Friday, February 08, 2013

Windswept, Soaked, Socked

It's an active weather day today, obviously.  This will be a high level overview of what to expect during the day, less of a full blown discussion and post about trends with the storm.

Temperatures early this morning are in the 30's across the region -- we're above freezing in MOST spots, with Upper Bucks, Allentown, and points north at or below freezing.  I included the 3 AM dew point reading  in green.  This gives you an idea of moisture in the atmosphere.  It will matter more when precipitation to our south moves in through the morning rush since a less moist atmosphere will allow air temperatures to knock back a few pegs at the onset of precipitation.  We'll see rain spread in over the next few hours from south to north, with rain likely from Philly on south. However, some sleet pellets could be included initially in the city and immediate burbs below the PA Turnpike as there's some dry air included in the lower atmosphere that could allow for some pockets of lingering chill at the onset of precipitation.  North of the city (above Doylestown) could see some snow at the onset before transitioning to a mix of rain and snow through the Lehigh Valley, with snow likely as the dominant precip type in the Poconos through the event.  It's touch and go on this in the Lehigh Valley but there will probably be just enough warmth aloft to cause some mixing for a while up there.

Rain becomes steadier and heavier through the afternoon hours as the storm intensifies, with colder air gradually working back in from the northwest.  This will lead to a changeover from rain to snow later in the afternoon (likely after 4 PM) from northwest to southeast.  It may take into the evening for this transition to take place...that's's going to snow most of Friday night.

Snowfall will be heavy at times north and east of the city and the highest snowfall totals are in line for those areas.  We'll give you a more thorough update on snowfall totals and projections later this morning.

Temperatures today top out in the upper 30's in the city, mid 30's in the immediate burbs north and west, lower 30's in the Lehigh Valley, and in the 40's at the Shore.  Those temperatures will back off during the afternoon as the storm intensifies, with mid 30's into the city by 5 PM.  Winds will increase to between 15 and 25 mph, with gusts to 45 at the Shore this afternoon and evening, perhaps a bit higher in the usual windy spots.  Inland, winds could gust to 35 mph along I-95 later this afternoon and tonight.