Pardon the anthropomorphism, but I believe the atmosphere is revealing clues to us on what's really going to happen, and I am trying to pin them down. A well-known forecaster at Accuweather made the point earlier today of a striking similarity between what is about to happen and that of the 3 day period prior to the Feb 03 Blizzard (insert reassuring statement here that neither he nor I are forecasting a blizzard). It's quite simple. Friday night into Saturday Feb 14-15, there was front runner clipper that brought 2-4 inches to the central Mid-Atlantic, and was all done Saturday night. Most of the public who were enjoying their President's Weekend weren't paying close attention, and went to bed Sat night thinking that was it. (Including me) The clipper brought in the Arctic High, the moisture gathered from the Gulf Coast and ran right into the High. Sunday morning we awoke to what no one expected: moderate to heavy snow falling in very cold temperatures. The high departed slower than we thought it would, the easterly fetch kept pumping in Atlantic moisture added to the tremendous surge of Gulf moisture already in place, and pow! Two feet later, the rest is history. Now, given that history lesson, look over the storm synopsis from a long time reader, Mr. E.H. of Boston, and let us know what you think.
SYNOPSIS OF WED-FRI STORM IMPACTS ON MID-ATLANTIC AND NORTHEAST submitted by long-time reader E.H. of Boston, MA.
STORM 1: THE MID-WEEK CLIPPER. This first system comes in Wednesday from the Ohio Valley streaking towards Pennsylvania, Maryland and Virginia. Snow will break out from DC to north of Philly as the center of the Low passes over central VA. I would expect a heavier band of snow somewhere from BWI-PHL-SNJ. Overall, I'm thinking a quick hitting 1-3" here with a few 4" amounts embedded outside the cities. A classic 1-4" clipper despite potentially low moisture amounts to start.
Then we watch the developing second system in the southern Gulf States. A southerly flow will try to ride over a fairly substantial cold air damming in place and this will allow for overrunning snows to take the place of the departing clipper snows in the Mid-Atlantic. Some may not even notice the switch from clipper snows to overrunning snows :)
STORM 2A: MID-ATLANTIC OVERRUNNING EVENT. Snow will streak up from Tennessee toward the I-95 corridor Thursday night before turning over to rain Friday in the cities and coastal areas, while staying sleet/freezing rain just northwest of the cities, where some significant icing will take place. Before the changeover, I could still see a couple inches accumulate, bringing an accumulative snowfall from WED-FRI averaging around 3-4"
STORM 2B: INTO THE NORTHEAST (Continuation of STORM 2A, just further north) As the Mid Atlantic's major cities start to transition to rain, we will see NYC and Providence-Boston get into the action. Snow will streak into the region from the southwest as we head into Friday night and Saturday could yield a snowy day. I am not saying heavy snows, but a moderate accumulation, perhaps a 3-6" snowfall for Southern New England with maybe closer to a 4-8" snowfall north of NYC. Not a major event, but a winter event nonetheless as I bask in 60 degree warmth while writing this in Boston.
OVERVIEW: Snow Wed PM in DC-BWI-PHL-SOUTHERN NJ. Heaviest from BWI-PHL. General 1-3", isolated 4". Late Week MESS Mid Atlantic. Snow to Ice to Rain (SE). Light Snow Accumulations Possible. Significant Icing Interior. Northern PA/NY State/New England Snow Friday PM - Saturday. Moderate Accumulations Possible. (Editor's note: Much appreciation to E.H. for putting this together, he and I have seen many a storm go WAY farther north than was orginally projected, so I'm leaving the calls for southern New England there.)
THE ON-AGAIN, OFF-AGAIN STORM IS ON AGAIN
8 AM MON 2/18: Today, I won't argue with anyone who wants to label me a "model hugger" in the sense that it comes across I'm just shifting my positions based on every individual model run. I normally follow the US generated Global Forecast System (GFS) and the European (ECMWF), to get an idea of general trends. Last night both were showing total suppression of precipitation to the Carolinas for Thursday into Friday. A professional meteorologist, Mr TQ, whom occasionally comments here, has helped set me straight that we are indeed dealing with a negative NAO middle to late next week. However, it seemed that the models were also just suppressing the precipitation too far south too quickly. Regardless of what was being projected, I felt the large scale dynamics were (and still are) going to produce an over-running event. Sure enough, that's what the overnight models came out with, as shown below.
