Update Friday Morning

Hope you are enjoying the bright snow. Winter is here, so we might as well enjoy it!

Friday:  All in all, I am pretty well pleased with how the storm turned out, although the snow amount (4.5" here in the valley) was a little overdone. But there are reports in Berks, Lebanon, York, and Lancaster counties that had 6-8" of snow. So, the forecast idea was really good. This storm was a classic arctic wave. It grew colder, snow fluffier, and it also showed the prowess of deep cold air. 


Sundays headache shouldn't be too much of one for us. Some freezing rain is possible, but since it comes mid afternoon or later, it shouldn't be much of a problem. There will also be a little rain during the evening/overnight. Again, not much here. Heavier rain will be along the coast into New England, and heavy snow from Extreme west PA through OH, IN, IL, MO, western KY, western TN and parts of AR.  But we get sandwiched between the two, with not much going on. However, temps will be increasing during the night. Don't be surprised to see it near 40 come Monday morning. 


Monday: the front will come through early in the morning, with some rain, but as front pushes east the rain will likely change to snow. This could be interesting as moisture from the Atlantic gets involved and we get a few inches on the backside of the front. I have seen this happen before. Not sure if it will happen this time, but the pieces are there, they just have to come together right. After this front, the temps will drop quickly to where we should be near or below zero Tue morning. 


Tuesday: Very, very cold. Windy with sunshine, but temps struggling to get to 5 above. It will get to about 5-10 below by Wed morning, and then rise toward morning as the coldest air moves east. This is the coldest air mass to visit since Jan 1994. So its been a while. Don't worry it will warm up starting Wed and then some snow for Thurs.  Full forecast Sat morning.  

Wednesday: I spoke of the model error that I felt was going on back on Monday's post. Well, sure enough it is correcting itself. instead of the front energy flattening everything and us getting hardly anything, it is focusing on the back energy which is where the storm will develop along the arctic boundary. This is a classic arctic wave that produces most of its snow on north and west side of itself and very little rain if any at all. The hard part is that it will be phasing with another storm off the coast. How this happens and when it happens will be key to how much we get. Also, the snow will be light and fluffy so that will increase the depth. 


I do realize that I was too cold for midweek here. The arctic boundary did not come as far south as I expected ... but I don't think anyone is complaining. Although we probably will next week with the coldest air mass in about 20 years invading the US this weekend and next week. Shiver me timbers! 



My final forecast for the rest of this week: 


Thu: cloudy with snow arriving later in the afternoon (3-4 pm). High: 32.  The snow will become heavy at times through the evening and into the overnight. It will be done snowing by sunrise.Expect 5-7".  It will turn very cold overnight and very windy as well. Temps will be near 10 or lower by morning. 


Friday: very cold with increasing amounts of sunshine. Windy. high: 12 Low. 0 (down to -5 in colder locales). 


Saturday: Sunny and milder. High: 28. Low: 15. 


Sunday: Cloudy and milder. Snow/rain arriving. High: 35. Low: 30.  


Some bitter cold air to take up residence next week. More on that later.  

Some adjustments are needed for later in the week due to the pending storm of Thu-Fri. It seems that the typical errors are occurring with pumping too much energy in front and not enough behind.  The image below will illustrate it. When there is too much energy out front the storm will be elongated and pushed out to sea, because it flattens the upper air flow. If there were less out front and more behind, it will sharpen the upper air flow to be more N-S rather than E-W. This results in a stronger storm that is closer to the coast and drops a lot more snow. Right now the ECMWF and the Navy NOGAPS are supportive of this scenario. The other models all have it, but it is more out to sea and we would only get light amounts. Right now I am sticking with my forecast and not changing a thing. A lot can change in the next 36 hours. 

Some cosmetic changes were done. Mostly to the temperatures. I was too cold midweek.  

1) Tue: could be some snow showers and a squall as a potent, but really small trough moves through. High: 28. Low: 16

2) Wed: Sun with increasing clouds. Some light snow possible. High: 27 Low: 15

3) Thu: Snow arriving, becoming heavy at times. High: 24. Low: 15   

4) Fri: Snow ending, windy and very cold. High: 18. Low: 5

The rest I will keep. 

Notice the X over PA? This is supposedly upper level vorticity (energy). This energy is knocking down the ridge in front. Now, notice it is in front of the other X down in Tenn/Alabama. This energy is diving into and carving a deep trough. What if the front runner in PA is too strong, and the TN/AL is stronger? Then the ridge in front is not knocked down as much and the trough is deeper. The end result is a much deeper storm close to the coast. This is a typical model error. But could it be right this time? Stay tuned.

That title is real and it means what it says. The weather will be wild and very wintry. Let's start in the beginning ... and see maps below for a visual look. 

1. Sunday's storm is unchanged from what I posted the other day. Mainly rain with some ice, but not  a lot. Then again, it doesn't take much to make a mess. Snow will stay to our west. Still think someone will get a "surprise" 4" snow out of this from Bedford-Altoona-State College-Willamsport corridor. The higher elevations yes, but I am talking valleys too. Back here it will be raw and cold with temps in the 30s. Enjoy it as it should be the warmest day of the week! 
2. Bitter cold arctic air will pour in behind this system as a big trough takes up residence in the eastern half of the USA. Highs will struggle to make the low 20s on Tue-Wed
3. A significant snowstorm is looming on the horizon for our area Thu-Fri. It looks like a system will try to develop in the central states, and redevelop along the Mid-Atlantic Coastline, and strengthen significantly. This would give us some heavy snow accumulations (over 6") but it would fluffier snow. Temperatures during this storm may stay below 20 throughout.  
   
4. Even colder air could surge south behind this storm. Not totally sure on how cold yet. But some below zero weather is likely for areas just to our north. 

Details of forecast below maps: 

This is just one depiction of the potential snowstorm. The UKMET, GGEM, ECMWF, and JMA all show this system. It fits the pattern and is what I was alluding to about something else to come late this week (see prior post).

It may a little small to see, but -39 deg C air (in eastern Canada not here) at 850 millibars is some serious cold. This is a good indicator how cold this air is, with the coldest being at the surface (cold air is heavier than warm air). Bundle up midweek.

Recall the core of the coldest air to our north, well after the snowstorm leaves to our north and east, the gates open for that air to flood south. The core of it heading for New England. So starting Monday it will remain very cold through next weekend.

Specific Forecast: 


Sunday: Miserable rain, with some icy spots, esp early. Rain ends during the evening. Some clearing late at night. High: 35. Low: 33. 


Monday:  Turning windy, with partial sunshine. Temps holding steady and then falling late. High: 35. Low: 18. 


Tuesday: Windy and cold. Flurries or a snow shower. Partly sunny. High: 24. Low: 14. 


Wednesday: Mostly cloudy after some early sunshine. Some light snow. Very cold. High: 20. Low: 10. 


Thursday: Cloudy with snow redeveloping and could become heavy at times late. Very cold. High: 20. Low: 15. 


Friday: Windy, cold, with any snow ending. Partly sunny. Cold. High: 22. Low: 5. 


Saturday: Mostly sunny, very cold. High: 23. Low: 14. 


Sunday: Increasing clouds, light snow developing. High: 30. low: 25. 


Hint for Jan 5 - 12:  Some moderation will occur starting Sunday, but the cold will not disappear. I would not be surprised to see another winter like storm late in the week or weekend. This one may go up to our NW meaning a snow/ice/rain mess. It is winter so enjoy :)