Potential Major Storm for Eastern US for January 26-27...
Current wavelengths are supporting a large synoptic storm east of the Mississippi River Valley during the January 26th to the 27th with widespread moisture from the Southeaast to New England. This setup is corresponded with highly favorable teleconnections. The NAO (North Atlantic Oscillation) remains negative but has shifted the higher heights more east-based. This causes less blocking upstream. Blocking is typically associated with suppression and tracks of coastal lows well over 100mi off the coast. Also blocking allows for a slower movement of low pressures ushering in cold air to the right of the low in the large cold sector of the storm. When the blocking is allowed to relaxed or becomes displaced as in this instance, it allows cyclogenesis to often occur a bit farther to the west offering warmer air with a southeasterly flow off the Atlantic. This upcoming coastal threat will favor the later with dampened upstream blocking. Also the MJO (Madden-Jullian Oscillation) is entering phases 7-8. The MJO is a measure of the positioning of the monsoonal rains across the Indian Oceans. Since all global weather patterns are interconnected, differing wavelengths of pressure in the Indian Ocean will in time affect areas downstream in the jet stream across North America. Here is the current composite 500mb mean charts for an MJO phase 7 during January from a meteorological study by Allan Huffman...
Link
As noted above, increasing ridging across the western United States with a deep trough over the east coast often occurs. This corresponds to the current teleconnective pattern over North America with a positive PNA (Pacific/North American Pattern) which favors high pressure over the western United States coupled with upper level ridging.
The teleconnections are certainly signaling the classic jet stream setup for eastern cyclonegesis. But several 'issues' will likely prevent a major east coast snowstorm for areas in the major metropolitan region of the United States. Paul Kocin and Louis Uccellini's monograph of Northeast snowstorms signals the classic setup for widespread historical snowfalls to be accompanied by an arctic high pressure to the north of the storm. Typically we would root for a large anticyclone to the north or north-northeast of New England across southern Canada. This helps usher in cold air funneling in the western periphery of the low pressure. Also this helps prevent the low pressure from running too far inland.
The current synoptic setup shows the high pressure to the north of the low quickly scooting to the northeast and eventually too far east to save many from the expected rainfall. The 1/21/11 12utc ECMWF shows the banana high displaced to the east in an unfavorable location.
Kocin/Uccellini's near miss historic east coast snowstorm often featured a high pressure in a similar displaced location. Typically this would then favor inland snows with a mix or rain across eastern areas. While a severe arctic air mass will be in place along with a fresh snow pack over the Northeast, oftern these air masses can disperse quicker than one would assume. Current GGEM/UKMET/ECMWF guidance supports the upper level trough becoming negatively tilted towards the easteern Mississippi Valley. With these higher amplitude trough, the banana high is quick to depart and allows the cyclogenesis to occur farther along the coast. The 1/21/11 12utc GFS shows this evolution a tad differently, but does appear to be an eastern outlier. The 12utc GEFS mean shows a farther west solution, which often argues that the operational model is too far east. Most of my analogs support the heaviest snows well northwest of I-95 as warmer invades from the east. Despite several global models showing the low becoming vertically stacked allowing H85s to crash, there will likely be a southeast maritime flow across eastern areas.
The track of the H5 low tracks across Virginia, which is a bit too far north for a favorable snowstorm for most areas south of Washington DC for certain. Given the departing arctic air mass I would expect areas that receive mainly rainfall still to receive snow accumulations on the front end of the storm. The ECMWF mentioned earlier supports a quick 4-8in along most of I-95 before rainfall.
At this point, those farther east will be hoping to look for the 500mb low to track farther south, the banana high to become more situated north and not northeast, and the exact placement of the negatively titled trough.
While the threat is several days away, current climatology and guidance supports a very high threat of a large storm system over the eastern United States in this time frame. Whether it is rain or snow, there appears to be a large amount of moisture involved with ECMWF QPF up to 4in in northern Delaware and southeastern Pennsylvania. I know many are critical of predictions of storms well in advance, but meteorology is about understanding the synoptic setup that leads to the development of these storms. Watching the evolution of this situation will be very interesting and I am becoming increasingly enthused for those well inland. Even along the coast heavy rain and high winds are possible with a western storm track so threats will be high with any storm scenario. Stay tuned for updates throughout the weekend. For now if I had to make a forecast, this would be the precipitation scenario map.
The exact placements of the trough/shortwaves/high pressures will change, but I have not seen such consistency in the computer models for a large event in a very long time. This is also backed up by a favorable wavelength pattern as mentioned earlier in the blog. I think there is a higher possibility of this tracking farther west and inland than it tracking east. The odds of all snow along I-95 to the coast remain low given the departing high pressure. Another concern is the poor modeling this winter and the trend for storms to phase later than expected. Something to keep reminded of... Stay tuned!
