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SYSTEM NUMBER 1
Timing: Tuesday Morning - Tuesday Afternoon
PRECIP TYPE: MOSTLY SNOW N & W OF I 78 in PA NJ
There are several components to the first system that will move through the Midatlantic. The BIGGEST component will be an Arctic HIGH that will establish itself over Northern New England Tomorrow afternoon (Monday). This high will bring down super cold air as far south as Philadelphia and Newark, NJ and it will settle through the day on Monday going into Tuesday Morning. As a GIANT storm that will dump 2' of snow over the Mid west pushes east it will erode the cold air and the high will begin to retreat towards the east. With cold air being so dense with the associated high and the positioning of the high working for snow lovers advantage all precip will start as SNOW! The TRUE warm air advection will still be situated over the Tenn Valley however we will see a HAIR pin warm front (slight warming of the 900mb level) begin to move in from the south and west. This warming combined with cold air in much of the column aloft will increase snowfall rates from everyone north of Wilmington, DE and (Baltimore being the wild card city at this point). I think we see a general 2-3" by Tuesday afternoon as the warmer air wins over and a more North Eastern wind component comes into play. The NE wind component that will pull down the front side of the departing Arctic high will NOT be a critical situation for areas north and west of I78 in PA and NJ because it will still be a cold wind inland further locking in a cold solution at all levels (essentially meaning no change over Tuesday Afternoon).
A TROWAL will setup over the Lehigh Valley into southern Massachusettes as Frontogensis will begin.
The image below shows the lift that will be associated with this development. I am NOT overly impressed with it .. YET... But snowfall rates could be in the .75-1" ball park range going into early Tuesday afternoon. Note the 0 Degree 850 line which is over I 78 the area's that I believe will NOT go over to sleet or rain.. South of that line will not have the dynamics to keep the column of air cold enough to continue to snow.. So a light sleet/rain event will be found. This band of precip should only be 100 miles in width which will make it interesting to see how much some may get.
The best precip looks to be north and west of Philadelphia to SE MA where you see the .25 QPF amts. I am willing to split the different out side of the I 78 to I84 area and call for a general 2-3" however, inside NW jersey, Lehigh Valley, Pocono's, and Litchfield hills in CT I could see a 4-6" snow event inside a very short window before the precip move east.
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SYSTEM NUMBER 2
Timing: PREDAWN WEDNESDAY- WEDNESDAY EVENING
PRECIP TYPE: MOSTLY SNOW N & W OF I 84 in PA, NY, CT, MA
MAJOR ICE STORM I 78 to I 80 in NJ, PA
HEAVY RAIN / SLEET SOUTH OF I 78 TO THE SHORE
Storm 2 is a different beast.. While this is essentially the same storm that influenced Tuesday's weather.. The main components of the system will move into the Mid Atlantic. Instead of slight warming of the Upper and Mid Levels we will see a True Warm Air Advection situation unfold. However as specified above cold air will still be situated to the north as we will have a dieing Arctic air mass still in place coupled with a relatively fresh snow pact still in play. The NAM model does decay the main low to a 1004 MB system which would decrease the Low Level Jet coming into play. I do feel that is NOT correct and I could still see a sub 1000 MB low in play. A weaker Ohio Valley low would essentially lower the amount of Warm air advecting north bound. What has me concerned is the fact the thicknesses are NOT overly high. We may have a 10 kt southern wind coming into the Lehigh Valley however the column may not even react to it with enough cold air locked into the column as the precip begins to pick up.
THE NAM MODEL.. WHICH I BELIEVE IS THE BEST TO HANDLE THE UVV'S SHOWS A REALLY GOOD AMOUNT OF LIFT ...INSIDE -15 UVV'S WHICH IS ENOUGH TO SUPPORT A COLUMN TO OVERCOME ANY KIND OF WARM AIR INTRUSIONS. However, THINK LA NINA and with CLIMO working into this solution I expect enough warm air to be inside the 900-875 MB layer to bring in sleet and snow from I 78 to I 80. It's outside of I 80 towards Hartford which will be the toss up considering the initial low still has to track east and the further south it bends will cut down on the amount of WAA that will make it north.
THINGS TO WATCH WITH STORM 2....
1. TRACK OF THE LOW.. FURTHER SOUTH.. COLDER SOLUTION.
2. INTENSITY! LESS INTENSE = LESS WARM AIR MOVING NORTH
3. COLD AIR... ARCTIC HIGH RETREATING SLOWER = COLDER AIR COLUMN LONGER!
MY PERSONAL THOUGHTS ARE.. KEEP AN EYE ON TUESDAY MORNING - TUESDAY AFTERNOON'S EVENT. I STRONGLY BELIEVE WE HAVE A SURPRISE SNOW EVENT FOR MANY OVER THE LEHIGH VALLEY, NW JERSEY, LOWER HUDSON VALLEY, AND INTO CT.
WEDNESDAY AM - PM EVENT STILL HAVE 3 BIG THINGS TO BE WORKED OUT IN THE MODELS.. ( LISTED BELOW) .. TOTALS MAYBE SIGNIFICANT .. BUT MORE SO CONFIDED TO HIGHER ELEVATIONS AND LESS DENSELY POPULATED AREAS.
YOURS IN WEATHER,
MIKE MASCO
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