Another storm brewing. Will it be Rain, Ice or Snow or all three?
The following is a special weather statement issued by Real Weather Services
12/05/09 2:20 AM
Effective 12/05/09
Time: 12 noon till 1 AM 12/06/09
The following is a Winter Weather Advisory effective for East Central PA and NW NJ , as well as SE PA.
Low pressure developing over the Southeast early this morning will continue to lift off towards the North and Northeast and should be in off the Southern New Jersey Coast by 00z Sunday. Precipitation associated with this area of low pressure will start to develop across the southern regions in the early morning hours. Around PHL..it should start out as rain but transition to snow as the day wears on. To the North and West (immediate burbs) there will be a mixture of rain and snow becoming all snow by early afternoon and the far Northern Suburbs should begin as all snow around Noon. Precipitation will begin to taper off by around midnight.
Total accumulations will be in the range of 2-4 inches with some locations receiving as high as 6 inches ..primarily North and West of the city of Philadelphia.
Stay tuned for further updates, watches or warnings if needed!
Taking a look at the latest steering currents ..The first thing that one notices is the high pressure out in the Atlantic..
This tells me that this is not going to allow the developing low pressure to escape too far off to the east as the latest GFS/NAM is showing. It also seems obvious that they are suffering from some convective feedback as well. Its interesting to note that the UKMET @ 00Z has a different story as far as where this low ends up compared to the GFS/NAM. Then again..this is pretty much why within 24 hours we depend more on nowcasting observations then the models themselves.
Looking at the current radar you would think that there was precipitation streaming up the eastern seaboard. However for the most part that is all virga that is streaming up into the area. However..that virga does have one purpose to it as it will help to cool the columns of the atmosphere. This is why its important to keep an eye on your Dewpoints despite where your temps may be because there is going to be dry air to overcome. And with precipitation falling overhead this will help in dropping your temperature closer to its dewpoint. So lets look at our current dewpoints...
As you can see current dewpoints are 30-35 and under across majority of the region so this means that your temps will potentially drop within this range as the precipitation works its way down thru the layers of the atmosphere.
Temperatures generally thru out this event should be in the 30s for most areas with the exception of among the immediate coast and in southern new jersey where I think it will probably be in the lower 40s. That area should see primarily rain but it may end as some flakes of snow.
As this storm rides up the eastern seaboard the one thing that it is going to encounter on its journey is some warm SSTS. This is going to cause the storm to deepen and perhaps quite quickly. I think that some are under estimating the effects of the SSTS on the development of the storm as well as potentially the models. So i think we are looking at a storm somewhere in the range of 990 MBS to 994 MBS.
Like I said looking at the radar one notices the virga..however the other thing that stands out when looking at the radar..
There is two areas of precipitation ..One on the eastern side streaking up the coast (virga up north) and the other on the western side (east of Lousianna) along with moisture streaking northeastward on that western side (again pretty much as virga). However..one question that has to be answered is how about what happens between those two areas of precipitation? Does that area fill in? This is something that is going to have to be watched because this is going to effect the snowfall totals that are being forecasted.
I think that areas will start off as rain along the immediate coast and perhaps in areas like NYC and PHL. However..I think these areas will changeover to snow and the potential is there for 2-4 inches before all is said and done.
On my map I have several different zones labeled ..the areas that start off as rain...will have as mentioned the potential for 2-4 inches of snow but more then likely will verify on the lower end of that range. However..i would not rule out that just outside the city..they could be on the higher end of that range.
So with all that said...here is my final map...One final note is that the yellow area could very easily see up to 6 inches..but for verification purposes have gone with the range of 2-4 but up to 6 inches in that zone would not surprise me.
As you know here at Real Wx Services we like to always provide verifications of our monthly outlooks. This was the month of November along with the actual departures.
The overall concept of a relaxation and reloading period was spot on and the overall concept of an above normal November was also correct but the specifics were not warm enough. The seasonal along the western side never occurred as the whole region just torched...
So overall it was not a bad call for the month of November just was not quite warm enough!