Short Computer Model Introduction
This is a pretty decent 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.
"Here northeast of Harrisburg 2010-2011 winter statistics"
(Snow Stats)
Current Snow Cover- 1-4in
Monthly Total (November)- Trace
Monthly Total (December)- 0.6in
Monthly Total (January)- 11.65in
Seasonal Total- 12.25in
Winter Weather Advisories- 5
Winter Storm Warnings- 0
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 1
Winter Storm Watches- 1
(Temperature Stats)
Lowest High Temperature- 23.7F
Lowest Low Temperature- -1.7F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
First accumulating snow - December 10 - 0.50in
Clipper light snow - January 7-8 - 2.25in then another 1in
Double Barrel Low - January 11 - 4.5in of snow
Coastal Low - January 17-17 - 1.8in of snow/sleet
Arctic Front - January 20-21 - 2.1in of snow
Lower Susquehanna Valley Doppler...
(Courtesy of WGAL)
This is the most difficult forecast I have ever had to make for the region. The gradient is going to be very sharp across the north and will make for a very high bust potential. This map is a bit bullish for northern areas. We shall see. Enjoy!
"Here northeast of Harrisburg 2010-2011 winter statistics"
(Snow Stats)
Current Snow Cover- 4-8in
Monthly Total (November)- Trace
Monthly Total (December)- 0.6in
Monthly Total (January)- 18.15in
Seasonal Total- 18.75in
Winter Weather Advisories- 6
Winter Storm Warnings- 1
Ice Storm Warnings- 0
Blizzard Warnings- 0
Freezing Rain Advisories- 1
Winter Storm Watches- 1
(Temperature Stats)
Lowest High Temperature- 23.7F
Lowest Low Temperature- -1.7F
Wind Chill Advisories- 0
Wind Chill Warnings- 0
(Snow Storms Stats)
First accumulating snow - December 10 - 0.50in of snow
Clipper light snow - January 7-8 - 2.25in then another 1in of snow
Double Barrel Low - January 11 - 4.5in of snow
Coastal Low - January 17-17 - 1.8in of snow/sleet
Arctic Front - January 20-21 - 2.1in of snow
Upper level/coastal low - January 26 - 5.75in of snow
Reader Comments
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Hahaha. Forrest with a twist...
Meanwhile, down the street, Joe Calhoun at WGAL issued a 9:00 AM update admitting that he didn't see this morning's snow coming, and that it should be clearing before picking back up around 2:00 PM
2:00 PM - 6:00 PM: 1-3 inches
6:00 PM - 1:00 AM - 3-6 inches
He then follows it up by showing the northern part of the LSV (Cumberland, Dauphin, Lebanon counties) at 1-4 inches, with 4-8 to the south.
What a dope.
seems just as reasonable as anything else i've heard
ummmm hellooooo!!!!!!!!!!!!!!!!!1
That's what the buzz is. Watch out for round 2.
Thats the band that went through Newark,DE a little bit ago. HUGE snowflakes at a rate of atleast 1" per hr. lasted 30-40 min.
I just measured as well - 4" on the dot and still fluctuating between light and moderate snow.
After that heavy stuff in Jersey moves through (assuming it makes it here) we could already have a half a foot up here before round 2 is even close to beginning.
What? Where are you? This thing has barely even begun and I'm at 4" Definitely not a bust.
Looks like another tough week for Bloomberg! 3 inches and counting in Manhattan and the streets are snow and slush covered. Need plows, but I haven't seen a one!
Yep, waaaaay too early to be using that word.
Here in central Jersey, we just scraped about 3 inches of snow off the car.
Really light snow and mix now falling... not as strong as the last two hours, but still coming down from the north-east.
Thanks to every one on the blog for making this the most entertaining and educational Weather Discussions Blogs out there.
URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1021 AM EST WED JAN 26 2011
...SIGNIFICANT SNOW EXPECTED LATER TODAY AND TONIGHT...
NJZ013-014-020>022-026-027-262330-
/O.CON.KPHI.WS.W.0004.000000T0000Z-110127T0900Z/
WESTERN MONMOUTH-EASTERN MONMOUTH-OCEAN-CUMBERLAND-ATLANTIC-
COASTAL OCEAN-SOUTHEASTERN BURLINGTON-
INCLUDING THE CITIES OF...FREEHOLD...SANDY HOOK...JACKSON...
MILLVILLE...HAMMONTON...LONG BEACH ISLAND...WHARTON STATE FOREST
1021 AM EST WED JAN 26 2011
...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 4 AM EST
THURSDAY...
