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Weekend Storm Discussion Part II, 2/18-2/19


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The euro has and always will hate us

Check this out:

http://www.hpc.ncep.noaa.gov/discussions/pmdhmd.html

THE 12Z/00Z ECMWF MOVE THE NORTHERN STREAM SHORTWAVE OUT A LITTLE

QUICKER THAN THIS SYSTEM...BUT ITS NEWER RUN ALLOWS THE SYSTEM TO

DECAY/SHEAR UNDER THE BASE OF THE NORTHERN STREAM

SHORTWAVE...WHICH IS AN IMPROVEMENT OVER ITS PRIOR RUN. THIS

LEAVES THE 00Z NAM/00Z GFS/00Z UKMET/00Z ECMWF SOLUTIONS AS

CONTENDERS. LOOKING AT THE 700 HPA LEVEL...THE 00Z NAM IS THE

DEEPEST OF THE GUIDANCE WITH THIS SYSTEM /ONE OF ITS BIASES WITH

POTENTIAL SNOW STORMS ACROSS THE LOWER 48/...EVEN AS IT SHOWS A

POSITIVE TILT/MORE OPEN LOOK ALOFT. THIS SYSTEM IS COMPOSED OF A

PAIR OF STRONG SHORTWAVES IN THE MID-LEVELS...WHICH MEANS EVEN IF

NOTHING ELSE IS CONSIDERED A MORE OPEN LOOK AT 500 HPA/700 HPA

LEVELS WOULD BE ADVISABLE ACROSS THE EAST AS THE SHORTWAVES DO NOT

APPEAR TO MERGE OVER THE LOWER 48. THIS ARGUES AGAINST THE 00Z

ECMWF/00Z UKMET SOLUTIONS. WILL THEREFORE PREFER THE 00Z GFS

SOLUTION HERE WITH BELOW AVERAGE CONFIDENCE CONSIDERING THE DETAIL

ISSUES OF THE DETERMINISTIC GUIDANCE...AND THE USUAL ISSUES WITH

NORTHERN/SOUTHERN STREAM SHORTWAVE INTERACTIONS.

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Gfs would be a 4-5 inch snowstorm ...still hoping for a northern trend today of about 50-100 miles

One of the things that worries me a little in terms of the bust potental is that the GFS has been very consistent with setting up a heavy band across WV but then during subsequent panels, the band seems to dissapate as the storm passes by the our south... the 00z euro does something very similar to this yet the band of snow initial sets up further south and west in to TN and then almost disappear as the storm exits the coast (hours 69-78 via wundermap- this is all a have access to). I would be curious to understand what the models are picking up on to cause this? Perhaps the storm is getting sheared out as it uncounters the westerly flow? Perhaps a met could comment.

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One of the things that worries me a little in terms of the bust potental is that the GFS has been very consistent with setting up a heavy band across WV but then during subsequent panels, the band seems to dissapate as the storm passes by the our south... the 00z euro does something very similar to this yet the band of snow initial sets up further south and west in to TN and then almost disappear as the storm exits the coast (hours 69-78 via wundermap- this is all a have access to). I would be curious to understand what the models are picking up on to cause this? Perhaps the storm is getting sheared out as it uncounters the westerly flow? Perhaps a met could comment.

Not a Met and will probably explain this poorly but the the problem looks to be the confluence. If you look at the 500mb charts you will see that the lines in the chart are converging to the north and east which means that air is piling up through that region. In the upper atmosphere when that occurs the air has only one direction to go and that is down which is not conducive to create precip. What you would like to see is diffluence where the lines are separating at 500mb which creates rising air flow from the lower levels which creates condensation and precip. Again not a Met so maybe one can explain it better or correct me if I am wrong.

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Weenie suicide alert if the precip slides east on the 12Z models.

We got a storm and the most suppressed models are outliers.

Cross your fingers and cross your toes for that northward trend

for the 0Z models this eve. Wear your PJs inside out. Buy TP

if you are using.

Im at work using their trashy computers,just waiting for the 12z nam.If it comes in south i'll probably be the 1st weenie suicide.No wait,i'll defenitly be the 1st.For my area I need a north shift of at least 50 miles,100 would be prefered.

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Not a Met and will probably explain this poorly but the the problem looks to be the confluence. If you look at the 500mb charts you will see that the lines in the chart are converging to the north and east which means that air is piling up through that region. In the upper atmosphere when that occurs the air has only one direction to go and that is down which is not conducive to create precip. What you would like to see is diffluence where the lines are separating at 500mb which creates rising air flow from the lower levels which creates condensation and precip. Again not a Met so maybe one can explain it better or correct me if I am wrong.

Awesome explanation... thanks!

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Im at work using their trashy computers,just waiting for the 12z nam.If it comes in south i'll probably be the 1st weenie suicide.No wait,i'll defenitly be the 1st.For my area I need a north shift of at least 50 miles,100 would be prefered.

Don't know if I would get to excited one way or the other until tonight's 00Z run of the NAM when it gets into it's wheelhouse of 36-48 hours.

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just saw the 6z nam and gfs...looks to me like we're on the northern fringe of a signficant event...just need a little jog north to get into our comfort level. at 60 hours out, i'll take it. also, this is obviously not pd2, but i remember even that storm coming north slightly more than advertised even with that huge high. i like (edit: i'm ok with) where we're at...at least for the next hour.

