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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Quoting Blizzard92:
Look at this monster!

Simulated radar later today...



i hope that verifies!! snow has slacked here

temp holding steady at 32f
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Look at this monster!

Simulated radar later today...
Member Since: December 14, 2007 Posts: 281 Comments: 15083
Good morning all - Blizz it's snowing with some rain mixed in here in Westminster MD. Cars & lawn have a coating but no real accumulation. I thought it was to change over sooner than this. Should we still expect heavy accumulation here? Lot's of big old trees around my home.
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Quoting TheRasberryPatch:


Thanks Mason...I have had the funnel and inner cylinder off since the day before because of call for freezing temps. What would you do if you weren't around the house? For future reference

Still rain here with temp of 36.0F and dewpt of 34.7F
Campbelltown, PA just east of Hershey



every event is a little different but for this one if i were away from the house id pull my funnels out and worry more about collecting snow qpf. snow is the more dominant precip type and you really wouldn't lose too much of the initial rain due to calm winds.
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Out of Greensburg, PA - moderate snow now falling, starting to accumulate on pavement(roads and sidewalks)
Member Since: August 23, 2008 Posts: 0 Comments: 140
Quoting Blizzard92:
Mason803- Report of 2.5in of snow coming from the Big Flat down your way. Think there is any truth to that?



probally i'm at 700ft and i'm closing in on 1" of snow. big flat is 2000ft
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Reports of snow back home for me just outside of Linglestown right now with snow ontop of Blue Mountain since about 8am.
Member Since: December 14, 2007 Posts: 281 Comments: 15083
Raining steadily in Lower Allen and wind has picked up. I swear I saw a few flakes mixing in occasionally but nothing heavy yet. Pressure has dropped steadily (my knee is feelin it for sure) but it looks like they've dropped our expected totals to 2-4in now :(
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Temps now down to 39 degrees. Still raining
Member Since: December 25, 2005 Posts: 0 Comments: 1744
Quoting Blizzard92:

Because they downplay everything. In a storm such as this, it seems irresponsible to deviate greatly from the NWS forecast. Everything is still going right according to plan for the forecast. Keep me updated from Fishing Creek!


"They" drive me nuts! LOL!!! I'll keep you posted!!!
Member Since: January 29, 2011 Posts: 0 Comments: 53
Quoting Mason803:


if you plan to be around the house today what i'd do is keep the funnel on as long as possible to catch the rain then once the precip switches to snow pull the funnel and cylinder out to catch the snow in the outside shell. (measure that amount and write in down somewhere) tomorrow morning melt down snow in outer shell and add the number you wrote down in the cylinder before the turnover to snow equiv number and that would be your 24 hr qpf total. hope that helps


Thanks Mason...I have had the funnel and inner cylinder off since the day before because of call for freezing temps. What would you do if you weren't around the house? For future reference

Still rain here with temp of 36.0F and dewpt of 34.7F
Campbelltown, PA just east of Hershey
Member Since: January 26, 2007 Posts: 72 Comments: 6247
Started seeing a few flakes mixed in with the rain about 20 minutes ago. Still mostly rain, though. Waiting for the changeover to see if I want to travel to Lancaster this morning.
Member Since: December 25, 2002 Posts: 0 Comments: 88
Mason803- Report of 2.5in of snow coming from the Big Flat down your way. Think there is any truth to that?
Member Since: December 14, 2007 Posts: 281 Comments: 15083
Quoting LivelySnow:


How come locals are only now saying 2-"maybe" 6? Something change overnight??? Snow mixing in with rain at the moment here in fishing creek valley.