A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 4 AM EST THURSDAY.
* PRECIPITATION TYPE: MIXED SNOW...SLEET AND RAIN ARE EXPECTED
DURING THE DAY TODAY. THE RAIN WILL CHANGE TO SNOW THIS
EVENING AND BECOME HEAVY TIMES.
* ACCUMULATIONS: 8 TO 12 INCHES OF SNOW.
* TIMING: SNOW AND RAIN ARE EXPECTED FOR THE REMAINDER OF THE
DAYLIGHT HOURS. THE MIXED PRECIPITATION WILL CHANGE TO SNOW THIS
EVENING...AND MAY BE HEAVY AT TIMES. THE SNOW IS EXPECTED TO END
BEFORE DAYBREAK THURSDAY.
* IMPACTS: SNOW MAY ACCUMULATE TWO OR THREE INCHES THROUGH THE
MORNING COMMUTE...WHICH MAY RESULT IN SLICK TRAVEL. ACCUMULATING
SNOW WILL BE FALLING BY THE END OF THE EVENING COMMUTE...AND
TRAVEL WILL BECOME MORE DIFFICULT AS THE EVENING WEARS ON.
@ 10:30am, 33.0F, Wind ENE 9pmph, Light Snow
Measured 3.0" new snow depth here.
Around 4" in Newtown PA.
Temp has risen +1.4F in the last hour.
Heavy burst of snow heading this way within a half hour. Wondering if any sleet involved with it.
The low is forming off Hatteras. This may not be a good sign for the LSV.
In other words, they're expecting about 6" - 9" in that area with part II this evening.
Did you actually measure that? It's 4" in Brooklyn, just a stop over on the L from Manhattan. You may have a bit more than you think. And yes, if we get what they were thinking tonight, we'll surely be at a foot or more.
We'll probably be at about 5" after that last band goes through
Others are saying that the convection to the SW of us is far outperforming and impressive which would bode well for us. I just don't know enough to decide which scenario wins. I wish P451 would chime in as he always had good insights on the now casting. Anyone wanna take a shot?
Well, as PP showed, the low is strengthening off of Hatteras, so that does indeed usually equate to your current fear. Could be an impressive storm, tightly wrapped up, where the coastal areas would see the strongest and most persistent bands. But, still a ways to go...don't lose hope yet.
However, I could be WAY wrong :)
To be quite honest, I live by The Weather Channel's "Current Surface Maps" and radar for the rain/snow/sleet lines. To me, they seem to be the most accurate. Try it. TWC, go figure...
Thanks Hoy... trying to regain feeling in fingertips. (that teaches me not to shovel 50 feet of sidewalk without gloves).
No worries...Energy #2 will be just fine.
It'd be nice to get confirmation that what's to follow this afternoon is actually going to be heavier or not. If it is... well then, wow.
wundermap
Yes, we are! :) Just went for a great walk; snowing hard with sleet just starting to mix in a bit. Temp 31F, 3.5" snow so far.
Yep, that's precisely why I haven't shoveled yet. Just waiting for that nice heavy stuff to get back in here and out again. Snow has been light for the last 25 minutes but it's starting to pick up a bit now.
Love it! :0)
Yep, especially since we're already approaching it from the first round. I think some areas will exceed 15"
Anduril- awesome link! That low over the Tenn Valley is no joke!
Mt Holly bumped my total up to near 10 inches. This morning storm really took everyone by surprise! Local schools are letting out early. Roads are nasty and slushy. This is very exciting!
Meanwhile, this harsh cold winter has left significant ice pack on local lakes. A man was skating on a lake near me with no trouble or fear at all, the first time since the 70s. "NO SKATING" signs are posted all over trees by the lake, and you could probably walk across it.
Finally, after all the snowstorms underdid it this year, we might have an overachiever!
Bring it!
FWIW-HRRR composite reflectivity looks pretty good. You can see how York, Lancster & Chester counties look to be on the heaviest axix but not bad for the next tier of counties.
Thing is, the models seem to want to scoot that second low directly over SE PA, but looking at the jet and the current radar, I can't fathom it. It looks like it's going to go over western PA from SW to NE to me.
Looks like that band is heading more east than north or am I wrong. Im currently in Cranford NJ, check out a map....i shouldnt have a problem getting under that should i? I want the heavy stuff
NWS just upped us to 8 - 12", so you're right in there TT. What I don't understand is that they say snow will be falling during the morning rush, and then in another place they say it'll end at 4am. ???
Yes, possibility.
I'll up my educated guess to 8" - 14" now with this I-95 runner that we're experiencing.
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