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I will be shocked if this isn't a solid hit in the area even up to Philly and the southern half of NJ. That's the way these suppressed gulf storms roll typically.

agreed...Of course I have been saying that over and over so I am going to look pretty bad if this is "suppressed".....I think we are still seeing the models try and figure out the track....once the general idea/track is similar then the jog north usually begins....so if the 0.5" cutoff at the 12z runs or 18z runs is 50-100 mi south of DC, over the next 24-36 hours we will see that jog north through precip shield expansion and a track/strength of low adjustment.....The euro was extremely concerning though with how a formidable healthy storm system just got b-itchslapped in a period of a few hours

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To be honest, when i say a 1000 over Birmingham, I get pretty excited, im having trouble finding the euro's reasoning for crushing the storm like that. However, i am with you thinking this will be north, ever since 12z today went south, i thought we'd see some hints tonight,

but the real return north would be 12z, which i strongly believe.

i don't know if it will be at 12Z or not if at all, but we still have all day today and tomorrow to finalize the details....The Euro was a really really bad run....dry through much of VA even......we need the euro on board....

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agreed...Of course I have been saying that over and over so I am going to look pretty bad if this is "suppressed".....I think we are still seeing the models try and figure out the track....once the general idea/track is similar then the jog north usually begins....so if the 0.5" cutoff at the 12z runs or 18z runs is 50-100 mi south of DC, over the next 24-36 hours we will see that jog north through precip shield expansion and a track/strength of low adjustment.....The euro was extremely concerning though with how a formidable healthy storm system just got b-itchslapped in a period of a few hours

The starting point for the Northward jog or precip expansion needs to be where the NAM and GFS has it IMO....if it's the euro then I think a lot of us may be toast

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i don't know if it will be at 12Z or not if at all, but we still have all day today and tomorrow to finalize the details....The Euro was a really really bad run....dry through much of VA even......we need the euro on board....

I'd like to be in the jackpot lol . The euro has pissed on us all winter with .03 and .04s...I think it's wrong this time

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agreed..if what the euro portrayed last night is realistic, we are kind of screwed though we could still back our way into a 1-3"event

Yeah....this thing is giving off the impression that any move North will not be large but very subtle....I do like the SREF probabilities for 4"+ of snow though for most of the area.....2-4" expectations should be where most of us should be sitting right now...we should have the colder air just not the precip...

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not that it matters much but my optimism was somewhat predicated on the idea that the southern stream could amplify sufficiently on its own without a phase even with confluence over New England...If we cant get hit by a storm with a negatively tilted trough and a 1000mb surface low over Birmingham then I may just be wrong.....hopefully it works itself out in our favor....I am chasing if it is going to be a miss here....

Just saw the Euro a little while ago. What strikes me is the surface low jump. As your posts went last night, everything was going great with the low going through N. Alabama into Georgia, then that low dies and the new one forms over SC and moves over Wilmington. That's when the precip shield stops its northern progression. It is a messy 500 map at that time, so I'm not sure I buy the surface depiction.

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Yeah....this thing is giving off the impression that any move North will not be large but very subtle....I do like the SREF probabilities for 4"+ of snow though for most of the area.....2-4" expectations should be where most of us should be sitting right now...we should have the colder air just not the precip...

2-4 is unacceptable with a storm this large.

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I'd like to be in the jackpot lol . The euro has pissed on us all winter with .03 and .04s...I think it's wrong this time

the run was goofy but the whole pattern is goofy.....I still think there is so much working against us for a high standard deviation/percentile event, but a 4-8" event isn't that uncommon or unreasonable....even 3-6"....The Euro is extremely concerning because the GFS/NAM beng where they are right now is not a bad thing.....I never extrapolate model runs and my maps are a bit coarse but Euro looked like a massive hit last night before things went wrong....I'm going to keep my mouth shut this afternoon during the run and just let it play out....Jason and I put a hex on the run....You can't screw with the euro...You have to show it respect and love and deference at all times or it will turn on you

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the run was goofy but the whole pattern is goofy.....I still think there is so much working against us for a high standard deviation/percentile event, but a 4-8" event isn't that uncommon or unreasonable....even 3-6"....The Euro is extremely concerning because the GFS/NAM beng where they are right now is not a bad thing.....I never extrapolate model runs and my maps are a bit coarse but Euro looked like a massive hit last night before things went wrong....I'm going to keep my mouth shut this afternoon during the run and just let it play out....Jason and I put a hex on the run....You can't screw with the euro...You have to show it respect and love and deference at all times or it will turn on you

The euro does look goofy as it has the confluence well north of us at 72 suggesting the heavier precip would get to us and then for some reason shears it almost due east. The ukmet has come north but only gives us around .40".

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the run was goofy but the whole pattern is goofy.....I still think there is so much working against us for a high standard deviation/percentile event, but a 4-8" event isn't that uncommon or unreasonable....even 3-6"....The Euro is extremely concerning because the GFS/NAM beng where they are right now is not a bad thing.....I never extrapolate model runs and my maps are a bit coarse but Euro looked like a massive hit last night before things went wrong....I'm going to keep my mouth shut this afternoon during the run and just let it play out....Jason and I put a hex on the run....You can't screw with the euro...You have to show it respect and love and deference at all times or it will turn on you

What bothers me some is that even though the GFS and NAM both still give the area a nice little snow...they both have been trending South with their 6z runs....12z needs show a jog North or at least a halt to any Southern movement for confidence levels to remain ok

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