Unprecedented, Destructive October Snowstorm!

By: Zachary Labe , 6:27 PM GMT on October 28, 2011

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"Current Temperature"


"Current Dewpoint"


"Current Surface Map and Weekly History of Jet Stream Position"


"Regional Radar"


"Regional Satellite"


"Regional Advisories"


"12hr Estimated Precipitation"


"Forecast Max Temperatures"


"Forecast Min Temperature"


"Forecast Weather at 2pm"


"Current Storm Reports"


"Forecast Model Links"
-NAM model 12z...Link
-GFS model 12z...Link
-NMM model 12z...Link
-SREF model 9z...Link

This is a pretty quick intro on computer model forecasts along with beneficial links. Computer models use the complex calculus algorithms to print out the forecasts. Despite our complaning with the models, without them much of us would be lost except in the short time. Some of the earlier computer models consisted of the ETA, NGM, and AVN, which forecasted generally less than 84hrs. They were highly inaccurate, but provided a basis. The ETA was actually the computer model that helped meteorologists predicted the "storm of the century" in March of 1993 so well in advance. But now more than ever we have a myriad of computer models available to the general public with many mesoscale models only available to NOAA. Lets start with the general. All current computer models are based off on the Zulu time. Zulu time is also known as UTC or Greenwich time . Generally to forecast timing of storms my special BUFKIT data transitions UTC time to EST time, which is helpful. But BUFKIT is a special download, which I won't get into, but the transition is helpful as for some reason I never am able to understand time zones too well, hahaha. Anyways let me start with each computer model...

-GFS (Mentioned most of all as it is a global model (Global Forecasting System))
~Available in 0z (initiates at 10:30pm), 6z (initiates at 4:30am), 12z (10:30am), 18z (4:30pm)
~Forecasts out to 384hrs
~Typical biases
Cold bias on long range on 18z run
6z and 18z slightly unreliable
Northwest trend on lows within 84hrs of event

-ECMWF (This is another global model run by an international organization (European Centre for Medium-Range Weather Forecasts))
~Available in 0z (initiates at 1:30am), 12z (initiates at 1:30pm)
~Forecasts out to 240hrs
~Typical biases
Overphases lows in 168hr range
Holds too much energy in southwest
Known as extremely accurate within 140hrs

-NAM (Mesoscale short range model)
~Available in 0z (Initiates at 9:30pm), 6z (Initiates at 3:30am), 12z (initiates at 9:30am), 18z (Initiates at 3:30pm)
~Forecasts out to 84hrs
~Typical biases
Highly inaccurate towards the 84hrs
Handles coastal storms very well and southwest overrunning events
Tendency for way too much QPF

Those three above are the most common models for a beginner in computer models, but there are many more. All of the global models consistent of ensemble models also, such as the GFS has a myriad of ensemble (small models) that create a mean solution known as GEFS. They typically are too cold and southeast with low pressures, but some reason the NWS seems to enjoy using them. There are also more global models than the GFS and ECMWF... The UKMET is run by an internation organization and forecasts out to 144hrs. This model typically comes out an hr before the ECMWF and usually is pretty similar to the ECMWF. The ECMWF may also be known as the EURO by the way. There is also a Canadian model known as the GGEM/CMC, which again contains ensemble models. All of the internation models only run 0z and 12z runs. This is probably for the best as all models only receive new upper air data in 0z and 12z runs, so this is why the American model runs of the 6z and 18z are usually worthless. There is also a high resolution Canadian model known as the RGEM, which is very similar to the American NAM. High resolution (mesoscale models) are important as they usually are able to pick up on fine details such as frontogenesis, advection, adebiatic cooling, convection, etc. Some of this high resolution models include the WRF, HIRES NMM, RUC, ARW. They all are usually very accurate, but the WRF and HIRES NMM usually have wet bias.

As mentioned above there are ensemble models which come up with a mean solution instead of using one computer model's algorithms like the global models use. These ensemble mean solution are known as the MREF and SREF with MREF being in the medium range and SREF in the short range. SREF is usually pretty accurate and forecasts within 87hrs of an event. There are also other computer models used for hurricane forecasting, but I will not get into them. For instance one is the GFDL, which you may have heard of. I find I use mainly the GFS, NAM, and WRF/NMM in the summer, but use all of the models in the winter.

