Winters Last Gasp!

Those of you who follow this blog know that we been talking about the pattern and how we are in a historical time frame for the AO being so negative and usually a - AO has two effects on the weather. It makes the weather colder then normal and allows in tandem with a negative NAO to form what we call atmospheric blocking. When this happens there is confluence across the Northeast.. and this confluence can press south with dry air and as precipitation advances into it ..it has trouble reaching the ground...

As you can see via the current radar it is showing snow falling across a good chunk of PA..

Never the less when you look at observations for the midnight hour you see the following...
SOUTHERN NEW JERSEY

CITY SKY/WX TMP DP RH WIND PRES REMARKS
POMONA CLOUDY 37 27 67 E8 29.67F WCI 31
RIO GRANDE* CLOUDY 37 28 70 E9 29.70R WCI 31
MILLVILLE CLOUDY 37 26 64 CALM 29.71R
WRIGHTSTOWN CLOUDY 36 26 67 NE5 29.67F WCI 32
LAKEHURST CLOUDY 47 27 45 NE5 29.68F
MOUNT HOLLY CLOUDY 37 27 67 CALM 29.69F
TRENTON CLOUDY 37 25 61 SE5 29.69F WCI 33

$$
NJZ001>014-250500-
NORTHERN NEW JERSEY

CITY SKY/WX TMP DP RH WIND PRES REMARKS
SUSSEX CLOUDY 37 22 54 NE7 29.71F WCI 32
MORRISTOWN CLOUDY 41 25 52 CALM 29.71F
NEWARK CLOUDY 41 24 51 CALM 29.72F
TETERBORO CLOUDY 40 27 59 CALM 29.71F
CALDWELL CLOUDY 39 25 57 CALM 29.71F
SOMERVILLE CLOUDY 39 25 57 CALM 29.69F
ALLAIRE* CLOUDY 37 27 65 E5 29.71F WCI 34

$$
PAZ043-044-047-054-055-060>062-066>071-250500-
EASTERN PENNSYLVANIA

CITY SKY/WX TMP DP RH WIND PRES REMARKS
PHILADELPHIA CLOUDY 39 24 55 E6 29.71F WCI 35
NORTH PHILA CLOUDY 37 25 61 E5 29.71F WCI 33
BLUE BELL CLOUDY 37 27 65 E3 29.67F
DOYLESTOWN CLOUDY 36 24 62 CALM 29.68F
POTTSTOWN CLOUDY 38 25 59 CALM 29.70F
LANCASTER CLOUDY 37 25 61 SE3 29.68R
COATESVILLE CLOUDY 36 28 75 CALM 29.70R
READING CLOUDY 40 25 55 SE9 29.67S WCI 34
ALLENTOWN CLOUDY 40 24 53 SE7 29.68F
MOUNT POCONO CLOUDY 32 20 61 E12 29.63F WCI 23
WILKES BARRE CLOUDY 36 21 54 VRB5 29.67F WCI 32

Cloudy skies being reported in locations where you see precipitation on the radar. 

Presently we have a primary area of low pressure and the secondary developing as the guidance suggested would... We can see this looking at the pressure falls..

Guidance over the past 24 hours has really cut back on QPF with this storm system. 

The GFS at 24 hours above. The NAM which at one point was showing a foot of snow now looks like this..

The RGEM looks like this... 

Guidance is in agreement that the heaviest QPF is going to be along the coast of New Jersey. 
So what we have done is we have taken a blend of the guidance and used a few factors in addition to this.
Factor #1 Majority of the precipitation is going to be falling during the daylight hours today.. This in combination with lighter intensity (exception along the coast) and the area closer to the primary ...the snowfall will have a hard time accumulating on anything other then the grassy areas. Again ..new Jersey and the area out west are exceptions. 

Factor #2 The confluence with the dry air.. This means we are going to lose precipitation to the dry air. It will look like its snowing on radar but when you look out your window you might not see anything ...*again new jersey and the area to the west are the exception cause of heavier intensity..

Factor #3 This storm system is going to be sliding further south and east then what the models were showing previously and with the confluence pressing south moisture will have a difficult time making it North....

So into places like NYC we are only expecting a Trace to an inch or so. 

The End Result...

If you are across south central PA into SW PA this will be a decent event but it is a far cry from what the models were suggesting a few days ago and a far cry from the HYPE of some weather outlets that thought just because we had a - AO it would result in a huge storm.  

For late March and into spring though this will end up respectable in areas to the east (New Jersey) and areas west..