R.W.S Winter Weather Advisory

The following is a Winter Weather Advisory issued by R.W.S. at 3:35 PM EST 1/13/09

The following winter weather advisory is in effect from 1/15/09 12 AM est to 1/15/09 12 noon Est ..

The Winter Weather Advisory covers the following counties.
In PA...
Berks, Bucks, Carbon, Lehigh, Northampton and Monroe.

In NJ
Morris, Sussex and Warren

An alberta clipper currently over the Dakotas will continue to drop to the south and east to central Missouri. At this point and time the clipper will move from west to east across southern ohio and track east from there to the south of the PA/MD border, tracking across Washington, DC, and moving east out to sea from there.
The snow will start to spread from west to east around midnight and should cover the entire region by 4 AM. There is not much qpf with this system. QPF ranges from .01 to the south to about .20 in the far NW suburbs. This will result in a 2-4 inch snowfall across Pa counties and 3-5 inches across the far NW Nj counties.

Remember that a winter weather advisory means that a light accumulation of snow/sleet or freezing rain is expected.
Also along with this winter weather advisory will be a potential for gusty NW winds after the storm ends. This will create blowing and drifting of the snowfall. Use caution when driving or venturing outdoors
Stay tuned for further winter weather updates

Update on Clipper Storm

Alright..due to the color code being wrong on the previous map I have decided to redo the map with some changes as well...
Last night at 5 AM when i was posting and watching the 6z GFS i was becoming a bit concerned with the northward extent of the precipitation. The 06 Z GFS was actually further south then the 00z GFS. I thought to myself at that time that it was just the GFS. ECM was not quite as far south as that 06 Z GFS was. However..I kept it in the back of my mind. Because the 6 Z GFS essentially moved the low from west to east off the Delmarva and did not even really turn it to the NE.

Now the 12 Z ECM comes out with the exact same thinking.....

QPF is relatively the same as previous runs..just now with the further south track becoming more and more apparent this will shift the snowfalls northern extent southwards...

SO with those thoughts in mind ..this is my updated final map
As i mentioned last night this is going to not have alot of QPF to work with. At the most .25 would be the highest. I am using 20:1 ratios. This is going to be a very fluffy type snowfall. One that will blow around quite easily and one that will be hard to measure due to the blowing around factor..

I do not expect Blizzard conditions by any means...

Throw that word out the window.
I could see some whiteout conditions if it gets windy enough because any snowfall will blow around easily. With all that in mind that is my final map and truly enjoy this snowfall as it is the type one can truly enjoy!

Jan 14,15th Final Map

Final Map based on a blend of the ECM/GFS/GGEM.. I have completely discarded the NAM and the UKMET...

A clipper is going to drop Southeast thru the Plain states and track to southern Ohio and then move east from there just south of the PA/MD border off the coast of southern Jersey before moving ENE...There is not alot of QPF associated with this storm ....Ranging from about 0.1 in Maryland to 0.7 in Philadelphia to about .25 in NNJ to southern New England. However...the snow ratios will be higher due to very cold air in place. Ratios could be as high as 30:1 to the north....

This will be a light fluffy snowfall that will blow around with any winds with ease. This will not be hard to shovel. This is the type of snowfall one can truly enjoy!

Omega Block Preliminary Map For January 15th Clipper Potential

Nothing much to describe here. Event seems pretty solid so far for accumulationg snows due to high ratios.

00Z-12Z ECMWF and 12Z GEFS blend used for the map, for this event being 2-3 days.

Storm should track over DC, and therefore areas to the north get most of the QPF that the clipper lifts out of the waters of the Atlantic near the coast.

Winter Weather Advisories, may be needed for the areas in the 3-5 inch range. My blog will consider the possibility to issue one on Wednesday, if conditions continue more or less how they are now, for the Tri-state area (NE NJ, NYC metro and SE NY, and SW CT).

January 15th Clipper Snowfall Potential

Winter Storm Warning Downgraded to Light Snow Advisory

Winter Storm Warning for the region has been downgraded to a light snow advisory effective 3 PM this afternoon thru midnight tonight.


Alright after digesting the complete 12 Z model suite... I have not really changed much thinking on the track of the storm. I still believe its going to track right across the PA/MD border due east and across the Jersey shore. Looking at radar it seems the precipitation is moving due east. The pressure falls that update each hour also appear to be moving due east. So i still think the track is above and then it will cut across ENE over southern Jersey.....

So everyone is on the same page here with my map ..I want people to understand that it is not the track of the storm that made me change the map. I am not sure how much snow has fallen out in western PA at this point so that area could be off depending on what has. However..my main concentration side is to the east....

What made me change my map is the intensity of the snowfall. According to the radar(s) it should be snowing here and aside from a flurry now and then it is not doing anything. We have had about an inch give or take. So i have cut down accumulations due to the intensity of the moisture.
Best lift and frontogenesis appears that it is going to be more to the north of the system even though the storm track is staying south of the region by going along the PA/ MD border...
So thats the explanation of the map and why the changes...

Another R.W.S Perspective By Dante