A few models to avoid...
JMA
KMA
CAMPASS
DGEX

Here is a list of links for explanations on how to interperate the models...

-PennState E Wall, which runs all of the models
http://www.meteo.psu.edu/~gadomski/ewall.html

-PennState E Wall tutorial on computer models (Check it out)
http://www.personal.psu.edu/adb241/eWallTutorial/ Main.htm

-Severe Weather parameters used on models, explanation
http://www.crh.noaa.gov/sgf/n=severe_weather_chec klist_paper

-Forecasting winter weather
http://www.crh.noaa.gov/lmk/soo/docu/precip_type. php

-NCEP; used to find American Computer models
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/

-Severe Weather Models
http://www.wxcaster.com//conus_0012_us_models.htm

-Winter Weather Models
http://www.wxcaster.com/conus_snowfall.htm

-Model Soundings
http://wxweb.meteostar.com/sample/sample.shtml?te xt=KMDT#

The last link is listed above as model soundings which takes all of the data to print out all sorts of information including precipitation type along with dynamics such as Omega. This is very complex and takes some time getting used to. Also you may see this data instead of in charts, it is sometimes used in SKEWT T charts.

I hope all of this information helped out... Keep in mind precipitation amounts is QPF, with 500mb aloft being the jet stream, 700mb aloft measuring relative humidity, 850mb aloft measuring 5,000ft aloft temperatures, 925-1000mb measuring surface temperatures. Generally I would look at the GFS and NAM first to get a hang of it along with reading the tutorial links. Use the 850mb and 2m charts for the GFS especially as they are pretty self explanatory and color coded. You will find some maps for international models are confusing and black and white.

Lower Susquehanna Valley Doppler...

(Courtesy of WGAL)

Follow my 24hr forecasts on Twitter... Link and Facebook... Link.

Please post storm reports in this blog from across the Northeast during the winter storm and please post location of observation in each report...

This blog is in progress. Check back soon...

Winter Forecast 2011-2012... Link

Historic October Nor'easter...
Higher cirrus will begin to flood the northern Middle Atlantic later in the day Friday after high temperatures in the mid 40s with partly cloudy skies. Clouds will begin to thicken and lower Friday night with precipitation moving northward as a 1000hPa coastal low pressure moves up the coast. The low pressure will follow an ideal track up and along the coast and if it were winter... this would be a major snowstorm for all of the Northeast including towards the coast. But given climatological means during late October, snow will only fall in certain locations well to the northwest. Precipitation will move northward as rain into Virginia and Maryland Friday night and move up into southern Pennsylvania also as rain. Evaporational cooling will begin as 2m temperatures fall to near dewpoint values late Friday night changing over to snow for southern Pennsylvania particularily for elevations above 800ft with a rain/snow mix in the valleys.

As the low begins to intensify further, a deformation axis will likely form well to the west of the center of circulation. The placement of this axis is key to the snow accumulation region as it will bring cold air down the surface in the form of dynamic cooling. Given the low track this axis is likely to form in eastern Pennsylvania up through central New England. Saturday will feature well below normal highs withs highs not reaching 40 as far south as Washington DC. Precipitation will intensify during the day. Ground temperatures initially in the 40s and marginal boundary layer temperatures will keep the highest accumulations in the higher elevations with several inches possible above 200ft (perhaps up to 12in as far south as South Mountain, Pennsylvania). Elsewhere valley locations can also expect some light snow accumulation as far south as northern Maryland. For the I-95 corridor, a mix of rain and snow is likely with no accumulation. Snow accumulations up through New England are likely 4-7in for the valleys and 8-14in for the higher elevations. I could even envision higher amounts given the strength of the deformation axis. Total QPF printout from guidance such as the ECMWF and GEFS suggest 1.0in-2.0in across the entire Northeast.

Most of the snow will fall during the day Saturday. If timing were a bit more favorable such as Saturday night, this would have been a potentially record breaking, rare October snow event.

