Newman

Welp the NAM, HRW-FV3 suite, and RRFS are all showing real solid hits now

NAM is widespread 3-5", lolis of 6" across SE PA. I do think this is one of those overamped NAM runs, especially with how stark the difference in that NS wave is from last run. Really want to see Euro jump on board with a sharper NS wave.

I'd love to read Mount Holly's night shift AFD on this one

The last 5 run trend of the GFS is wild, at some point do we see this stop trending? I still think this run is over the top and we see something more like the ICON or Euro, but it's been a long time since we've seen such significant shifts in guidance to produce a *favorable* outcome within 72 hours of an event

GFS is a real solid hit. Are we really doing this? Lol

GFS looks solid for SE PA. Like I said, keep ticking this slowly each run up until Sunday night and it's gonna be a legit storm

The Euro OP showing a similar shift is intriguing, as well as other guidance shifting towards it. If we can slowly tick that southern vort more progressive and that northern stream a tad slower/sharper from here until game time, we'll have a snowstorm on our hands. Still not buying it yet, but the 12z EPS is way north as well

Here are the individual AIFS ensembles. I counted about 24/50 members have plowable (3" or greater) snow into Philly. Just about that many have 6"+ or even 12"+ as well. Truly boom or bust. It all depends on if we phase or not with the NS wave. Let's ride member 29, 46 or 50 and call it a winter. And just to clarify, I'm not calling for a significant snowstorm with this one yet. I will need to see substantial shifts in other guidance and for the AIFS to hold the line in future runs.

AIFS ENS is more tightly clustered off the Mid-Atlantic coast, QPF mean is 0.7" in Philly (some of that is probably rain at initial onset). There's probably a few big ones in the AIFS ENS individuals

I haven't chimed in on this threat really because it's super thread the needle, but the Euro AI has the favorable changes we need at hour 48-54 with that piece of northern energy. Also, our southern vort is a bit more progressive which allows for more constructive phasing vs destructive phasing between the two shortwaves. The flow is so progressive so I'm just not sure how we get that NS wave to phase in, but crazier things have happened

EPS is a 3.4" mean in Philly, 55% chance snow totals > 1", compared to only 33% at 6z

About 0.6" new snow in Fleetwood overnight and this morning. Current temp is 10° and dropping. Reading is currently blowing at 25 mph with gusts up to 45.

Long way out there, but it seems like models are hinting at two potential storm chances coming up: 2/11 and 2/15. Depending on how strong the first wave gets, it could dampen the flow and cause 2/15 to stay suppressed (ala 12z Euro AIFS). Everything will also depend on how strong the confluence holds across New England/southern Canada. Just first look seems like a SWFE would be favored with thump to ice/rain. Expect lots of changes until then

Flurries are flying in Tallahassee, FL right now.

Looking forward to this cold here in Tallahassee. Might take a nice long walk Sunday morning in the single digit wind chills ha. The 3k NAM continues to show a Gulf effect snow band setting up across Pasco and northern Hillsborough counties around 10-11pm tomorrow. I'm excited to see the potential MCAO cloud streets across the Gulf on satellite imagery. That's something you don't see everyday!

I had a call with some of Governor DeSantis' cabinet yesterday about the cold and potential Tampa snow flurries. People are being dumb and freaking out. True story. The extreme cold though... Not a joke. Single digit wind chills throughout North Florida, including here in Tallahassee. I'm a bit twisted and looking forward to it lol. The Ag business, not so much. Hope you picked your oranges already farmers! In PA weather news, I think KABE could very easily break the top 10 for longest stretches of temps at or below 32°, though it'll depend on Tuesday. Current forecasted high is 31

Ha, I would love to hear his thoughts. I actually have no real issue with the NBM being used as a basis for the NDFD grids. In fact, I believe that's what it's really for. I just don't like how you can tell some WFOs get lazy and just send out the NBM or MOS guidance verbatim without even trying to input real climo or meteorological expertise. Also, speaking with the NWS Miami met, the NBM is being pushed programmatically in a way that it's not mandatory yet but highly encouraged. Let's be real here, what NWP guidance is even getting snow showers back to the I-95 corridor? I'd imagine very very few, and those that are are coming from the perturbed ensemble guidance like the GEFS, EPS, SREFs, etc. So right away I can tell you this forecast is heavily weighted by the NBM (which inputs those into it). In reality it could actually be a good forecast, if we believe the inevitable NW trend that hasn't commenced on guidance yet will occur so in that I give NWS Mount Holly plenty of kudos for not just sticking to the deterministic GFS and Euro. But also, I don't see any way it snows back to I-95 this weekend outside of a miracle personally.

I was actually talking with an NWS Miami met the other day about the NBM and we expressed some disagreement in its implementation. Simply put... I don't believe it's operationally sound enough to use in such an automated way that it is in some WFOs. Case in point this map here (which by the way it's showing so much snow because it's time lagged with old data). If the NWS wants to move towards "automating" their gridded forecasts, the NBM is just not it IMO! Especially in certain unique setups like this weekend storm where the models it blends can be polarizing and opposite. It's exactly as it sounds... A national blend of models. But anytime you are faced with an 80th or 90th percentile scenario, it will only give you the 50th percentile "mean" blend of all models. It happens a lot with temperatures, for example, where local climo will beat out an NBM forecast but the NWS still uses the NBM for their grids... Maybe it's just the WFOs down here in Florida, idk. I totally understand the want and need to automate some NWS jobs, but I'm old school and wish we weren't moving in that direction. Anyway, there's my rant and possibly unpopular opinion on the NBM today lol.

The models didn't trend as sharply as we needed them to last night tbh. This threat is not dead yet, but we're going to really need some dramatic shifts north with where the low closes off and the confluence over New England. I think back to the system in the middle of this month that had the models sending NS energy way south and cutting off over the TN valley. Well it ended up cutting off over the Great Lakes... The models were too "dig" happy. Different setup here with the decaying block pushing everything south, but we'll see

^Also, that analysis is all for nothing if we begin to trend towards the recent Euro runs. This was just to show how close we were to a big solution on the 18z GFS

Top two pictures are from the 6z Euro from YESTERDAY (1/26) that showed what would've been a top 5 NESIS event. Bottom pictures are from the most recent 18z GFS. From a broader view, you'd think the recent GFS would result in a major snowstorm with a closed off 500mb low about to roll under us. In fact, the confluent vorticity ribbon over northern New England isn't all too different, perhaps a bit further south on the GFS. However, the problem comes down to 6-12 hours of timing. The GFS is 1. 6-12 hours slower in evolution and 2. Just a bit too positively tilted (and slower). What that does is allow the PVA/southern stream energy to escape way out east of the trough before it gets pulled back into New England. Have you seen the GFS seemingly having "convective feedback" issues with multiple lows east of the center? Well, that is why. It doesn't know where the low center should be. The 6z Euro from yesterday though was faster, tilted neutral to negative 6-12 hours sooner, and that phase scooped up that southern stream shortwave/PVA and straight into the Jersey shore. GFS, with the PVA offshore because of a later phase and later tilt neutral/negative: Euro, which had better timing, tilt, etc:

GEFS looking better at hour 78. More separation of our TPV and better ridging between the two systems already. Not surprised though as the GEFS usually follow the OP. The western ridge also got better.

GFS... Lol. It's gonna hold or even be better here.

Let's hope 12z was rock bottom with this threat. 18z ICON ensembles much better and the mean sends 0.5" QPF well into southern PA. Yes this is not meant to be taken that seriously, but hey it's a good start to 18z

A blend of the 12z Allen Iversons (AIs) would put I-95 on the western fringe.