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FXUS66 KMFR 260554 AFDMFR

Area Forecast Discussion National Weather Service Medford OR 1050 PM PDT Thu Apr 25 2024

Updated Aviation Discussion.

DISCUSSION
Another wave is moving onshore, which will bring behind it the bulk of the moisture from this system. The timing and intensity looks in line with the current forecast, so no changes were made. Friday morning snow levels still look to be at their lowest point, in the 4700 to 5200 foot range. However, snow related impacts should be very minimal because so far road temperatures have proven to be quite warm with snow melting on contact. Overnight temperatures will also continue to fall over the next 48 hours, so be sure to check your local forecast in the event you have any gardening related concerns.

.AVIATION (25/06Z TAFs)... MVFR ceilings are expected to continue along the coast through this TAF cycle and likely areas of IFR ceilings overnight, too. For all other areas, VFR will be the more dominate category with areas of MVFR in heavier showers. Cloud cover continue to cause mountain obstructions across the region, too.
Friday afternoon, winds at least east of the Cascades are expected to become gusty.
-Miles/CC

MARINE
Updated 800 PM Thursday, April 25, 2024...A front is moving inland this evening. Behind the front, breezy to gusty west to southwest winds and steep fresh seas will continue tonight into Friday. While wind speeds gradually diminish late Friday afternoon and evening, steep west swell will result in seas hazardous to small craft. These conditions are likely to last into late Friday night.
By Saturday afternoon, another front will push into the area, and seas may become chaotic once again into Saturday evening.
Additionally, we are going into a rainy pattern with chances over the waters nearly every day in the forecast through middle next week.

-CC

PREV DISCUSSION
/Issued 453 PM PDT Thu Apr 25 2024/

DISCUSSION...

Short Term
Tonight through Saturday Night
Currently, widespread showers cover much of southern Oregon and far northern California, with snow levels currently around 6000 feet. Shower activity will continue through this evening, then will reintensify as the upper level trough axis swings overhead tonight and tomorrow.
As this occurs, snow levels will lower to 5000 feet, and snowfall rates will peak between roughly 2 AM through midday Friday.
Amounts of 5 to 12 inches are forecast with highest amounts for the back country and highest elevations. Recent warmth is sure to limit amounts on roadways, but at the very least those traveling around Crater Lake, Diamond Lake, and Willamette Pass should be prepared for reduced visibilities. The highest peaks of the Siskiyou Mountains, Warner Mountains, and Siskiyou County can also expect to receive measureable accumulations.

Precipitation will taper off Friday evening into Friday night, then after a short break Saturday morning as weak ridging passes overhead, the next shortwave arrives Saturday. This will be a quick moving and somewhat weak wave, but it will be the leading edge of sustained zonal onshore flow that will persist through at least Saturday night. This pattern is known to produce ongoing light showers, and this is no exception, although most precipitation will remain confined mainly along and west of the Cascades. Snow levels are expected to remain fairly consistent, throughout this time, hovering roughly around 5000 feet.

Temperatures throughout the short term will remain right around normal for this time of year. -BPN

LONG TERM...Sunday morning through Thursday night.

This cool unsettled flow will continue into Sunday with the best chance of precipitation west of the Cascades and within Oregon.
However, locations east of the Cascades and in northern California are anticipated to be dry. This is most likely due to weak forcing and a lack of moisture farther to the south under this zonal flow.
This synoptic pattern will likely continue into Monday as short waves move through this zonal flow.

Heading into Tuesday, 500 mb heights appear more zonal over Oregon as another short wave swings through the state of Washington. This appears to be the driest day as the chance of rain is generally below 15% everywhere except along the coast near Cape Blanco and Coos Bay. Given this drier trend, temperatures should push into the 70's in Medford, Grants pass and the upper 60's in other locations across our forecast area.

Eventually, an upper level low out of the Gulf of Alaska will likely push into the Pacific Northwest around Wednesday. This should result in another round of wetting rain, although the NBM probability of precipitation of 0.01 inches over 12 hours only show a 50 to 60% chance of rain. Therefore, some of the ensemble members might show different times of arrival of the front on Wednesday night and Thursday morning or it is drier than what some of the deterministic data show.

The other thing that this low will bring is some cooler more unstable air behind the cold front. This can be seen in the snow levels falling down to 4000 feet behind the front, which should eventually pass through sometime around Thursday. Even with plenty of solar heating, high temperatures are still anticipated to push into the lower 60's in many cities east and west of the Cascades.

Overall, the extended forecast looks active yet with little to no impacts. We're lacking significant moisture or forcing to bring impactful rain or snow to the region. One may say it is very Spring like for our forecast area.

-Smith

AVIATION (25/00Z TAFs)...
MVFR ceilings are expected to continue along the coast through this TAF cycle and likely overnight, too. For all other areas, VFR will be the more dominate category through this cycle. Rainfall could bring ceilings down to MVFR, but the region will move into a few hour lull in activity, before another wave move onshore around 6z. Cloud cover continue to cause mountain obstructions across the region, too. Winds have been gusting between 20 and 30 kt this afternoon and it is expected for them to lower before the start of the 06z TAF cycle. Friday afternoon though, winds at least east of the Cascades are expected to become gusty again.
-Miles

MARINE
Updated 200 PM Thursday, April 25, 2024
A small craft advisory remains in effect for all of the waters as a front continues to make its way onshore today. The northern waters will experience the strongest wind speeds with a couple isolated areas perhaps seeing gales this afternoon. The front also brought widespread rainfall to the area earlier today, but rainfall over the waters has diminished quite a bit. In fact, satellite is indicating some clearing in our western waters, and we are likely to see a lull in activity over the waters until later tonight into Friday morning when the next round of rainfall is anticipated.

While wind speeds diminish tomorrow, swell remains over the waters and will keep seas hazardous to small craft. These conditions are likely to last into Saturday morning. By Saturday afternoon, another front will push into the area, and seas may become chaotic once again. Additionally, we are going into a rainy pattern with chances over the waters nearly every day in the forecast through middle next week.

MFR WATCHES/WARNINGS/ADVISORIES
OR...Winter Weather Advisory until 2 PM PDT Friday above 5000 feet for ORZ027-028.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Saturday for PZZ350-356-370-376.

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