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STORM MODE THREAD- January 22-23 Mid Atlantic Storm Thread #4 - No Banter

stormtracker

By stormtracker,
in Mid Atlantic

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MN Transplant

MN Transplant

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Correct - Feb 10, 2010 there was the burst overnight (small compared to what we expect from this) and a ton of worry on the board at eastern that it was over - and a few mets pointing out it was about to get good - then the pivot happened and a blizzard ensued for a lot of the area (but not SW of DC I don't believe).

 

Of course that was a true Miller B, so a bit different.

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dtk

dtk

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I was too lazy to respond to this before, but I saw the question several times about recon/special observation availability for the non-US operational models.  All of that data is distributed via GTS and made available.  For example, here are the raobs and dropsondes that went into the ECMWF 00 UTC last night:

 

ps2png-atls15-95e2cf679cd58ee9b4db4dd119

 

The green dots are dropsondes from recon missions.  There was a mission over the GOM as well as a Hawaii based mission for some ENSO rapid-response campaign.  I'm certain that the Canadians, UKMO, etc., all used these observations.  [Feel free to move this to banter if you see fit].

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SomeguyfromTakomaPark

SomeguyfromTakomaPark

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  Last night's NCAR ensemble, which we've found often does quite well, has a mean snowfall for most of DC Metro in the 24-36" range by 00z Sunday.

 

http://ensemble.ucar.edu/images.php?d=2016012200&f=snowacc_mean&r=MATL

 

Hey,  I found that product in a State College AFD and have been using it to forecast the upslope events for the ridges in WV and it has been excellent.  

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dtk

dtk

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  Last night's NCAR ensemble, which we've found often does quite well, has a mean snowfall for most of DC Metro in the 24-36" range by 00z Sunday.

 

http://ensemble.ucar.edu/images.php?d=2016012200&f=snowacc_mean&r=MATL

Yeah, I've started looking at this much more regularly now.  If you look at the individual members (postage stamp simulated reflectivity), you can see there are a couple of members that do some funny things regarding the dry slot, but this should ease concerns....somewhat at least.

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eurojosh

eurojosh

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I was too lazy to respond to this before, but I saw the question several times about recon/special observation availability for the non-US operational models.  All of that data is distributed via GTS and made available.  For example, here are the raobs and dropsondes that went into the ECMWF 00 UTC last night:

 

 

 

The green dots are dropsondes from recon missions.  There was a mission over the GOM as well as a Hawaii based mission for some ENSO rapid-response campaign.  I'm certain that the Canadians, UKMO, etc., all used these observations.  [Feel free to move this to banter if you see fit].

 

Same proviso about moving this to banter if needed...

 

2 questions - how long before the model runs is the data cutoff?  1-2 hrs?

 

Can special dropsonde missions 'bias' the outcome by over-sampling certain (stormy, moist) areas?

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clskinsfan

clskinsfan

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  Last night's NCAR ensemble, which we've found often does quite well, has a mean snowfall for most of DC Metro in the 24-36" range by 00z Sunday.

 

http://ensemble.ucar.edu/images.php?d=2016012200&f=snowacc_mean&r=MATL

 

Its cool how that shows the heavy snow on top of the mountain ranges. 

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dtk

dtk

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Same proviso about moving this to banter if needed...

 

2 questions - how long before the model runs is the data cutoff?  1-2 hrs?

 

Can special dropsonde missions 'bias' the outcome by over-sampling certain (stormy, moist) areas?

1) It's different for each model:  For the GFS, the start time is roughly 2h45 after synoptic time ... so 0245 UTC for the 00UTC cycle.  Any observation that is arrived by then and is valid for the window between +/- 3 hours (2100 UTC - 0300 UTC) will be assimilated.  ECMWF is even later with a longer assimilation window.

 

2) No.  These extra observations are not likely to significantly change the outcome at least in terms of the large scales.  See for example here:  http://journals.ametsoc.org.proxy-um.researchport.umd.edu/doi/abs/10.1175/MWR-D-12-00309.1

 

They *may* be useful for helping to nail down specifics such as timing, where small scale features set up in the very short term (<24h), etc.  The reality is that so much data goes into modern day NWP that small subsets of observations don't have as much impact as they used to.

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eurojosh

eurojosh

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1) It's different for each model: For the GFS, the start time is roughly 2h45 after synoptic time ... so 0245 UTC for the 00UTC cycle. Any observation that is arrived by then and is valid for the window between +/- 3 hours (2100 UTC - 0300 UTC) will be assimilated. ECMWF is even later with a longer assimilation window.

2) No. These extra observations are not likely to significantly change the outcome at least in terms of the large scales. See for example here: http://journals.ametsoc.org.proxy-um.researchport.umd.edu/doi/abs/10.1175/MWR-D-12-00309.1

They *may* be useful for helping to nail down specifics such as timing, where small scale features set up in the very short term (<24h), etc. The reality is that so much data goes into modern day NWP that small subsets of observations don't have as much impact as they used to.

Awesome, thanks.

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