[dT-REX]

...SET CONDITION CHARLIE .... SET CONDITION CHARLIE EVENT #6

WWCINC -- Weather Weenie Commander in Chief -- has issued CONDITION CHARLIE advisory #6 effective for the approximate time of MARCH 1 to MARCH 3 of a M.E.C.S. (Major East Coast Snowstorm) / H.E.C.S. (Historical East Coast Snowstorm) Event

Condition CHARLIE shall by declare whenever the Supreme Commander in Chief of Northeast US snowstorm weenies --WWCINC -- sees the atmosphere pattern shifting into a more favorable state for S.E.C.S. (Significant East Coast Snowstorm) event or "Higher:…. or S.E.C.L. (Significant East Coast Low) development



CONDITION CHARLIE is NOT a forecast. Instead this statement represents a paradigm shift by WWCINC in overall outlook regarding the chance of this POTENTIAL development.

The Potential has increased enough to issue advisories for snow mongering Weenies to watch out for a MILLER A event that qualifies as a Possible M.E.C.S. / H.E.C.S. during the time period of 200902.28 to 200903.02.



The areas of concern … based upon the latest data:

… TENN VALLEY… including high terrain over far northern AL and northwest GA
… WESTERN and CENTRAL NC
… All of VA…
… All of MD….
….All of far eastern PA (east of the I-476)…
… Far southeast NY (south of I-84)…
… All of Long Island…
… Far southeast New England… (CT RI Boston to Cape Cod)


SITUATIONAL ANALYSIS:

This is not a high probability event. This could easily blow up in my face.

The model data has increased in its consistency over the past few runs so as a result I am issuing a condition Charlie statement. Let me point out again that a Condition Charlie statement is not to be interpreted as a forecast. That is not the point of the Condition Charlie statements. The purpose is to lay out some foundational ideas and things to watch out for in the model runs over the next several days so that meteorologists and weather hobbyists alike can focus more on the forecast process as opposed to simply looking at the latest 18z GFS or pathetically useless JMA.


There has been and remains a fundamental misunderstanding between the patterns which produce significant snowstorms for the Southeast and lower middle and experience as opposed to the classic Northeast snowstorm. Looking at the latest runs (0Z) of the European as well as a Canadian and looking at the data verbatim... and that is a key point here... I am looking at the model data VERBATIM .... the event for March 1-2 is primarily a North Carolina Tennessee Valley Virginia MECSW/ HECS... and NOT a northern mid-Atlantic/ New England MECS / HECS.

It may or may qualify as a SECS for the Northern Atlantic or New England... but that is still very much up in the air.


That being said to me point out that I am NOT in anyway forecasting a major or historic snowstorm for the Tennessee Valley Western and Central North Carolina and Virginia. If you cannot distinguish the difference between this model analysis... key ideas to watch out for ....and a Forecast... then do us a favor and please stop reading because you are probably an idiot and the rest of this is going to go over your head.



The gap in the pattern recognition regarding the key differences between a lower middle Atlantic / Southeast snowstorm and one which affects the Northeast has become wider over the past several years because of the severe lack of any sort of significant snowstorms for the Tennessee Valley interior Southeast and lower mid-Atlantic areas!. The only two which recently come to mind happened to be 25 JAN 2000 and 2 JAN 2002.

Let me use this time therefore to elaborate some key fundamental differences between what a Tenn Valley / NC VA snowstorm pattern looks like versus a Northeast snowstorm pattern such defined by the famous KU research / study.

The major difference between the two events is that for the Tennessee Valley NC VA snowstorm event the northern branch of the jet stream... usually the Arctic jet or AJ .. does NOT Phase with the major short wave moving through the eastern half of the US towards East Coast. Instead because of a different synoptic pattern over eastern Canada the Arctic jet stays along the northern Great Lakes and Northern New England which provides a source of very cold air but also prevents the southern short wave from turning the corner and making a run up the coast.

Typically these sorts of situations to big cities of I-95 do see SOME snow and sometimes enough to qualify as significant snow... BWI/ DCA 4"..... PHL/ LGA 6" BDL/ BOS 8".


Here are some classic cases of of TN valley NC VA snowstorms events... some of which you may have heard of and some of which you may have not. In each of the following examples I have highlighted the three branches of the jet stream to enhance the understanding of these events ... using the abbreviations of STJ = subtropical jet PJ =polar Jet and AJ =Arctic Jet.


The first event is the January 3-4 of 2002. As you can see from this clearly highlighted event there was a deep closed 500 low which developed over the Southern Mississippi Valley and rotated through the Tennessee Valley to the North Carolina South Carolina coast. Even though there is rampant speculation in the weather community and on the various weather boards that this 500 Low would come up the East coast as a Major nor'easter it did not. As you can see the huge vortex or southeastern Canada was so intense that the Arctic jet did not get a chance to Relax or buckle which prohibited any phasing.


