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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Maryland does well.
"new NAM says moderate to heavy snow storm for SNE. Will be a little while yet before the new GFS comes in."
What are you thinking for the coastline of Ct???...say Old Saybrook
According to the NAM it looks like 8 to 15 inches will be the general average. If the GFS gets any colder in its next run, and still has the same blockbuster storm just inside the benchmark - then 20 to 30 inches would not be out of the question. However, we here in SNE are still in the risk area for mixing or even just plain rain. So what we want is over or just slightly inside the benchmark. And we want the storm to develop fast enough to pull down cold air, but not so fast that it curves due north right into us... or even west.
edit - parts of the Mid-Atlantic would receive well over a foot if this run of the NAM pans out.
does this include SW CT?
G I DNT NO HUNY, I CUD RLY GO FR A STK TNITE. WUD U MND MAKNG THAT FR ME? THT WUD B SWELL
yes however western CT may get into the lighter totals due to sharp cutoff. A blend of the 18z NAM and 12z GFS would yield a storm similar (but lasting a few hours longer) to the January 12th storm, except with much more wind. 18z GFS should be out within an hour. This may end up being a combination of the post-Christmas blizzard and the record breaking 1/12 storm. One trend looks consistent though. The idea of massive warm air intrusion is slowly fading away.
im wi u guys. mch smplr. lol
You joke, but I think it was last winter a guy at CTP was making commentary about how he's screwing up because it was his first week doing night shift.
DC, central and NE MD, as well as lots of central VA, if you believe the latest NAM, that is. It looks to me like this run has the back side of the storm dropping heavy snow on us.
Not sure if I believe it, but it would be nice.
How great is that?!?!?
Part of a weak shortwave/clipper moving through. I imagine it will dry up.
OPERATIONAL ECMWF/GFS BASICALLY IN LINE NOW WITH LOW TRACKINGNORTHEASTWARD ACROSS THE CAROLINAS AND OFF THE MD/DE/NJ COASTWHICH LOOKS TO KEEP EVENT FAIRLY MINOR FOR MUCH OF CENTRAL PA.BIGGEST THREAT CONTINUES TO BE ACROSS SE HALF OF CWA...WITH AREAEAST OF SUSQ RIVER AT HIGHEST RISK.
apparently they're sticking to the NAM?
Your loss is my gain! I dont think there will be any confidence in anything until tomorrow late morning at the earliest so dont sweat it just yet
Wash your mouth out with soap and snow. Now think about what you said and never, ever repeat it again on this blog. There are children listening.
ready to see some green grass and bring out the clubs?
The only model bringing less than .5in of QPF to the region is the NAM. The Lower Susquehanna Valley is not like northern Pennsylvania. People here cannot handle a 4-10in snowfall; they panic. Lol.
that used to be the perfect setup for a big snowstorm for the Baltimore area. not for LSV?
"THE SNOWMAP MAY BE 3 INCHES ON THE HIGH SIDE BUT
SHOULD MORE OR LESS DEPICT WHERE THE CONCERNS FOR WINTRY WX ARE
GREATEST."
Got this from NWS in NYC's new Facebook site!
I keep rereading this hoping it says "The only model bringing less than .5in of QPF," but there is that glaring "NOT" in there. Lame. Winter is over.
The NOT is not supposed to be there, hahaha. I just fixed it.
http://www.weather.com/outlook/weather-news/news/articles/northeast-winter-storm-late-january_2011- 01-24
18z GFS... These sharp cutoffs are ridiculous. The synoptic pattern screams for this to be farther west, yet somehow it still produces a solid wet snowstorm for I-95 by some miracle.
I'm liking this.
If this works out for NYC/NJ, then it was by pure luck with the timing. The pattern definitely argues against it with the absent blocking and slightly displaced ridge across the western United States. Talk about luck.
what's even more amazing is 12/26 was our first snowfall of the year. Since then, we have had about 55 inches of snow statewide.
Thanks for rubbing it in. LOL
Yeah I know. GFS bombs it just in time for them this run. Would think if it bombed earlier it would be better for us (although I'm not in to bad of a spot attm)
Still 36 hours our so to go and there are still going to be some changes. Wouldn't be surprised if it nudges west more. Be interesting to see what happens when the recon data is ingested in the models.
So, we'll shoot for 26"
I'm at 2.7" for them here in Springfield. Ha.
Wow i think it looks great. They quickly noted that they do not see another big storm beyond this one.
National Weather Service Mount Holly New Jersey
419 PM EST Monday Jan 24 2011
Synopsis...
high pressure is moving east and out to sea tonight. A weak cold front
crosses the region Tuesday afternoon while low pressure forms in the
Gulf of Mexico. That low will intensify as it moves northeast...reaching
a position east of the middle Atlantic coast Wednesday evening. It will
deliver a variety of wintry weather elements to our area...possibly
substantial. The storm will head for the Maritimes Thursday. Weak
high pressure will build back over the region for the end of the
week. Low pressure crosses New England next weekend.
&&
Near term /until 6 am Tuesday morning/...
tonight...a small chance of warm air advection light snow northwest fringe of the forecast area overnight.
Continuity of the middle shift forecast with the 09z/24 sref was maintained.
Not as cold as this morning. Any free falling Countryside temperatures this
evening in the still mostly clear skies before 7 PM will grind to
a halt overnight as skies become cloudy.
