As of 12 Z/18 Z model runs today..the models are now diverging on the next system to effect the region after the frontal passages of the 20-21st. Just 24 hrs ago the models were suggesting that the region could be dealing with another snowstorm in parts of the region. In particular they were suggesting this to occur from East Central Pa into NW NJ back into NE PA. They were pretty much ALL in agreement on this potentially happening!
We are going to look at the models that still essentially stick with the potential that they had yesterday and this will be the GGEM ..and the UK at least from what can be seen thru 72 hrs.
As you can see the GGEM does keep things cold enough in the aforementioned areas where this would be kept as a primarily frozen event and to the south of those regions it would be rain.
UKMET essentially looks like it would be along the same lines as what the GGEM suggests and perhaps even what the ECM had suggested 24 hrs ago.
On the other side of the coin we have the ECM which is basically straddling the middle line so to speak.
The ECM appears to be straddling the line in between its two prior runs. AVP for example looks like it would not be all snow (about .61) versus 00z last night which was all rain. ABE for example surface temps never get no higher then 34-35 with 850s well cold enough to support frozen but those surface temps are marginal. Last nights run same area was all rain as well. So it seems as if it is in between the two solutions from the last 24 hrs.
The GFS on the other hand ..is now suggesting a mainly rain event until you head N of the PA /NY border.
GFS clearly is suggesting that it will be warm enough to be a primarily rain event for those that are south of that PA/NY border.
While there is still time to watch this system on the guidance ..we are beginning to lend more credence towards the GFS and its solution over the GGEM/ECM which would be a colder solution and still maintain that snow chance in those regions.
Several reasons why we are leaning that way. Its a pretty well known fact that the 18 Z GFS tends to be colder and have a SE bias with systems. Just an observation that has been made by alot of weather enthusiasts thru the years. We do not see that at 18 Z. Second reason would be that even though the GGEM is suggesting it would be cold enough for snow..the models ensembles say completely opposite.
According to the means there would not be any snow until on the backside of the system and that would be Northern PA , NNJ and points Northwards. Pretty much the GGEM means agree with the GFS @ 18 Z..so this leads some credence towards the warmer rainy solution.
So right now, we here at R.W.S are leaning more on the warmer side of things and another big factor of this is climo and this time of the year..snowfall is generally held to the Northern New England area as well as the higher elevations such as the Poconos and NW NJ.
One thing we are going to have to continue to watch is the WAA (warm air advection) and how strong that is. Generally when you have a system that is tracking into Northern Ohio and then generally eastwards before redeveloping off the coast..You run into strong Warm Air Advection. Without any strong High pressure over the region..this could cause even those higher elevations to warm up enough for rain.
So we are not closing the door completely on the frozen scenario but at the present time climo and the reasonings stated above suggest that this could be a rain event and a decent amount of QPF across the region.
Stay Tuned for more updates and information!
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