textproduct: Portland

SYNOPSIS

Dry conditions expected through the end of the week as temperatures trend slightly warmer into the weekend. Temperatures generally expected to remain near to slightly above seasonable normals for late April. Chances for showers increase Sunday and Monday, particularly over the higher terrain of the Cascades and foothills. Potential for warmer temperatures by the middle of next week if high pressure builds over the region.

DISCUSSION...Now through Thursday

Clouds lingering across northwest Oregon and southwest Washington early this afternoon are holding on as weak onshore flow persists in the lower levels. But clouds are expected to gradually break and allow for temperatures to warm into the lower 60s later today. Lows tonight are expected to drop into the upper 30s to low 40s. There is a low chance, around 10- 30%, for temperatures to drop below 37 degrees in the southern Willamette Valley and slightly better chances of 20-50% in the Upper Hood River Valley that are elevation dependent. Will hold off on frost products given the low probabilities but early morning frost is possible locally.

The amplified pattern is expected to continue heading into Friday. The upper level ridge will build into northwestern Canada while the digging trough stalls and deepens into a closed low over south-central Canada and into the northern Plains. An area of shortwave energy is expected to drop southward between these two features toward the PacNW. Conditions are expected to remain mostly dry and seasonably warm to slightly above normal into the weekend. Highs in the mid 60s to upper 60s can be expected Friday through Monday for interior lowlands with upper 50s to low 60s along the coast. Overnight lows in the upper 30s to low 40s are expected but with mostly clear skies, could see some cooler spots. There is a 10-30% chance for temperatures to drop below 37 in the Willamette Valley and Clark and Cowlitz lowlands, highest in the southern Valley. The Upper Hood River Valley has a better chance over dropping below 37 at 40-60%, elevation dependent. Beyond Saturday, there are low probabilities around 10-15% each night through Sunday night into Monday morning.

Potential for shower activity has decreased over the central Oregon Cascades for Saturday afternoon with around 10-20% PoPs. Depending on the strength of the upper shortwave and amount of mid-level moisture, chances for showers may increase Sunday and Monday afternoons, with around a 10-20% chance of rain showers across the lowlands and 30-50% over the Cascades and Cascade Foothills.

Uncertainty remains in the forecast heading into next week. Ensemble clusters do show ridging pattern developing over the eastern Pacific and PacNW but strength and exact position are unclear. This is reflected in the high temperature spreads heading into the middle of next week with lower end max temps in the mid 60s and high end max temp potential into the lower 80s. Chances for precipitation remain low (less than 20%) through Thursday. DH/19

AVIATION

VFR conditions and southerly to southwesterly winds under 8 kt continue throughout the airspace. KAST is the only exception, with sustained winds around 8-12 kt with gusts up to 20 kt expected to weaken to under 8 kt by 00Z Fri. VFR conditions will likely continue through at least 00Z Sat. Current BKN to OVC clouds between 3000-5000 feet throughout the airspace are expected to clear through the evening. Winds will become light and shift to north-northwesterly around 00Z Fri, then ranging from northerly to north-easterly by 06-12Z Fri. Approaching 17-18Z Fri, winds will shift more easterly and increase at most terminals, with sustained winds around 8-12 kt and gusts up to 20 kt.

KPDX AND APPROACHES...Expect VFR CIGs through the TAF period, with current OVC clouds around 4500 feet gradually clearing through the evening. Southerly winds around 4-7 kt will become light and north-northwesterly around 00Z Fri, then northerly around 09Z Fri. Approaching 18Z Fri, winds will shift northeasterly and increase to around 8-12 kt with gusts up to 18 kt.~12

MARINE

Steep seas continue over the waters with wave heights around 10 feet at 11-13 seconds. Small Craft Advisories continue for all zones including the Columbia River Bar. The northwesterly swell continues to decrease through the day with wave heights dropping below 10 feet late this afternoon. Small Craft conditions are expected to end by 5 PM PDT.

Light southerly winds continue to shift to the northwest around 10 kt this afternoon and evening, with Buoy 46050 already showing winds from the west as of 2 PM PDT. On Friday, an offshore pressure gradient will bring northeasterly winds, with gusts between 20-25 kt possible in both inner and outer waters south of Cape Falcon during the afternoon and evening. There is currently a 50-80% chance of wind gusts exceeding 21 kt. Wave heights will continue to subside to 6-8 feet on Friday.~12

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory until 5 PM PDT this afternoon for PZZ210- 251>253-271>273.

Small Craft Advisory from 3 PM Friday to 2 AM PDT Saturday for PZZ252-253-272-273.