Given the high leaf foliage in some areas, the combination of wet snow will cause major tree damage in some locations especially in eastern Pennsylvania. Power outages are possible. Snow ratios will be near 6/7:1 with rates up to 0.5in/hr at times. Given the heavier snow rates at times, even areas with boundary layer temperatures at 34-35F may see a quick accumulation.

I want to raise a few critical points...

1) Current ground temperatures really have little to do with snow accumulation when rates fall above 0.5in/hr. Snow can accumulate even on roads. The sun angle in late October is like mid February and has little impact. Combine this with marginal temperatures, cloud cover, and heavy snow rates this will cause snow to accumulate very easily after the initial lighter snow.

2) The biggest concern is the trees which I have been hyping for the last 24hrs. Snow accumulations possibly over 10in in some areas of south-central Pennsylvania up through New England could bring devastation to trees. The heaviness of the wet snow on foliage is a disaster. And looking a records, this has never happened before in many areas!

3) I-95 is a tough forecast and is dependent on exact low track. But given the dynamics of this storm which may cause even thundersnow, the big cities should all change to snow at some point.

4) Given the time of year, water temperatures are very warm and the temperature gradient and the natural baroclinicity along the coast will cause the storm to rapidly undergo bombogenesis with very unusual mesoscale features. This will cause some areas to see rapidly high QPF totals.

Selected City Accumulations for the Northeast...
Hagerstown, MD- Rain/snow then heavy snow. Accumulations 5-12in
Baltimore, MD- Rain changing to snow. Accumulations up to 4in especially the higher hills.
Salisbury, MD- Mostly rain with a trace of snow
Pittsburgh, PA- Rain/snow then snow. Accumulations 2-4in
State College PA- Moderate snow. 5-7in
Williamsport, PA- Heavy snow. Accumulations 5-10in
Altoona, PA- Moderate snow. Accumulations 5-7in
Harrisburg, PA- Heavy snow. Snow accumulations 6-14in
Lancaster, PA- Heavy snow. Snow accumulations 6-13in
Philadelphia, PA- Rain/snow changing to snow. Accumulations 1-3in+
Allentown, PA- Heavy snow. Snow accumulations 6-14in
Scranton, PA- Heavy snow. Snow accumulations 6-12in
Washington, DC- Rain changing to rain/snow. Spotty 1-3in accumulations are possible
Wilmington, DE- Rain changing to rain/snow. Spotty 1-4in accumulations are possible
Dover, DE- Rain changing to rain/snow with trace accumulations
Trenton, NJ- Rain/snow changing to snow. Accumulations 2-4in
New York City, NY- Rain/snow changing to snow. Accumulations 1-6in depending on location.
Poughkeepsie, NY- Heavy snow. Accumulations 5-10in
Binghamton, NY- Light snow. Accumulations 3-6in
Ithaca, NY- Light snow. Accumulations 2-4in
Albany, NY-Moderate snow. Accumulations 4-8in
Hartford, CT- Rain/snow changing to heavy snow. Accumulations 4-7in
Concord, NH- Heavy snow. Accumulations 5-10in
Providence, RI- Rain changing to rain/snow. Spotty 1-3in accumulations
Worcester, MA- Heavy snow. Snow accumulations 6-13in
Boston, MA- Rain/snow with spotty accumulations 1-3in
Nantucket, MA- Heavy rain and high winds up to 60mph
Hyannis, MA- Heavy rain and gale force winds in excess of 60mph
Portland, ME- Heavy snow. Accumulations 4-9in
Bangor, ME- Heavy snow. Accumulations 6-12in
"Subject to Change"

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Pcroton.....we already crushed previous October snow records here so the rest is gravy. We are playing with house money now!!!!!!!!
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Good points, Daniel, it'll be interesting to see how the system winds up. We got part one going on now... and then part 2 will be interesting in terms of where it sets up and how deep it gets.

Never know if the second one will hit full force or not - sometimes part 1 becomes so dominant it takes over..and once that's done the storm is done.

Will have to wait another four hours I would think to see if the second one takes over and you see it tilt negative with the banding.
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Was just told that trees are down all across Passaic Avenue which runs along the border of Essex and Morris County.
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Quoting TheRasberryPatch:


only 2.5"? really? i guess you are on the west side of the storm? I am close to 6" if not more.

