textproduct: Seattle/Tacoma

SYNOPSIS

A strong upper level ridge will continue to maintain dry conditions across western Washington through the rest of the week. A weak system will pass through this afternoon for increased cloud cover across the area. High pressure will then rebuild on Friday and into the weekend, with no precipitation expected through the first half of the week.

SHORT TERM /TODAY THROUGH SATURDAY/

High pressure continues to remain in place over western Washington this morning, with once again the development of fog over the area. Recent satellite imagery shows fog spreading from the coast into the south and central puget sound, also within the mountain valleys and Bellingham. Places like the South Sound could also see the chance of freezing fog, as temperatures this morning are ranging from the upper 20s into the low 30s.

A weak system will pass on through the area later this afternoon which will bring some increased mid to high level clouds over the area. This system is fairly weak and has mo moisture associated with it. We'll be looking at another dry day with afternoon high temps in the low to mid 40s.

Upper level ridging will continue Friday and Saturday with a slightly cooler airmass, high temperatures will stay in the low to mid 50s both days. Temperatures will also cool slightly overnight, with low temperatures in the mid to upper 20s. Most of the region will see below freezing temperatures overnight and into early on in the morning. Freezing fog could have the potential to create slippery conditions, especially in the early morning hours.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Ensembles continue to remain in agreement that high pressure will remain over western Washington for the first half of the week. Most of the models have backed off on a weak system arriving Sunday into Monday, with barely any moisture with that system now. Temperatures look to warm back up into the upper 40s and lower 50s through Wednesday. There may be a system entering the area on Wednesday for some precipitation, but confidence is low at this time,.

Mazurkiewicz

AVIATION

Northerly flow will continue aloft through the TAF period as an upper ridge resides over the northeastern Pacific. A passing disturbance embedded in the flow aloft will drop down into the region today and may bring some light showers to the coast. Otherwise, the only other impact from this system will be increased mid to high cloud cover streaming into the region overhead.

Satellite imagery shows fog expanding across the interior again early this morning. As a result, conditions at the area terminals are primarily IFR to LIFR in fog and MVFR to VFR for terminals outside of fog. Cold overnight temperatures have also led to the development of freezing fog in spots overnight, especially for terminals like KPWT and KOLM. For terminals in fog, expect to see improvement back towards VFR conditions between 18-21Z. The exception remains KOLM, which may briefly improve for a few hours this afternoon, but will likely see fog linger again through much of the day. Surface winds will be light and variable, persisting at 3-6 kt. Winds will remain light, but become more northerly area-wide again by this evening. Another round of fog and freezing fog will be possible at the area terminals on Friday morning.

KSEA...Conditions LIFR with fog at the terminal this morning. Freezing fog may develop at the terminal over the next few hours as temperatures slowly approach freezing. An improvement to VFR conditions is expected between 18-20Z. Winds will be light and variable through the day, persisting at 3-6 kt, before becoming more northerly by this evening. Another round of fog is possible at the terminal on Friday, with guidance showing roughly a 20-30 percent chance of LIFR conditions redeveloping by 12-15Z.

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MARINE

The main impact to the area waters today will be fog expanding across the interior waters early this morning, which may bring visibilities down to 1 NM or less at times. Otherwise, a weak system will move into the coastal waters today, which will weaken the offshore flow and briefly turn the flow more northerly across the waters.

High pressure will then build back into the waters in its wake while a thermal trough builds northward along the coast. Offshore flow returns on Friday as a result and may be breezy at times, especially along the central and western Strait of Juan de Fuca and along the gaps in the coastal terrain. Fraser Outflow will increase early Friday morning and will also bring breezy northeasterly winds to portions of the Northern Inland Waters on Friday, where gusts to 25-30 kt will be possible. Offshore flow will persist through the weekend, but will be weaker.

A weak frontal system looks to reach the waters by early next week, allowing for winds to gradually shift back to the south across the area waters by Monday. Southerly winds look to increase Tuesday into Wednesday as another, stronger frontal system approaches the region. Seas will hold steady between 3-6 ft through the weekend, but look to build closer to 10 ft near the middle of next week as the stronger systems move back into the area.

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HYDROLOGY

No river flooding is expected during the next seven days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.