Cold rains for Seattle this weekend

Synopsis...2 weather systems will be affecting the Seattle area this weekend. They are labelled "1" and "2" on the weather map to the right, which shows these systems circled on a satellite image with their forecast movement. System 1 will be bringing widespread rain into the area tonight, with scattered showers lingering during the day Saturday. System 2 will affect the area on Sunday. Rainfall amounts of up to an inch expected in Seattle this weekend. Snow levels will be around 2000 feet. Forecast models are in good agreement. On the scale very low, low, moderate, high, very high, confidence for this weekend's forecasts are high for system 1 and moderate for system 2, as the timing of the rains could be slightly off for Sunday.

Tonight...Rain developing, should become widespread by midnight. Cold with temperatures in the upper 30's. Chance of rain near 100 percent.

Tomorrow...Rain early, tapering off to scattered showers, possibly heavy at times. Chance of rain 70 percent. Highs around 45.

Saturday night and Sunday...Rain developing Saturday night and possibly lasting through much of the day on Sunday. Rain will taper off to showers behind the cold front, forecast to pass Sunday afternoon at this time. Low of about 38 and high of about 45. Chance of rain 90 percent.

Weekend forecast update

For Seattle.
Synopsis...A high pressure is currently settling in over the region providing cold and dry conditions. Temperatures will drop below freezing tonight and Saturday night. This pattern will persist through much of the weekend, however a weak upper level disturbance may bring a chance of precipitation on Sunday. With cold air in place, the precipitation could be in the form of snow. There is very little confidence in the forecast for Sunday as the forecast models are in great disagreement at this time.

Forecast confidence/certainty explanation:
Forecast certainty (FC) levels: very low, low, moderate, high, very high.
FC = very high means there is a lot of certainty in the forecast.
FC = very low means there is little certainty in the forecast.

The forecast:
Friday night...decreasing clouds and cold with lows in the mid 20's to around 30 in urban areas near water. FC = high.

Saturday....Partly cloudy with highs around 40. FC = high.

Saturday night...Partly cloudy with lows in the mid 20's to around 30 in urban areas near water. FC = low.

Sunday...Increasing clouds with a 30% chance of precipitation. Highs around 40. There is a 20% chance the precipitation will be in the form of snow. FC = very low. Monitor the forecasts throughout the weekend for updates.

Weekend outlook

An upper level trough combined with offshore flow at the surface will give us a cold but dry weather pattern for this weekend. Temperatures will be below average as highs may struggle to get out of the 30's Friday and Saturday. With a lack of cloud cover, expect temperatures to drop below freezing Friday and possibly Saturday morning. There has been some talk of snow on Sunday, but due to a lack of moisture and only marginally cold temperatures, the prospect of getting more snow is very unlikely.

Wettest day in Seattle history, 2nd wettest day in Sea-tac history

Yesterday, December 3, 2007 was the 1st wettest day on record (running 24-hour totals) in the city of Seattle and 2nd wettest on record at Sea-tac airport. The pattern that set this up was the so called "Pineapple Express" where the jet stream was pointed from near Hawaii straight into western Washington providing plenty of unobscured moisture. Further, there was a lot of melting snow from a system on Saturday that gave 1-4 inches of snow in the Seattle metro to several feet in the mountains.

Be careful when reading articles from the media, as they are mixing and confusing 24-hour totals (best measurement of "storm" events) with calendar day totals (inaccurate representation of a "storm" event).

Here are some peak 24-hour precip amounts ending Monday evening 3 Dec 2007:
Bremerton, 10.78 inches
Sand Point NWS: 5.07 inches (*** All time 24-hour rainfall record ***)
115th and Greenwood: 4.65 inches (2100 PST 3 Dec 2007)
Lake Forest Park, 4.44 inches (2100 PST 3 Dec 2007)
Pacific Science Center, 4.40 inches (2100 PST 3 Dec 2007)
Capitol Hill, 4.39 inches (2100 PST 3 Dec 2007)
UW, Atmospheric Sciences U of WA: 4.37 inches (2200 PST 3 Dec 2007)
Boeing Field, 4.33 inches (2200 PST 3 Dec 2007)
Seatac, 4.11 inches (***2nd wettest 24-hour period on record; record = 5.01 inches Oct 20, 2003***)
Sequim, 0.28 inches (The Olympic Mountain rain shadow really works!)