A lot of trees are down around here or trees have split.

major roads have been treated here, but still have snow on them. secondary roads are terrible.


really getting dumped on now. prob close to 4"
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Radar definitely showing signs that storm is beginning its tilt....and snow line is advancing towards the coast. wet snow continues to fall on central nassau county/long island....tho ground continues to be just slightly off white. snow has started to fall sideways now, as winds are definitely beginning to pick up.

I apologize on behalf of the meteorological community for the dry slot....would love to fix it for ya'll...but on the positive side, the back end of the snow has stopped advancing northward and is stuck right over northern virginia/DC area.....watch for the wrap around snow to pull its way closer to the coast.

The intellicast radar has definitely shown more blue the last hour, and noticeable heavy banded structures starting to set up....some ppl are reporting very heavy snow now and that will continue for hours in spots...making it possible that some people will see well over a foot of snow from this. please be careful in those areas as branches easily could take down power lines....
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Just had 3 good power flickers. Lost it for 1 minute with the last one. Too much foliage on the trees and the stuff is sticking good. Hearing the occasional cracking limb in the woods coming down.
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324. bwi
Oh crud, I forgot to get my plants inside, and now it's snowing on them. Gonna freeze tonight. Back later.
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Warnings now through Queens, NY for up to 10 inches of snow. This is pretty amazing. Our totals here in Roseland NJ are up to 8 to 12. We have about 4 now. Trees are looking quite stressed. The dry slot is moving north but I'd imagine it will begin to get close just as the pivoting of the Low causes the direction of the precip to move more from Northwest to Southeast. Should be interesting to see if this thing slows down by 5 or 6 pm or if it keeps cranking into the overnight period. Thoughts?
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322. bwi
First flakes just NE of DC. Coming down pretty good, but not sticking yet. Temp has fallen from 39 to 36 in an hour.
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Quoting Mason803:
6" at 1200ft just to the west of cashtown. here in cashtown we have received 2.5" so far. Just got back from running 5 fire calls including wires and trees down and 2 vehicle accidents


only 2.5"? really? i guess you are on the west side of the storm? I am close to 6" if not more.

A lot of trees are down around here or trees have split.

major roads have been treated here, but still have snow on them. secondary roads are terrible.
Member Since: January 26, 2007 Posts: 72 Comments: 6256
Already having some decent sized branches snapping and falling. Heavy wet sticky snow and a lot of leaves are left on the trees. They can't handle it. Will probably lose power.

You can see everything bending.





Falling at 2" per hour right now. Approaching 4".
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6" at 1200ft just to the west of cashtown. here in cashtown we have received 2.5" so far. Just got back from running 5 fire calls including wires and trees down and 2 vehicle accidents
Member Since: November 5, 2008 Posts: 0 Comments: 1139
This...............sucks.........



nada.


nuttin.


nil.
Member Since: May 16, 2009 Posts: 0 Comments: 213
Quoting TheRasberryPatch:
do I see a dryslot around Lancaster?

I'm in it right now. Looks large, too. Yuck.
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Getting some snow here in Fairfax county VA, west of DC. Not sticking at this point -- temps around 40F.
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Member Since: January 31, 2007 Posts: 9 Comments: 2250
I feel like I'm missing out in this storm yet Mt Holly has upgraded my area on their snow map from 1" to 2-4"
Member Since: August 28, 2008 Posts: 79 Comments: 3578
PPL is currently reporting around 150,000 without power in their service area and rapidly rising. The Allentown area seems to be particularly hard hit with 52,000 people without power in Lehigh county.
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Quoting TheRasberryPatch:
I heard Palmyra (the town, not the mean old man) has lost power


mean old man? i'm far from old, although i feel it sometimes. i actually wish wunderground would allow me to change my sn as I haven't even set foot in Palmyra since April. doesn't surprise me that they've lost power.
Member Since: January 31, 2007 Posts: 9 Comments: 2250
Quoting danielb1023:
Question for you all.....are the local authorities prepared for something like this? Will they be treating or plowing the roadways? Or is this an old fashioned free for all?


