AgWeatherNet Weekly Weather Outlook for September 29 to October 5, 2012

Warming Through Monday with Lingering Smoke; Changes Likely Next Week

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

Following a period of improved air quality earlier this week, some smoke has returned to the east slope valleys, as the wildfires continue to burn. Another very weak system is currently passing through the region, which may partially clean the air mass. However, building high pressure suggests increasing inversions and stagnation this weekend. Temperatures will increase through Monday, with highs in mid 70s to mid 80s, except possibly cooler in areas of smoke. Western Washington will be in the 60s to low 70s on Saturday, and warm to the upper 60s to 70s by Sunday. Monday will be a warm day area wide, with highs from the 70s to low 80s in western Washington, to the upper 70s to mid 80s east of the Cascades.

Around Tuesday night of next week, it appears likely that a pattern change will occur as the upper level air flow turns northerly. While the timing and details remain uncertain, cooler weather is likely to arrive around the middle of next week. Even though temperatures should not drop to significantly below normal, the change will feel marked in some areas, following several months of mostly above normal temperatures. With most of the cool air headed into North Dakota and Montana, northeastern Washington is most likely to be the coldest region. Meanwhile, southwestern Washington may receive only a minimal influx of cool air, along with offshore flow descending from the mountains, which could keep that region relatively warm. Highs across most of the state will range from the 60s to mid 70s. Frost becomes possible again by late next week, as dew point temperatures drop to near or below freezing. However, wind will initially keep most areas safe. If winds decrease late in the outlook period, frost becomes a better possibility for cold areas. Lows in the 30s are likely late next week in colder areas.

The stronger flow is expected to improve air quality conditions later next week. However, significant rain is still not expected. The firefighting efforts will be helped by cooler temperatures, but also hampered temporarily by increased winds. Overall, next week's weather is likely to be more changeable than it has been in recent weeks, as we transition into October.

Temperatures
  • Continued above normal, with warming temperatures through Monday.
  • Warm Tuesday, but breezy and cooling late in the day in the north and east.
  • Potentially significant cooling to near to slightly below normal around mid next week in the east.
  • Minimal cooling to near average in the west.

Rainfall
  • A slight chance of showers in western Washington on Saturday morning.
  • A slight chance of rain around the middle of next week.
  • Mostly dry overall.

Wind
  • Generally light through Monday.
  • Becoming windy on Tuesday or Wednesday, especially in the east.

Important Points about Next Week's Weather

South Central Washington
  • Normal conditions for this time of the year would be highs in the low 70s and lows in the low 40s.
Weekend
  • Partly sunny, with areas of smoke.
  • Highs in the upper 70s to low 80s.
  • Lows in the mid 40s to mid 50s on Saturday morning, and 40s on Sunday morning.
Next Week
  • Partly sunny with areas of smoke early. Windy by Wednesday, with decreasing smoke.
  • Highs in the low to mid 80s on Monday, and cooling into mid 60s to mid 70s later in the week.
  • Lows in the mid 40s to mid 50s early, and cooling into the mid 30s to mid 40s later in the week.

North Central Washington
  • Normal conditions for this time of the year would be highs in the upper 60s to low 70s and lows in the low 40s.
Weekend
  • Partly sunny, with areas of smoke.
  • Highs in the upper 70s to low 80s.
  • Lows in the upper 40s to mid 50s on Saturday morning, and 40s to around 50 on Sunday morning.
Next Week
  • Partly sunny with areas of smoke early. Windy by Wednesday, with decreasing smoke.
  • Highs in the upper 70s to mid 80s early, and cooling into the 60s to low 70s by later in the week.
  • Lows in the mid 40s to mid 50s early, and cooling into the mid 30s to mid 40s later in the week.

Eastern Washington
  • Normal conditions for this time of the year would be highs in the mid to upper 60s and lows in the low 40s.
Weekend
  • Partly sunny, with smoke at times.
  • Highs in the mid to upper 70s.
  • Lows in the mid 40s to mid 50s on Saturday morning, and 40s on Sunday morning.
Next Week
  • Partly cloudy, and becoming windy by mid week.
  • A slight chance of rain around mid week.
  • Highs in the mid 70s to low 80s early, and cooling into the upper 50s to 60s by later in the week.
  • Lows in the 40s to low 50s early, and cooling into the mid 30s to low 40s later in the week.

Western Washington
  • Normal conditions for this time of the year would be highs in the mid to upper 60s and lows in the mid to upper 40s.
Weekend
  • A slight chance of showers early Saturday in the north.
  • Highs in the 60s, except low to mid 70s in the south on Saturday.
  • Highs in the mid 60s to mid 70s, except upper 70s to around 80 in the south on Sunday.
  • Lows in the upper 40s to mid 50s on Saturday morning, and 40s to low 50s on Sunday morning.
Next Week
  • Periodic morning clouds, and then afternoon sunshine.
  • Highs in the upper 60s to mid 70s, except low 80s in the south early in the week.
  • Highs falling into the 60s to low 70s later in the week.
  • Lows in the mid 40s to mid 50s early, and cooling into the upper 30s to 40s later in the week.
Washington State University