Here are some peak wind gusts:
Lincoln City, OR: 108 knots (125 mph)
Cape Blanco OR: 95 knots (109 mph)
Cape Arago OR: 78 knots (90 mph)
Clallam Bay: 78 knots (90 mph)
Newport OR: 71 knots (85 mph)
Destruction Island WA: 81 knots (93 mph)
Sekiu, WA: 81 knots (93 mph)
Tatoosh Island WA: 75 knots (86 mph)
Cannon Beach, OR: 69 knots (80 mph)
Bellingham, WA: 63 knots (73 mph)
Aberdeen, WA: 54 knots (62 mph)
Long Beach, WA: 52 knots (60 mph)

Gale Warning, Freezing Spray Warning

Synopsis...A low pressure is moving south into the Davis Strait from Baffin Bay. Winds will continue to be on the increase Monday.

*** Gale Warning, Freezing Spray Warning in All Areas ***

Monday...Cloudy, with snow likely and very windy. Strongest winds beginning in the Davis Strait near Baffin Island early and working its way southeast toward Nuuk and the Greenland coast. Northerly winds will be sustained at over 40 knots at times. Expect significant wave heights of 5-6 meters.

Winds picking up again on Sunday

Synopsis...A low pressure will move well south of the Davis Strait, however pressure gradients will increase on Sunday possibly increasing the winds to gale strength in the southeast waters.

Sunday...Winds shifting to winds from the north and increasing, especially in the south. Winds will increase to 30-35 knots southeast of the Davis Strait near the Greenland coast by evening. Lowest winds will be in the Davis Strait near Baffin Island where the northerly winds will be increasing to about 20 knots. Seas will be roughest in the waters near Greenland towards Nuuk, with possible wave heights reaching 5 meters.

Monday...A low pressure will be moving south from Baffin Bay. This will help increase the chances of precipitation and maintain the winds. Strongest winds will be near the Greenland coast once again, south of the Davis Strait, where sustained winds may exceed gale strength.

Calm day Saturday

Synopsis...Things will be calming down on Saturday in all areas. Winds will begin to pick up again on Sunday as a weaker low pressure moves south of the area.

Tonight and Saturday....Northerly winds gradually diminishing in all regions from west to east. Winds will be light on Saturday, ranging from 5-10 knots north to 15-20 knots south. Expect breaks in the clouds but temperatures will remain cold, near 0 degrees Celsius.

Sunday...Northerly winds increasing to 20-30 knots. Increasing clouds with a chance of snow, especially south.

Gale Warning Continued

Synopsis....Strong northerly winds will continue in the Davis Strait and surrounding waters over the next 24 hours.

*** GALE WARNING CONTINUING FOR ALL WATERS ***

Friday...High winds will be shifting southeast throughout the day. The strongest winds will occur later in the Day in the "Brevoort East" area southeast of the Davis Strait near the Greenland coast, where sustained winds will be over 40 knots. Significant wave heights may reach 6-8 meters in this area as well. Winds will be decreasing to 20-25 knots in the western Davis Strait near Baffin Island. Also expect scattered snow showers over the waters possibly mixed with rain over land.

Saturday...Winds are expected to diminish in all areas.

***Gale Warning in all areas****

Synopsis...A low pressure over the Davis Strait has moved southeast and merged with a low pressure near the southern tip of Greenland. This is allowing pressure gradients to strengthen rapidly and northerly winds to increase to gale strength.

*** GALE WARNING IN EFFECT FOR ALL AREAS THROUGH THURSDAY ***

The rest of today...Northerly winds increasing to gale strength. Cold with light snow showers likely.

Thursday...Very windy and cold. Sustained northerly winds expected to exceed 40 knots late. The strongest winds will be in the western strait near Baffin Island. Significant wave heights could reach 6-8 meters, especially in the western strait.

Outlook...Sustained winds of 35-40 knots is expected to continue into Friday.

Weather taking a turn downhill

Synopsis...A low pressure is currently moving into the Davis Strait, bringing clouds and some snow. As the low pressure moves past the Davis Strait, winds will increase significantly. Winds are expected to reach gale force in all areas by Thursday.