Because they downplay everything. In a storm such as this, it seems irresponsible to deviate greatly from the NWS forecast. Everything is still going right according to plan for the forecast. Keep me updated from Fishing Creek!
Member Since: December 14, 2007 Posts: 281 Comments: 15083
Quoting TheRasberryPatch:
Mason - a question for you...i am getting rain right now in my large cylinder....I already turned in my 730 reading for the amount of rain....when the precip turns over to snow how do you get an accurate reading for the amount of water content of the snow when it finally stops? I guess this can occur even if it was all snow and the first bit of snow melted in the cylinder?


if you plan to be around the house today what i'd do is keep the funnel on as long as possible to catch the rain then once the precip switches to snow pull the funnel and cylinder out to catch the snow in the outside shell. (measure that amount and write in down somewhere) tomorrow morning melt down snow in outer shell and add the number you wrote down in the cylinder before the turnover to snow equiv number and that would be your 24 hr qpf total. hope that helps
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Quoting Blizzard92:
Good morning! Everything is going according to schedule. Changeover within the next hour for LSV although many areas are already snow. Once I changes to snow it will fall heavy and accumulate shortly.


How come locals are only now saying 2-"maybe" 6? Something change overnight??? Snow mixing in with rain at the moment here in fishing creek valley.
Oh...and "Good Morning" Blizz!!!!! :)
Member Since: January 29, 2011 Posts: 0 Comments: 53
I was upgraded to winter storm warning from an advisory! 6 to 10 inches for western essex cnty weat of the gsp! wow.....i still have doubts
butcant wait
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Mason - a question for you...i am getting rain right now in my large cylinder....I already turned in my 730 reading for the amount of rain....when the precip turns over to snow how do you get an accurate reading for the amount of water content of the snow when it finally stops? I guess this can occur even if it was all snow and the first bit of snow melted in the cylinder?
Member Since: January 26, 2007 Posts: 72 Comments: 6247
No lake effect snow really after this storm due to high shear, dry air aloft, and high pressure moving in.


This radar gives a pretty near accurate representation of rain areas versus snow...
Member Since: December 14, 2007 Posts: 281 Comments: 15083
solid covering here. 0.2" of snow @ 7am


myersdale 7am had 4" (highest report i saw)



cashtown pa

Member Since: November 5, 2008 Posts: 0 Comments: 1139
Quoting pittsburghnurse:


Yeah, what'dya think? Hey Weatherman, how's Greensburg this morning?


LoL, I wasn't sure because they didn't say anything about it on local weather/weather channel. it could boost are totals here then. Greensburg is a slushy coating on grass/wood surfaces, still light snow.. I see Pitt is about the same thing
Member Since: August 23, 2008 Posts: 0 Comments: 140
Quoting weatherman321:
hey Blizz, any chance of lake effect snow occurring in western-southwestern PA due to the wind shift soon to becoming from the north, those lakes should still be pretty warm, could boost snow totals in and around that area??


Yeah, what'dya think? Hey Weatherman, how's Greensburg this morning?
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hey Blizz, any chance of lake effect snow occurring in western-southwestern PA due to the wind shift soon to becoming from the north, those lakes should still be pretty warm, could boost snow totals in and around that area??
Member Since: August 23, 2008 Posts: 0 Comments: 140
A warm 41 degrees here and raining. (Media, PA; 2o miles west of south Philly) I've seen widely varying forecasts for us - from rain with a few flurries to 1 - 3 inches of accumulating snow. Time will tell. I'm hoping for some solid nighttime snow as I'll be at an outdoor party! :)
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so far light to moderate rain and temp of 36.6F
Campbelltown, PA just east of Hershey

looking at the radar it appears the precipitation is starting to wrap around and the snow will be in the area soon with colder temps
Member Since: January 26, 2007 Posts: 72 Comments: 6247
Good morning! Everything is going according to schedule. Changeover within the next hour for LSV although many areas are already snow. Once I changes to snow it will fall heavy and accumulate shortly.
Member Since: December 14, 2007 Posts: 281 Comments: 15083
Will be ordering my snow tires TODAY without fail.
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Temps dropped 2 degrees since I woke up here in Wilmington DE. Was 43 now down to 41. Have to go to Wawa to get my breakfast hoagie but I am not feeling inspired to go out in the cold rain.
Member Since: December 25, 2005 Posts: 0 Comments: 1744
Good morning from Pitt. Snow currently fallng, 32.4F. Wet snow currently falling. A slushy light accumulation on non road surfaces with trees and powerlines flocked. Expecting about an inch today. My first October snow of more than just a few flakes. Looks like my December 3 prediction just got the boot.
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snow here, coating on grassy surfaces (Westmorland County, PA)
Member Since: August 23, 2008 Posts: 0 Comments: 140
Good Morning from SO MD....Pouring and 42 degrees.....just ugly down here.....
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Quoting HeavySnow:


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! ;-)
Member Since: December 25, 2002 Posts: 0 Comments: 88
Quoting Snargle:
Just light rain here in Swatara Twp. (east of Harrisburg). I thought for sure something would be happening by now. It's leaving me in a quandary...supposed to attend an event in Lancaster at 10:30 a.m. If just rain this morning, then it's OK, but heavy snow will keep me off the roads.


Yes, yes, I will keep you off the roads. Stay off the roads Snargle, it won't be safe for you.
Member Since: July 7, 2004 Posts: 18 Comments: 2989
Quoting TheRasberryPatch:


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


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.
Member Since: September 3, 2008 Posts: 0 Comments: 444
Just light rain here in Swatara Twp. (east of Harrisburg). I thought for sure something would be happening by now. It's leaving me in a quandary...supposed to attend an event in Lancaster at 10:30 a.m. If just rain this morning, then it's OK, but heavy snow will keep me off the roads.
Member Since: December 25, 2002 Posts: 0 Comments: 88
moderate rain here. frozen precip seems to be on my doorstep.
Member Since: July 7, 2004 Posts: 18 Comments: 2989
Still a light mist and 38 here. Wasn't it supposed to have changed/cooled down by now?
Member Since: January 31, 2007 Posts: 9 Comments: 2250
Quoting Mason803:
33f and all snow here in cashtown (western adams county)


Sweet!!!
Member Since: July 7, 2004 Posts: 18 Comments: 2989
33f and all snow here in cashtown (western adams county)
Member Since: November 5, 2008 Posts: 0 Comments: 1139
Good morning everyone it's just like rain here in Hershey. To bad I have to work in Mt Joy today. I'll miss all the heavy snow.
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just light rain at the airport.
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We had about half an hour of rain/snow mist and since then, nothing. Still 40 degrees.
Member Since: January 31, 2007 Posts: 9 Comments: 2250
I'm up...can't quite tell what it's doing outside. But it isn't crazy yet.
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Steady rain now in West Chester, PA.
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Snow beginning to mix in with rain here in Camp Hill. 41.0 F
Member Since: January 31, 2007 Posts: 9 Comments: 2250
I'm getting some very light rain here now with a temperature of around 40F.
Member Since: August 5, 2010 Posts: 0 Comments: 588
Quoting PalmyraPunishment:


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. :)
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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.
Member Since: January 31, 2007 Posts: 9 Comments: 2250
Freezing rain over western North Carolina. Boone is down to 32. Upper 20s in the highest spots.

Snow and sleet appears to be isolated to the most extreme spots down here for now.
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Light snow on ground in Bridgewater, Va. West Central Shenandoah Valley. Lightly falling not sticking to streets or sidewalks. Air temp 33.5 F/0.8 C.
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steady cold rain here in westmorland county, PA, temps are now down to 36 degrees
UPDATE : rain is now beginning to mix with some light sleet/snow .. temp at 35 degrees
Member Since: August 23, 2008 Posts: 0 Comments: 140

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About Blizzard92

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

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Personal Weather Stations

Linglestown, PA
Elevation: 520 ft
Temperature: 24.2 °F
Dew Point: 15.2 °F
Humidity: 68%
Wind: Calm
Wind Gust: 9.0 mph
Updated: 10:37 AM EST on January 18, 2014

About Personal Weather Stations