THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


PROBABILISTIC HEAVY SNOW AND ICE DISCUSSION




PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
823 AM EST MON FEB 08 2016

VALID 12Z MON FEB 08 2016 - 12Z THU FEB 11 2016


DAYS 1 TO 3...

...MIDWEST/OHIO VALLEY/APPALACHIANS/MIDDLE ATLANTIC/NEW ENGLAND...

AS THIS EVENT GROWS CLOSER...THERE DOES APPEAR TO BE MORE MODEL
CONSENSUS THAN EARLIER EVEN THOUGH THERE ARE SOME MESOSCALE
DETAILS THAT REMAIN UNCERTAIN AS TO TIMING AND LOCATION. A VERY
ACTIVE COMPLEX SERIES OF WEATHER SYSTEMS CONTINUE TO MAKE THIS A
CHALLENGING FORECAST.  THERE DOES APPEAR TO BE MORE CONSENSUS FOR
A SIGNIFICANT SNOWFALL ACROSS EASTERN NEW ENGLAND ON DAY 1/MONDAY
INTO TUESDAY MORNING...WHILE THERE IS ALSO MORE CONFIDENCE FOR
SIGNIFICANT SNOWFALL ALONG THE SPINE OF THE APPALACHIANS FROM THE
NORTH CAROLINA MOUNTAINS ACROSS WEST VIRGINIA INTO WESTERN
MARYLAND AND SW PENNSYLVANIA.  THERE IS EVEN MORE CONFIDENCE FOR A
POSSIBLE SMALLER SCALE SNOWFALL EVENT NEAR THE
MARYLAND/PENNSYLVANIA BORDER BUT THE EXTENT AND DIMENSIONS ARE
STILL QUITE UNCERTAIN FOR DAY 1 INTO DAY 2/MONDAY INTO WEDNESDAY
MORNING.

A POWERFUL CYCLONE OFF THE SOUTHEAST COAST WILL MOVE NORTHEASTWARD
WHILE A STRONG JET ENTRANCE REGION OVER SOUTHEASTERN CANADA INTO
NEW ENGLAND WILL BE ASSOCIATED WITH THE NORTHWARD EXPANSION OF A
LARGE AREA OF QPF ASSOCIATED WITH THE STORM. SOME OF THE HIGHER
RESOLUTION MODELS PRODUCE OVER AN INCH MELTED QPF OVER
SOUTHEASTERN MASSACHUSETTS ON DAY 1 INCLUDING THE ARW/NMM AS WELL
AS THE NAM/SREFMEAN. MOST OF THE RECENT OPERATIONAL RUNS/ENSEMBLE
MEANS PUT .5 TO 1 INCH QPF ACROSS SOUTHEAST MASSACHUSETTS. THERE
IS A HIGH PROBABILITY OF GREATER THAN 8 INCHES OF SNOW JUST SOUTH
OF BOSTON WITH A LOW TO MODERATE PROBABILITY OF GREATER THAN A
FOOT OF SNOW.

WHILE THE INTENSE STORM AFFECTS THE NORTHEAST COAST...THE
AMPLIFYING TROUGH OVER THE CENTRAL EASTERN PORTION OF THE NATION
WILL CAUSE SNOW TO BREAK OUT OVER THE UPPER LAKES AND SPREAD
EASTWARD ACROSS OHIO/THE APPALACHIANS FROM THE NORTH CAROLINA
MOUNTAINS INTO THE MARYLAND AND SOUTHERN PENNSYLVANIA ON DAY 1 AS
THE LEADING EDGE OF A SIGNIFICANT SHORTWAVE ASSOCIATED WITH THE
DEEPENING TROUGH ENCOUNTERS A REGION OF UPPER DIFFLUENCE ACROSS
THE APPALACHIANS AND MIDDLE ATLANTIC STATES.  THERE ARE MODERATE
PROBABILITIES THAT ACCUMULATIONS WILL EXCEED 4 INCHES IN THESE
LOCATIONS ON DAY 1 AS A NEW AREA OF LOW PRESSURE DEVELOPS OFF THE
MIDDLE ATLANTIC COAST AND MOVES OFFSHORE.

A SECOND IMPULSE EMBEDDED WITHIN THE DEEP TROUGH WILL FOLLOW ON
THE HEELS OF THE FIRST SYSTEM AND WILL KEEP AN AREA OF LOW
PRESSURE NEAR THE MIDDLE ATLANTIC COAST AND SEVERAL OF THE MODELS
INDICATE THAT ANOTHER AREA OF SNOWFALL WILL REDEVELOP ACROSS PARTS
OF THE MIDDLE ATLANTIC STATES ON DAY 2/TUESDAY INTO WEDNESDAY
MORNING BEFORE THIS RELATIVELY WEAK SYSTEM ALSO MOVES OVER THE
WEST ATLANTIC OCEAN.  WHILE YESTERDAYS MODELS HAD A REALLY
DISPERSED SOLUTION...TONIGHTS MODELS SUGGEST THAT THE HIGHEST
PROBABILITY FOR ADDITIONAL SIGNIFICANT SNOW COULD BE LOCATED
ACROSS THE WEST VIRGINIA INTO SW PENNSYLVANIA MOUNTAINS AS WELL AS
NEAR THE BORDER OF PENNSYLVANIA/NORTHEAST MARYLAND AND NORTHERN
DELAWARE.  THERE IS A LOW TO MODERATE PROBABILITY OF GREATER THAN
4 INCHES OF SNOW ON DAY 2. ANOTHER IMPULSE MOVING ACROSS THE GREAT
LAKES WILL HELP FOSTER LAKE EFFECT SNOW DOWNWIND OF THE GREAT
LAKES ON DAY 2 AND THEN PRODUCES SOME AREAS OF GREATER THAN 4
INCHES OF SNOW ACROSS THE GREAT LAKES AND CENTRAL APPALACHIANS ON
DAY 3.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

KOCIN






Last Updated: 823 AM EST MON FEB 08 2016