 3JAN02.gif (33.39K)
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The next event we can look at is the January 1965 Tennessee Valley NC VA snowstorm which occurred during a Moderate La Nina winter. Again as you can see there is a closed 500 low in the southern branch of the jet stream but the northern branch does not phase and as a result of the coastal low did not turn up the coast.


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JAN 1980 .. this was a historic snowstorm for much of eastern Virginia and North Carolina even the coastal areas which received 1 to 2 feet of snow. Again the pattern is very clear what happened.. there was a huge for PV -- Polar Vortex over eastern Canada and a large 50/50 over southeastern Canada right before the event began. The intensity of these two features prohibited the Arctic jet from relaxing and therefore there was no phasing between the streams.

 jan1980.gif (31.6K)
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MARCH 1980 this was Historic Noreaster / snowstorm for the Tennessee Valley NC and eastern half of Virginia ...so severe that the National Guard was called out for southeastern Virginia with exceptionally high winds and snow amounts of 2 feet. I remember this event as a kid looking at the surface map wondering why it could not come up the coast. Again the issue is obvious... a huge Polar vortex that covered much of Canada was so massive and so intense that the Arctic jet circulating around the vortex was simply moving with velocities that were too high to enable any sort of phasing to occur. Result.... NO Phase.


 march1980.gif (35.49K)
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MARCH 26 1971... this is historically late March snowstorm dropped a heavy amount of snow over North Carolina Central and Southern Virginia as well as the Tennessee Valley. The 500 mbar pattern clearly shows why this event also did not turn up the coast. We did have a classic looking 50/50 Low in position and we actually had a block over northern Québec which was... a one-point part of a large -NAO. But we had a very strong Pacific jet that season and combined with the large vortex over north-central Canada the Arctic jet again was moving at a speed that was so strong that we simply do not get the phasing that one might think could occur in the sort of pattern.


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THE CURRENT POSSIBLE EVENT... MARCH 1-2

as we can see from the 0z 24 FEB Euro /CMC runs we are facing a similar sort of situation potentially with this event on March 1 -- 2. The models are clear that at this particular time they do not show a phase between the AJ and the STJ/ PJ. That does not mean a phase COULD not not occur OR WILL not OCCUR ...sSso yes this could change .

But as we get closer to the event ... this idea to look out for is whether or not the models are showing the northern branch phasing with the southern branch. If we do not see that then the odds of this being a major snowstorm for the northern Atlantic and New England are significantly reduced.



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Despite all this there are still so many things with this event that could go wrong it is hard to list them all.

For example the 500 low in the southern branch could stall over Alabama or Georgia as opposed to off the Georgia coast. If that happens then we are looking at mostly a rainy that for the Tennessee Valley North Carolina Virginia area!


Also there is NO closed deep 50/50 Low over southeast Cananda at all gig INTO this Potemtial event which is alawys BAD sign. In ALL of the cases listed above -- ALL of them --there was either a HUGE PC or a deep 50/50 Low. We have Neither in this possible event .

Another item... FEB 27-28 look to be pretty warm BEFORE that cold front moves through from the Midwest. We are going to have to get a LOT of CAA into the Middle Atlantic ...espcially for the TN valley NC and VA. Those areas could have a great 500 MB paten but still get screwed because of low level residual warmth and BL temps.


In addition as I have stated many times this event would go against the seasonal trend which has not been supportive of Southern track / Miller A events. Without a doubt every single significant or major event on the medium-range models this winter which has initially been portrayed as a Southern stream event/ Miller A ....has turned out to be a northern stream Miller B event. And as most of you should know by now ....strongly favors the Midwest and New England. Not surprisingly those areas again are having another record or near record winter!

[East_TN_Snowhound]

Great write up and obviously something you have been working on for several hours. Obviously a very low probability situation, but interesting nonetheless. Thanks for the post.

[sarwx2.0]

DTwxrisk, on Feb 24 2009, 10:39 AM, said:

...SET CONDITION CHARLIE .... SET CONDITION CHARLIE EVENT #6


This is not a high probability event. [size=2]I could easily blow up in my face.

:lmao:

[Matt Rogers]

My favorite DT quote of all time just now: I could easily blow up in my face.

[dT-REX]

mrwx72, on Feb 24 2009, 11:48 AM, said:

My favorite DT quote of all time just now: I could easily blow up in my face.

bite me matt :thumbsup:

[Midlo, va. home snow maker]

very good layout DT. top notch

[Pondo1000]

DTwxrisk, on Feb 24 2009, 11:39 AM, said:

[size=5]...SET CONDITION CHARLIE .... SET CONDITION CHARLIE EVENT #6

Hey Dave. Is there any chance that this phases earlier and puts the interior sections at risk?

[capecod04]

Awesome job DT.. :weight_lift:

[JERSEYSNOWROB]

Thanks for the update. KEEP HOPE ALIVE! :snowwindow:

[snowbrain]

Nice write up, I am sure some idiots will make assinine comments, they always do.

