Ph.D. Student - Earth System Science (UC Irvine), B.Sc. - Atmospheric Sciences (Cornell University)
By: Zachary Labe , 8:52 PM GMT on January 18, 2008
Good afternoon! Sorry for the late update, but was a little too busy yesterday to post.
With this cold weather lately I have noticed ice forming along the major rivers including the Susquehanna River here in Harrisburg, PA. Remember though the ice is not near thick enough to walk on so take caution if around waterways. Hypothermia easily can occur in water for only a few minutes. Every year the are a few deaths across the state for people falling into ice. Awareness is what we all need to spread about water/ice safety.
Pictures of ice on Susquehanna River (just north of Harrisburg)...
Anyway last night a weak disturbance moved through the region and actually created some snow. The upsloping factors of the mountains actually helped to create the lift and by the early morning hours snow was falling. A widespread 1-3inches of snow fell around the I-80 area. About 25miles on either side of the interestate was the region of accumulating snow. And it went as far east as Williamsport. State College area seemed to get hit the hardest. Now the left over snow showers are still moving through the northern half of the state. Currently near DuBois a pretty intense snow shower is moving through and may limit visibility to near 1mile for a time. A additional half inch accumulation is possible in that region.
Then tonight another little more potent disturbance moves through and affects the whole state. Warm air advection snow will break out across just about everywhere. Some drier air across the eastern part of the state may limit the snow. But from the extreme western part of the state to the York-Harrisburg-Wilksbarre-Scranton line is where the accumulating snow will be. Another C-3inches of snow looks likely. The 3inches will be confined to elevations above 2000ft. That disturbance is currently located over Wisconsin and will begin dropping southeast towards the northern middle atlantic by nightfall. Snow showers should end by 10am Sunday morning in all locations. Temperatures tonight will be in the mid20s which will create snow ratios of 15:1-20:1. This will enhance the snow. In areas that do see snow, it will accumulate on the roads so take care driving around late tonight and Sunday morning.
There has been lots of talk about the coastal storm developing tonight and moving northeast about 100-200miles off the coast. This will have no impact on Pennsylvania weather. Some areas in Cape Cod and Nantucket may get scaped by some precipitation that may be heavy for a time, but it shouldn't cause too many problems as it will be only a mix of wet snow and rain. Warmer air will get drawn in into these coastal areas. This storm will make loops in the open Atlantic for a few days due to the blocking high over Newfoundland, but should not cause many problems to any land masses. The only problems will be found in shipping lanes. To the United States we will only see the Massachusetts and Maine coastlines impacted with the mentioned already precipitation and some light coastal flooding with wind gusts to 50mph. Overall the storm should not be that big of deal.
Then by Monday across Pennsylvania things should quiet down and we will be stuck in the clouds for most of the day while temperatures go 5degrees above normal with southern areas seeing highs approach 40 for the first time in a while.
Ok, for the short term. The forecast is for the first half of the week. Temperatures are going to go above normal by about 5-6degrees. The highest temperatures will be found around Philadelphia with them about 45degrees. These above normal temperatures will occur for Monday and Tuesday. During this time a front will approach from the west. This will be a strong front with moderate rain accompanying it. There may be a large temperature drop that could turn the precipitation to snow after the front moves through for a few hours across western and central areas. The for Wednesday it begins to get cooler with temperatures going back to near normal to just a few degrees above normal. Some people are calling this a January thaw, but not me, it is only going to get a little warmer and it will only last for 2-3days. By thursday another front with a low pressure approaches. Many, many questions remain with this front. Some models including the DGEX bring heavy, heavy snow across the state. Other models such as the GFS bring very warm temperatures with a possible severe weather outbreak. For now I am not even sure what is close to happening. So stay tuned. After that we are entering a stormy weather pattern.
Ok, some interesting things are going on in the long term. THe current pattern we are in is with a strong trough over the eastern and central United States. This has been bringing arctic air and for the most part dry conditions. Most coastal storms have been pushed out too sea. And clippers have been entering too dry off an atmosphere to really produce much. Also lake effect snow was at a westerly flow preventing it from becoming too widespread. So overall not too widespread of precipitation, which would be snow due to the cold air.
But now things are changing. Now the long term models, GFS and EURO, are hinting at not as cold of an airmass, but more stormy with just enough cold air for snow. Also it appears the high pressures will become more blocky during these storms. The GFS hints at a wild time during the beginning of February with storm after storm after storm after storm. All of them take a similar storm track of coming out of the gulf of mexico heading through the lower Tennessee Valley and then across the Appalachians then heading up right along the coast moving inland to Massachusetts. In alot of these storms it appear precipitation would start off as heavy rain but then change to snow as the storm moves to the northwest.
Now todays NAO is more negative than yesterdays approaching -1 by some members. This may set the stage for one of these systems in the long term to ride up the coast.
Also to note the NAO was neutral the entire time of this current arctic outbreak.
Now I know most of you are saying to yourself that the GFS always has these monster storms that never happen. This is true. And I am not saying that this inparticular storm will happen. But the point is that we are headed into a new weather pattern similar to the pattern in early December. We will have cool temperatures and possible big storms around.
This winter is not over yet, and I think it still could pull some surprises. So watch out as we are headed into a stormier weather pattern. I do think though after about the 20th of February things begin to warm up before they get cold again in mid March.
Also it will be interesting to see what today's 18z GFS run brings. As that model run for some reason always really intensifies the cold and storms in the long term. It is fun to dream about some of the storms that never come to fruitation. For now stay warm as more arctic air is moving in for Thursday.
*Note the negative trend.
*Note the trend of becoming neutal.
"Just to throw out there"
Well in this section I am quickly going to give my prediction for the rest of January.
I think that this week the arctic air sticks around before it slowly begins to moderate temperature wise. I do think the models too quickly throughout the cold air for this weekend. Then for next week it slightly warms up to slightly above normal temperatures, but then it cools down by the end of the week where some significant storms could enter the picture. Temperatures during the very end of January will probably be near normal. I do not think most people see any much more snow statewide before January comes to a close. The jet stream appears to favor storms heading up through the great lakes putting us in the warm sector.
*Note I will issue my February forecast during the first few days of the new month.
"Regional Forecasts" (Saturday)
1. Eastern- (Allentown, Southern Poconos)-
Cloudy. Flurry in northern sections. High 33.
2. South Central (Harrisburg, York, Lancaster)(my home)-
Cloudy with a passing flurry late. High 32.
3. Southern- (Philadelphia)-
Mostly cloudy. High 35.
4. Central- (State College)-
A few snow showers. Additional Coating of snow. High 24.
5. Northern- (Erie, Bradford, Williamsport)-
Snow showers. Additional C-1inch of snow. High 23.
6. Western- (Pittsburgh)-
Flurries with a passing snow shower. Cloudy. High 27.
7. Johnstown, Altoona-
A few flurries with cloudy conditions. High 25.
My snow totals (10miles northeast of Harrisburg)...
07-08 Seasonal Total so far... 9.25inches
Monthly Total... 2.75inches
Daily Total... light coating
Snow Cover... .5inch in shaded areas
***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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