SUNDAY 2/17 PM: I am providing the other side of the discussion, in the event this bears out come mid week. Above was the Sunday night GFS projection for Thursday and Friday. As you can plainly see, very little if any precip in the Mid-Atlantic for that period. Except for the yellow mark over Baltimore that'll represent egg on my face if there's no storm. The strong 1040 mb high coming behind the current storm moving through the Great Lakes looks to charge southeast according to many models. (That was the overall thinking Sunday night).
41 comments:
Mr. Foot, I'd spread this question to the Eastern Wx Forums. Good question, one that I cannot answer.
For nostalgic purposes, I was looking at old posts from back in the day...winter 04-05 when I first saw this site and wow, it seemed like every other day we were talking at least 3-6" events and 6-12" events were the norm.
This year is a different story, but all it takes is that one good storm and everyone is satisfied.
Good idea, but please don't mention it came from me, or mention this site. With all due respect I do not have the emotional fortitude to deal with the onslaught of minor league meteorological minions that infest Eastern.
Aside from those folk, there still are a lot of smart people and mets there. Would be interesting to see what any of them had to say.
Also..funny you should say about old posts. I was doing the same earlier today, reviewing my notes online from the Feb 07 Storms. I was, in effect, escaping from my escapism.
Not sure where you/re seeing a forecast for +NAO index on 2/21 b/c...
http://www.emc.ncep.noaa.gov/gmb/ssaha/indices/day1/nao_fd4.gif
...shows -NAO from four global models.
PNA index is forecast 'positive.' This Ridge-W / Trof E configuration is driving the HIGH into the mid-Atlantic. where the southern stream and northern stream converge.
http://vortex.plymouth.edu/cgi-bin/gen_grbcalc2.cgi?re=namer&id=&zoom=.6&ti=0&ge=800x600&mo=ecmwf&le=500&va=hght&in=60&pl=cf&ft=h96&cu=latest&overlay=yes&mo=&le=sfc&va=slp&in=4&pl=ln&ft=h96&cu=latest
What am I missing?
Looking at the previous post 'Something/s Brewing...' I noticed the use of the D+14 NAO forecast which I think may be causing some confusion.
1) This chart is a running depiction of D+14 forecasts. It/s not a time-series of the daily NAO forecasts from today forward.
2) Note the correlation value of negative 0.1454 in the upper right corner. A negative correlation means when the forecast is for an increase...the observed index decreases (and vice versa). This indicate very poor model performance b/c when the index is forecast to go in one direction...the observed value should go the same way.
Better to look at the dailies in the links above.
Thank you tq for your response, I figured you would be reading and able to help out there. True I was using the D+14 chart, but isn't the black line simply showing the recorded daily values. The readings I use are from CPC:
http://www.cpc.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html
And the 4 MRF ensemble forecasts show NAO to remain generally positive over the next 1-7 days, at least according to what I am seeing/interpreting. The ensembles all seem to point to a basic positive trend with about .5 of a deviation on either side.
Obviously a tiny little blip above 0 for 2 days is not a hugely positive trend, but in layman's terms... I have not in the few years I've followed it seen the "blue line" tip positive for just a short time then head back negative. Would be fair to say all this could simply be my own learning curve issues.
Not that I'm emotionally tied up in my forecast, would rather not have a storm so it does not interfere with a student ski trip this weekend. What irks me is the reason why the high is projected to position so far south. Just seems so unusual and out of place for a winter without such trends.
The only explanation left I supposed is that despite what I seen on the CPC site, the NAO will indeed go noticeably negative, hence the southern suppresion trend models are showing.
Well, what we do know is that we have the highest positive PNA of the season with a seemingly "bouncing" NAO that may decide to go negative again. I'm wondering how this very positive PNA will affect all this, as this was higher than any predictions I saw. I think it goes without saying though that I'm disappointed in the recent GFS, but at least we'll have a clearer picture tomorrow...right...? Maybe not, heh :-)
You are correct. The black line represents the observed values.
The yellow line referenced is the D+14 forecast from each day. I think the trend analysis would be improved if the D+7 Ensemble forecast was used b/c the D+7 forecast has a correlation coefficient (R) of ~0.67...which is OK but not great. Certainly better than the D+10 or D+14.
Better yet..is the D+7 operational GFS with R = 0.74.
http://www.cpc.noaa.gov/products/precip/CWlink/pna/nao_index_mrf.shtml
More better are the (now) D+4 dailies from the four global LR models (GFS...ECMWF...UKMET...and Canadian).
http://www.emc.ncep.noaa.gov/gmb/ssaha/indices/day1/nao_fd4.gif
All four show a -NAO index on 2/21 ranging from -0.45 (ECMWF) to -1.1 (Canadian).
Add 1) beefy +PNA (+1.15 to +2 STD) to the mix and the northern stream HIGH is pushed well S of 40°N and 2) the merging northern and southern streams inhibit a turn to the N and quickly shoot the southern system short wave offshore
With all due respect I do not have the emotional fortitude to deal with the onslaught of minor league meteorological minions that infest Eastern.
Which is why I am there infrequently any more...
:)
Mr. foot emailed you. Awaiting reply. Also posted that bufkit info, but it's under the other comment section.
Joy in mudville over at the forums...00z GFS and GGEM went well...just wait till 12z tomorrow and there will be more name calling and suicide watches.
Aside from that, still looks like a nice 1-3" call for the THU-FRI overrunning event from DC-BWI.
Then it gets to convoluted to even try and explain what will happen.
Thank zak, I saw your posting there in the other section, thank you very very much. I remember spending a hour once last winter trying to find bufkit. I did learn it was invented by the Buffalo NWS. Will go check email now.
Well folks, you have to side with tq's assessment of the NAO issue.
Now we know why the High is being shunted south, squeezing the moisture out and to the East. It makes good sense now. If we were already in negative terrority and trending neutral as in Feb 03, we would have something to talk about. But as Jim Kirk might say, "Not this time."
Congrats on the love expressed on Justin Berk's site. Nice job!
Oh the times, they are a changin'
This is a Russ L alert that we could be looking at the arrival of cousin of the Dec 5 Little Storm That Could... this Wed
A front runner clipper ahead of the Arctic High appears to be aiming for the Mid-Atlantic Wednesday. Given colder temps and evap cooling issues, though QPF is light, we could see a light snow event Wed night. That could interrupt things Thu AM, leading into the Thu-Sat storm.
So it remains a possibility for students and teachers that a short week could end up a whole lot shorter.
Well thanks to cms and Justin. Wasn't seeking additional attention or visibility. Just going with my gut and memory of previous times I should have done that.
To Justin's credit, it is important to keep in mind a lot could change, and the call for 4 inches might be premature, but I put it on there to eliminate having to answer the same question multiple times. In fact, if we throw in possible light snow from the Wed system, we could end up near 4" by Fri night.
Your welcome. Bufkit is a great tool. Awsome in severe wx season to see what kind of storms are possible that day.
Okay, so I typed out this whole long synopsis on the model runs through midday and I went to post and there was an error.
I will try to replicate it, but won't go into as much detail this time. I will break it down now.
STORM 1
This storm comes in from the OV streaking towards the Mid Atlantic states on Wednesday. Snow will break out from DC to north of PHI. I would expect a heavier band of snow somewhere from BWI-PHI-SNJ. Overall, I'm thinking a quick hitting 1-3" here, not budging from my thoughts from the past few days. Embedded a few 4" amounts will be noticed in that heavier band in the outline cities. A classic 1-4" clipper. Then we watch the developing storm system in the southern Gulf States. A southerly flow will try to ride over a fairly substantial CAD in place and this will allow for overrunning snows to take the place of the departing clipper snows in the MA. Some may not even notice the switch from clipper snows to overrunning snows :)
MID ATLANTIC STORM 1B (OVERRUNNING EVENT)
As I said the overrunning snows will streak up into the DC-PHI stretch before turning over to rain in the cities and SE, while staying IP/ZR just NW of the cities, where some significant icing will take place, hopefully mainly IP and not ZR. Before the changeover, I could still see a couple inches accumulate, bringing an accumulative snowfall from WED-FRI averaging around 3-4", but as a general rule, I would go 2-6" ATTM.
STORM 2 (Continuation of STORM 1B, just further north)
As the Mid Atlantic's major cities start to transition to rain, we will see NYC and BDL-PVD-BOS get into the action. Snow will streak into the region from the SW as we head into FRI NIGHT and Saturday could yield a snowy day. I am not saying heavy snows, but a moderate accumulation. If I had to put numbers to my madness, I would go for a 3-6" snowfall for SNE with maybe closer to a 4-8" snowfall north of NYC. Not a major event, but a winter event nonetheless as I bask in 60 degree warmth while writing this.
BOTTOM LINE
. Snow Wed. PM DC-BWI-PHI-SNJ
. Heaviest from BWI-PHI
. General 1-3", isolated 4"
. Late Week MESS Mid Atlantic
. Snow to Ice to Rain (SE)
. Light Snow Accumulations Possible
. Significant Icing Interior
. Northern PA/NY State/New England Snow Friday PM - Saturdy
. Moderate Accumulations Possible
So MID ATLANTIC FOLKS, if you thought winter was over, never came, bring back out that shovel because you will need it this week. (hint, hint)
EH I know exactly how that feels, it happened to me several times this winter, wrote a full report only to somehow stupidly delete the thing (so that explains the faint screaming I heard to my northeast...it was you?)
Great summary though, you won't mind if I put that in the main post and credit you. We were out enjoying a slice of summer at the park, just to prove I don't spend all day at the computer analyzing model runs! (Course I am back now).
No problem...if you need to, just touch up some of the points I made..I did it pretty quickly...just want to mention that we should highlight that the forecast for later this week...(STORM 1B and 2) is still all up in the air basically...just saw the 12z GGEM and its going much larger than the 12z GFS. Its all wait and see...probably won't be pretty certain until 12z THU, I would say.
The clipper snows look like a good bet ATTM.
BTW, how's your HEAT WAVE this President's Day...just saw obs out of BWI and its 70F there! Wow. Here in Boston, Logan has shot up to 60F and now the sun is out and my home thermometer is 59F.
Snow cover last night was between 4-5" in MBY and now NADA. Hopefully we can replenish it later this week.
mr foot
like you, i have been outside enjoying this 70 degree weather. thought i would check on the week's weather. i'm hoping all these storms this week are "the little storms that could" i would not mind seeing a decent amount of snow before spring sports (march 1st) begin. does this storm seem to be one that is-- what you see on thur-fri is what you get? in other words-- we really won't know until it happens?
Okaaaaaay Mr. Foot and EH ...
I am sufficiently psyched for some flake accumulation.
Difficult to believe, as I have the kitchen door open, enjoying spring-like warmth -- but that's what makes it even BETTER! Seventy degrees then SNOW!
However I'm a little worried that warm ground temps NOW will prevent snow from actually piling up THEN ... build me up, Buttercups!
Madame Buttercup:
Cold air arriving in a 2-3 day period before and during the next 2systems will produce the following effects:
1. The ground will chill sufficiently.
2. You will realize cold air has returned and eventually close your kitchen door.
12z EURO just came in with a LP moving towards BUF! Now, I think this is a complete outlier, but time will tell. I think it is underestimating the cold air damming and fact that NAO could be slightly negative.
The key to this will be when we see the phase. A quicker and harder phase and the EURO would be correct in its depiction...ie RAIN for the I-95 for STORM 2.
If it doesn't phase until its further east and stays in more of a split flow, then you get your snows to ice MA and snows in the NE. (GFS and GGEM depiction) I like the GFS depiction ATTM, as its a good compromise between the two extremes: GGEM and EURO. UKMET looks in line with GFS/GGEM as well.
Lets take it one storm at a time though..as always, excellent posts and analysis Mr. Foot. Like I said, its like the good old days...we are just all a little older.
Yanno, I have always been really impressed with the quality and accuracy of the forecasts you present Mr. Foot.. Having been a Foot Follower since 04 I rely on what you present! ::whispering:: is like "old times" gearin' up for a Big Kahuna!
I thought it was amazing that on DEC 16 you posted this in your comments.. "We may blowtorch into the 70's come January, and even 80 one day in February. Then it will all come crashing down, oh, say 1-2 days AFTER the spring Equinox.
Get ready to go tropical, after the 1st of the year. You won't have to head south for the holidays, the southlands are coming here. Just wait and see, January may end up feeling more like June!"
It was dayum near 80 today .. dunno the exact temp, but as I was out back with the puppy doing yard work (scary for FEB huh?) I called weather and it said 77 degrees!? HELLOOOOOO!!
I am slightly bummed that you mentioned some snow around March 15th since we have a scrimmage planned for then.. but oh well....
Anyway.. I have a meeting WED night... should I be prepared to postpone!?
Thanks again Mr. Foot.. and EH..
Tony Pann's blog also starting to hint towards a lil disturbance..
http://www.wusa9.com/news/columnist/blogs/tonypann.aspx
Y'all should read the latest AFD's... NWS offices really starting to realize this is going to be complex situation and not cut and dry (wet) storm.
Hey Russ...they even mentioned your storm in the Sterling Disc. Go take a look, you will be thrilled to see what was written in the Tue-Sat portion.
One thing I am settling on, none of these puppies are going to head for the lakes.
"One thing I am settling on, none of these puppies are going to head for the lakes."
Mr. Foot, I couldn't agree more. That is just not representative of the incoming pattern. But I've got to tell ya...I have got spring fever today...High temp at my house was 62 and it smelt awesome out there. DP was up near 60 for a while...very odd afternoon.
Now folks, it's back to winter...needasnowday, you may just get what your name suggests.
...and I quote:
NWS Balto/Wash
1603 local
SNOW IS POSSIBLE WITH PASSAGE OF A CLIPPER LOW THAT WILL MOVE
ACROSS THE REGION DURING THE DAY ON WEDNESDAY. SOME ACCUMULATION
OF SNOW IS POSSIBLE EAST OF THE BLUE RIDGE.
MORE UNSETTLED WEATHER IS EXPECTED TOWARD THE END OF THE WEEK.
THERE IS POTENTIAL FOR WINTRY PRECIPITATION FROM LATE THURSDAY
INTO SATURDAY.
...the plot thickens...
Yes, it does terpguy.
18z GFS came in and is still a significant hit for STORM 2 from DC to Boston. Same ideas for the Mid Atlantic, snow to IP/ZR...with it changing to RN SE of the cities...but just NW of the cities of BWI-PHI-DC could be quite treacherous with freezing rain possibly as ground temperatures could stay below freezing (upper 20's to around 30) with rain falling and freezing on contact.
NYC looks more winterlike in the latest run...maybe a few to several inches of snow followed by sleet.
SNE and Boston looks to be the bonanza per this run with widespread snowfall of 'at least' 6inches ~ fluff factor to be determined.
Clipper still looks on par with previous thoughts, but am hedging towards lower end accumulations on my 1-3" call. More one and two inch amounts with 3" lollipops. Could change, stay tuned.
Now that 'the event' is inside the short-range window...it/s useful to compare output from the NAM and SREF.
84-hr NAM and SREF verifying 2/22/00z (Thursday evening) shows the arctic HIGH centered well west of the offshore GFS soln.
Also notable is 1) the GFS position of the 85H 0°C isotherm over VA / NC border compared to its position ~150 miles farther S along the NC / SC border in the NAM / SREF and 2) the flatter 5H flow in the GFS (pushing the HIGH offshore) vice the NAM / SREF (keeping the HIGH over land).
http://bp0.blogger.com/_AMnne6QOtig/R7n_OEcRRiI/AAAAAAAABFk/GFFVxvoN1Dg/s1600-h/7_feb22_nam_gfs_comp1.png
Mr. Foot I have a few questions regarding the storm????
1. Why isnt this going to be a coastal storm and give a lot of precip to the mid Atlantic.
2. In the 03 storm the temps were becomming marginal for snow or ice and it snowed. Could it be anything like 03 and a huge suprise to everyone.
3. If an artic air mass is coming down then wouldn't that create lots of cold air damming to take place.
Please give me your thoughts on these ideas/questions and this week will be a fun one!!!
Actually, I have the same general questions as 'snow lover', so I too would appreciate the answers, thanks! I'm really hoping this one will be a big surprise and be the one us snow lovers are waiting for. Also, I know it's premature, but any thoughts on the possible upcoming storm next week? Thanks for all the updates!
Am putting little ones to bed so can get to those Q's after lights out.
Sounds like the drumbeat has begun.
Thancks I am looking forward to them.
Anyone else finding themselves refreshing this site/comments ahhhLOT!??!
:)
yeah
Well, time to kick off a new round of comments in a fresh post. Will have to start scaling back the imagery for school folk, as I know Balto Co servers block most of my images. Will go with text only and try to make it as succinct as I can since most of my colleagues don't have 15 min to burn in their planning period reading the weather.
For your questions, will put them as part of the new post writing now.
I'll try and give my amateaur attempt at answering some of these questions...
1. Why isnt this going to be a coastal storm and give a lot of precip to the mid Atlantic.
This storm is going to be a coastal storm first off. However, in you case for the MA, you want a quick transfer of energy to the secondary storm system so that it has time to wrap around the moisture to places like BWI-DC-PHI. As depicted in the GFS, it develops a little bit too late for good wrap around for MA, but that could still change. Key is quick decay of the parent LP in the OV and quick and explosive redevelopment over NC.
2. In the 03 storm the temps were becomming marginal for snow or ice and it snowed. Could it be anything like 03 and a huge suprise to everyone.
It could be like 03, but unlikely. First off there was a 1042 HP in SE Canada during that storm. Days prior to that storm I was in the mid teens for highs with lows below zero here in Boston. We won't see that. In fact, I will have highs on Wednesday and Thursday in the low 30's..the cold before the storm, antecedent cold I believe, will not be as pronounced as in '03 and without a MEGA HP like in '03, it would be a big feat to just get an all out snowstorm in the MA. The key is redevelopment off the MA coast...the quicker and stronger it is, the better chance of having those winds shift in a more northerly component. Still, I wouldn't doubt a quick couple inches of snow in DC-BWI before the switch to a mess...and maybe a few to several inches in PHI and more north of there...NYC could do very well.
3. If an artic air mass is coming down then wouldn't that create lots of cold air damming to take place.
Yes, it would. Sometimes the models, esp the GFS don't pick up on this cold air damming (CAD) very well and that could keep temps below freezing for much of the event even when 850 thicknesses would support rain...then you just get freezing rain, which can cause a great amount more havoc than snow would.
Okay...now we can wait for Mr. Foot's analysis, which will be much more in depth than mine...mine was just the preliminary stuff just to whet your appetites and give you something to read while refreshing your tabs lol.
That was great stuff EH and I'll include that in the forthcomimg writeup.
Thancks for the answers EH. Mr foot when will the update be ready???
It's on now. I have to finish a short project in the basement so will check back shortly...and post that map from the day before the Feb 03 storm.
Post a Comment