textproduct: Portland

UPDATED AVIATION DISCUSSION

SYNOPSIS

Dry conditions and seasonable temperatures with north to northwesterly winds expected through Sunday. A warming trend expected early next week, with Moderate HeatRisk likely on Tuesday for many urban areas as there is around a 50% chance of exceeding 90 degrees. Temperatures cool again to near or slightly above average by Wednesday as high pressure shifts east. Chances for rain remain low (less than 10%) through Thursday before increasing late next week into next Saturday.

LONG TERM...Wednesday through Saturday

There is relatively high confidence that temperatures cool back into the 70s on Wednesday and persist through the end of the week, remaining near to slightly above average temps for early June. Models and their ensembles are in fairly good agreement that a low pressure system in the NE Pacific weakens as it moves toward the Gulf of Alaska on Wednesday. An associated frontal band well ahead of the surface low will approach the coast, but guidance continues to trend down with much, if any, precipitation spreading inland. In fact, NBM guidance generally shows less than a 10% chance of rain through Thursday. But, there remain a handful of ensemble members that do show some QPF, so we cannot rule out some precipitation yet. Uncertainty in the forecast increases late next week as cluster mean analysis shows varying degrees of troughing offshore, leading to increasing chances for precipitation later Friday into Saturday. /DH

AVIATION

VFR conditions generally persist tonight into Sunday morning at all terminals as the flow aloft turns northerly. However, we'll have to watch some low clouds shown by satellite (as of 05-06z) building along the west flanks of the Cascades. These have to potential to shift towards I-5/The Portland Metro during the 12-17z period Sunday morning before dissipating with a 15-25% chance for MVFR conditions at KPDX/KUAO and a 30-40% chance a KTTD. Otherwise, higher confidence in VFR conditions the remainder of the forecast period. Winds along the coast and in the central/southern Willamette Valley increase as Sunday progresses with gusts around 20-25 knots possible.

KPDX AND APPROACHES...VFR conditions are favored through the TAF period with persistent northwesterly winds. These winds likely increase around 17-19z Sunday with occasional gusts around 18-20 knots in the afternoon. It's worth noting there is a 15-20% chance for MVFR cigs between 12-17z Sunday morning as clouds slosh towards the terminal from the east - something to watch. -99

MARINE

High pressure builds through the weekend which will lead to a typical summer like pattern through the weekend. High pressure will start to move eastward tonight and through Sunday, which will result in increasing north/northwesterly winds across all waters. Gusts up to 25 kt are expected across zones PZZ272, PZZ252, PZZ271 and PZZ251. Gusts up to 30 kt are expected in zones PZZ273 and PZZ253, with a 15-25% chance for gusts up to 35 kt. Therefore have issued a series of Small Craft Advisories across all waters starting late Sunday morning in our southern waters and spreading northward through the early afternoon. Seas 6 to 8 ft expected through the weekend.

The ridge continues to shift eastward and intensify through Tuesday but overall will have minimal impact to the marine environment. By Monday, conditions are expected to be below Small Craft Advisory thresholds across all waters. A pattern change expected on Wednesday as a series of systems look to dive down out of the northeastern Pacific through the latter part of next week, but minimal impacts are expected with these systems at this time. /42

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 2 PM Sunday to 2 AM PDT Monday for PZZ251-252. Small Craft Advisory from 11 AM Sunday to 2 AM PDT Monday for PZZ253. Small Craft Advisory from 5 PM Sunday to 2 AM PDT Monday for PZZ271. Small Craft Advisory from 2 PM Sunday to 9 AM PDT Monday for PZZ272. Small Craft Advisory from 11 AM Sunday to 9 AM PDT Monday for PZZ273.