Marine Weather and Tide Forecast for Skamokawa Valley, WA

SHORT TERM
Now through Thursday...The core of the upper- level trough which brought widespread rain and locally breezy conditions to much of the region has moved northeastward out of our CWA and into Washington state. Model guidance maintains broad WNW flow across the region today with diminishing shower activity and slightly cooler than normal temperatures. While this pattern can be favorable for weak thunderstorm activity, and the NBM which generally drives the base layer of our forecast suggests a 10-20% chance for thunderstorms this afternoon, deterministic CAM soundings reveal CAPE values of 100-200 j/kg and is rather shallow in nature (surface to 8,000 ft) with the CAPE pool well below charge separation level which occurs around -10 degrees C to -20 degrees C.

Wednesday is the start of the next major pattern change. Upper- level troughing which has been the dominant synoptic pattern to the start of the week will continue to get slowly shoved eastward by an upper-level ridge amplifying over the eastern Pacific. As this high pressure develops and becomes the dominant synoptic feature, daytime highs are expected to warm into the mid 60s to low 70s across the inland valleys, low to upper 50s for the Cascades and mid 50s to low 60s along the coast.
Thursday, looks to be very similar to Wednesday with dry conditions persisting, with daytime highs to be 5-10 degrees warmer than 24 hours prior. /42

LONG TERM
Friday through Tuesday...Hot and dry conditions will be well entrenched across the Pac NW. Expect daytime highs to be the hottest of the year so far. These conditions are the main driver of our weather impacts through the remainder of the week, over the weekend and into the start of next week. Friday through early next week, models and their respective ensembles are in very good agreement that an upper level ridge will continue to strengthen over the far northeastern Pacific before shifting eastward. This will result in daytime highs about 5-10 degrees warmer than normal (normal this time of year is in the 60s along the coast and Cascades and in the 70s for inland valleys). By Saturday, June 13th, the NBM probabilities for daytime highs above 90 degrees F are 20-50% for the Willamette Valley. NBM probabilities for daytime highs at or above 100 degrees F on Sunday June 14th are 15-40% and 20-70% on Monday June 15th, with the highest probabilities each day towards the northern portions (Portland/Vancouver Metro) of the Willamette Valley. Also, there is a 5-15% chance for daytime highs on June 14th and June 15th of 105 degrees F or higher for locations between Salem, OR and Kalama, WA.

For reference, HeatRisk levels are as follows: Little to None, Minor, Moderate, High and Extreme.

Probabilities for a Moderate HeatRisk or higher on Saturday June 13th are 85-95%, then on Sunday/Monday (June 14th and 15th) 90-99% across almost the entire region. For Major HeatRisk, there is a 55-80% probability on Sunday June 14th and 25-80% probability on June 15th (highest Portland Metro, lowest near Eugene and along the coast). At least through this period the probability for Extreme HeatRisk across the CWA is 5-15% or less. Anyone who is sensitive to heat or those who have outdoor plans should prepare for and takes steps to mitigate potential heat impacts. For those planning to seek relief by swimming in local area rivers and/or lakes to cool off, be mindful of cold water temperatures and swift currents which can become life threatening if precautions like wearing a life preserver is not taken.

It's worth noting with this upper level pattern, a thermally induced surface trough also will establish itself somewhere west of the Cascade Crest-line which could result in locally breezy winds within the Cascades and/or Willamette Valley depending on its orientation. As daytime highs increase, relative humidities will also decrease. Therefore, with conditions drying out AND the potential for gusty winds, there are increasing fire weather concerns for the latter part of this week through the start of next week. So, be aware of potential ignition sources such as chains dragging on the pavement, hot vehicle components, as well as cigarette butts as these could easily result in the ignition of dry, fine fuels. Larger fuels may not have the time to dry out, but this is a variable that is being closely monitored by State and Federal Fire Partners.

By June 16/17th (Tuesday and Wednesday of next week), ensemble modeling systems do hint at the ridge finally breaking down and shifting eastward, bringing a return of relatively cooler, westerly flow. However, there's a large degree of uncertainty as to whether this transition takes place on Tuesday or Wednesday, but at least the majority of models do push temperatures downward back into the 70s and 80s by the middle of next week as in general the 25th-75th percentiles fall in-between these two values. The latest NBM only gives the inland valleys a 10-15% chance for highs to exceed 90 degrees F on Wednesday. So, confidence is moderate to high in a return closer to normal daytime highs by the middle of next week. /42-99

AVIATION
Radar imagery as of late Tuesday evening depicts scattered light showers across far northwest Oregon and southwest Washington as an upper level low over the Pacific Northwest weakens and moves eastward. CIGs trend predominately VFR for most areas while coastal terminals maintain a 20-40% chance for MVFR CIGs at any given hour between 06-18z Wed. Showers should gradually decrease overnight and completely dry out by late morning Wednesday. High pressure re-builds Wednesday afternoon, leading to increasing cloud breaks and scattered high clouds by the evening. Winds generally light and south-southwesterly, turning more north-northwesterly after 18-21z Wed with high pressure.

KPDX AND APPROACHES...Predominately VFR conditions through the TAF period. Showers in the area will gradually decrease overnight and dry out Wednesday morning. High-end VFR CIGs scatter out after 00- 03z Thu. -10

MARINE
Lingering Small Craft conditions through the late evening across all waters as winds and seas gradually subside. Seas around 8-10ft at 9-10 seconds will slowly subside toward 5-7 feet by Wednesday morning and remain there through the weekend. Westerly winds with gusts up to 25 kt will also decrease through tonight and fall below 15 kt gusts by the middle of the week. From here our focus shifts to high pressure building offshore through the remainder of the week. West winds of 10-15 kt on Wednesday evening/Thursday will become more northerly. Typical summertime northerlies lock in place from this point forward, with gusts up to 25 kt each afternoon and evening from Thursday through the weekend.
This may necessitate daily Small Craft Advisories. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...Extreme Heat Watch from Sunday morning through Monday evening for ORZ109-111-112-120.

WA...Extreme Heat Watch from Sunday morning through Monday evening for WAZ206-207-209.

PZ...Small Craft Advisory until 11 PM PDT this evening for PZZ210- 251>253-271>273.