Area Forecast Discussion
Issued by NWS Portland, OR
Issued by NWS Portland, OR
149 FXUS66 KPQR 150509 CCA AFDPQR Area Forecast Discussion...Corrected National Weather Service Portland OR 843 PM PDT Fri Jun 14 2024 Updated Aviation Discussion .SYNOPSIS... Cooler over the weekend as a weak cold front pushes inland from the northeast Pacific. Will see rainfall and a slight chance (20%) for thunderstorms along the northern portions of the forecast area. Coolest temperatures will fall on Sunday before a trend towards a warmer and drier pattern comes mid next week. && .SHORT TERM...Now through Sunday Night... Now through Sunday Night...Minimal change in the forecast as the overall pattern remains on track. The low pressure system and associated front spin just offshore with rain falling along the north Oregon and south Washington coasts. This rain will intensify through the evening, but will be more showery in nature so there will be periods without rain. High resolution models are quite "bubbly" with the simulated reflectivity which can be connected to very sporadic yet moderate rainfall at times. Chances for thunder have remained the same (around 20%), but the overall areal coverage is greater. The HREF is showing around a 20-30% chance of thunder, especially in southern Washington. However, given the overall strength of this system, even if chances are higher, the number of strikes remains limited. Have decided to lower chances to around 20% to account for this. Areas with the higher probabilities are along the northern coast and northern Coast Range. Rain will be more widespread, as will temperature drops tonight through Sunday. Rain accumulation does not appear impressive, but, considering it will be showery, there may be periods of heavier rain. Precipitable water amounts are not robust enough for any kind of concerns...moreso washing your car level rain. Models have come into better agreement on Sunday with a more fine detailed forecast. There may be some lingering instability which can be observed in the vorticity advection and the alignment of the jet to the area. However, the trough is flattening, and the jet is pushing further south inching us out of the left exit region (more convective portion of the jet), and into more "neutral" territory. Sunday will be dominated by cooler air and a few lingering showers. -Muessle .LONG TERM...Monday through Friday...The overall synoptic pattern is comprised of a broad trough transitioning into a ridge. Ensemble clusters are in very good agreement, especially given the length of time into the future. Overall will see a warmer and drier pattern starting Tuesday. Seasonable temperatures in store with light winds, and no precipitation. -Muessle && .AVIATION...A weak cold front continues to cross Oregon this evening with another, stronger cold front inching closer to the area. The second front will begin to cross the area around 06Z and exiting the region by around 12Z. Cooler air moving in aloft behind the front will increase instability late tonight and into Saturday, supporting increasing shower activity and possibly a few thunderstorms. This pattern will support variable conditions with VFR conditions expected outside of any precip and MVFR/IFR conditions within any showers or storms that may develop. This second front will also result in a slight chance of thunderstorms (25% probability) for areas north of KCVO starting around 12Z-15Z Saturday. Any thunderstorms will have the potential to produce small hail along with gusty and erratic winds. Southerly winds across the airspace will become more westerly after the first frontal passage. PDX AND APPROACHES...VFR under scattered and broken mid level clouds (6-8 kft) will give way to low- end VFR/high- end MVFR conditions, with cigs likely hovering around 2-4 kft as a series of fronts move eastward through 18Z Saturday. The post frontal airmass late tonight into Saturday afternoon will support showers and a slight chance (25%) for thunderstorms. -Batz/42 && .MARINE... Relatively benign conditions through the weekend and into the start of the upcoming week. Seas around 5 to 7 ft at 9 to 11 seconds. A weak front will bring southerly winds through the evening, before a stronger front will cause winds to become more westerly tonight/early Saturday morning. Late Sunday/early Monday strong northwesterly winds will return and will likely bring marginal Small Craft Winds to all waters. There is still some uncertainty in the timing and strength of the Monday system. -42 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland