textproduct: Portland

SYNOPSIS

Onshore flow persists over the next week with cooler than normal temperatures through Thursday. Within the zonal flow, weak high pressure forms which will allow for skies to clear and temperatures to warm. Looking at temperatures around more seasonable, or slightly above normal on Friday through at least Tuesday.

DISCUSSION...Now through Wednesday

Very minimal change in current weather conditions and the overall forecast from the last package. The synoptic pattern can be best described as zonal onshore flow, with weak high pressure forming on Friday through early next week. 500 mb height ensembles are in excellent agreement with this overall pattern, and sensible weather forecasts remain on track with very little variation.

Model guidance continues to suggest little change to the overall weather pattern on Thursday in comparison to Wednesday. Clouds will still be present with a few sun breaks but overall, impact wise, the forecast will remain unchanged. Temperatures will rise by a few degrees into the 70s, except into the 60s along the coast. Will note that all chances for precipitation have nearly disappeared or dropped below 5%. Conditions trend sunnier and warmer Friday into the holiday weekend as upper level flow transitions from northwesterly to westerly and 500 mb heights begin to increase a bit. By Friday, widespread highs around 75-80 degrees are expected for inland valleys. Highs will likely warm into the low to mid 80s for July 4-7 (70-90% chance each day), except in the Cowlitz Valley and along the lower Columbia where highs in the mid to upper 70s are the most likely outcome. Despite warmer temperatures inland, the coast will stay stuck in the 60s each day due to persistent onshore flow.

It is important to remember that while things will be warming up, many of our natural water bodies remain cold. Please practice safe water practices and note that rivers are fairly quick moving and can quickly sweep you away. Wear life jackets, and visit with a buddy. -27/23

AVIATION

Satellite imagery and terminal observations as of late Wednesday evening depicts increasing stratus across the area with predominately low-end VFR CIGs. An exception is the north Oregon coast including KAST where there are already MVFR CIGs around 2 kft. High confidence KAST will maintain MVFR CIGs between 1-2 kft through 18z Thu, before lifting in the afternoon to 2-3 kft. Low confidence that KAST improves to VFR tomorrow as there is a weak front moving into western WA which will maintain low CIGS. The central Oregon coast including KONP is also trending MVFR tonight through 18z Thu, but enough mixing will support improvement to VFR in the afternoon. For inland locations, mostly low-end VFR CIGs (3-4 kft) through the morning before breaking out into high level clouds. Light and variable winds under 5 kt across the area through 18z Thu, becoming north-northwesterly around 5-8 kt in the afternoon at any given terminal. An exception is KAST, where winds will be more southwesterly due to the weak frontal passage.

KPDX AND APPROACHES...Predominately low-end VFR CIGs through 18z Thu with a 10-25% chance for MVFR CIGs at any given hour between 10-18z Thu. High level clouds above 10 kft in the afternoon. Northwesterly winds under 10 kt. -10

MARINE

Seas have been a bit more dynamic today than previously thought. While most of the buoys shows seas less than 7 ft at 10 seconds, buoy 46050 continues to show periodic seas of 8 ft at 9 seconds thus equating to steep seas. However, these conditions are marginal and likely associated a bit with some of the breezier diurnally driven winds. Not expecting these conditions to be widespread though so have allowed the Small Craft Advisory to expire. Cannot rule out periods of these conditions though so be aware if in the outer waters south of Cape Foulweather. Winds are northwesterly around 6-8 kt with gusts of 15 kt except right along the coast where gusts up to 20 kt have been reported. Seas fall to 4-6 feet by late Wednesday night and then hold steady through the upcoming weekend.

Meanwhile, predominately northwest winds are expected to continue through Friday with general wind speeds becoming even weaker each day. A thermally induced surface trough will build northward up the south Oregon coast over the weekend, bringing increasing northerly winds with gusts up to 20-25 kt. As is often the case during this typical summertime pattern, wind speeds will be strongest during the afternoon and evening hours each day with daytime heating. Although significant wave heights are not expected to increase much, the increasing winds will result in choppier seas. -27/23

PQR WATCHES/WARNINGS/ADVISORIES

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