Thanks for presenting the nuts and bolts in a clear way for most to understand.

[ezweather]

Dave,

Great post. Thanks for taking the time to post your thoughts. I'm glad you stated that this is not a forecast, because some folks out there think that yeh, Dave said a HECS for the lower Mid-Atlantic. Glad you made that clarification. You probably should have used font size 40 on that one. Nice and bold.. I think the threat is there and its something you have monitor.

For me, whether we get a great storm next week, well, I just don't know. A part of me says yes, but the other says no. Give that all this winter the pattern has been so hostile for major winter storms, does that change next week? I think right now we can do some verification on how the models are handling the upper air. At least get some clues on what may happen for next week.

One thing that has been pretty amazing has been the wind this winter. It really tells me that the flow has been so fast, but maybe its telling me that a major storm may be in the offing.... The question may be now how, but when...

[WEATHER53]

I understand it's a discussion, a very skilled and detailed one. However, why not wrap it up and state what you think is most likely to occur?

[ShoreWXgal]

Wonderful discussion DT...Thank you for putting all the options out there!!

[RaleighWX]

good post, Dave,

here is my presentation from the EUS wx conference on southeast snowstorms

http://raleighwx.eas...resentation.zip

I also have reanalysis maps for alot of the events Dave posted if anyone wants them

[winterymix]

Looks warm.



Will it be white or wet?

[MDsnowstorm]

Considering how poorly modeled storms have been this year, and there being a rain event before this one, honestly I think DT is being smart not to go out on a limb and feeding the weenies with that information.

If you can't say something will occur with more than about 10-20% certainty, why throw it out there? You know even if he says his confidence is 10%, people will use his prediction against him.

How many times have we seen long term "most likely scenarios" issued with another event between the forecast date and the discussed storm coming back to act differently than progged and blowing up the long term potential, resulting in weenie suicides, or attempted ones?

It's sort of like predicting the record of NFL teams for the current season right before training camp opens.... injuries, Implosions (though with TO, that can be counted on every year), and other issues pop up and blow those standings forecasts apart.

WEATHER53, on Feb 24 2009, 12:02 PM, said:

I understand it's a discussion, a very skilled and detailed one. However, why not wrap it up and state what you think is most likely to occur?

[nesis]

ATTENTION: You Philly folks!

East of 476 is very close to PHL--In fact PHL is right on the line if you extrapolate 476 southward.

This event is highly UNPROBABLE for the Philly metro area to receive 8 inches or more over a widespread area.

IT DOES NOT HAPPEN WITH A:

Pos NAO
Neg PNA

But as DT said, this is more a threat to our south and west -- DIFFERENT CLIMO AREAS THAT HAVE DIFFERENT PATTERNS WITH RESPECT TO NAO AND PNA THAN WE DO.

Make sure you actually read every word of DT's post.

Much love,

[RaleighWX]

For a major snowstorm to occur in Raleigh, (6+ inches), it almost always falls into two categories.

1. Cut off 500mb low forms or moves into Ga/SC. This can occur either as a 500mb low that cuts off over the lower Miss River valley, or Deep South and than moves east or it just forms over Ga/SC. This usually either pops a strong low in the gulf that takes the right track, (Miller A) or forms a coastal low off the Ga/SC coast that is close enough to spread moisture back into colder air.
2. A supressed overrunning setup, which features strong southwest flow aloft, (usually a subtropical jet) advecting copious moisture, while the northern branch is strong enough and far enough south to lock in surface high pressures in the Great lakes/Northeast and provide low level cold air.

[ezweather]

Good points... That does not sound encouraging on what you say about the NAO and the PNA...

I think that there is a low probability. I don't think you can say not likely. I think the threat is there. Obviously, need to just monitor it for now. I think given that we saw a norlon event near the Philly airport, you can never let your guard down. So, I would say, we just need to monitor things and see what we may have the end of the week.

nesis, on Feb 24 2009, 12:18 PM, said:

ATTENTION: You Philly folks!

East of 476 is very close to PHL--In fact PHL is right on the line if you extrapolate 476 southward.

This event is highly UNPROBABLE for the Philly metro area to receive 8 inches or more over a widespread area.

IT DOES NOT HAPPEN WITH A:

Pos NAO
Neg PNA

But as DT said, this is more a threat to our south and west -- DIFFERENT CLIMO AREAS THAT HAVE DIFFERENT PATTERNS WITH RESPECT TO NAO AND PNA THAN WE DO.

Make sure you actually read every word of DT's post.

Much love,

[harryliv]

I remember the 80 storm Dave.I live in sw jersey and it snowed lightly all day ,but, you knew it wasn't gonna come up the coast here cause we had a constant NNW wind all day.The shore ,I believe, got some significant snow though.