18z model runs of the GFS and NAM are not showing the cold air as strong as before. Right now, the GFS is the warmest with 850mb temperatures just below 0C over Cheshire County. This will promise frozen precipitation, however more icing is probable rather than the earlier thought, period of steady 12:1 snow. At the moment, advisory level snow is still possible, and advisory level icing is all but guarenteed. In addition, highest accumulation amounts have moved south of the area, and now target MA. My icing forecast hasnt changed too much; still looking at .25 to .35 inches of freezing rain accumulation plus up to half to one and a half inches of sleet accumulation. The previous snowfall forecast of 3 - 6 inches is now looking a tad high. An inch off (2 - 5 inches) is probably about right at the moment. Things will probably change tomorrow though.

CPC forecast:

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
516 PM EST SAT JAN 13 2007
 
VALID 00Z SUN JAN 14 2007 - 00Z WED JAN 17 2007

DAY 2...

THE MAIN UPPER TROF SHOULD START OVER THE CENTRAL PLAINS AND THEN
TURN MORE EASTERLY...PASSING ALONG THE SOUTHERN AND EASTERN GREAT
LAKES BY THE END OF THE PERIOD.  WARM AIR AND MOISTURE ADVECTION
NORTH OF THE SYSTEM SHOULD PRODUCE MORE FREEZING RAINFALL ALONG
AND NORTH OF THE TROFS PATH...WITH A SHIELD OF SNOW/SLEET
EXTENDING BACK INTO THE COLD AIR.  AS MENTIONED EARLIER...HIGH
SNOW TO WATER RATIOS SHOULD LEAD TO A STRIPE OF 4 OR MORE INCHES. 
IN ADDITION...THERE SHOULD BE A SEPARATE BAND OF SNOW OVER PARTS
OF NEW ENGLAND THE FORMS IN DIFFERENTIAL PVA AND WAA PATTERN.  WE
TENDED TOWARDS THE WETTER NAM IN THE GREAT LAKES REGION.  THE 12Z
ECMWF TAKES IT H85 LOW FROM MO INTO THE SRN GREAT LAKES...ON A
PATH THAT PUTS SNOWS NORTH OF EVEN THE NAM.  GIVEN THE MODEL
UNCERTAINTY...WE HAVE A FAIRLY BROAD AREAL COVERAGE OF SLGT RISKS
AT THIS POINT. 

THE RISK OF FREEZING RAINFALL EXTENDS SOUTH WEST INTO THE SRN HIGH
PLAINS ALONG THE FRONTAL BOUNDARY.  THERE IS A PERIOD WHERE COLD
AIR UNDERCUTS A SOUTH/SOUTHWESTERLY FLOW OF WARMER AIR WITH MORE
MOISTURE.  THE PROBABILISTIC MAPS WERE BASED ON THE ENSEMBLE
MEANS/NAM/ECMWF.  

DAY 3...

NORTHEAST/GTLKS...
THERE ARE STILL SOME MODEL DISAGREEMENTS WITH THE DETAILS OF THE
SYSTEM AS IT PULLS NORTHEAST ACROSS NEW ENGLAND...ALTHOUGH THE
DISAGREEMENTS ARE NOT AS LARGE AS BEFORE.  THE IDEA OF SNOW AND A
TRANSITION ZONE OF FREEZING PCPN STILL IS IN ORDER BEFORE COLD
ADVECTION SWEEPS ACROSS THE AREA IN WAKE OF THE LOW.  ONCE AGAIN
WE TENDED TO FAVOR THE MORE NORTHERLY AND WETTER TRACK OF THE
NAM/ECMWF.  THE GFS AND ECMWF LOOK TO BE TOO DRY IN THE AREA. 
  
BANN