50s.
Next Week
  • Light rain likely on Monday morning and breezy.
  • Mostly dry, with a slight chance of rain for the rest of the week.
  • Highs in the 60s to low 70s.
  • Lows in the mid 40s to low 50s early, and then upper 30s to 40s later in the week.

North Central Washington
  • Normal conditions for this time of the year would be highs in the low 60s and lows in the upper 30s.
Weekend
  • A chance of rain on Sunday and breezy.
  • Highs in the mid 60s to around 70.
  • Lows in the mid 40s to low 50s.
Next Week
  • Light rain likely on Monday morning and breezy.
  • Mostly dry, with a slight chance of rain for the rest of the week.
  • Highs in the 60s.
  • Lows in the mid 40s to low 50s early, and then upper 30s to 40s later in the week.

Eastern Washington
  • Normal conditions for this time of the year would be highs in the low 60s and lows in the upper 30s.
Weekend
  • A chance of rain, and then rain likely by Sunday night, and breezy.
  • Highs in the 60s.
  • Lows in the mid 40s to low 50s.
Next Week
  • Rain and wind early, with a slight chance of rain later in the week.
  • Highs in the upper 50s to mid 60s.
  • Lows in the mid 40s to low 50s early, and then upper 30s to 40s later in the week.

Western Washington
  • Normal conditions for this time of the year would be highs in the upper 50s to mid 60s and lows in the low to mid 40s.
Weekend
  • Areas of rain on Saturday, especially in the north.
  • Heavy rain moving southward on Sunday, and breezy.
  • Highs in the mid 50s to mid 60s.
  • Lows in the mid 40s to mid 50s.
Next Week
  • Rain and wind early, with a chance of rain at times later in the week.
  • Highs in the mid 50s to mid 60s.
  • Lows in the mid 40s to mid 50s on Monday morning, and then in the 40s to low 50s for the rest of the week.

Washington State University