NWS SC Take
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
*Increasing potential for plowable to possibly heavy snow Monday
night into early Tuesday | February 12-13th
The latest 09/12z GEFS/ECMWF mean guidance are reasonably
clustered and show a deepening sfc low tracking ENEWD from the
Central Appalachians (NC/TN/VA/KY/WV borders) to the southern
DelMarVa Monday night and off the southern New England coast by
early Tuesday. This remains generally in line with the earlier
09/00z and 09/06z model guidance, but with a slightly more
amplified and deeper (less progressive) run/run trend.
Given the marginal to potentially "manufactured" cold air due
to dynamic wet-bulb cooling, the GFS/EC operational model runs
seem to be at least somewhat overdone with cranking out swath of
heavy snow. There will also likely be a significant snowfall
rate and elevation dependency that further adds to the ptype
complexity of the impending storm system. While just outside the
gridded snow accumulation period with this cycle, the
probability for a stripe of 3-6" of snow continues to increase
over central PA with higher amounts possible. The north/south
position of the axis remains uncertain, but latest guidance
favors the central portion of the forecast area extending ENE
with wrap-back and banding into the Poconos. To further
contextualize the model spread, the NBM 25th-75th percentile for
State College currently ranges from 0 to 4 inches. Timing has
come into better agreement with the heaviest precip rates
occurring Monday night into early Tuesday. Still plenty of
details issues to be resolved with the most likely travel
impacts and disruptions centered in the Monday night to early
Tuesday timeframe.
The potential phasing of the upper jet and rapid coastal
intensification response could result in strong northwest
winds across the area on the backside of the storm and trigger
lake-enhanced/upslope snow showers across the western
Alleghenies.
The pre-Valentine`s Day storm will trigger a pattern reversal
back to seasonable winter cold for the rest of next week.
Additional chances for snow appear limited outside of some snow
showers downwind of Lake Erie and with a couple of clipper-type
systems.
