Temperatures will drop below the freezing mark for all locations more than 2-3 miles from Lake Ontario. For areas south of the Thruway, your lows might end up in the low 20s with a hard freeze surly damaging sensitive vegetation.

For more on this, please read the article I spoke of…

http://weatherblogging.com/2010/04/13/a-possible-volatilel-situation/

Over the next two days, two low pressure systems– one a Miller Type A cyclone that’s moving its way into New York City, the other a weaker land-based low coming over the Appalachians– are going to converge over upstate New York and the Twin Tiers. The question is this: what does this mean for residents of the Western Twin Tiers? Well, believe it or not, not much. We will get some snow, but according to virtually all of the models, the epic snowstorm is going to miss us.

Part of the issue is that we are under an upper-level low pressure system with the jets steering everything to our north. Over the next few days, this will shift to a relatively rare easterly jet, but again, according to the models, any body of precipitation is going to hit the Catskills and Adirondacks, hitting them with the major snow and dying out by the time it reaches us in the upper Appalachians. The metropolitan Buffalo-Rochester-Syracuse corridor, however, will largely be unprotected since the storm will move straight up the Mohawk Valley.

So, how much snow will we here in the Twin Tiers get? Well, despite the reports in the major metros suggesting 12 to 24 inches, I think that’s an estimate on the high side. A minimum of 6 inches is likely, but I don’t see us getting any more than 12 inches. The exception is Allegany County, where one of the models is projecting a piece of the heavy snow to clip the county.

The snow will reach us Thursday night and Friday.

As for winds and high temperatures, winds shouldn’t reach more than about 15 mph. Temperatures will likely be in the mid-to-upper 20s for most of the Twin Tiers area for both today and tomorrow, with low temperatures tomorrow morning in the low 20s.

The National Weather Service has issued a Winter Weather Advisory for the Western Southern Tier and Northern Pennsylvania. A Winter Storm WARNING is in effect for all counties south of the Twin Tiers.

However, the Twin Tiers need their forecast for the week, and that’s why I’m here. Unlike the last snowstorm that just grazed the area, this one appears to be headed right for us. We have a surface low coming right across the Appalachians, another low sweeping down the plains and looking like it will combine with the Appalachian low, and a high pressure bubble just to the east of these two that will prevent a “type B hop” toward the East Coast. (Type B refers to the direction of a snowstorm like this: A goes around the Appalachians from the south, B goes across the Appalachians by generating a cyclone to the east of the original and causing the original to disappear, and C goes around the Appalachians from the north; C is the one that usually affects us, and that’s what this one’s turning out to be.)

The roles, as it turns out, are going to be a bit reversed from last weekend’s storm: the major city corridors are likely going to get less than the last one (but still nothing to sneeze at) while we brace for the worst. The good news is that with storms coming up across the Appalachians, it forces a lot of the heaviest snow out of the system through orographic lift down in West Virginia and deep in coal territory, well before it reaches us. Reading the NWS discussion, they’re only calling for 2 to 4 inches. That’s a stretch I think, and I think it’s based on the development of a type B situation. I don’t think it will happen. I will be bolder and call for at least 6 inches.

After the storm passes, it will establish a northwesterly flow over the area, bringing colder than average temperatures, but seasonably cold (low-to-mid 20s for highs, as opposed to the average of 29).

Tuesday:
Snowfall begins in the afternoon. Afternoon highs in the upper 20s. Easterly wind becoming stronger as the day progresses. Tuesday night, snow.

Wednesday:
Snow continues. Early morning low in the upper teens. Highs in the mid-20s.

Thursday:
Snow begins to dissipate. Colder. Early morning lows in the mid-teens. Highs in the low 20s. Northwesterly wind.

Friday:
A mix of sun and clouds. Early morning low in the upper single digits. High temperature in the low to mid 20s.

More in the Weekend Outlook.

~JMF

We have prefect conditions out there tonight for prime radiational cooling. Winds at the surface and through much of the lower atmosphere are already calm and/or light, we have clear skies, and the dew point has already dropped below 30 degrees.

Tonight’s record low at the Rochester airport is 27 degrees set way back in 1876. It’s possible we could come very close to that low, maybe not at the airport, but a few backyard thermometers will see readings in the upper 20s.

We will keep the cool weather around for Columbus Day. Our daytime high will only make it into the upper 40s. Well below normal for this time of the season.