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Wintry Machine Learning Mauler 1/30-2/1

iGRXY said:
snku_acc-imp.us_state_nc_va.png

Absolutely smoked
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Now that was ICONic.
 
Stormsfury said:
On hr 48, it actually popped a new low east of Charleston after having one further north off ILM. Cyclonically looped.
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To me it makes sense for the low to pop somewhere between CHS to ILM. I mentioned it this morning but there is a very sharp change in SSTs in that area that can create a natural baroclinic zone
 
Stormdoc said:
I kind of have a hunch the models are slowly seeing this process. Instead of a typical north trend, we will see the models continue with a west trend, pulling the low closer to the coast. This should bring the heavier precip further west, similar to Jan 2000. Of course, this only happens if the better west trend of the upper low and more negative tilt continues.
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What’s the analysis outside of the hunch?
 
Well @WeatherNC has been saying it, slp closer to the coast, almost instant occlusion and watch precip explode. He's done these things a time or two before and models seem to be heading in that direction. QPF steadily increasing and backing w/nw, never underestimate a bombing lp right along the Gulf Stream. We might not be done
 
RBR71 said:
Well @WeatherNC has been saying it, slp closer to the coast, almost instant occlusion and watch precip explode. He's done these things a time or two before and models seem to be heading in that direction. QPF steadily increasing and backing w/nw, never underestimate a bombing lp right along the Gulf Stream. We might not be done
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Murphy to Manteo.......Goals!
 
superjames1992 said:
Super confused by this as well. I would expect the National Blend of Models to more or less reflect the models I see, but it often doesn’t seem to. Also, what is the difference between the NBM and the Parallel NBM?
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NBMv4 has these models/weights:

NBMv5 (parallel) is a bit different but the weights haven't been released. Pretty sure they removed SREF and added AI Models (like AIFS). They also do some different bias correction methods in v5 such as probability matched mean to achieve more accurate/unsmoothed outputs.
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RGEM at hr42 here

Jan 29 RGEM Snow.png


Here is the Charlotte sounding at that time. 19 degrees at the surface with a DEEP Dendrite Growth Zone from 925mb up to 680mb

Jan 29 RGEM Sounding.png


On top of that, there's mid-level frontogenesis going on here in the purple at 850mb. When air parcels collide in the mid-levels, they must rise!. The frontogenesis being co-located within the Dendrite Growth Zone - we don't see that crap around here - that's what happens in New England. Typically, we have fronto in the 850 to 700mb layers, but our DGZone is up near 600 - 500mb. Potential here!

Jan 29 RGEM Fronto.png
 
RBR71 said:
Well @WeatherNC has been saying it, slp closer to the coast, almost instant occlusion and watch precip explode. He's done these things a time or two before and models seem to be heading in that direction. QPF steadily increasing and backing w/nw, never underestimate a bombing lp right along the Gulf Stream. We might not be done
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Taking the 0z RDPS surface reflection at face value, it bounces around initially but in general it's parked in roughly the same spot due east of Cape Lookout at hrs 42 and 60, during that time it drops 34mb. That's almost unheard of at our latitude.

Granted the northern Mid-Atlantic and southern New England get some orapgfrhic enhancement as you head inland but still, Winchester/Front Royal are often jackpots for big MA bombs, similar are the Catskills for bombs which affect southern New England.

I'd expect a continued uptick in QPF associated with the coastal, somewhere in the 1.4" imo seems reasonable top end for areas fortunate to get under the best 700mb fronto, right now that looks like the southern Coastal Plain, Duplin/Wayne/Sampson. 1" amounts should be fairly common east of 95 and south of 64, possibly down to Lumberton and Florence, then east to ILM.
 
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JQPublic said:
What’s the analysis outside of the hunch?
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I have noticed in the past, just like with the northwest trend, models start seeing better the surface features of these bombing lows, which consolidates the precip more heavily to the northwest of low pressure systems, “filling it in” just like we are seeing with the NAM and ICON
 
griteater said:
RGEM at hr42 here

View attachment 191549


Here is the Charlotte sounding at that time. 19 degrees at the surface with a DEEP Dendrite Growth Zone from 925mb up to 680mb

View attachment 191550


On top of that, there's mid-level frontogenesis going on here in the purple at 850mb. When air parcels collide in the mid-levels, they must rise!. The frontogenesis being co-located within the Dendrite Growth Zone - we don't see that crap around here - that's what happens in New England. Typically, we have fronto in the 850 to 700mb layers, but our DGZone is up near 600 - 500mb. Potential here!

View attachment 191551
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Almost like we're setting up some kind of TROWAL or something?
 
griteater said:
RGEM at hr42 here

View attachment 191549


Here is the Charlotte sounding at that time. 19 degrees at the surface with a DEEP Dendrite Growth Zone from 925mb up to 680mb

View attachment 191550


On top of that, there's mid-level frontogenesis going on here in the purple at 850mb. When air parcels collide in the mid-levels, they must rise!. The frontogenesis being co-located within the Dendrite Growth Zone - we don't see that crap around here - that's what happens in New England. Typically, we have fronto in the 850 to 700mb layers, but our DGZone is up near 600 - 500mb. Potential here!

View attachment 191551
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Yup, this is another reason why I kept saying this is very New Hampshire-like snowstorm with epic forcing, deep cold, and borderline blizzard conditions with the wind (plus actual blizzard in the OBX). Up north, we're usually looking for two bandings of FGEN at 850 and 700.
 
WeatherNC said:
Taking the 0z RDPS surface reflection at face value, it bounces around initially but in general it's parked in roughly the same spot due east of Cape Lookout at hrs 42 and 60, during that time it drops 34mb. That's almost unheard of at our latitude.

Granted the northern Mid-Atlantic and southern New England get some orapgfrhic enhancement as you head inland but still, Winchester/Front Royal are often jackpots for big MA bombs, similar are the Catskills for bombs which affect southern New England.

I'd expect a continued uptick in QPF associated with the coastal, somewhere in the 1.4-1.7" imo seems reasonable top end for areas fortunate to get under the best 700mb fronto, right now that looks like the southern Coastal Plain, Duplin/Wayne/Sampson. 1" amounts should be fairly common east of 95 and south of 64, possibly down to Lumberton and Florence, then east to ILM.
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Winchester up into the Catoctins and northern MD always jack in those MA bombs while DC gets a minima. Famous dform band there with a little orographic enhancement
 
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