Probably should have delayed the onset of skycover and lowered
temperatures a few more degrees near and east of the Delaware this evening
over the snow cover. Was focused primarily on the storm ahead.
&&
Short term /6 am Tuesday morning through Thursday/...
please reference the hwophi and the snow map posted. The weather grids
were derived from the 12z/24 GFS partial thicknesses and the top
down weather tool. The NAM was not used too much for this forecast per NCEP
pmdhmd et cetera. The snowmap may be 3 inches on the high side but
should more or less depict where the concerns for wintry weather are
greatest.
Tuesday...warm air advection North Peaks in the morning...and the
best chance of snow will again be across northern areas. Further
south... a period of light rain or snow showers is possible Tuesday
morning. Since this is not a high confidence forecast for this
particular forecast element...continued slight chance for now.
As the warm air advection ends...middle and low level clouds should
thin during the afternoon...and a few places may even see some
sunshine during the late afternoon. The boundary layer warms
considerably during the day Tuesday...and highs were based mainly
on the 12z GFS MOS with a check against our prior forecast and the 12z
European model (ecmwf).
Tuesday night...it may clear more than indicated in our forecast
north of phl and radiational cooling will develop. Temperatures Tuesday
night might drop down close to 10f in northwest New Jersey and NE PA. Confidence
low on published temperatures for Tuesday night in northwest New Jersey and NE PA and
probably need to lower in future forecasts.
***Winter storm likely from 10z Wednesday to 10z thursday***
12z GFS UKMET rgem ggem model guidance confirms the past several days
of gefs and more recently the sref trends for a substantial winter
weather event.
Please reference the NCEP discussions on model choice...winter weather and
quantitative precipitation forecast.
Essentially... we will be in the developing comma head of a Gulf
Coast intensifying short wave that lifts NE into a compact closed
low through the middle Atlantic coast that has deformation zone banding on
the southeast edge of the deeper relative humidity ..looks unstable aloft in that region
per GFS.. for late Wednesday aftn/evening. That could mean decent snowfall
rates of an inch or so an hour in an area that will have less than
1 inch of frozen water equivalent quantitative precipitation forecast.
The i95 region looks like a mess with rain/sleet and some snow
changing to all snow as the low pulls away in the evening.
Looks alike all snow /possibly a prd of sleet mix/ from somewhere
near kukt north and west....certainly Allentown north and west.
Southeast New Jersey and southeast 2/3rds del should be mostly rain with maybe a little
ice at the start near dawn Wednesday and maybe a 0.5 to 3 inch
event snow event in the backlash comma head rotating south behind
the departing low Wednesday evening.
Wind Advisory potential continues along the del S New Jersey coast for
late Wednesday afternoon and evening.
Thursday...blustery winds diminish late.
&&
Long term /Thursday night through Monday/...
a generally quieter long term period with precipitation possibility
centered around Saturday and Saturday night. An upper air trough is
forecast to move through our County Warning Area on Friday. For now precipitation
mention was called flurries in the northwestern third of our County Warning Area toward the
deeper moisture.
A low pressure system is forecast to pass north of our County Warning Area about
Saturday night. Pending a perfect forecast and being on the relative
warm side, should limit the amount of precipitation. Given the
forecast light precipitation intensity, which would be needed for
this to occur, the possibility of rain showers or rain mixed with
the snow was brought as far northwest as the i95 corridor on
Saturday afternoon. A secondary cold front is then expected to pass
across the area on Sunday with less forecast moisture and thus just
flurries are forecast for now.
Another Arctic high pressure system is then forecast to build into
the northeast on Monday. We did not deviate too much from MOS
guidance through the period except for Monday because of the Arctic
high where we went lower. We might be too high with maximum and min
temperatures at the start of the long term pending the snowfall with the
Wednesday coastal system.
&&
Aviation /21z Monday through Saturday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
The high pressure system is now drifting off to the east. Other
than a few middle and high clouds, skies remain mostly clear this
afternoon. Weak low pressure north of the Great Lakes will drag
an equally weak frontal zone into our area later tonight into
Tuesday. Expect VFR conditions with high SC/low ac ceilings with this
system tonight into Tuesday. Could see the clouds thin out Tuesday
afternoon into early Tuesday night as slightly drier air pushes in.
Winds tonight into Tuesday will be light and variable. They should
swing around to the SW to west 5 to 8 knots Tuesday afternoon.
Outlook...
it is becoming more evident that yet another East Coast storm will
hit our region Wednesday and Wednesday night. Some milder air will
wrap into the system Wednesday bringing wintry precipitation mix.
The timing and track of the storm will determine how far north and
west the rain/snow line moves. The precipitation will spread from
south to north across the area Wednesday and continue well into
Wednesday night. The storm is forecast to intensify off the middle
Atlantic coast Wednesday night and begin pulling away to the
northeast by Thursday morning. Colder air could possibly move back
into our area Wednesday night before the precipitation ends. This
will allow whatever rain or mixed rain and snow to change back
over to all snow before ending. No matter what type precipitation
is falling, flying conditions will lower to IFR/LIFR Wednesday
morning and continue through much of Wednesday night. As the low
pulls away, conditions will begin to improve by daybreak Thursday.
Expect VFR flying conditions for the latter part of the week as
high pressure pushes back in.
Viewing: 851 - 901
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