UPDATE.....INFO and ACCUMULATIONS!!!

[RNS]

First off...the answer to a question reagrding the snowfall across the lower hudson valley...catskills and NE PA (from another thread):

As the precipitation continues to fall into the dry layer...Relative humidity will increase...the atmosphere will moisten up and the snow will start. In addition to a quick drop in temps courtesy of evaporational cooling as temperatures fall to the wetbulbs.

the banding features will continue to increase in intensity and coverage as saturation is acheived releasing CSI. Some folks may even see thunder and lightning in stronger convective bands and clusters.

very nice isentropic ascent evident...in addition to pronounced frontogenesis (frontogenesis is the horizontal tightening of the thermal gradient)...which will intensify further as the coastal front begins to take shape. The frontogenesis will maintain the symmetrically unstable environment across the lower hudson valley and northeast jersey.

Note the symmetrically unstable environment would be located in the region to the north of the main vort max underneath the downstream ridge where absolute vorticity is weakly positive or slightly negative.

Snowfall totals are as follows:

Washington DC 6-12"
Philadelphia 9-15"
New York City 12-20"
Boston 12-20"
Harrisburg 14-22"
Allentown 14-22"
Scranton 12-20"
Binghamton 12-18"
Albany 10-18"
Poughkeepsie 14-22"
hartford 12-20"

local accumulations may reach two feet in some places before all concludes.

Other critical features:

1) Strong easterly LLJ at H85 will develop to the north and east of the H85 low pressure center helping to increase precipitation efficiency...which combined with the warm ocean temps will help to increase precipitation rates inland. within the next 12 hours...this feature appears to be aimed right at E PA...NJ...the lower hudson vly and far southeast new england.

2) heavy precipitation will also be supported by increasing UVM associated with divergence in the left front quad of a very intense upper level speed maximum. This combined with the presence of the LLJ at H85 and the potential for strong banding...leads me to believe that the models may be undercutting the precipitation amounts in and to the south of the lower hudson valley.

Divergence at the mid and upper levels above low level convergence is considered very favorable for intense upward motions and heavy precipitation.

3) As the coastal low Wraps-up tomorrow near the benchmark...winds will increase along the coast to 40-45 MPH with much higher gusts...this combined with the falling snow could make for near blizzard conditions at times with near zero visibility across southern new england.

4) watch the progression of the -8C H85 isotherm...dendrite growth rates are normally maximized at this temperature (as it usually fortells a deep layer thermal profile consistent with maximized crystal growth)

the rain long the NJ and DE coasts will change to snow with as much as 2-6 inches possible by the conclusion of the precipitation.

Snow/Liquid ratios will increase as colder air is brought down behinfd the coastal system. we should conclude the event with a 12 or 15:1 ratio across the major cities with as high as a 20:1 ratio in the higher elevations of the poconos...catskills and berkshires.

[Stormchaser16]

RNS, can you please go onto instant messanger for a little while? If not then what are you thinking regarding the second event for me here in hunterdon county.

[RNS]

Hunterdon county...over a foot.

[thstorm87]

RNS? Do you really see 9-15 for philly? maybe north and west but you really believe their could be 9-15 in the city proper?

[RNS]

I went with a very large spread due to the Uncertainty invloved...totals could range greatly from 9" in the south to as much as 15" across the immediate northwest burbs...thus my reasoning. remember also that a portion of that total has already fallen.

[iCez2003]

RNS it seems Philly might be dry slotted, what are your feelings towards this...

[jdt]

Snow to liquid ratio already close to 20 to 1 at my place in NW NJ. Last offical measurment was taken at 6PM with 2.9" of snow and 0.13" of liquid.

[RNS]

IF (and thats the key word here) PHL gets dry slotted,,, the precip would only slacken off for a little while before re-developing.

Precipitation continues to develop off to the SE...which would reduce the time in which PHL sees slackening of the precip.

very heavy snowfall is now beginning to develop across south central PA (per radar trends) this area will expand and intensify as it moves northeastward overnight.

