Slowly Coming Together...Too Slowly

With the evening now upon us, radar is showing the couple of pieces for this storm trying to come together.   The storm is organizing a bit farther offshore than most model guidance anticipated (NAM was the exception) and is coming together more slowly as the upper trough isn't digging as sharply...instead it's shearing the storm a bit due to a more broad nature of alignment (U shaped, not a sharp V trough that helps in rapid intensification).   As such, the storm is spitting rain across the region but is not developing at an explosive enough clip to provide the ingredients necessary for a widespread snow thump across the higher elevations to our north.

Hope is not lost for the Pocono snowstarved overnight -- energy back across West Virginia this evening will lift through and will likely provide enough juice to the atmosphere to allow for rain to change to snow in the higher elevations of the Poconos and perhaps down to Allentown overnight.   Some snowflakes could mix in across Upper Bucks, Montgomery, and Chester Counties -- particularly over the higher elevations.

With that said, while the storm is slow to develop it doesn't mean that it won't rain...even steady at times overnight.   It's not going to be completely "dudsville" but rain will fall off and on overnight and is upper level energy fuses in later we can see some changeover taking place.

Snowfall totals for the region:

Allentown:  Around 1"
Poconos and North Jersey below 1500' elevation:  1-3"
Poconos and North Jersey above 1500' elevation:  3-7"

We'll see if Mother Nature pulls another trick from her sleeve overnight but based on the slower and more eastern development of the storm this is probably what will fall overnight.

More:   Current Weather Page

Light Snow Scooting South

Not all that impressive but this morning's light snow system is tracking along to the east, bringing light snow to the Delmarva, including parts of Southern Delaware where an inch or two of snow can't be ruled out this morning.   Winter Weather Advisories are out for Sussex County in Delaware until Noon.   While radar returns show some light precipitation over New Jersey, nothing is falling from the sky at this point.   Most, if any precipitation, should be confined to Sussex County and perhaps Cape May through midday before precipitation cuts off.

Sunshine will gradually...and slowly...return from north to south through the next several hours as this system pulls off the coast.  Expect another cool afternoon as the region struggles to get into the mid 40's for high temperatures.

More:   Current Weather Page

Snow or No....Still A Close Call

Advisories and warnings are out for parts of the Delaware Valley with the upcoming winter spring weather event that's going to move through the region over the next 30 hours.   Winter weather advisories are out for Bucks, the Lehigh Valley, and Berks for tonight and tomorrow morning.   Winter Storm Warnings are out for the Poconos through Thursday morning.   No advisories are out for Philadelphia or South Jersey.

The event that's poised to hit is about 10 hours away, likely to move in after 3 AM tonight.     This event will start as a mixed bag for chunks of the region --particularly around Philadelphia and the northern burbs, with mostly snow farther north.

Computer guidance still holds to the three camps that we outlined in prior posts -- with the NAM the coldest of the guidance and the GFS the warmest.    There is some certainty in the models showing a mixed bag at the front end...that should move in on Wednesday morning, with a sleet/snow/rain mix in the city and suburbs, snow/sleet mix in the northern parts of Bucks/Montgomery County, and snow farther north.   The main brunt of Wednesday morning's precipitation will reside to the north of the city initially but with more precipitation slugging in from the west we'll see everyone get precipitated on throughout the course of the midday and afternoon hours.

This looks to be an elevation dependent event as well -- meaning the higher up you are the better your odds for snow.   This could be a situation where some of the higher hills in Bucks and Montgomery County get an inch or so while lower elevations get rain during the morning round of the storm.   The heavier the precipitation is on the front end of the storm tomorrow the better the odds for some snow, especially north, as colder air aloft gets pulled down through the atmosphere.  

We should see a transition to rain from south to north -- with solely rain falling for a time in the Lehigh Valley and perhaps the southern parts of the Poconos.   This transition time could occur when precipitation may be lighter in intensity during the later afternoon hours -- could be drizzly in some spots as well.  The question then turns to Wednesday night, with the NAM (above) being the exception to the computer guidance consensus in showing a heavy swath of precipitation moving through that could lead to a transition of rain to snow even down into Philadelphia.  Again, the NAM is an exception...with the GFS and Euro not showing this heavy swath of precipitation at all.

Precipitation totals should average out to no more than an inch in many locations -- the highest will be north of the city where it could be more snow than not -- with a half to three-quarters common across the immediate city and suburbs, less than that south.

Regarding snowfall, our projected totals are elevation dependent but we think the best chances for heaviest snows are over the higher elevations of the Poconos.  I can see 3-6" of snow across there and Northeastern Pennsylvania.  Across the Lehigh Valley, 1-3" looks like a reasonable bet.  An inch is possible across the upper parts of Bucks and Montgomery Counties, perhaps even into Chester County's higher elevations.     Snow/sleet mix can't be ruled out into Philadelphia at the start of the event...and if the NAM is correct, it may end as that as well.

