textproduct: Seattle/Tacoma

SYNOPSIS

A weak ridge of high pressure will produce partial sunshine and somewhat warmer temperatures across Western Washington today. Another weak frontal system will clip the region on Sunday for additional cloud cover and cooler temperatures. A warming trend commences Monday and Tuesday as high pressure rebuilds into the region. A general trend toward more unsettled and cooler conditions is expected for the second half of next week.

SHORT TERM /TODAY THROUGH MONDAY/

Shortwave ridging will bring a return of some sunshine and modestly warmer temperatures for most of the region today. But it will be short-lived as another front clips the region on Sunday for additional clouds, cooler temperatures, and perhaps a spotty shower or some drizzle. Upper ridging begins to amplify over the Pacific Northwest on Monday as an upper low cuts off several hundred miles offshore of Northern California. Monday will feature a return of sun by the afternoon, but breezy north winds in the afternoon should cap high temperatures in the 60s to near 70.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Tuesday continues to shape up to be the warmest day of the upcoming week as upper ridging remains in control and the low level flow turns weakly offshore for a brief period. Per the usual, the NBM approaches this conservatively with mid/upper 70s in the warmest spots, but it wouldn't be surprising for a few locations to make another run at 80 degrees from around Seattle southward.

Uncertainty continues to play a significant part in the forecast from the middle portion of next week onward. While ensembles continue to struggle with the speed of transition, they do seem to be latching onto the idea of a flip to more consistent cyclonic flow with mean troughing taking up residence over the Northeast Pacific. Given the time of year, it's nothing terribly exciting, but it does tip the scale back towards an extended period of near (or a little below) normal temperatures and periodic chances of some light precip. 27

AVIATION

A brief trough with weak flow aloft will transition into a southwest zonal flow with winds aloft increasing ahead of another trough off in the Pacific approaching the coast into Sunday. There remain areas of stratus with a dry frontal system moving through, and this will continue into the morning (particularly along the coast and inland into the Puget Sound/Mountains. MVFR is the most probable ceiling category but can't rule out a couple spots of IFR briefly. Models have the lower areas of stratus transitioning to high clouds around 18-22Z (with the coast taking a little longer to clear compared to inland terminals). Southwest winds 5 kt or less this morning (with a couple light and variable spots) will transition to northwest winds 5-10 kt this afternoon becoming light and variable for most tonight. Stratus probabilities for Sunday remain confined to the coast due to the likelihood of high stratus overnight.

KSEA...Pocket of stratus down to MVFR drifted into the terminal this morning from Lake WA. Models have stratus lifting to a high ceiling by around 18Z late this morning with VFR/high clouds for the afternoon. Probabilities of low ceilings for Sunday morning is low. Southwest winds around 5 kt this morning will shift to the northwest around 18Z, picking up to around 4-8 kt in the afternoon, shifting to the northeast around 5 kt or less late.

HPR

MARINE

A weak frontal system will push through the waters early this morning. High pressure will rebuild into the offshore waters this weekend into next week. The main concern in this period is diurnal pushes through the Strait of Juan de Fuca, where winds at times may exceed 20 kt. The next likelihood of this occuring is Sunday afternoon and evening. Otherwise, winds will remain light and primarily out of the north going into next week. A few ensembles hint a more organized system midweek next week.

Seas 4-6 ft with a couple areas potentially seeing 7 ft seas next week at times.

HPR

HYDROLOGY

The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed.

SEW WATCHES/WARNINGS/ADVISORIES

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