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Wintry Feb 6-8 2022 Winter Potential

rburrel2 said:
Guys the NAM is only warmer at the surface b/c it doesn't have much precip. It would wetbulb in the upper 20's like the rgem if it started showing a solid precip shield.
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Yes, but why does it not have much precip?
 
Ollie Williams said:
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If this doesn’t show how cold biased the RGEM is, I don’t know what would. Don’t just focus on your area. Look at how much colder it is in VA, TN, etc. Also, Jackson, MS, for example, where it has 16 vs 30 for the other models. It has Birmingham at 23 vs low 30s on others. Washington, DC, at 12 vs 20s others.
 
I think the big X factor would be how early precip gets in .. I could see an earlier arrival and that would mean an area of light freezing rain at least for a lot of the area with how cold dews are we certainly could wet bulb down to freezing .. but I certainly wouldn’t expect warning criteria nothing around here unless every other model decides to trend colder as well (which looks unlikely)
 
Starting to think some light ZR is becoming a possibility Monday morning, wouldn’t last long given the lack of a cold feed and diurnal timing, minor event at best
 
It’s worth noting the HRRR/RAP brings in precip earlier, in the morning, which is why there’s ZR in the first place, GFS brings it in around noon
 
15z rap continues to show freezing rain, it’s worth noting that while temps are marginal, the precipitation looks light 501B3E30-8693-4034-BB0D-6E7235EB3C1B.png2F84FF28-4A8B-48D8-82C1-E2C6041CFFC9.png570724D3-04A6-45B7-BDDD-F105B2536EDC.png
 
Myfrotho704_ said:
It’s worth noting the HRRR/RAP brings in precip earlier, in the morning, which is why there’s ZR in the first place, GFS brings it in around noon
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Yep this is what I was talking about earlier .. sometimes these type of light events like to spread precip over us quicker but only time will tel .. the earlier the more of an issue it could be
 
Key here is timing of precip .. CMC and short range have precip coming in earlier so you get more icy situations (which eventually go to rain) but Gfs doesn’t see any precip at that point and brings precip in after 12 164EE775-A39A-4BA5-91AD-8D4441F25BA7.jpeg1A819BC7-4F3F-428C-9609-7AA14214846D.jpeg
 
This is a thin margin, novelty event. Fun to track. That said, its fools gold to side with the soon to be deceased NAM verse other modeling. Again we are discussing 1 to 3 tenths precip here and surface temps trending 1 -2 degrees eitheir way. Obviously big impact to sensible weather. RDPS and euro been on this for past several cycles.
 
Yep, the NAM is still pretty good with thermals if it's showing the accurate weather outcome imo... but it's so horrible in predicting the weather you can't use them. I'll take the NAM thermals in to consideration when it finally starts showing a similar evolution to the modeled consensus.
 
I'll say this too.... in the past, when models have busted badly being too warm in the short range it's typically related to not modeling dew points/wetbulbing accurately and as a result wetbulbing is way under modeled. This happened in 2015 with an in-situ wedge event.

This could be the same kind of sneaky set up where models are showing a lot of 32-33 degree light rain but people under consistent precip wind up wetbulbing down to 28-29 instead. The dewpoint depressions being shown Monday morning certainly support that possibility. Here are my notes for the 2015 storm.

February 16, 20151 inch of sleet 1/10th inch of ice27huge bust in our favor, hi-res models at 31/32 for low temp and freezing rain to rain day before event, got 90% sleet and just a little freezing rain, wetbulbed to around 27 and temp was still 31 as final band came through
 
rburrel2 said:
I'll say this too.... in the past, when models have busted badly being too warm in the short range it's typically related to not modeling dew points/wetbulbing accurately and as a result wetbulbing is way under modeled. This happened in 2015 with an in-situ wedge event.

This could be the same kind of sneaky set up where models are showing a lot of 32-33 degree light rain but people under consistent precip wind up wetbulbing down to 28-29 instead. The dewpoint depressions being shown Monday morning certainly support that possibility. Here are my notes for the 2015 storm.

February 16, 20151 inch of sleet 1/10th inch of ice27huge bust in our favor, hi-res models at 31/32 for low temp and freezing rain to rain day before event, got 90% sleet and just a little freezing rain, wetbulbed to around 27 and temp was still 31 as final band came through
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That ended up being a largely sleet event here when the forecast was for .3-.5” of ice accrual. If I remember correctly, there was a small mesohigh that formed over VA that helped keep lower dews locked in
 
These setups can indeed be very tricky, but welcome to the frickin' Southeast lol. If the moisture could roll in during early morning hours with heavy enough rates to crash the column, perhaps we could have predominately sleet. Then again, especially pertaining to the past few years, what I think I know versus what has occurred?? Someone will probably get half a foot of snow??(Disclosure: This is not a forecast.)
 
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