AgWeatherNet Weekly Weather Outlook for January 11 to 17, 2014

Major Storm This Weekend; Mild and Becoming Drier Next Week

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

A major storm with a tropical connection will impact Washington with heavy rain, high winds, and mild temperatures this weekend. This is likely to be stronger than the weather system that affected Washington in late September.

As a potent low pressure system approaches Vancouver Island, wet weather will spread across the state from west to east tonight. The rainfall should be heavy from the Cascades westward for tonight and into the first part of Saturday, with as much as 5 inches in the mountains. This very moist storm is expected to be dynamic enough such that most of the state will receive at least some rainfall, although strong southwesterly flow will shut off the rain fairly quickly in south central Washington on Saturday morning. Due to the extremely dry antecedent conditions, widespread flooding is not expected, although flooding is quite possible along the more flood-prone western Washington rivers. In fact, the energetic system may be accompanied by enough moisture and instability for isolated thunderstorms at the coast on Saturday.

Perhaps the larger issue will be the statewide strong winds that are expected to first develop at the coast and in western areas overnight, and then move east of the Cascades on Saturday. Sustained southwesterly winds of 30 to 40 mph are likely, with gusts over 60 mph possible at times. There may well be downed trees and power outages. Due to the moist and well mixed atmosphere, temperatures will be very mild this weekend. Lows will be in the 40s to around 50 degrees west of the Cascades on Saturday morning, with above freezing temperatures for most areas east of the Cascades. High temperatures in south central Washington will be in the 50s, with 60 degrees possible in some spots due to the Chinook winds.

Snow in the mountains will be a tough call, since warm air will surge northward in advance of the storm, before cooler air floods in behind the cold frontal passage later on Saturday. While some snow is possible tonight at pass level, and then later on Saturday evening, the heaviest precipitation with these systems tends to fall during the warmest part of the storm. Hopefully, some mountain snow will occur on Saturday night, since much of the pre-storm snow will be washed away on Saturday morning.

Rain should continue west of the Cascades on Sunday, as eastern areas dry out, while remaining breezy and mild. As high pressure continues to build from the southwest early next week, most of the active weather will be shunted north of the region, although some rain will continue to clip northwestern parts of the state. By later next week, a ridge of high pressure should be firmly over the region, leading to drier and calmer weather statewide. Despite the continued warming aloft and in the high mountains, the increased stability may lead to developing inversions, especially in the lowlands east of the Cascades. Cooler low temperatures would be likely, although generally mild conditions should persist. As always, the biggest question mark will be the potential for low cloud and fog development, as well as air stagnation for later next week. It will depend upon the duration of the event, which is currently uncertain. Presently, it appears that the ridge may give way to a southwesterly jet stream flow as early as next weekend, or sometime during week two, which could lead to increasing precipitation chances, but even milder temperatures.

Temperatures
  • Well above average statewide through the period.
  • Cooler in the lowlands, especially at night, later next week.

Precipitation
  • Heavy rain west of the Cascades this weekend, with rain in eastern areas as well.
  • Rain possible in central Washington on Saturday morning, but mainly dry this weekend.
  • Rain at times in especially northwestern Washington early next week, but mainly dry elsewhere.
  • Becoming mainly dry everywhere by mid to late next week.

Wind
  • Damaging wind possible on Saturday, and decreasing but remaining strong on Sunday.
  • Breezy at times early next week, and becoming calmer later in the week.

Frost Risk Summary
  • This weekend: Low risk on Saturday morning, and moderate risk on Sunday morning in the east.
  • Next week: Generally low to moderate risk early in the week, and increasing risk in the lowlands later in the week.

8 to 14 Day Outlook - January 18 to January 24
  • A pattern change may occur during this period, as we transition from a dry ridge of high pressure to a more progressive and wetter southwesterly flow. Overall, above average temperatures and near average precipitation are expected during the 8 to 14 day time frame.

Important Points about Next Week's Weather

South Central Washington
  • Normal conditions for this time of the year would be highs in the upper 30s to low 40s and lows in the 20s.
Weekend
  • Damaging winds on Saturday. A chance of rain on Saturday morning.
  • Highs in the 50s to around 60 on Saturday, and upper 40s to mid 50s on Sunday.
  • Lows in the upper 30s to 40s on Saturday morning, and upper 20s to 30s on Sunday morning.
Next Week
  • Mostly dry. Fog possible later in the week.
  • Highs in the 50s on Monday, and cooler later in the week.
  • Lows in the 30s to mid 40s on Monday morning, and cooler later in the week.

North Central Washington
  • Normal conditions for this time of the year would be highs in the low to mid 30s and lows in the upper teens to low 20s.
Weekend
  • Windy, especially on Saturday. Rain likely on Saturday morning.
  • Highs in the mid 40s to low 50s on Saturday, and upper 30s to 40s on Sunday.
  • Lows in the mid to upper 30s on Saturday morning, and mid 20s to mid 30s on Sunday morning.
Next Week
  • A slight chance of rain on Monday, but mainly dry overall.
  • Highs in the mid 40s to mid 50s on Monday, and cooler later in the week.
  • Lows in the 30s on Monday morning, and cooler later in the week.

Eastern Washington
  • Normal conditions for this time of the year would be highs in the mid to upper 30s and lows in the mid 20s.
Weekend
  • Very windy. Rain on Saturday, with a chance of rain on Sunday.
  • Highs in the mid 40s to mid 50s on Saturday, and 40s on Sunday.
  • Lows in the upper 30s to low 40s on Saturday morning, and low to mid 30s on Sunday morning.
Next Week
  • A slight chance of rain on Monday, but mainly dry overall.
  • Highs in the mid 40s to mid 50s on Monday, and cooler later in the week.
  • Lows in the mid to upper 30s on Monday morning, and cooler later in the week.

Western Washington
  • Normal conditions for this time of the year would be highs in the mid to upper 40s and lows in the 30s.
Weekend
  • Heavy rain, especially on Saturday morning, and windy.
  • Highs in the mid 40s to mid 50s.
  • Lows in the mid 40s to around 50 on Saturday morning, and upper 30s to mid 40s on Sunday morning.
Next Week
  • Rain likely in the north on Monday.
  • Mainly dry region-wide later in the week.
  • Highs in the mid 40s to 50s.
  • Lows in the low to mid 40s on Monday morning, and cooler later in the week.

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