My street was just plowed.
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Thundersnow being reported now in NYC...lightning data confirms.
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Question for you all.....are the local authorities prepared for something like this? Will they be treating or plowing the roadways? Or is this an old fashioned free for all?
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do I see a dryslot around Lancaster?
Member Since: January 26, 2007 Posts: 72 Comments: 6256
Quoting PalmyraPunishment:
HOLY THUNDERSNOW!


Nice!
Member Since: October 14, 2006 Posts: 1 Comments: 639
no thunder here....thankfully but the electricy has gone off for 2 secs at least 10 times. I heard Palmyra (the town, not the mean old man) has lost power
Member Since: January 26, 2007 Posts: 72 Comments: 6256
Quoting wxgeek723:


Same here, major battlefield between rain and snow, sleet getting into everything.

Rain mixed back in with sleet and snow... Still, trees are covered, road is starting to turn white. 34F. NWS raised us to 3 - 6 inches. That would be too cool!

It's good to see everyone here. I was on the blog a little during the warm months, and it really does get quiet.
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Quoting PalmyraPunishment:
Just had another very loud crack of thunder.

This is just crazy...it's been thundering for over a half hour now in the Harrisburg area. I'm on the southeast side of an extremely heavy band of snow looking at the State College radar.
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Quoting BullShoalsAR:

You think it's time to get the heated blankets out of the closets and make one last trip to the market for some coffee, Kahola, Dark cream de menthe, and Bailey's irish cream. Rather veg in good company than with the bad company, ya know.
Already well stocked-up on various types of antifreeze...so far, so good.
Member Since: December 25, 2002 Posts: 0 Comments: 88
Quoting Gaara:


Looking forward to your end-of-storm update. Still planning on making it to Warwick tomorrow.

Just about an inch of wet snow (giant flakes) here in Milford--about two miles from the coast. Coming down quite hard.


Will be sure to update! I am hopeful the roads will be cleared pretty quickly so everyone can be up and about without danger tomorrow.
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umm.. it stopped raining. nothing is currently falling from the sky. I almost want to kick something. lol
Member Since: May 16, 2009 Posts: 0 Comments: 213
heavy snow...trees look bad.

approx. 5" on the ground with snow covering everything. roads are covered with a few inches

temp 32.7F dewpt 31.9F
Campbelltown, PA just east of Hershey
Member Since: January 26, 2007 Posts: 72 Comments: 6256
292. bwi
LWX snow map continues to move west.

However, winds in DC are becoming more NW than NE, and temps down a degree or two in the last hour. Now it's just all about whether the precip gets all the way back around the coastal storm or if we just go dry now that it's finally getting cold enough to hope for snow!
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Sleeting here in springfield , MA just started about 10 mins ago. Where's the snow?!
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Just had another very loud crack of thunder.
Member Since: January 31, 2007 Posts: 9 Comments: 2250
rain....rain....more rain....yep, still rain... a few teaser giant snow flakes, some ice, and...........more rain...


blah.
Member Since: May 16, 2009 Posts: 0 Comments: 213
Had several short power outages in the last 30 minutes. Just a few seconds each, but enough to reset all the clocks, and kick all the computers off line. Going to be a long day, I'm afraid.

(Location: Harrisburg, PA)
Member Since: December 25, 2002 Posts: 0 Comments: 88
283. Gaara
Quoting LettyS:
Snow now pretty close to moderate here in Warwick, NY. Roads still just wet, trees and lawns quickly becoming snow-covered.


Looking forward to your end-of-storm update. Still planning on making it to Warwick tomorrow.

Just about an inch of wet snow (giant flakes) here in Milford--about two miles from the coast. Coming down quite hard.
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Quoting weathergeek5:


I have rain too *sigh*


Back to reality on the coastal plain, I guess...
Member Since: August 28, 2008 Posts: 79 Comments: 3578
Around 11:46
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Quoting wxgeek723:
I feel like I'm the only one reporting rain as dominant precipiation :/
Quoting weathergeek5:


I have rain too *sigh*

So the name isn't the only thing you two share ;)
Member Since: January 20, 2009 Posts: 0 Comments: 1503

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Cornell University- Atmospheric Sciences Undergrad; Research Assist.- Onset of Spring Indices Toolbox; Interests- Small spatial scale climatolology

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