*** Gale force winds expected Thursday***

Wednesday....Mostly cloudy and cold, with snow showers. Northerly winds increasing, starting near Baffin Island and working it's way across the whole strait. Winds will be reaching 30 knots (sustained) in the evening.

Thursday...Windy and continued cold. Sustained northerly winds could reach over 40 knots. Significant wave heights may exceed 6 meters.

Light winds today...winds picking up late Tuesday

Synopsis...There are no major weather systems near the Davis Strait, leaving weak pressure gradients and weak winds today and tomorrow. A low pressure will be arriving on Tuesday, and the pattern may return to a more windy one after the low passes on Wednesday.

Rest of today...Mostly cloudy with possible fog in the evening. Winds should be less than 10 knots and from variable directions, with the exception of the south Strait which may have 10-15 knot winds at times. Temperatures remaining near 0 degrees Celsius.

Tuesday...Increasing clouds with a chance of snow showers. West winds increasing at the mouth of the Hudson Strait, but remaining light on the Davis Strait until late. Winds will begin to increase on the Davis Strait to about 20 knots by days end.

Outlook...There is a possibility of gale force winds in all areas on Wednesday as northerly winds behind the low pressure will be increasing.

"Good" weather continuing

Snyopsis...South winds may increase a bit today as a low pressure moves through Baffin Bay.

The rest of today...Breezy at times, with a south wind possibly increasing to 20-25 knots, especially in the western Strait near Baffin Island. Winds should reduce back to to 10-15 knots everywhere late.

Monday...Generally calm conditions, with winds of 10-15 knots.

Outlook...A weak low pressure system is expected to reach the area on Tuesday.

Good weather this weekend

Synopsis...a ridge of high pressure will be building south of the strait this weekend, cutting off the pressure gradient and winds.

The rest of today...Mostly cloudy with some light snow showers possible. Windy southeast of the strait near the Greenland coast. Winds ranging from 10 knots in the far western strait near Baffin Island to over 40 knots near the Greenland coast south of the strait. Winds will be diminishing tonight everywhere.

Saturday and Sunday....Calmer weather and lighter winds with winds dropping to generally 10 knots or less in most areas. A low pressure will move into Baffin Bay Sunday, but the impact on the Davis Strait looks minimal at this time.

Gale's picking up in southeastern strait

Synopsis....Yet another low pressure near the southern tip of Greenland will increase winds once again in the strait for Friday. The strongest winds will be on the Greenland side, and south of the strait where winds will likely reach beyond gale force. Winds look to be calming down this weekend.

Tonight and Friday...Northerly winds increasing, especially in the eastern strait near Greenland. Weakest winds closest to Baffin Island. Winds will range from 15 knots in the western strait to over 40 knots south of the strait near the coast of Greenland. Winds will begin to decrease everywhere late in the day. Scattered light snow showers are possible, with temperatures near freezing.

Outlook....Looks like a calm weekend, with winds diminishing to near 10 knots!

Calmer conditions

Synopsis...The gale warning for the southern Davis Strait has been discontinued as winds have dropped to below gale strength in all areas. Winds will generally be lower as the pressure gradients are relaxing.

Rest of today...Northerly winds sustained around 30 knots will be gradually decreasing to around 20 knots in all areas by later today. Winds may briefly pick up to around 30 knots in the western strait near Baffin Island tonight.

Thursday...Winds increasing to 30-35 knots in the eastern Strait near the Greenland coast, 20-30 knots elsewhere.

Outlook....No major systems coming.

Gale Warning from the Davis Strait southward

Synopsis....A strong low pressure near the southern tip of Greenland has increased the winds to Gale force from the Davis Strait southward. Winds should gradually decrease Wednesday and Thursday.

*** Gale warning ***
Rest of today....A gale warning is in effect for the area circled in red on the map. Northerly sinds will peak at around 00 UTC with sustained winds of 35-40 knots. Winds in the north strait will be slightly less.

Wednesday...Winds gradually decreasing, dropping to below 30 knots by around 15 UTC.

Outlook...Winds should continue to decrease through Thursday.

