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Displaying AFOS PIL: AFDPQR Received: 2016-10-14 10:57 UTC
421 FXUS66 KPQR 141058 AFDPQR Area Forecast Discussion National Weather Service Portland Oregon 357 AM PDT Fri Oct 14 2016 .SYNOPSIS...Rain is transitioning to showers behind the front, which will continue on and off through the day today. Seeing thunderstorms over the waters, with a chance continuing over the waters and along the Coast and Coast Range through early this afternoon. Will see a bit of an increase in winds along the Coast this afternoon, but not expecting winds anywhere close to what we saw yesterday. Next up is the strongest storm yet, the Ides of October Storm, will push into the region Saturday. This will likely bring potentially strong damaging winds and another round of heavy rain to much of the region. Unsettled weather continues into early next week. && .SHORT TERM...(Today through Sunday)...The low that brought strong winds to the Coast has now moved off to the North. Though still seeing breezy conditions, winds are much less than we saw yesterday afternoon and evening. Today will see post-frontal showers continue on and off through the day today. Instability generated by the relatively warm low-level southerly flow and cooler air from the upper-level low moving over the waters is generating thunderstorms over the waters this morning. Will continue to see a threat for thunderstorms along the Coast and in the Coast Range through the morning hours into early this afternoon. The bent back occlusion from the Low to the north will bring increased southerly winds to the Coast midday today through early this afternoon. Later this afternoon winds will come back down but continue to be breezy through this evening. As this low moves out of our region, we now move our focus to the Saturday system, referred to as the Ides of October storm. This system incorporates the remains of Typhoon Songda, which is currently around 43N, 153W. This system has sped eastward along the strong Jet Stream over the Central Pacific. Models have come into better agreement on a track bringing the low pressure center into the Coast somewhere in western Washington. The GFS is the farthest south with the landfall, but has a weaker Low as it moves onshore. Am a little skeptical with the depth of the Lows from the 06Z run, as they are weaker than previous runs. The location of these systems in the left exit region of a strong upper-level jet as well as the energy brought to this system from the typhoon makes me think there is a chance the system comes in stronger than the 970 mb that the models are suggesting. Have weakened the forecast winds a bit from the forecast yesterday, but there's a chance that the 12Z runs come in with a deeper Low which would lead to an increase again in winds for the system on Saturday. Either way, will see strong winds along the Coast again on Saturday. The question is how far inland the strong winds will get. Leaving the High Wind Watch across the area this morning. Just a reminder, keep an eye on this system. Any shift in the storm track means a change in the forecast that could be significant. Will see more rain through Saturday night, with perhaps as much as 3 to 6 inches coastal mountains, and generally 2 to 4 inches for the coast and Cascades. Should see 1 to 3 inches in the valleys. At this point, there appear to be enough breaks in between the systems to prevent river flooding. But with leaves falling off trees now, expect areas of low-lying and other poor drainage areas, and some urban flooding that could be exacerbated by leaf-clogged storm drains. There is a high probability of some high surf impacts with Saturday's system. However, the highest seas and surge currently appear to fortuitously occur during a low tide, so we may escape the most serious impacts. If the timing is off by just a few hours, though, there could be high surf in addition to some coastal flooding. Will be keeping a close eye on the potential for those impacts. -McCoy .LONG TERM...(Sunday night through Thursday)...No changes. Previous discussion follows...Broad upper trough will remain over the Pacific Northwest coast Sunday night and Monday morning with an associated front likely moving through Monday morning. After that models begin to diverge some with timing of lows moving toward the coast. This is due the the difficulty the models having in picking up on tropical moisture from the western Pacific being injected into the westerlies. GFS has been consistently showing a 1000mb low moving onto the Washington coast Tuesday with the ECMWF having a much slower solution bringing this system over a developing weak ridge on Tuesday night with rain brushing Northwest Oregon. Both the ECMWF and GFS build the ridge Wednesday and Thursday pushing the storm track mostly into Washington. I have lowered the chance of precipitation some for Wednesday night and Thursday, but will still leave a chance or slight chance of rain in the forecast due to the uncertainty in the models. Schneider && .AVIATION...Pattern has turned showery with flight conditions mostly VFR with occasional MVFR cigs. There is a slight chance of a thunderstorm for the coastal TAF sites through the afternoon. Inland conditions should generally remain VFR through Friday with breezy winds out of the south gusting to around 20-25 kt. Coastal sites will see more of a mix of VFR and MVFR with gusts as high as 35 kt. KPDX AND APPROACHES...Breezy winds out of the south with gusts up to 25 kt through the day. Mostly VFR conditions with occasional MVFR in showers. Bowen && .MARINE...A surface trough should maintain gales through midday today with possibly a secondary peak in winds with gusts to 40 kt during the late morning and early afternoon hours. Then there will be a lull later today into early Sat between systems. Seas should drop below 20 ft during this time, but remain between 15 and 18 ft. A considerably stronger low pres system will bring another round of strong winds Saturday with increasing potential for hurricane force winds and seas above 30 ft. The general model consensus is now for a low to develop around 40N, strengthening rapidly as it turns sharply north inside of 130W. The models currently have the low bottoming out somewhere around 970mb, then moving onshore somewhere along the Washington coast or southern Vancouver Island. There is a high probability of some high surf impacts with Saturday's system. However, the highest seas and surge currently appear to fortuitously occur during a low tide, so we may escape the most serious impacts. If the timing is off by just a few hours, though, there could be high surf in addition to some coastal flooding. Will be keeping a close eye on the potential for those impacts. Considerably lighter winds should spread into the waters Sunday and Monday, which will likely allow seas to subside well into the teens during this period. Bowen && .PQR WATCHES/WARNINGS/ADVISORIES... OR...High Wind Watch from Saturday afternoon through Saturday evening for Cascade Foothills in Lane County-Cascades in Lane County-Central Coast Range of Western Oregon-Central Oregon Coast-Central Willamette Valley-Coast Range of Northwest Oregon-Greater Portland Metro Area-Lower Columbia-North Oregon Coast-Northern Oregon Cascade Foothills-Northern Oregon Cascades-South Willamette Valley. WA...High Wind Watch from Saturday afternoon through Saturday evening for Greater Vancouver Area-I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-South Washington Cascades-South Washington Coast-Willapa Hills. PZ...Gale Warning until 1 PM PDT this afternoon for Coastal Waters from Cape Shoalwater WA to Florence OR out 60 nm. Hurricane Force Wind Watch from Saturday morning through Saturday evening for Coastal Waters from Cape Shoalwater WA to Florence OR out 60 nm. Small Craft Advisory for Rough Columbia River Bar until 5 AM PDT Saturday. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. The area is commonly referred to as the forecast area.