Cascade Head to Florence OR from 10 to 60 NM Marine Forecast
| Today...N Wind 15 Kt With Gusts To 20 Kt. Wind Waves N 3 Ft At 4 Seconds. S Swell 1 Ft At 15 Seconds. |
| Tonight...N Wind 15 Kt With Gusts To 20 Kt. Wind Waves N 4 Ft At 5 Seconds. S Swell 1 Ft At 14 Seconds. |
| Wed...N Wind 15 Kt With Gusts To 25 Kt. Wind Waves N 3 Ft At 5 Seconds. Sw Swell 1 Ft At 14 Seconds. |
| Wed Night...N Wind 15 To 20 Kt With Gusts To 25 Kt. Wind Waves N 4 Ft At 6 Seconds. Sw Swell 1 Ft At 13 Seconds. |
| Thu...N Wind 15 To 20 Kt With Gusts To 25 Kt. Wind Waves N 4 Ft At 6 Seconds. S Swell 1 Ft At 13 Seconds. |
| Thu Night...N Wind 20 To 25 Kt, Easing To 15 To 20 Kt After Midnight. Wind Waves N 4 Ft At 6 Seconds. W Swell 2 Ft At 7 Seconds. |
| Fri...N Wind 15 To 20 Kt. Wind Waves 4 Ft. W Swell 2 Ft. |
| Sat...N Wind 15 To 20 Kt. Wind Waves 4 Ft. W Swell 3 Ft. |
| Area Forecast Discussion ...UPDATE National Weather Service Portland OR 959am PDT Tuesday July 27 2021 Updated Aviation discussion Synopsis Above normal temperatures continue through the forecast period as high pressure strengthens across the intermountain West. Hottest temperatures are expected Thursday and Friday. These hot temperatures and increasing monsoonal sourced moisture will bring periods of showers and potential thunderstorms primarily across the central Cascades more days than not through Monday. Short Term Today through Friday High pressure which originated as a 4-corners high, has become very expansive to cover most of the CONUS. The center has also shifted eastward to over the front range of the Rockies and the western plains. This has opened up the region to southerly flow and an influx of a moist air mass originating from the desert southwest monsoon. A shortwave rotating northward around the high this morning has brought mid-level forcing from frontogenesis to bring lift through the moist layer and has resulted in a very narrow and training line of thunderstorms running from roughly Roseburg northeast to Mt. Jefferson. Unfortunately, cannot find any record of rain reaching the ground and have seen around 60 CG lightning events recorded thus far. The lack of rain being recorded does not bode well for fire ignitions, however with the training effect, do suspect rain is reaching the ground in part and may simply be missing the stations. Am disappointed in the 00Z HREF convective allowing models which have largely missed out on the timing and placement of this event. The previous 12Z suite only faired a little better with only a couple of the members having any indication. And not surprising should any of the developers happen to read this, the Storm Prediction Center and plan view based thunder probabilities continue to struggle with nocturnal/high based events. Moving forward, expect the current activity has just about run its course with lightning activity having greatly diminished over the last hour. The next area of interest is currently along the northern California coast east of the Arcata airport. This area should reach the Lane County Cascades before but it's somewhat questionable whether it will end up east of Willamette pass or not given the current trajectory. Regardless, expect the thunderstorms will generally end by 10am or so. After a several our break in the action, surface instability will bring the thunderstorm threat back along the central Cascade crest for the afternoon and evening hours. This round may have a better chance of getting some decent rainfall under the cores, however, not all lightning likes to occur inside the rain shafts so new ignitions will again be of concern. Temperatures today will be similar to yesterday or perhaps a little cooler given additional cloud cover from the invading mid level moisture. Wednesday will be a little warmer with Valley locations in the lower to mid 90s. Thursday will be the warmest yet as the upper high axis tilts closer to the PacNW and brings increasing 500 mb heights. Have stayed pretty close to the NBM deterministic temperatures given the relatively persistent pattern which lends to the bias corrections. Doing so has brought inland temperatures up to the mid and upper 90s for Wednesday and to the upper 90s and low 100s for Thursday. As these temperatures will be well above expected norms, even for this time of year, will likely be needing some form of heat products to be issued for Thursday/Friday, especially given dew points well into the 50s may make it a struggle to drop below 60 degrees Wednesday and Thursday night. Friday will be only a few degrees cooler. The coast should remain relatively cooler as onshore flow as the surface heat low/thermal trough generally remains well inland aside from drifting west to along the I-5 corridor Wednesday night and Thursday night. Meanwhile, each afternoon from now through Friday will bring at least a minimal convective threat along the central Cascades. Have included a thunderstorm mention each day although Wednesday and Friday may see potential storms remain well east of the crest. Generally expect any of these storms to be more of the nuisance variety and at least more likely to produce surface rain than not. /JBonk Long Term Friday night through Monday...Low pressure starts digging south from the Gulf of Alaska late in the week and starts pushing the upper ridge axis slowly eastward. This will also push the thermal trough east of the Cascades allowing for a more persistent onshore flow to keep temperatures cooler. Overall flow will still be moist and rather southerly so brought a thunderstorm mention back to the central Cascades Saturday and Sunday afternoons/evenings. Temperatures inland will continue the cooling trend through Monday, however, they will still be several degrees above climatological normals and broadly in the upper 80s. Coastal areas will likely remain under a summertime typical morning clouds with afternoon bouts of sun and breezy winds regime. This will keep those areas much cooler and in the 60s. /JBonk Marine No changes. High pressure remains offshore with thermally induced low pressure over SW Oregon and NW California. This will bring the typical northerly wind pattern over the next several days. Winds may briefly touch SCA (Small Craft Advisory) criteria this afternoon for our southernmost waters, with northerly gusts of 25-30 kt possible. Model guidance confines these stronger winds to our southernmost waters, so we refrained from issuing a SCA (Small Craft Advisory) for the time being. Seas are primarily wind-driven, with just around a foot of southwesterly background swell. Northerly winds are likely to increase slightly Wed/Thu, and at this point it appears likely that our southern waters will need an SCA (Small Craft Advisory) Wednesday afternoon, and all our coastal waters may need one for Thursday afternoon. Weagle .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. |
Portland OR Radar