Wind and some more wind

Synopsis....A 1038 mb high pressure centered near Cape Dorset along with a 984 mb low off the Canadian maritime coast is causing windy conditions in the Davis Strait from the north-south pressure gradient. This will remain the story over the next couple days as new low pressures will continue to move south of the area while a high pressure center will persist over Baffin Island.

Rest of today....Mostly cloudy, and cold, with north winds sustained around 30 knots everywhere.

Tuesday...Continued windy and cold conditions. Northelry winds may increase to sustained winds of 35 knots at times.

Outlook...No major low pressure systems are forecast to move into the Davis Strait area.

Winds picking up a bit

Synopsis....High pressure is in control of the area and will remain so over the next couple days. However as low pressure systems move well south of the area, the pressure gradient will be increasing at times, increasing the northerly winds. Gale force winds are possible in all regions of the Davis Strait on Monday, but most likely in the eastern Strait.

Monday....Increasing winds. Sustained winds will begin to reach 30 knots in the eastern strait around 00 UTC, and will spread through the whole strait by 12 UTC. Strongest winds will be in the eastern strait, possibly reaching 35-40 knots with higher gusts near the Greenland coast around 18 UTC. The roughest seas will be just south of the central Davis Strait with significant wave heights of 4-6 meters beginning around 08 UTC and spreading to all regions of the Strait.

Tuesday...Northerly winds of 30 knots are expected to continue in all regions.

Lowest winds today

Synopsis...Calm weather today as a high pressure is moving into the region. Winds will be on the increase periodically as low pressures well south of the area will be increasing the pressure gradient as they go by.

The rest of today...Mostly cloudy, with northerly winds of 10-15 knots. Winds will begin to increase to 20 knots in the eastern Strait late. Continued cold with temperatures near 0 degrees Celsius.

Sunday....Partly cloudy and breezy. Sustained northerly winds increasing to 20-25 knots, strongest in the eastern Strait. Temperatures remaining cold.

Outlook...There may be gale force winds in the eastern strait beginning Monday 00 UTC.

Gale warning in eastern Davis Strait

Synopsis....a gale warning is currently in effect for the eastern Davis Strait (see the area circled red on yesterday's forecast labeled 'Gale force winds expected'). Winds will peak today around 13 UTC, then gradually die down. There will be a break in the winds for about a 12 hour period overnight tonight. Then winds (not as strong as today) will be picking up throughout the day Saturday lasting into Sunday.

*** Gale warning in the eastern Davis Strait for today ***
Rest of today....Windy, especially in the eastern Davis Strait with light rain or snow showers. Strongest winds in the eastern strait, where winds will be sustained at 35 knots from the south with the strongest winds around 13 UTC. Winds will diminish to about 20 knots by 00 UTC. Weakest winds will be in the western strait near Baffin Island, where winds will be about 15 knots. There should be a period where the winds drop to around 10 knots or less in all regions of the strait from about 00 UTC tonight (Oct 6) to 12 UTC Saturday (Oct. 6).

Saturday...a strengthening low pressure well south of the region will still manage to kick up winds again and a chance of snow showers as well. Northerly winds will be increasing in all regions of the Davis Strait to about 25 knots around 18 UTC.

Outlook...it may take the better part of the day before winds of around 25 knots diminish. High pressure will slowly be building in, so there is hope in sight for some calm weather.

Forecast Update

Update....
A low pressure in the Foxe Basin is beginning to spread clouds and increase winds in the area. Winds are expected to reach Gale force later today (by 00 UTC Oct. 5), with strongest winds in the eastern Davis Strait.

Rest of today....Cloudy with snow developing. Southeasterly winds increasing to 30 knots (sustained) by 00 UTC Oct 5.

Friday...Snow, possibly changing to or mixing with rain, and windy. Sustained southerly winds of 35-40 knots possible from 00 UTC - 20 UTC, strongest in the eastern Davis Strait. Significant wave heights of 6-7 meters possible during this time, also greatest in the eastern strait.

Outlook....Winds should die down a bit Oct 6. Clouds and precipitation could hang around through Oct. 7. High pressure may finally build in afterwards.

Gale Warning South of Davis Strait Oct 4,5

Synopsis:
A low pressure will be moving up Hudson Bay towards Baffin Island Thursday and Friday. Winds will be shifting to a southeasterly (from the southeast) direction and increasing in strength. They will reach Gale strength in the "Brevoort" region circled in red on the map on Thursday, lasting through Friday.

Thursday....Southeasterly winds increasing everywhere. Winds will be strongest south of the Davis Strait where Gale Warnings are in place (the red circled region on the map). Winds there will be sustained at around 35 knots. Winds in the Davis Strait will be sustained at up to 20 knots at times. Mostly cloudy skies with rain or snow possible late. Temperatures near 0 degrees C.

Friday....a weak low pressure may develop near the mouth of the Hudson Strait. This will increase the southerly winds in the east Brevoort region, and increase the northerly winds in the west Brevoort region. Strongest winds expected in the east Brevoort region with sustained winds up to 40 knots. Southeasterly winds increasing to 25-30 knots in the Davis Strait. Significant wave heights of 4-6 meters expected in the Davis Strait. Snow likely everywhere, then possibly changing to rain or mixing with rain.

Almanac for Nuuk:
Day High(F)/Low(F)/Highest sustained wind speed (knots)/Highest wind gust (knots)/weather
Oct. 1 42/30/32/60
Oct. 2 39/32/46 /67/rain,snow
Oct. 3 33/32/15/-/rain,snow

Low pressure moving away from region

Picture: Weather map for the area today.
Wind directions are in Red, Low pressure and it's forecast path in black.

Synopsis:
A strong low pressure moved over the Davis Strait last night, with an estimated minimum central sea level pressure of 974 mb. This brought rain, snow, and strong winds to Nuuk as well, with reports of winds gusting up to 78 mph (67 knots). The low pressure is now exiting the region, but strong winds will persist over the waters today, gradually diminishing from west to east Wednesday.

The rest of today... Gale warnings are in place for all waters. Winds are sustained at 30-40 knots with higher gusts, especially over the West Davis Strait and near the mouth of the Hudson Strait. Significant wave heights of 6-8 meters expected, everywhere, with the roughest seas at the mouth of the Hudson Strait. Temperatures cold, with scattered light snow showers likely, possibly mixed with rain in Nuuk.

Wednesday...Winds will be diminishing from west to east, with winds dropping below a sustained wind speed of 20 knots on the west Davis Strait by around 12 UTC. Winds in the waters around Nuuk are expected to be sustained at 35 knots with higher gusts from 00 UTC to 09 UTC, then gradually diminishing but remaining above 20 knots the rest of the day.

Outlook: A new, weaker, system will be approaching on Thursday. Winds should shift to southerly on Thursday ahead of this system and clouds will be on the increase. Will monitor this and update in the next forecast post. At this time the low does not appear to be a major event.

Map of areas to expect high winds

Hopefully you can see the map I attached. I circled 3 areas in red, labeled (1), (2), and (3). Those are the areas that will see the strongest winds and roughest seas.

(1) Southerly winds ahead of the low pressure system will pick up here in the eastern Davis Strait around 21 UTC today (Oct. 1) and will last for about 12 hours. Sustained winds will be up to 35 knots with higher gusts. Significant wave heights will be 5-6 meters. Also expect the most precipitation here during this time, probably in the form of snow.

(2) Westerly winds sustained at 40 knots out of the Hudson Strait will be picking up at about 00 UTC Oct. 2 and lasting until 00 UTC Oct. 3. Gale warnings are in place here. Significant wave heights of 5-6 meters expected.

(3) Northerly winds sustained at 30-35 knots with higher gusts on the back side of the low pressure will pick up in the west Davis Strait last, probably around 15 UTC on Oct. 2. Signifcant wave heights of 6-8 meters expected. Winds will gradually diminish Oct. 3, dropping to below 20 knots around 12 UTC Oct. 3. Expect scattered light snow showers as here during this time as well.

Low pressure taking aim at area

Synopsis: A strong low pressure system currently apporaching Baffin Island is slightly stronger than originally predicted. Minimum central sea level pressure expected to reach 979 mb over the Davis Strait early Tuesday. This will slow the eastward progression down a bit, with the main impact over the Davis Strait now expeced to occur Tuesday, and lasting into Wednesday.

