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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Hi Blizz, any estimates for snowfall for the Annapolis, MD area tomorrow? My (insane?) sister is plunging into the Chesapeake Bay for the annual Polar Bear Plunge to raise funds for MD Special Olympics.
Yep, just let it melt away. Dumping it over the side is probably plausible, but I like my snow.
You're quite welcome, Philly :)
Heck of an observation, LT. I'm impressed.
Whatever...I'll do what I want!
Lol nah, I'm sure the biggest snow event of my young life will be Snowmaggedon. This year won't throw anything like that at us. But even with all these big events recently, I still feel like this winter is yet to unleash its best storm. Hahaha, just a gut feeling. Probably wrong though.
Cashtown 1S
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
136 PM EST FRI JAN 28 2011
VALID 12Z MON JAN 31 2011 - 12Z FRI FEB 04 2011
...MAJOR WINTER STORM SETTING UP NEXT WEEK FROM THE ROCKIES TO THE
NORTHEAST...
THE MOST PROMINENT SFC SYSTEM FOR WHICH SHRTWV UNCERTAINTIES COME
INTO PLAY IS FCST TO TRACK NEWD FROM THE SRN PLAINS TUE ONWARD.
TO VARYING DEGREES THE 00Z GFS AND ECMWF HAVE MADE MEANINGFUL NWWD
ADJUSTMENTS FROM FAIRLY SUPPRESSED TRACKS IN MULTIPLE PREVIOUS
RUNS. THE ECMWF TREND IS MORE EXTREME AS ITS PREVIOUS TWO RUNS
WERE ON THE SERN SIDE OF THE ENVELOPE AND THE NEW 00Z RUN IS NOW
ON THE NWRN SIDE OF GUIDANCE. THE CANADIAN IS A FAST EXTREME TO
BRING SWRN CONUS ENERGY INTO THE PLAINS AND IS ALSO IN THE NWRN
PART OF THE SPREAD... WHILE THE UKMET TRACK IS NOT QUITE AS FAR
NWWD AS ITS PREVIOUS RUN. OVERALL PREFER A GEFS MEAN/12Z ECMWF
ENSEMBLE MEAN SOLN THAT FALLS IN THE MIDDLE OF LATEST AND RECENT
GUIDANCE GIVEN THE SENSITIVITY OF SHRTWV DETAILS AND SIGNIFICANT
RUN TO RUN CONTINUITY CHANGES.
AS SHORTWAVE ENERGY MOVES INTO THE FOUR CORNERS REGION EARLY
TUESDAY AND ARCTIC HIGH PRESSURE PLUNGES DEEP INTO THE PLAINS WITH
GREATER THAN 20 DEGREE NEGATIVE TEMPERATURE ANOMALIES. THIS WILL
BRING STRONG UPSLOPE FLOW INTO THE CO ROCKIES FRONT RANGE WITH
MDT/HVY SNOWFALL TO THE SRN ROCKIES SPREADING EWD INTO THE CENTRAL
PLAINS. MID LEVEL ENERGY SHEARS OUT EWD AND A MDT SFC LOW DEVELOPS
OVER ERN TX BY TUESDAY. THIS LOW MOVES NEWD INTO KY/TN WED AND
REFORMS OFF THE MID ATLC CAPES AND RAPIDLY MOVES NEWD OFF NOVA
SCOTIA BY THURSDAY. MDT TO HVY RAINFALL POTENTIAL SOUTH OF THE LOW
PRESSURE TRACK WITH SNOW ACROSS THE CENTRAL PLAINS AND MAINLY
NORTH OF THE OH RIVER AND MASON DIXON LINE INTO NEW ENG. HEAVY
SNOW THREAT INDICATED BY OPERATIONAL MODELS QPF OUTPUT/ANALOGS AND
FAVORABLE MID AND UPPER LEVEL JET STRUCTURE WITH ICING THREAT
ALONG THE CHANGE OVER AND THEN THE DAMMED IN AREA IN THE MID ATLC
PIEDMONT.