We'll provide another update on the storm tomorrow morning.

Lull In The "Action"

Update, 9 AM: The earlier radar returns over Central Pennsylvania have fizzled, leaving us in a relatively dry lull for the next few hours. More precipitation is still across Western Pennsylvania. Depending on whether that activity survives the trek over the mountains, we could see some showers this afternoon. Skies are trying to brighten somewhat around town, with temperatures in the 40's south of the city and 50's in Southern Delaware.

This morning's current temperature, radar, and warning overlay shows the first round of the storm across Northern and Northeastern Pennsylvania, pulling east.  Last night's "storm" dropped a coating of snow across the northern burbs and brought snowflakes mixing in with rain to the city proper, while areas to the north saw measurable snowfall.  Totals range from those coating amounts in the suburbs to a couple of inches in the Lehigh Valley to 3-6" across the Poconos this morning.  Along with a wide array of snowfall totals comes a wide array of temperatures as warm air lurks to our southwest this morning.   Temperatures range from the 20's in the Poconos to the 50's down in Washington this morning, with low and mid 30's around the Philadelphia region.  The milder air to our southwest will work into Delaware and perhaps South Jersey for a time near midday before some rain moves back in this afternoon.

Advisories and warnings remain out for parts of the region -- with a winter weather advisory out for Bucks and Montco until 10 AM due to the potential for some slick spots on some of the side roads around town and the potential for more precipitation to move in towards mid-morning.  That precipitation is just showing up on the radar overlay up above and is quickly moving east.   It should move in here in the form of rain after 9 AM, moving through by midday.

Round two is back in the Midwest and will move on in tonight, with snow for parts of the region and additional accumulations for areas generally south of the Pennsylvania Turnpike and Route 70 in New Jersey. We'll highlight the "how much for round two" later on today (won't be a ton of snow but it should be enough to shovel overnight).

Snow To The North, Not So Much Of Anything Here

Computer modeling for tonight's event is pretty much set on a snowy scenario to our north, with little to nothing around town as we get clipped by a larger surge of moisture that should generally cruise east along I-80 overnight tonight.   Precipitation is working east through the Ohio Valley this morning and should lift a bit more northeast as the day progresses, meaning that most precipitation should fall generally to the city's north overnight.   Timing wise, expect precipitation after 9 PM in Philadelphia.   High resolution radar (below) suggests precipitation starts up around 11 in Philadelphia.

Temperatures tonight will cut it rather close to freezing -- I'm not expecting the city to drop below freezing but there may be enough cold air aloft to allow for some snow or sleet to mix in with any rain in the city proper.  The farther north one goes, the better the moisture support, dynamics, and the better chances one will have for a snowy scenario.  In fact areas north of Scranton could see several inches of snow overnight.   Another concern for the folks in the Lehigh Valley and far northern suburbs is the potential for some icy rain to mix in as temperatures aloft warm before the surface.   The Lehigh Valley, Berks could see an inch of slush with a bit of icy rain on top of that slush.  

Assuming the higher resolution guidance is correct, precipitation won't last long in and around Philadelphia and most of the suburbs, meaning that the precipitation burst that we get tonight will be brief and won't amount to much.  The northern suburbs could end up with some coating type accumulations but widespread major snows aren't likely from round one of the one-two combination that we're getting over the next 48 hours.   The city should not see much, if anything, besides some snow or sleet possibly mixing in.  Even that, at this point, doesn't seem terribly likely but is certainly a possibility.

Due to the potential for more snow farther north, Winter Weather Advisories are out for the Poconos and Northeastern Pennsylvania for tonight and tomorrow morning.

Winter Weather Advisories for Saturday

Winter weather advisories are out for Saturday for areas north and west of the city due to the potential for a mixed bag of slop in the suburban counties, with the potential for snow across the Poconos.  Winter storm watches were out in the Poconos last night but the National Weather Service decided to place advisories across the region due to guidance light night suggesting a less robust development in low pressure.  That doesn't mean it's not going to snow, especially over the Poconos where a good number of inches of snow are expected, but the trends suggest a more modest event as low pressure develops on a slower scale.

The advisories in the suburban counties are more for the potential freezing rain that could accompany the event after a brief period of snow to start.  A few hours of light freezing rain can't be ruled out before temperatures rise above 32.  No ice storm is expected on the order of what we went through on Wednesday but a couple of hours of light freezing rain is still bad enough from a driving standpoint.   However, temperatures should rise above 32 south of Blue Mountain during the event on Saturday and conditions should improve gradually as the day marches on.

We'll probably tweak the snowfall forecast over the Poconos later today but will wait for the midday guidance to make sure that's our intent.