Monday...Sunny, then increasing clouds. Possible breezy conditions at times in the Nuuk area, but strongest winds will remain offshore. Northerly winds will be shifting to southerly winds late. High temperatures in the mid 40's.

Tuesday...Mostly cloudy and breezy, with rain likely. Expected arrival time of precipitation between 00 UTC and 06 UTC in Nuuk. Frozen precipitation over the Davis Strait. Strong winds will form first at the mouth of the Hudson Strait, with westerly winds sustained at 30-40 knots from about 03 UTC till 00 UTC Wednesday with higher gusts. Strong northerly winds developing on the Davis Strait around 20 UTC, with winds at that location also expected to be sustained at 30-40 knots with higher gusts. Temperatures will be colder, only reaching to around freezing on the Davis Strait.

Wednesday....The low pressure will be weakening as it moves further east of the strait. However, northerly winds will be slow to die down in the strait, but should gradually weaken throughout the day. Temperatures will be cold, with highs of only 0 degrees C expected.

Outlook...No other major weather systems expected.

Almanac for Nuuk:
Sunday (through 5pm local time): High = 41 degrees F. Low = 36 degrees F. Maximum wind speed = 13 knots.
Saturday: High = 35 F. Low = 32 F. Maximum wind speed = 17 knots.

Strong low pressure system to arrive late Monday

Sunday...Partly cloudy over the strait, clouds increasing toward Nuuk. A low pressure system will be moving over the southern tip of Greenland. Most precipitation should stay south of Nuuk, with most of the effects being clouds and gusty winds in the Nuuk area. Winds will be strongest over the eastern strait with sustained winds reaching up to 35 knots. Strong and gusty localized winds also possible in the Nuuk area, especially late. High temperatures in the mid 40's.

Monday...Increasing clouds with precipitation likely developing. Winds will begin to shift from a northerly (from the north) to a southerly (from the south) direction. By the end of the day, southerly winds will be sustained at 30 knots throughout most of the strait. Wind shift will occur later in the day in Nuuk. The low pressure center is now expected to reach the Davis Strait at 00 UTC on Tuesday, with a strength of 984 mb. The strongest winds will be on the backside of the low pressure, where winds will be northerly and strong, lasting throughout the day Tuesday.

Tuesday...Possible strong northerly winds down the strait expected to perist. Winds of over 30 knots expected. Temperatures cooler and light precipitation will me mixed with light frozen precipitation at times.

Outlook...Conditions are expected to improve everywhere by Wednesday.

Possible low pressure system to arrive late Sunday and all day Monday

Saturday...Partly clouds with winds picking up in the eastern strait to around 30 knots (~15 m/s) in the evening. Temperatures near 0 C.

Sunday...Windy, especially in the eastern strait as a strong low pressure system will move well south of the strait (near the southern tip of Greenland). Sustained winds may be in excess of 30 knots (~15 m/s) from around 00 UTC Sunday to 00 UTC Monday in the eastern Strait. Otherwise expect increasing clouds as a low pressure will begin to effect the whole area late. Temperatures up to a few degrees above 0 C.

Monday...A possible major low pressure system is expected begin to spread clouds and precipitation by 00 UTC Monday. The current forecasted minimum sea level pressure is 984 mb and is currently forecasted to pass directly over the Davis Strait at 18 UTC Monday. Expect southerly winds ahead of the low pressure and then a switch to northerly winds late Monday after it passes. This could provide very windy conditions and rough seas, especially on the backside with the northerly winds as they could be accelerated by the geography of the strait. The exact timing and strength of this system is rather uncertain at this time.

First weather outlook for Davis Strait

Friday Oct. 28th and Saturday Oct. 29th...Partly cloudy skies with temperatures just above 0 C. Winds light and variable.

Sunday Oct. 30th....Partly cloudy skies. A low pressure will move well south of the strait, but north winds down the strait toward the low pressure may pick up a little. Strongest winds will be on southeast side, possibly reaching 30 knots (~15 m/s) at times.

Outlook: A low pressure and cold front is expected to arrive Monday. Will keep a watch on and update more in next forecast.

Steven's weather vortex

Since this is called "Steven's weather vortex" I thought I'd actually put a picture up of a real "weather vortex." There is a picture on the right showing one such vortex, from August 9, 2007 near Cambridge Bay, Nunavut.