


Area Forecast Discussion
Issued by NWS Medford, OR
Issued by NWS Medford, OR
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924 FXUS66 KMFR 182252 AFDMFR Area Forecast Discussion National Weather Service Medford OR 252 PM PST Tue Feb 18 2025 .DISCUSSION...Radar is showing light returns with over running precipitation along and ahead of a warm front. This will continue into this afternoon. However, precip amounts will be very light and intermittent. Satellite image shows an upper trough digging out near 140W and moving east towards the forecast area. All indications are the upper trough will become negatively tilted late tonight into Wednesday morning as it reaches the coast, which is indicative of strengthening or deepening low. There is a general consensus showing a surface low developing inside of 130W along with an increasing pressure gradient. There are a couple of outliers, but this may be suspect given the upper trough will become negatively tilted. In addition, the GFS shows pressure gradients between Arcata and North Bend peaking out at 12.2 mb around 7 am pst, but still greater than 8.0 mb between 4 am and 7 am pst. The NAM is weaker and peaks out at 7.1 mb early Wednesday morning. Given the above, have issued a High Wind Warning for the headlands and exposed areas along highway 101 for the south Oregon coast from Cape Blanco south. The pattern is also one that is favorable for moderate to strong winds in the Shasta Valley near Weed and the Rogue Valley with increasing southeast winds later tonight into Wednesday morning. Winds will be strongest near Weed and south of Medford to Ashland during this time, and a Wind Advisory has been issued. Please see NPWMFR for more details. The duration of winds for the coast, Shasta Valley and Rogue Valley should be of shorter duration, but the impacts are there, thus it is prudent the Warnings and Advisories were issued. A cold front and upper trough will reach the coast late tonight, then moving inland Wednesday morning with snow levels falling in the morning, then rebounding some in the afternoon due to diurnal effects. Snow levels will vary depending on precip intensity since we`ll be in a convective environment from late Wednesday morning and afternoon. Generally they are expected to be between 4000-4500 feet. Precipitation Wednesday will be mainly concentrated along the Cascades and coastal mountains in southwest Oregon. Along the Cascades, snowfall rates of an inch per hour are likely for about a 6 hour period from late Wednesday morning through Wednesday afternoon along with visibility lowering towards a 1/4 mile during times of heavy snow. This was the driving force for issuing a Winter Storm Warning. Please see WSWMFR for more details. Showers will continue Wednesday evening, then diminishing Wednesday night as the upper trough shifts south. Upper ridging will builds into the area Thursday resulting in dry and milder weather with the storm track shifting north. The upper ridge will flatten out some Friday, with some precipitation slipping through along the coast, offshore and northwest Douglas and Coos County in the afternoon. This lines up with the majority of the individual ensemble members solutions. The storm track will shift south Saturday afternoon with precipitation increasing along the coast and northwest Douglas County, then shifting south and east over a good portion of the area Saturday night. There has been some question as to where the heaviest precipitation will be, but it`s a good bet the highest precip amounts will be along the north coast. This can vary depending on how the frontal boundary moves Saturday afternoon and Saturday night. However, the majority of the individual ensemble members and operational models suggest it will be in the above mentioned areas. Snow levels during this time will be high with any road snow concerns confined to around Crater Lake. Even then it`s not expected to be much. The frontal boundary is expected to remain nearly stationary Sunday into Sunday night, then lifting north briefly before returning Monday afternoon as an upper trough and front approaches. Upper ridging returns Tuesday with dry weather expected. -Petrucelli && .AVIATION...18/18Z TAFs...With the exception of some lingering MVFR visibilities at Klamath Falls, VFR levels under high ceilings are present across northern California and southern Oregon. A warm front moving over the area is bringing some showers west of the Cascades that may locally lower visibilities, but substantial activity is not expected through this afternoon. An impactful system will approach the Oregon coast this evening, bringing widespread showers and gusty southerly winds into Wednesday. More precipitation is expected, especially along the coast and over the Cascades. Snow levels of 5000 feet or higher will limit snowfall to the highest areas, with heavy snowfall expected over the Cascades near the end of the TAF period. Low level wind shear over higher terrain may also be present as the system moves over land. While guidance does not show this shear directly over Medford, shear over the surrounding mountains follows the same timing as Roseburg. Shear across the area looks to disperse by the end of the TAF period. -TAD && .MARINE...Updated 230 PM PST Tuesday, February 18, 2025...Steep seas continue this afternoon in all waters ahead of an approaching low pressure system. This system will bring widespread marine rainfall, Conditions will rapidly deteriorate as the system approaches. Gusty southerly winds are forecast to reach gale strength late tonight through Wednesday morning. Wind gusts may locally reach over 50 kts in all waters. The highest chances for these 50 kt winds will be on Wednesday morning, from Port Orford and northward and within 30 nm from the coast. The system is forecast to move away to the north late Wednesday morning, but very steep and hazardous seas could continue in all waters through Thursday morning. While a brief period of below Advisory level seas is possible late Thursday, another front arriving on Friday will likely rebuild steep seas going into the weekend. -TAD && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory from 1 AM to 7 AM PST Wednesday for ORZ026. High Wind Warning from 1 AM to 7 AM PST Wednesday for ORZ021- 022. Coastal Flood Advisory from 4 AM to 4 PM PST Wednesday for ORZ021-022. Winter Storm Warning from 7 AM Wednesday to 4 PM PST Thursday for ORZ027-028. CA...Wind Advisory from 1 AM to 7 AM PST Wednesday for CAZ081. PACIFIC COASTAL WATERS...Coastal Flood Advisory from 4 AM to 4 PM PST Wednesday for PZZ350-356. Small Craft Advisory until 10 PM PST this evening for PZZ350-356- 370-376. Gale Warning from 10 PM this evening to 10 AM PST Wednesday for PZZ350-356-370-376. Hazardous Seas Warning from 10 AM Wednesday to 4 AM PST Thursday for PZZ350-356-370-376. && $$