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January Storm Term Threat Discussions (Day 3 - Day 7)


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16 minutes ago, Ralph Wiggum said:

Surface low is actually farther W and maybe a mile N of the 12z run.

The secondary yes...but its ALL about the primary to our west...we need that to hold on longer...and this ICON run kills the primary a little quicker further south then the 12z run.  That is the key because the flow becomes more compressed the further east you get.  Once the storm transfers I expect absolutely no northward component and the precip will actually likely start to sink southeast from there.  We need the primary to hold on and create that "inverted" trough feature to train moisture along from as the secondary forms.  That inverted trough banking up against the compressed flow to the northeast creates a really strong focus for lift.  That is the mechanism to get the precip NW.  If the primary dies too soon the secondary will wrap up like that ICON run did to our south.  Ideally we want to get the primary to hold on into WV or southern Ohio.  Yes I know that sounds like blasphemy to some who equate a west track to rain...but once the transfer happens there is likely to be no further northward component to the precip shield so we need the primary to hold until AFTER we get the inverted trough up through our area and the heavy precip is overhead.  Then it can make the jump.  If it jumps to our south...we get that icon solution.  

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10 minutes ago, psuhoffman said:

Before I say this let me preface that I am still optimistic for this storm.  I think we are in a pretty good spot.  I think this will work out.  But I wanted to highlight the double bind we are in right now and why we keep failing despite what has been one of the better longwave patterns we have had in many years all winter long.  

Look at this from the 18z EPS.

18zEPS.thumb.png.e84aa804d5dd068bc05bf7c895083224.png

Now...that was a pretty good run...but we still need a north adjustment.  The target was still just a little south of DC on that run.  There were some nice hits but too many misses still.   So we need a little more ridging or relaxing of the suppressive flow over the northeast to get the storm to trend north some...but look at where the "cold" boundary is as the storm approaches there!  How much can we even afford to "give"?  And yes the temps crash after once the storm secondary's and bombs to our southeast...but because of the suppressive flow to our north we need to get the primary up into southern Ohio or WV before it transfers to get heavy snow here.  But what if that ridging does shift north say 50/100 miles?  How much further before that primary maybe holds on into western PA and the transfer ends up to off NJ instead of off VA Beach and we get a miller b jump over us solution?  And about 9 members of the 18z GEFS had just that.  We're walking a razor edge on EVERY possible snow solution right now because of "THIS" double bind.  Right there...on that run...we have barely enough suppression to prevent warmth from surging north of us ahead of the wave...but its slightly too much suppression for a storm to amplify enough to "crush" us.  We have absolutely no margin of error because the cold is so freaking pathetic that to resist warmth from surging north of us ahead of any wave we need such a suppressive flow that it prevents any storms from amplifying.  If the suppression relaxes we can get a storm but its rain.  

 

I debated not posting this... but I think we can keep this from becoming an out of control debate about "you know what".  I am not going to even say its all "THAT".  There are some factors that maybe aren't permanent.  The PV got sent to the other side of the globe, the pac torched north america all fall and early winter and so perhaps the base state is even warmer now then just due to AGW.  But regardless of all that...this is the bind we are in right now trying to get snow regardless of the pattern.  The same exact equation is playing out Monday also.  That storm is suppressed so much it becomes a strung out mess that barely gets heavy precip to the mason dixon line...and NYC is on the northern fringes.  Yet DC can't get any snow???  If the storm was suppressed much more there would be no heavy precip anyways...this keeps playing out time and again all winter long.  

The storm Thursday to Friday I think is further North and west and will have heights building out in front.  Thinking the SE ridge bumps this north to about Ocean City Maryland then moves east-northeast from there in response to the 50/50 block up north. This has lots of potential. 

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11 minutes ago, psuhoffman said:

The secondary yes...but its ALL about the primary to our west...we need that to hold on longer...and this ICON run kills the primary a little quicker further south then the 12z run.  That is the key because the flow becomes more compressed the further east you get.  Once the storm transfers I expect absolutely no northward component and the precip will actually likely start to sink southeast from there.  We need the primary to hold on and create that "inverted" trough feature to train moisture along from as the secondary forms.  That inverted trough banking up against the compressed flow to the northeast creates a really strong focus for lift.  That is the mechanism to get the precip NW.  If the primary dies too soon the secondary will wrap up like that ICON run did to our south.  Ideally we want to get the primary to hold on into WV or southern Ohio.  Yes I know that sounds like blasphemy to some who equate a west track to rain...but once the transfer happens there is likely to be no further northward component to the precip shield so we need the primary to hold until AFTER we get the inverted trough up through our area and the heavy precip is overhead.  Then it can make the jump.  If it jumps to our south...we get that icon solution.  

The magic spot for this scenario up here in  NE Maryland extreme southern Pa is that primary low to stop within 50 miles of Elkins West Virginia. The NAM illustrates this perfectly then has that east west norlun trough  as the weak primary is long gone. 

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4 minutes ago, Kevin Reilly said:

The storm Thursday to Friday I think is further North and west and will have heights building out in front.  Thinking the SE ridge bumps this north to about Ocean City Maryland then moves east-northeast from there in response to the 50/50 block up north. This has lots of potential. 

I agree but I was pointing out that even though we need a "north" trend...we really barely have a cold enough profile to begin with.  That's indicative of a larger scale issue then just this specific event.  

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Again...I think we are very possibly in the very very narrow "sweet spot" for this one.   But this illustrates my point...we needed a north adjustment...but if you payed attention to the whole setup we really didnt have a lot of wiggle room with the thermal boundary to begin with.  So we get a north adjustment and suddenly rain becomes an issue again.  No margin for error either way.  Luckly I think we might be in the razor thin "win" zone for this one.  But damnit it can't keep being this difficult or we are rarely ever going to win.  

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