[RNS]

Snow to liquid ratio already close to 20 to 1 at my place in NW NJ. Last offical measurment was taken at 6PM with 2.9" of snow and 0.13" of liquid.

for your location that would be the rule (and prehaps could increase depending on boundary layer temps)...in the major cities...where it is considerably warmer initially...it will be nowhere near as high IOW...10:1 or below then increases as sfc temps fall

[jdt]

Snow to liquid ratio already close to 20 to 1 at my place in NW NJ. Last offical measurment was taken at 6PM with 2.9" of snow and 0.13" of liquid.

for your location that would be the rule (and prehaps could increase depending on boundary layer temps)...in the major cities...where it is considerably warmer initially...it will be nowhere near as high IOW...10:1 or below then increases as sfc temps fall

Being a life long resident of the area I'm use to having a higher ratio, not always, but much of the time. The snow is a beautiful dry powder. Great for the local ski resorts in Vernon, NW NJ which are scheduled to open tomorrow!!. Along with the high ratios I would expect some orographic enhancement thru NW NJ, the Poconos and into the Catskills and further NE into the higher ground of Southern interior New England. The biggest key to who gets the jackpot(s) will be where the heavy banding features form and how long they remain over any particular area. Either way you slice it a lot of snow for a lot of people. 12"+ for just about everyone from Eastern and NE PA, Northern NJ including the NYC metro area, SE NY into Southern / Central New England. Highest totals in the NJ/NYC area probably 18-20" with up to 24" as a high number further NE.

[R0bb0871]

Hello RNS,

Here in Dover, New Jersey (Northwestern Morris County) we have close to 5 1/2" of the fluffy, white stuff. Any predictions for tomorrow?

[mdguy25]

RNS.. first off love your post why did u stop posting over at WWBB.. and to my question according to the most models precip should be filling in to Va at any moment but radars show no hint of it.. when will this take place if at all..

btw didnt catch your initial forecst but here in b-more we generally received 4 to 8 inches from first impulse not bad at all.. -tony

[RNS]

i dont think accumulations will exceed 24" in most places however in the favored oragraphic regions there is the potential for up to 2 feet.

[RNS]

Hello RNS,

Here in Dover, New Jersey (Northwestern Morris County) we have close to 5 1/2" of the fluffy, white stuff. Any predictions for tomorrow?

Nope...the ideas expressed above look pretty good for now. and i see no reason to deviate.

Morris county...14-22"

[Heady Guy]

RNS:

I have a question for you also:

I have seem many Lows develop on the coast. AKA noreaster's. Many times they go according to plan and sometime they don't. Some times these big storms have a few tricks in them as they develop. Farther from coast, further inland etc. Banding setting up in unpredicted locations. I know you can't predict any tricks, but do you feel this is all set in stone with track and strength.

Thanks.

[RNS]

NOTHING in meteorology is EVER set in stone...but confidence is as high as it can be for such and event IMO. I am comfortable with the ideas experessed above and the overall trend as the handoff of energy to the coastal system is now beginning to really get going.

[Stephanie]

Thank you RNS for your forecast!

Your totals are high - the highest I've seen so far, but then again, I have Mt. Holly as the office that does the forecasts. I'm really amazed how quickly this storm's totals have added up within the last 36 hours or so.

[RNS]

Thank you RNS for your forecast!

Your totals are high - the highest I've seen so far, but then again, I have Mt. Holly as the office that does the forecasts. I'm really amazed how quickly this storm's totals have added up within the last 36 hours or so.

thats one of the keys to this...the main event hasent even begun yet (in a sense) and we already have between 5 and 9 inches across the PHL forecast area.

[pawlee]

you kids are so lucky... my final measurement obs sent in to the NWSILX was 2.1. total liquid melt in the gauge was .41 with .11 being as rainfall before switching over early friday AM. as always though (seen below), nature provided a wonderful overnight photo op! hope those who are stuck in make the best of the weekend. sure knows how to time it... p

http://pawleewurx.blogspot.com/

[Stephanie]

Thank you RNS for your forecast!

Your totals are high - the highest I've seen so far, but then again, I have Mt. Holly as the office that does the forecasts. I'm really amazed how quickly this storm's totals have added up within the last 36 hours or so.

thats one of the keys to this...the main event hasent even begun yet (in a sense) and we already have between 5 and 9 inches across the PHL forecast area.

Yeah, so I'm thinking that what you are projecting is probably right on!