A Wet and Dreary Halloween in the Northwest

By Matt Alto, Meteorologist
October 31, 2012; 12:15 PM
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A storm system rich with tropical moisture will continue to keep the Northwest dull and damp through at least Thursday and may impact Halloween festivities taking place across the region.

Ahead of a slow-moving cold front associated with a storm system off the coast of the Pacific Northwest, breezy conditions and heavy to moderate rain will fall across the coasts of Washington and Oregon, the coastal range as well as the Cascades.

Many areas throughout western Washington and northwestern Oregon have already picked up between 0.50 to 1.50 inches of rain from Tuesday's storms.

Locations in the mountains will pick up anywhere between 2 to 5 inches of additional rain through Thursday, while the valleys and lowlands receive between 1 to 3 inches. Some locations could pick up higher amounts, especially from heavier and persistent bands of rain.

As the rain falls on the already saturated ground found throughout the region, there will be the potential for some minor flooding issues over portions of western Washington and Oregon.

In fact, some flood watches and warnings have already been posted in parts of western Washington and northwestern Oregon.

Small streams and rivers are the primary concern for flooding. Areas prone to flooding as well as low-lying and poor drainage areas will have to be monitored. Leaves that clog storm drains will also lead to minor flooding and ponding in roadways.

Meanwhile, snow levels should remain well above all mountain passes.

While showers occur across these areas on Wednesday morning, the heaviest rain probably won't arrive until Wednesday afternoon and evening as the cold front pushes onshore.

All the ghosts and goblins who will be venturing out this Halloween from Seattle and Portland down into the towns and communities of northern California will want to grab the rain gear and umbrellas for trick-or-treating.

For those west of the Cascades, the forecast looks mainly dry over the eastern third of Washington and Oregon for Halloween celebrations. Spotty and light showers won't move into these locations until the middle to second half of Wednesday night.

The heavy rainfall on Wednesday night will give way to decreasing showers on Thursday as the storm system marches across the interior of the Northwest.

A weak area of high pressure will bring a brief period of dry weather on Friday, but unsettled weather will likely make a return to parts of the Northwest for the start of the weekend.

Thumbnail photo courtesy of Photos.com

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