textproduct: State College

WHAT HAS CHANGED

Nothing.

KEY MESSAGES

1) Blustery. Light rain/drizzle in the Laurels and a mix of snow and rain over the northwest will taper off through the day.

2) Dense fog is possible in the east until the wind kicks up early today.

3) January thaw ramps through late week with above normal temperatures and periods of rain Friday into Saturday;

4) Monitoring river rises from rain + snowmelt for ice jams

5) Turning windy and seasonably colder Sunday with snow showers downwind of Lake Erie

DISCUSSION

KEY MESSAGE 1...

Upslope in westerly llvl flow will keep some showers of rain going in the Laurels and rain/snow showers over the NW. The temps are going to be a little too warm (32-35F) in the NW to allow much more than a little slush to briefly coat the ground this morning. It will likely melt as it falls, though. Westerly wind behind the cold front moving through this morning will increase briefly, but lower a little as high pressure builds in from the west and the gradient relaxes.

KEY MESSAGE 2...

Fog is going to have a short life over the eastern zones for the next 6-8 hrs. But, the null flow or even a light upslope like there is at Zerby Airport (Schuylkill Co) will allow for the moist ground to contribute negatively to the visibilities this morning. As the front passes and mixes things up/deepens the mixed layer, the fog will get blown away, or succumb to the rising temps. Don't expect much fog past 10-12Z depending on just how quickly the air aloft can mix down. We'll monitor for a possible dense fog advy, but at this point, the vsby is only bad at isolated locations.

KEY MESSAGE 3...

The high pressure from TX slides NE thru the next couple of days, setting up a good Gulf connection. 8H temps rise into the upper single digits or even +10C (SW) by Friday. Sfc warm front should move through on Friday, but the sfc low will be well into nrn ONT by then. The (first) cold front may not clear the state as it hangs up, laying out W-E. Another low will form on the deep moisture feed from the Gulf, sliding just west of the CWA. A rumble of thunder isn't out of the question Sat as some of the area may get into the warm sector. But, Sat's a little far away to trust details like that.

KEY MESSAGE 4...

As the temps warm and rain falls finishing off any remaining snowpack, some of the water will make it's way into the waterways. Ice has formed over the past couple of weeks. But, the warm up before the rain arrives should help the ice soften or melt away. Still, a couple of waterways could see an ice jam or two. Ice jams are a very random thing and all we can hope to do is recognize that this is the time and pattern to have them happen. The heavier the runoff, the more widespread the threat would be as the ice would be broken up faster and moved more easily. A jam below Marietta (above Safe Harbor Dam) on the Susq has caused the water to rise there. But, the river is well below flood stage and inching downward as the ice melt and slide down-river. Again, just something to keep in mind at this point. Ice effects are seen at many sites. There is always a discussion on how to forecast the river stages when the volume of water flow (at Marietta currently = 17kcfs/35ft) is literally 4x less than what the river stage shows (looks like 76kcfs/40ft) due to the ice effects. In addition, different types of river gauges work in different ways and will be affected differently by the presence of ice. As always, the best course of action if you live along the river is to watch the progress of the ice and where the water actually is on the banks instead of what the actual flow would normally have the stage read.

KEY MESSAGE 5...

The low pressure area lifting away from us on Sunday will continue to deepen as it gets into ONT and QUE. The cold front should be off the coast before sunrise Sunday. The low will thus be pulling in cold air rapidly from the high pressure dome to our NW (coming from the Canadian Plains) and drop the 1000-500hPa thickness down to around 510dam. A truly Arctic airmass will slide over the Eastern US, turning the wind to the NW and cranking up the lake effect snow machine. 0C 8H temps make it to the FL panhandle. Our lofty 8H temps of +10C Friday will fall very quickly to that much or more below zero on Sunday, shocking the senses. The wind will be gusty as the gradient will be tight and vertical flow well-aligned. Gusts into the 40s may be on tap for the higher elevations. It won't last all that long as the high pressure moves to the east. That should direct milder air back in during the first half of the new week.

Maxes will fall 10-20F from Sat to Sun (most drastically in the NW - Warren/McKean Cos). The coldest air will be overhead Sun night/Mon. Mondays temps will be coldest, but not far off normals. Temps go right back above normals Tues on the srly flow.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

A wide range of conditions overnight.

Far eastern areas not that warm, while most of the area had a mix of clouds and some fog.

Far western areas had the temperatures jump well into the 40s, with gusty winds.

As of 6 AM, still a cluster of rain showers across the far northeast. Isolated snow flurries at BFD, as the far west cools back down. Far southeast areas now having some dense fog.

As the cold front moves further east this morning, expect any precipitation to taper off, and eastern areas to improve as the winds pick up and the low clouds and fog mix out.

Outlook...

Thu...Mainly VFR.

Fri-Sat...Restrictions with a batch of steady rain and cold front Sat night.

Sun...Snow showers possible mainly west of UNV.

CTP WATCHES/WARNINGS/ADVISORIES

None.