PACIFIC RECON FLIGHTS REQUESTED INTO THE CRITICAL UNCERTAINTY AREA
AHEAD OF THIS SYSTEM IN THE NE PACIFIC. IF A FLIGHT IS AVAILABLE
THIS DATA COULD GET INTO THE MODEL SYSTEMS BY THE RUNS OF SUNDAY
00Z/12Z 30 JAN. RAUSCH/ROSENSTEIN
Ñ
try your local tv stations. at least one in your area should have a good radar for snow
LOL, Fredneck, it always cracks me up when someone calls it that!
Yeah. It was great! Heavy snow with big quater sized flakes.
Lol that would be rain for us!
Mixing possibilities somewhere between 11am and 9pm Wednesday when the bulk of the precip, 1.20" is expected to occur. Snow with mixing possibilities over the entire Mount Holly CWA at the moment. Lots of details to work out...
POP's 60% - 70% across the area for Wednesday.
While a big winter event seems probable, lots of run-to-run inconsistancies regarding details.
That's not at all what I wanted to hear. My flight leaves in the afternoon. Hopefully this system arrives LATE.
Don't forget to bring a towel!
I have seen snow fall quickly before but I've never seen it fall like rain. Last night was phenomenal. Unfortunately, my sister can't visit this weekend for the dismemberment plan concert in NYC because her car was struck by a tree.. Again. Twice in 31 days.
Wow, that's some bad luck. Good luck too, as she wasn't inside it either time, I assume.
And there's a chance it could be a major ice storm for me (DC area), yikes!
TT, why does Mount Holly have us under a chance of rain Wednesday? Do they gain some kind of sadistic pleasure out of crushing our hopes for snow?
Hmm, wonder if it's time to finally break down and buy a generator.
She's okay, just a little bummed. We were gonna have a train car full of people going down to the city!
Light snow - 32.2 degrees
TT- Thats such a problem most people dont even think of. Fews years ago my dad and I were sitting in our hunting cabin in sullivan county ny and the roof started making creaking sounds. Very scary. We got everything off before a bad situation. But could only imagine.
Hoy- I know we have the same local mets, this morning they were reported very low confidence with weds storm system. What do you think?
Did you hear about the Staples store in Manahawkin that had a roof collapse a week or so ago? They had solar panels on it. I expect their will be new building codes here after this winter. The panels were installed at a high angle and I'm guessing they had drifting on the roof that normally would not have happened if they were flat. Add in 1" of rain and the weight must have been too much.
Yeah, I don't watch them because I don't watch television, but if they're anything like most local mets, well, I wouldn't trust their opinions until we're less than 72 hours out. Except this year, this year I don't buy anyones opinion...even a day before.
Except Blizz, he seems to be correct most of the time. Which says something for the future of forecasting in general.
Looking at the 18z gfs, it looks like there could definitely be issues late wed into thurs. Hopefully Thursday. 32 degree line is on top of us, so it could definitely be wetter than this one we just had. Again it looks to me like inland they'd get more snow, but that last storm looked the same way for a while.
Toss a coin.
Link
wish it to happen.
Link
If Chuck Norris had been holding the roof up, it wouldn't have collapsed. Actually, if Chuck Norris were there they wouldn't have needed solar panels - they could have run the lights off of Chuckowatt hours.
Blizz - it's been like this most of the day. You better conjure up lots and lots of clouds for next Wednesday. Speaking about it...I never knew that Feb. 2nd was the middle of winter. I was reading in the Farmer's Almanac and each season has a middle day. I had no idea that people used to have some celebration/tradition on that day
Clouds? The snow was much too light today and too warm outside to really stick except on the existing snow pack. It was 32-33F here must of the day. Tomorrow will be another clipper and I cannot rule out 1-2in of snow here.
It's been snowing on and off all day...like you said too warm to accumulate on anything but other snow. there was a time this morning where it came down pretty good, but just too warm
Yes, clouds. I don't want my groundhog, Pardon Me Pete, seeing his shadow. now you understand?
The GFS suggests the midweek storm will have temperatures in the teens and low 20s for much of the precipitation until the very end where we rise to the upper 20s. Also looks like arctic air for the weekend; maybe below zero again?
Oh, hahaha... Well you may want to root for the opposite. Despite the statistics being 50/50 that he is correct, I think I read before that he is 75% wrong most of the time, lol.
Lol, welcome!!! Storm next week looks very interesting. All of the models are showing very heavy precipitation amounts for a possible long duration.
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