Unprecedented, Destructive October Snowstorm!
"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"
Reader Comments
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Tequila shots in the igloo bar?
Day After Tomorrow viewing together at the Ice Hotel in Sweden while complimenting each other's blinding awesomeness?
I come in peace.
I think I hate LA Nina!LOL
We did get 1"+ last night tho and it's still on the trees and the ground.
I've heard, "duh", "like that is so, um, like cool", "give me another cigarette", "purge time". They're saying just about the same things as the old models. Wait, what, not that kind of...
Checking in here from Bucks County PA! It's nice to see some familiar names posting, and I'm glad that Blizz has been able to make time to check in with his old friends!
I am amazed and a little skeptical. Snow accumulating during the day in the city. In October. But I hope the forecast verifies. I like snow :)
Where in Baltimore are you? I grew up in Towson.
Stan - you had a cold day I guess with all of the snow still visible
No changes really since early this afternoon. I think solutions and forecasts are beginning to hone in and settle down. A heavy swath of 6" - 14" seems highly likely northwest of the I-95 corridor.
Wanna add New Brunswick, NJ
or Cheesequake / Matawan , NJ
to the expected list?
:)
Looking forward to some snow... but fear for my 100 year old oaks... they are still laden with leaves that only started to change color this week.
One thing i have noticed... not many acorns. I was once able to predict a good winter by the amount of acorns. They are almost non-existent this year (yet, it is early for them to drop. Usually, in Nov. i need a hard hat to rake). Don't know if it's a fluke from Irene.
I sent her a Tex message this afternoon to let her know she has a snow storm coming..
she text me back.. Mom we had snow this morning and expecting more this weekend!!!
and they are not happy about already getting snow and it is still October...
So now I will continue to check in at your blog since my daughter and her husband and my grandson ,now live in Eastern Mass!
New Brunswick is probably looking at around 1-4in of snow starting mainly as rain.
Hi! That sure is odd. I have not heard anything nor am I familiar with any naming technique. Huh.
Federal Hill.
That blog is not official. I googled the "DCWS WINTER STORM CENTER" and found it is the abbreviated name of the Dublin Coffman Weather Service. It seems to be a site for a high school weather club.
Three months ago their account on wikipedia was deleted for spamming.
1. Looks like the remains of Rina are linking up with our system. Is that going to really get the moisture pumping, or more the fact that our system is going to move out over the relatively warm N. Atlantic, or are the two items going to produce a "perfect storm" scenario?
2. Speaking of Rina, why aren't the models tracking it anymore? They all still have it as stalling off Cancun.
3. Water vapor loops for our storm don't show much of anything, which is counter-intuitive. Is this again a result of the system not yet being out over the Atlantic? If so, then why is there so much precip on the radar already (Northern VA). Can't all be orographic lift can it?
Sorry for all the questions; I'm trying to learn as much as I can about these things, and my Intro to Meteorology class just isn't cutting it (great class, just a little too basic for these types of questions). If I have time next semester, I'm def signing up for the advanced class. TIA and Cheers~
12-15 inches for SE PA? Is this for real??? Oops, I edited out the scale. The innermost pink before the red is 12-15 inches. Link provided for details:
NAM Storm Total
I don't buy the NAM. Just seems too cold in its thermal profile.
I just don't think we'll see accumulating snow in the city. Temps have to fall a long way before we do.
Was that storm complex over Florida forecasted? It seems like it may steal moisture before it reaches here.
We need heavy precip to cool the air column down too.
I think interior PA, NW Jersey, and 30 miles NW of NYC will see good snow. Worcester in MA. But I'm just not sold on accumulating snows in the big cities.
Anyone.....Anyone..............Bueller.....??
I'm thinking the other way, that the moisture feed is being rained out over Florida.
To get a record breaking early snow in the big cities all the conditions have to be perfect. Or nearly so. I'm not seeing perfection here.
And it's too bad cause I want some snow!
I dont know. I just want SNOW. lol
UPDATE : rain is now beginning to mix with some light sleet/snow .. temp at 35 degrees
Snow and sleet appears to be isolated to the most extreme spots down here for now.
EARLY-SEASON HEAVY SNOW...WITH RATES OF 1 TO LOCALLY 2 IN/HR...WILL DEVELOP AND SPREAD NNEWD AFTER 09Z...AND CONTINUE THROUGH SATURDAY MORNING.
SNOWFALL RATES OF 1 IN/HR WILL BE LIKELY THROUGHOUT THE DISCUSSION AREA. HOWEVER...THE MOST FAVORABLE JUXTAPOSITION OF THE AFOREMENTIONED FORCING MECHANISMS COULD SUPPORT LOCALLY HIGHER RATES /POSSIBLY UP TO 2 INCHES PER HOUR/ WITHIN 35 MILES EITHER SIDE OF A LINE FROM STAUNTON VA TO HAGERSTOWN MD TO HARRISBURG PA. ALSO IN THIS AREA...NAM/GFS CROSS SECTIONS OF THETA-E AND GEOSTROPHIC MOMENTUM SUGGEST CONDITIONAL SYMMETRIC INSTABILITY DEVELOPING IN THE MID LEVELS TOWARD 12Z...COINCIDENT WITH SLANTWISE CAPE INCREASING TO 150-200 J/KG PER EXPERIMENTAL NAM OUTPUT. THIS WILL FAVOR WSW-ENE-ORIENTED HEAVY SNOW BANDS...AND AN ISOLATED LIGHTNING STRIKE OR TWO CANNOT BE RULED OUT. THE HEAVY SNOW WILL LIKELY CONTINUE THROUGH SATURDAY MORNING...WITH RATES TAPERING OFF FROM SSW TO NNE AFTER 18Z. FOR LOCATIONS FARTHER EAST /INCLUDING AREAS FROM BALTIMORE TO THE DISTRICT OF COLUMBIA/...FORECAST SOUNDINGS SUGGEST THAT WARMER THERMODYNAMIC PROFILES WILL BE LESS CONDUCIVE FOR HEAVY SNOW.
OMG, talk nerdy to me. I actually understood most of that. :)
Sweet!!!
Kinda. This time of year it stays "cold" here. The low was 25F. The high was about 40, But then it was only that high for a few hours.
Blizzard,
31F, slight breeze out of the east, very humid with a bit of fog.
Yes, yes, I will keep you off the roads. Stay off the roads Snargle, it won't be safe for you.
You're a mean one, Mr. Snow! ;-)
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