Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 12:57 AM GMT on December 27, 2007
Well good afternoon! Today is another nasty day around the state of Pennsylvania. In the north a few snow showers moved through causing a coating of snow in some spots. In the south is has been only a few rain showers and drizzle. Well this upcoming weekend looks interesting weatherwise. Friday nights a large storm will bring heavy rain across the whole state. Many areas may see over one inch of rain. Then Sunday a possible other storm may affect the southern 2/3rds of Pennsylvania with some snow. This storm though is still not yet in agreement with the computer models. Then arctic air moves in for next week, with maybe a surprise coastal storm with all snow?
Currently at 1200pm here north of Harrisburg it is 38degrees with clouds and fog. Across the state there are a few rain showers with snow above elevations of 1800ft. But expect little accumulation. Then for the rest of today look out for dense fog on the ridge tops due to low clouds at about 800ft. For tommorrow sun may break out in the eastern part of the state, but I doubt it. Rain will move in across the state by nightfall with rain totals approaching one inch state wide. In the far western and northern part of the state near Erie there may be a change from rain to snow at the tail end of the storm but I doubt it. If this happens still expect no accumulation. Then for Saturday it stays mostly cloudy with some sun across the east.
We are in a very active weather pattern with alot to talk about. First off the Sunday-Monday storm. The is limited cold air, but it may be just cold enough for a little snow storm in the southern half of Pennsylvania. The GFS keeps precipitation to the south of the Mason-Dixon line. The EURO brings in the cold front and a wave develops off of that and becomes a small coastal storm with many areas seeing snow. From about the line from Garret county, Maryland to Baltimore, Maryland, to Wilmington, Delaware, to Philadelphia, Pennsylvania, to the coast of New Jersey. Anybody to the north of that line has a chance to see moderate snow accumulations if the EURO is true. The CANADIAN model is in between the EURO and GFS with just light snow from a weak wave developing off of the cold front. So for now I will stick with that forecast for light snow north of the line I mentioned earlier. This forecast could change though. Check out the EURO for the 31st...
After that storm arctic air moves in with high temperatures for next week from 32degrees in Philadelphia to 20degrees in the mountains of northern PA. The question though for next week is if a coastal storm can develop. This would happen if a shortwave gets taken in by the trough and heads up the eastern seaboard spreading all snow. So far the models show no storms, because they think the trough will be too far east so even if a coastal storm would develop then it would be too far east to affect anyone. We will just have to wait and see. Also for todays NAO. It shows us getting highly positive for midmonth and then dropping possibly back to negative later in the month.
Well the 12z GFS shows enough cold air, but no precipitation for the sunday-monday storm. I will have another update as soon as the 12z EURO comes out.
Well the 12z EURO is out and it shows a wave still going through Virginia, and then developing a coastal low. The model run is almost the same as the 0z run, execpt the 12z run shows more in the way of precipitation
Well the 18z GFS is still saying it should be a flat wave through southern Virginia with precipitation not getting even as far north as Washington, DC. But it does show a lot of cold air over the region. I just checked Henry Margusity's 430pm blog, and he believed the GFS will come around to the coastal storm scenerio. So I believe anybody north of the line I mentioned earlier has fair game in getting snow from this storm. But still the storm is many days away and things will probably change. I am starting to understand why the coastal storm might happen, so I am leaning towards that solution.
Well a possible major lake effect snow outbreak looms in the future. After the clipper moves through on Monday with snow showers then the arctic air moves through with a west,north,west flow setting up. It looks as if some impressive banding could occur here in Pennsylvania. And when shortwaves move through next week this will enhance the lake effect snow and bring banding all the way to just east of the mountains. Areas in the laurel highlands and northwest mountains should prepare for a possible major snow event from the lakes. Some spots even is central Pennsylvania may see an inch or two of snow if the banding sets up. It looks like Tuesday will be the worst of the days for lake effect. I will have much more on this possibility this weekend.
My concerns for Sun-Mon Storm
A. Marginal cold air mass
B. Why does a big storm blow up like the EURO shows
C. The GFS forecasted the recent coastal better than the
D. The storm just heads out to sea
"Just to throw out there"
For the storm on Sunday, the GFS shows little precipitation for anyone in Pennsylvania. Now remember the GFS also predicted yesterday's coastal storm more accurately than the other models. So maybe the GFS is right. We will have to wait and see.
"Regional Forecasts" (Thursday Night)
1. Eastern- (Allentown, Southern Poconos)-
Cloudy. Low 31.
2. South Central (Harrisburg, York, Lancaster)(my home)-
Cloudy with areas of fog after 2am. Low 32.
3. Southern- (Philadelphia)-
Mostly cloudy. Low 35.
4. Central- (State College)-
Cloudy with dense fog late. Low 29.
5. Northern- (Bradford, Williamsport, Erie)-
Mostly cloudy with patchy dense fog late. Low 29.
6. Western- (Pittsburgh)-
Cloudy. Low 31.
7. Johnstown, Altoona-
Cloudy with widespread dense fog. Low 29.
***Note on regional map, the number equals which region in Pennsylvania. I chose regions with similar climates, geography, and elevation to make my overall forecast for the region.
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