National Weather Service Area Forecast Discussion for Long Beach, WA USA
000 fxus66 kpqr 171006 afdpqr Area Forecast Discussion National Weather Service Portland, OR or 252 am pdt tue may 17 2022 .synopsis...southwesterly flow aloft and surface high pressure will bring seasonal conditions today. the next weather system reaches the coast late this evening and moves inland wednesday. the result will be a return to a cooler and wetter pattern. snow levels lower to just below the cascade passes wednesday night. the yo-yo pattern continues friday and saturday with warmer and drier conditions. chances for rain increase again late in the weekend into early next week. && .short term...(today through thursday)...satellite reveals broad southwesterly flow aloft over the ne pacific with a developing shortwave near 47n 131w. but for today will see increasing high clouds from this system while remnants of clouds back building from the cascades across the valley dissipates. the aforementioned shortwave will bring rain to the north coast later this evening then spread south and east overnight. models are in decent agreement in timing of rain with the latest hrrr notably slower. wednesday will be a rather damp day with about a 0.1 to 0.25 inch in the valley, 0.25 to 0.35 inch at the coast and coast range, and 0.5 to 0.75 inch in the cascades. snow levels will be well above the cascade passes wednesday morning, but lower 3000 to 3500 feet by late wednesday night as another, cooler system slides into the region from the gulf of alaska. models generally maintain the upper 500 mb pattern as a open trough as it slides southeast across the region towards the great basin later thursday. a strong jet stream accompanies this trough with the core of the jet over the northern part of the cwa. thunderstorm (12-hr) chances per nbm remain in the 15-25 percent chance thursday. however, model soundings show some thin cape thursday afternoon, but there is a capping inversion above the -10c level, which would limit potential for lightning. so for now have chose not to include thunderstorms in the forecast. .long term...(thursday night through monday)...the broad and expansive upper level trough migrates east thursday night and friday to the great basin. however, there are model differences regarding how fast this occurs. ncep cluster analysis bears this out with various clusters show differences in the strength and position of ridge building over the northeast pacific into the pacnw. friday and saturday look mainly dry, though friday may end up with higher chances for showers, mainly over the mountains. nbm increases pops on sunday and this looks reasonable with a weakening upper ridge and increasing southwest flow over the region. in a nutshell, kept close to nbm output for sunday and monday, but with some of the uncertainty in the model analysis the forecast may trend drier for late in the weekend. /mh && .aviation...upcoming 12z tafs: stable air mass across region, with westerly flow aloft and with light low-level onshore flow. do have mid-deck clouds (5000 to 7000 ft msl) persisting over the cascades, and to west a bit over parts of the willamette valley early this am. this deck will gradually dissipate this am. elsewhere, still expecting pockets of low end mvfr cigs along the coast into the coast range valleys, as well as into parts of sw washington such as the cowlitz valley. these clouds too will break up and thin out by 18z. otherwise, vfr today with increasing high clouds. this as front well offshore approaches. as front draws bit closer, will have clouds thickening, with increasing mid-level clouds after 00z. for detailed regional pac nw aviation weather information, go online to: https://weather.gov/zse kpdx and approaches...vfr this am, with scattered to broken 6000 ft deck very slowly dissipating. otherwise, vfr today with variable high clouds. increasing mid-level clouds after 00z. /rockey && .marine...transition weather today, with high pres over the coastal waters. this high will shift inland tonight, as a moderately strong front approaches from the west. this front should hold together long enough, that with decent gradients, should pop southerly winds of 20 to 30 kt on the northern waters later tonight. gusts 30 to 35 kt likely. so, will upgrade gale watch to a gale warning for later tonight through wed am. winds not as strong to the south, but enough to warrant small craft advisory, with gusts up to 30 kt at times. front will push onshore mid to late wed morning, with winds becoming more west to southwesterly, and easing. but, do have bit more swell arriving, with 9 to 11 ft swell for wed. as such, will likely need to maintain small craft advisory for winds/seas for wed afternoon through wed night. models are coming into agreement high pressure should return to the northeast pacific late this week. this should bring a quieter stretch of weather and allow seas to subside back below 5 ft towards friday and into the coming weekend. && .pqr watches/warnings/advisories... or...none. wa...none. pz...small craft advisory until 8 am pdt this morning for columbia river bar. gale warning from midnight tonight to 11 am pdt wednesday for coastal waters from cape shoalwater wa to cascade head or out 60 nm. small craft advisory from midnight tonight to 11 am pdt wednesday for coastal waters from cascade head or to florence or out 60 nm. && $$ www.weather.gov/portland interact with us via social media: www.facebook.com/nwsportland www.twitter.com/nwsportland
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