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Misc Winter Weather Support Group

Myfrotho704_ said:
also another thing models bust at when it comes to wedging, is ruining your nice 74 degree day in April to it being 48 and foggy outside
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models struggle with CAD for a few reasons:
-how much solar radiation actually makes it to the surface is sometimes overestimated- models will render that fog layer as "sun" sometimes
-interface between stable surface layer and warm mid level- that's broken down via turbulent forces and tough microphysics for models to handle (they are making a lot of assumptions)
-topography is tough to render; CAMs have better vertical resolution which is why i like to let CAD events get within 60 hours or so before truly writing them off
-models are also terrible with the thermodynamics- both cooling from melting/sublimating snowflakes and the subsequent latent heat release of those raindrops back to sleet. that's a model forecast predicated on both the depth/intensity of the CAD and how much qpf falls- a model could theoretically have the preceding airmass perfect but could still be way off if the guidance on qpf is off by a wide margin

I still think they are by far the thorniest thing to predict around these parts and can really trip up models. one issue is that we haven't had a true, bona fide winter storm w wedging from hell to deal with in years. so there's a lot of mid tier events. the 1025s anchored on PA are easier on the models than the 1041s anchored in the fingerlakes. feb 13 2014 was a storm with a wedge from hell and i think if we had a storm of similar caliber, both in wedging and impact, we would see a lot of surprises as the storm was borne out. you're probably right on the marginal events though- getting easier for models to nail
 
ILMRoss said:
models struggle with CAD for a few reasons:
-how much solar radiation actually makes it to the surface is sometimes overestimated- models will render that fog layer as "sun" sometimes
-interface between stable surface layer and warm mid level- that's broken down via turbulent forces and tough microphysics for models to handle (they are making a lot of assumptions)
-topography is tough to render; CAMs have better vertical resolution which is why i like to let CAD events get within 60 hours or so before truly writing them off
-models are also terrible with the thermodynamics- both cooling from melting/sublimating snowflakes and the subsequent latent heat release of those raindrops back to sleet. that's a model forecast predicated on both the depth/intensity of the CAD and how much qpf falls- a model could theoretically have the preceding airmass perfect but could still be way off if the guidance on qpf is off by a wide margin

I still think they are by far the thorniest thing to predict around these parts and can really trip up models. one issue is that we haven't had a true, bona fide winter storm w wedging from hell to deal with in years. so there's a lot of mid tier events. the 1025s anchored on PA are easier on the models than the 1041s anchored in the fingerlakes. feb 13 2014 was a storm with a wedge from hell and i think if we had a storm of similar caliber, both in wedging and impact, we would see a lot of surprises as the storm was borne out. you're probably right on the marginal events though- getting easier for models to nail
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Yep. Even jan 2022, the first weekend winter storm had a pretty deep cold CAD event. sfc temps in low mid 20s, and that one busted cold not at the sfc but aloft at 925mb around the Charlotte area and turned what was suppose to be a big ZR event to a big sleet event
 
Since December 1st we've had 2 severe storm threads and 1 "winter storm" thread. I wonder if we finish this winter with more severe or more winter storm threads....

Tough call...if this was Vegas it would be even money.
 
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