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PZZ210 Columbia River Bar- 227 Am Pdt Sat Jun 1 2024
In the main channel -
General seas - 3 ft building to 7 ft Sunday afternoon.
First ebb - Ebb current of 3.75 kt at 1259 pm Saturday. Seas 3 ft.
SEcond ebb - Ebb current of 5.24 kt at 146 am Sunday. Seas 4 ft.
Third ebb - Ebb current of 3.59 kt at 202 pm Sunday. Seas 7 to 9 ft.

PZZ200 227 Am Pdt Sat Jun 1 2024
Synopsis for the southern washington and northern oregon coast - A weak front moves to the waters today. Then an unusually late season storm system brings stronger southerly winds to the waters Sunday. Unsettled conditions continue through mid next week as additional fronts move to the waters.

FXUS66 KPQR 011040 AFDPQR

Area Forecast Discussion National Weather Service Portland OR 340 AM PDT Sat Jun 1 2024

SYNOPSIS
An unseasonably strong Pacific jet stream is taking aim at the Pacific Northwest, and will lead to increasingly active weather this weekend. Today will be a bit of a transition day as high pressure aloft weakens enough to allow a weak frontal system to brush the forecast area. A stronger and much wetter system will follow for Sunday, with locally heavy rain possible along the coast and in the higher terrain. Rain will taper to showers later Sunday night, persisting through Monday and likely into Tuesday. A turn toward warmer and drier weather appears likely by the end of the week.

SHORT TERM
Today through Monday...Latest GOES-West infrared and water vapor imagery reveals the first in a series of disturbances presently approaching the Pac NW as high pressure weakens over the region. Temperatures Friday afternoon climbed well into the 70s for the inland valleys, with a handful of locations reaching 80 degrees.
The warm air mass and subsidence associated with high pressure aloft dried out the low to mid levels considerably, so this first disturbance will struggle to bring much more than a few sprinkles east of the Coast Range today/tonight. However the onshore flow and increased cloud cover should prevent anyone in our CWA from reaching 80 degrees today. For those who enjoyed the warm day Friday, at least today won't be a total bust - NBM probabilistic guidance suggests a better than 75% chance our interior lowlands will climb into the 70s this afternoon. Overall - today will see near-normal temps and a mix of sun and clouds for most of the CWA, with the best chances of precipitation likely limited to the coast.

For as normal as today is expected to be for the first day of June, Sunday will be anything but normal as a potent late-season low pressure system couples with a moderate to strong atmospheric river to bring a very wet day to SW Washington and NW Oregon. The 00z ECMWF Extreme Forecast Index (EFI) continues to suggest a high-end event climatologically, with EFI values in excess of 0.9 for most of our Cascades and a Shift-of-Tails (SOT) in the 1 to 2 range. The SOT values in excess of 1 indicate the potential for rainfall to approach record levels for this time of year. In other words, Sunday's system will behave much more like one of our moisture-laden mid- to late-autumn frontal systems than the typical weaker systems we would come to expect in late spring. If anything, the 00z GEFS has more moisture involved with Sunday's system, with NAEFS means solidly in the +4 to +6 standardized anomaly range for moisture transport and a return interval (in late May/early June) on the order of 10-30 years.
All this points to a high-end rainfall event for early June, and one that will qualify as a significant rain event for any time of the year across our region.

Perhaps the most concerning aspect of this system is the combination of unusually deep moisture with an unusually strong early June system, along with strong orographic enhancement for the Coast Range and Cascades. Fortunately, most of our rivers are starting off low or near summertime base flows, which should mitigate most hydro concerns for this event. However, the potential for extreme rainfall rates is there, especially for the higher terrain where HRRR 90th percentile rain rates suggest there could be a solid 6-12 hour period with rainfall rates exceeding 0.25-0.40"/hr. This could be enough to cause some minor debris flows, especially in recently burned areas. Such rainfall rates could also cause some of our flashier creeks and rivers to jump their banks - the Grays River in particular comes to mind, but much will depend on the alignment of the atmospheric river during the peak of our event.

Overall, based on NBM deterministic guidance, inland valleys can expect 1-2 inches of rain from this event through Monday night, though downsloping may hold Hood River short of 1 inch. The coast can expect to see 1.50-3.00 inches, with 2-4 inches likely for the Coast Range and Cascades. Looking at 75th percentile NBM guidance, there is the possibility for some Coast Range/Cascade locations to exceed 4 inches. This potential rings especially true after looking at the 00z HRRR mean QPF, which only runs through 5 PM Sunday but already shows multiple areas in the Coast Range/Cascades exceeding 2 inches by then... with 6-12 hours still to go before the steady, locally heavy rain comes to an end. WPC suggested a marginal risk of issues due to excessive rainfall in their Day 3 outlook for 12z Sun to 12z Mon - which certainly seems warranted considering all these factors.

Latest deterministic guidance brings an end to the steadier rain Monday morning as a fast-moving cold front sweeps across the Pac NW.
Cool air aloft behind this system will result in plenty of showers Monday and, depending on how many sunbreaks there are, potentially even a couple thunderstorms. Sunday through Monday will see occasionally blustery S-SW winds as mixing increases and 850 mb winds occasionally push into the 40-50 kt range, though the strongest winds appear to be focusing on Sunday night based on the latest guidance.
Given the potential for mixing down of the stronger winds aloft is higher than it usually is during our winter events due to the stronger sun this time of year, just about anywhere in our CWA could see 30-40 mph gusts at times Sunday through Monday. Exposed, higher elevations in the Cascades could easily see periods with W-SW wind gusts exceeding 50 mph Sunday through Monday. All in all, the weather Sunday and Monday is likely to bring the all-too- familiar "June-uary" back into our lexicon here in the Pac NW. For those who are craving more typical summer weather, you won't have to wait long - see the long term discussion below for details on a potential heat wave by next weekend. Weagle

LONG TERM
Tuesday through Friday...Subtropical moisture remains entrained in the broader baroclinic zone stalled across the NE Pacific and Pac NW Monday night. Meanwhile, most deterministic guidance continues to depict a fast-moving shortwave being pushed toward the Pac NW on the unseasonably strong jet stream. Some models guide this system closer to the Canadian border, while others such as the 06z NAM hint at a track far enough south to bring another round of significant rainfall to at least our northern zones. Given the moisture rich environment and the recent rainfall from Sunday, this system will need to be watched closely as another shot of heavy rain Tuesday could push some drainages out of their banks. NBM median QPF for Tuesday's system is less than 1 inch throughout the CWA, but looking upwards to the NBM 90th percentile QPF, one can see that there is some potential for higher 1-3 inch amounts for the Coast Range and Cascades north of about a Tillamook-Detroit line.
Conversely, NBM 10th percentile QPF shows less than 0.25" anywhere in our CWA, so considerable variability remains.

Starting midweek, models are suggesting a high likelihood of a strong upper level ridge of high pressure developing somewhere over the Western United States. Looking at the 00z WPC cluster analyses, all clusters are now indicating positive 500 mb height anomalies over WA/OR (i.e. above-normal temperatures in most cases) by Thursday.
Therefore confidence in above-normal temperatures by the end of the week is very high - the challenge is in determining just how much above normal temps will be.

Most 00z WPC clusters suggest the upper ridge axis will be far enough inland to maintain at least some vestige of onshore flow in the low-levels, so this does not appear to be the type of warm spell that reaches the coast. The WPC cluster most favored by ensemble members is also the hottest one, with the most significant 500 mb height anomalies. However this solution is still only shown by 40-50% of members - mostly from the EC ensemble suite - so things can still change. Unsurprisingly though, NBM probs of reaching 90 degrees for the inland valleys have increased a bit, reflecting the greater number of members showing the hot solution. As of the 07z run of the NBM, the probabilities of reaching 90 degrees in the interior lowlands were generally 30-60% for Friday and Saturday, but the probabilities of reaching 100 degrees remain below 15%. Pattern recognition-wise, this has the look of a prolonged but low-intensity heat event with multiple days in the upper 80s to mid 90s for the inland valleys. This type of heat event, while not necessarily record breaking, can still be problematic for those who are sensitive to heat. With all this in mind, those sensitive to heat should pay close attention to the forecast the next few days, and perhaps consider where they may go to stay cool late next week should the hotter forecast guidance prevail. Weagle

AVIATION
VFR conditions prevailing, but with marine stratus along the coast for low MVFR to IFR conditions. A weak front associated with an upper trough to bring some light showers to the coast today. The marine stratus along the coast is expected to deepen later this morning and afternoon with MVFR expected to prevail. Inland areas will see variable mid and high clouds with cigs above 5000 ft.

Potent for June storm approaches overnight with rain bringing widespread MVFR to IFR conditions late tonight to the coast.
Along with lower cigs, visibilities likely reduced due to the rain. Inland areas likely to remain VFR but will see clouds filling in over the mountains. HRRR shows about a 20-40% chance for MVFR cigs over the valley after 08Z Sun.

PDX AND APPROACHES...VFR conditions expected through the entire TAF period with cigs above 5000 ft and a few sprinkles this afternoon. As the next front approaches, HRRR shows a about a 20% chance for cigs near 3000 feet. Better chances for rain develop closer to 12Z Sun. Light winds in the morning becoming westerly 5-10 knots after 20Z Sat. /mh

MARINE
A weakening Pacific front moves to the waters today and stall over the waters. A more organized and stronger storm system will move into the northeast Pacific Sunday shifting winds southerly. Small Craft Wind gusts are likely with 90+% chance of gusts exceeding 21 kts. There is a 10-20% chance for Gale Force winds of 35 kts per the NBM. But deterministic and HRRR guidance have trended stronger with a 50-80% chance for gale force gusts on Sunday. At this point, gale are more likely over the outer zones (10 to 60 NM) during the day Sunday, so have issued a Gale Watch. Also issued a Small Craft Advisory for the inner zones for Sunday into Sunday evening. Will have to watch for a coastal jet to develop just as the front nears the coastline Sunday afternoon.
This could result in a short period of gales to the coastline.

Seas will build to 8-10 feet at 10-12 seconds Sunday afternoon, persisting into Monday. Another westerly swell will enter the waters toward the middle of next week with seas of 10-12 feet at 14-16 seconds.
/mh -Batz

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.
WA...None.
PZ...Small Craft Advisory from 5 AM to 11 PM PDT Sunday for PZZ251>253.

Gale Watch from late tonight through Sunday afternoon for PZZ271>273.

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