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Wintry January 29th-30th ARCC Slam Dunk Winter Weather Threat

The fact that we are within 12 hours and not all of the models are in agreement, is a good thing. I think it could still go either way. It’s worth keeping an eye on it.
 
Crankywxguy on twitter said this thing is gonna be severely moisture starved and will undercut expectations.

His twitter handle tells me all I need to know. We are model to model, hi res vs global, forecast vs nowcast at this point. I’m not sure who’s opinion to trust.


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My experience in these situations (and being burned many years ago when first following weather models) is as follows.
1. The cold air is usually slower to arrive than modeled.
2. The back edge dries up quickly as earnest CAA kicks in.
3. Many times these “cold chasing moisture” scenarios end up with flurries at best on the backside.
4. The 3km NAM and RGEM blended is the best way to go in the short range.

Having said that I sure hope this event turns out differently but trusting the globals over high res models this close usually isn’t a good idea. Good luck everyone, I hope you get a nice snow!
 
My experience in these situations (and being burned many years ago when first following weather models) is as follows.
1. The cold air is usually slower to arrive than modeled.
2. The back edge dries up quickly as earnest CAA kicks in.
3. Many times these “cold chasing moisture” scenarios end up with flurries at best on the backside.
4. The 3km NAM and RGEM blended is the best way to go in the short range.

Having said that I sure hope this event turns out differently but trusting the globals over high res models this close usually isn’t a good idea. Good luck everyone, I hope you get a nice snow!
not the normal "cold chasing moisture" setup..as most of the precip is behind the front to begin with.
 
The cause for these storms are steep low level lapse rates and little sfc cape, would not be surprised if there’s a small hail report as mid level lapses get better 31E76421-896B-4661-955B-9FB3EA380185.png56D6059E-ADFB-46D5-8B5E-05D52C9D8B0A.png
 
NWS now saying snow/rain mix as far south as I10 in coastal counties of Ala/Fla More of course further north.
Hazardous Weather Outlook
National Weather Service Mobile AL
410 PM CST Mon Jan 28 2019

ALZ056>060-261>266-FLZ201>206-MSZ078-079-292215-
Conecuh-Butler-Crenshaw-Escambia-Covington-Mobile Inland-
Baldwin Inland-Mobile Central-Baldwin Central-Mobile Coastal-
Baldwin Coastal-Escambia Inland-Escambia Coastal-Santa Rosa Inland-
Santa Rosa Coastal-Okaloosa Inland-Okaloosa Coastal-Stone-George-
410 PM CST Mon Jan 28 2019

This Hazardous Weather Outlook is for south central Alabama,
southwest Alabama, northwest Florida and southeast Mississippi.

.DAY ONE...This Afternoon and Tonight.

A moderate risk for rip currents can be expected along the Gulf
beaches of Alabama and Northwest Florida by tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

A moderate risk for rip currents can be expected along the Gulf
beaches of Alabama and Northwest Florida Tuesday night through
Wednesday night.

Tuesday morning there is a potential for a mixture of rain and light
snow along and north of I-10, but little to no accumulations are
expected at this time. For those that may be driving further north
into central Mississippi and central Alabama, it should be noted
that roads could become hazardous Tuesday morning due to
accumulating snow. This will be especially true for bridges and
overpasses.
 
not the normal "cold chasing moisture" setup..as most of the precip is behind the front to begin with.

It’s definitely a cold chasing moisture setup. Temperatures through the entire column have to cool enough before snow can fall and is the reason the RGEM and 3km NAM are very light with snow and show mostly rain before a brief ending as snow. Global models struggle to pick these things up. Trust me, I learned the hard way many years ago when I first started following the weather closely and watching models.
 
It’s definitely a cold chasing moisture setup. Temperatures through the entire column have to cool enough before snow can fall and is the reason the RGEM and 3km NAM are very light with snow and show mostly rain before a brief ending as snow. Global models struggle to pick these things up. Trust me, I learned the hard way many years ago when I first started following the weather closely and watching models.
I just said it's not the normal setup. Usually most moisture is ahead of the front and it's truly trying to catch up before it's gone. In this case most will end up behind the front and it's only a matter of the changeover...not with flurries, but the most moisture being snow. We don't get winter storm warnings for true cold chasing moisture events...there is some back building of moisture behind the front..that's why some areas may get hit hard in Alabama, while up in Tennessee, not much at all. True cold chasing moisture events do better farther north.
 
I just said it's not the normal setup. Usually most moisture is ahead of the front and it's truly trying to catch up before it's gone. In this case most will end up behind the front and it's only a matter of the changeover...not with flurries, but the most moisture being snow. We don't get winter storm warnings for true cold chasing moisture events...there is some back building of moisture behind the front..that's why some ares may get hit hard in Alabama, while up in Tennessee, not much at all.

Wishing you guys the best of luck, I don’t see the NWS or global models verifying with this one but hope you all do see some snow!
 
Let's just be honest with ourselves. We are trying to predict ( in most cases guess) a small amount of precip. of up to a few tenths of an inch and predict (guess) precisely when and if the column will cool to allow snow to fall and how much of the small amount of precip (if any) will change snow. To predict one of the variables is hard. Add the variables together, virtually impossible to nail until now time. The best public mets in the SE (Mellish and Spann in my book) as well as NWS offices are consistently burned trying to do this. I have seen them all burned both by over and under forecasting these situations. January 14 and December 17 stand out on the good side, but there are many others. For someone on this forum to speak as if they think they know what will happen is merely foolish. Most of the time when folks try to prove how much they know, they usually prove just the opposite.

I could make similar comments on the LR, but that is for another thread.
 
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