metallikat34

Whats the MAD thread?

Is this technical discussion from the met office?

Lol. This would be the correct assessment from a purely dynamics standpoint. However, that dew point depression always drys our the air columns as well. Wrap around precipitation with deepening lows is always overdone in models, and often underperforms in reality. Essentially like a mini dry slot.

Appreciate your assessment! And I totally recognize that I am the new guy (2 years now) here in the Edinburgh area. But I am not so sure I'd fully characterize this as a purely frontal event. Some really decent dynamics in place once that storm center hits the water early on Thursday morning. Could see a good 3-6 hour thumping of snow and the overnight timing helps with temperatures and precip type.

Sitting at 95 m ASL and I'd just take a solid coating at this point!

Jeez. Unless I am reading this wrong, the GFS ensembles continue to be feast or famine with low level snow.

I am not enthused looking at the latest ensemble snowfall output. The majority of the ECMWF 12Z ensemble members show some snowfall in Edinburgh, which is good news. But the numbers have skewed low. Likely a reflection of the more suppressed nature of the storm center.

Yes, this is definitely a curious one to watch. As some have mentioned, I am a bit miffed at the Met Office warnings issued this afternoon. I suspect they are only comfortable issuing warnings for hazards and locations they are quite confident will verify. And regardless of model variations, lots of England and Wales will see heavy rain. But the wildcard spot is for sure Scotland. ECMWF has been consistent with the low pressure position from run to run (image below). There is little doubt that areas above 200/250 meters will get dumped on. But I need to see some thermal profiles for lower locations as we get closer to the event. I only have access to the GFS vertical profiles, and as some may have heard (and I was able to confirm with a former colleague at NOAA this week), the new GFS is really struggling with meoscale variables at the moment. This is a very fluid situation (pun intended!) and I fully expect a lot of changing forecasts in the next 48-72 hours.

I am also a bit surprised at the Met Office issued warnings. I suspect that they are heavily relying on the UKMet output. The ECMWF has been quite consistent over the last few runs with the low pressure position at 6am on Thursday. Now, how much of this falls as snow below 200m is a very good question. I can't really get access to a range of upper level temperature profiles beyond the GFS. And the GFS has been a bit too inconsistent over the last 12 hours to place much trust in their thermal profiles. Bottom

12Z GFS operational output....that bottom line

Well, the 12Z GFS is doubling down on a significant snow event for Scotland Wednesday Night/Thursday. If nothing else, at least for the Cairngorms and hills in the Borders. Central Belt is likely to see some measurable snow based on these model trends. Note the low pressure position in the GFS 12Z (left) and the 6Z GFS (right) for 6AM on Thursday morning. The trend has been to keep the center of a deep low pressure system close to the coast of Northumberland and making slow progress towards the North Sea for 6-12 hours. Lots of support for precipitation on the backside and what should be sufficiently cold air for several hours of moderate snow. The early morning timing is a good thing for locations below 100 m in the Central Belt as there is a higher likelihood of near 0 or below temperatures. Should be fun (and frustrating) watching this storm develop in the models over the next few days!

Yeah this is an interesting and potentially frustrating 48-72 hours of model watching on tap! Flow is too cluttered across the major global models at the moment. I'll say this, the position of the low pressure system on Thursday afternoon (western edge of the North Sea) is favorable for snow. And that's a decent looking upper air profile via the GFS at 6pm on Thursday. No need to worry about 850 temps in this scenario!

Wednesday/Thursday looking interesting! Will be very interested to see 12Z runs today

Always impressive to see the sharp snowfall gradient!

Did you get anything? I am right at 100 m ASL on Comiston Road and it never snowed here!

Yup, just some sleet mixing in here in Edinburgh at the moment

Yeah, I think the freezing rain threat is being a bit underplayed. Could make for some really hazardous travel this afternoon.

What I just said, in visual form

Watching the 6Z GFS come in. Increasingly concerned about freezing rain. Big time inversion aloft with below 0 temps at 925mb and above 0 at 850. Only saving grace is the timing (late afternoon) means that surface temps will be in the 1-3 degree range, which may mitigate some of the freezing rain threat. However, any areas that are sheltered or slightly elevated (and therefore will have surface temps close to 0) are at risk!

Yuck on those 850 temps tomorrow afternoon!

Interesting. I'm 5 miles to your northeast and I've got light rain at 1C

Nothing yet here in southern Edinburgh, but that radar looks promising!

Impressive cold later this week!

Yeah I'd tend to agree with the Met Office on this one. Sitting at just over 3º here in southern Edinburgh, with a RH of 90%. Temperature hasn't moved much in over 6 hours. If any of these little convergence zones pass overnight, may be helped somewhat by dirunal temperatures. Otherwise, it's going to be hard to get anything to accumulate on anything but grassy surfaces around me.

Just having a look at the 12z GFS. Showing an early morning event on Tuesday. Looks cold enough for snow, but some rain mixed in as well.