lorenzo

http://www.hpc.ncep.noaa.gov/mdlbias/index.html

Panto was fantastic, much cheerier place to be than looking at the models this evening. Allan Stewart and Andy Gray are superb. Kids loved it. Only the second show of the run so plenty of stuff going wrong, lines forgotten, props going wrong, timing all out. Added to the fun, won't mention much else as don't want to spoil it for folks who might be going this month.

Thanks Ian for the invaluable input this afternoon, a real insight to what is happening with the forecast for this week, and adds another dimension to the excellent discussion already on the thread about this week and also looking beyond. Steve, you're firing on all cylinders today ! I read a lot that Polar lows are never visible on any NWP output, amazing data on that image, couple of notable plots on the control run there, if consistent with a solution, would these be translated to the main UKMO run or are they used to say adjust the Fax output? Where would we be without Dalmatians and Shannon Entropy ! Also re: GEM, it isn't so bad at 72 hrs, compare with UKM & JMA here.

Update from fergieweather on snow probabilities & Polar Lows, which by the time you get through the thread to find, will either be in a previous thread or buried in an avalanche, no pun intended, of other posts. 10-20cm possible in places, blizzards & drifting. It had me at 10cm... http://forum.netweather.tv/topic/78631-model-output-discussion-30th-november-onwards/page-30#entry2850785 Well deserved one of these.. To add, post on the previously mentioned Polar Low threat, W. Norway. This referred to as the Dalmatian Plot. http://forum.netweather.tv/topic/78631-model-output-discussion-30th-november-onwards/page-32#entry2850835 Some great posts from Fergie today explaining why the met see ECM too amplified and therefore blend in GEM and GFS. What a period of model watching we have coming up. 12z will be pantomime this evening, going to miss them by being at a real Pantomime!

Yep Hawesy. I think the real attraction with this is the exceptional depth of the cold. For those of us in the Central Belt. The well advertised wishbone effect. WE can hope for a trough to develop in the flow and the faxes will be getting closely scrutinised, as will the NW coastline of Norway, Polar Low spawning grounds. Raided the GFS 06z run on NetWx for some of the charts now it has decided to join in the fun as Meto. Winter begins. Thursday mid-day sees the first advances of cold air making its way south. Before the above wishbone Northerly becomes apparent. Can't resist posting up these Potential Equivalent charts... Properly Arctic. 850 hPa temps are just incredible, sorry I may be a stuck record by midweek ! No surprises then with the 0 degree Isotherm, anything falling will be snow. Friday morning minimum temps are brutal. Closer up on the snow risk chart for Scotland, the Northerly signature is clear. So, whilst we are hoping for another couple of features to pop up to provide interest for all, the real feature here will be the clean Arctic hit of air.

Distance to Earth countdown back up and running.. http://www.cometison2013.co.uk/perihelion-and-distance/

Fergieweather mentioned the shades of '53, not an event I was aware of, this is a good find in our Regional Thread by Blitzen on that evolution, with Wetter archive Gif. Update, thanks to GU Weather, Blitzen had lifted this from an overnight post in here. Original charts.

Welcome to Winter GFS.

This thread is like a 24 hour garage these days, folks up at all hours posting !! Good stuff. Winter arriving right on queue, some great cold charts on offer today. Yes, just over Iceland that IS a -17 850hPa temp reading !! Looking higher up solid -40 profile, old school colours on the meteogroup one, fits well just looks frozen. Dust off the satellites and radar, a real Polar Low watch / opportunity!! We have a couple of things to trust, 1) the models are doing very well at picking up on these Northerly hits from a decent range, they wobble here and there en route, but the trend is doing very well at verification. This is going to feel bitingly cold. Edit - add temp chart This from the 00z GFS, 06z not at the weekend yet, a proper swathe of cold right down into the continent.. which is good for other potential set ups that shall not be named for fear of spooking them...

Bone chilling blast of cold, sharpest of the Northerly hits so far, great to be seeing proper wintry looking output on 01st December. Satellite will definitely be worth a watch for non NWP features going by the 500hPa temp profile. Stunning. Out to mid month and commented on by Nick wrt NAEFS anomaly, the ECM control run in FI also parks this Scandi/Euro Block. Which would lead to another spell of good model watching, with NWP notoriously wobbly in modelling strong cold blocks, with the addition of frontolysis and fronts getting chewed up. How much colder can this weeks blast get...

Weather models are not horses !

Very sad news, thoughts go out to those affected by what is such a surreal accident. A routine shift at work, or a Friday night visit to a pub to see a band impacted by the completely unexpected.

GLAAM tendency still falling into the low momentum phases. GEFS forecast sees the orbit through phases 2 and 3 Composites below Then onwards to MJO plots for the models are still quite scattered, GFS bringing in phase 2, however ECM and UKMO not in support. From Adrian Matthews page, only the briefest of forcing which possibly will not qualify as an active MJO. Saw a good post where it was discussed that some anomalies creating transport on the wheeler diagram for MJO forecasts are a result of CCKW, Convectively Coupled Kelvin Waves, they create a noise signature in the models which mimics OLR and hence we get an MJO forecast. Might need to start looking more closely at OLR - Outgoing Longwave Radiation plots in conjunction with whatever is forecast for verification. With the above in mind, would be following what the vortex is up to and comparing what is the lead on the 100mb strat charts.

Remains annoying that the ECM removed those postage stamps, still saves us all some worry. More sensible odds than the 80:20 split in the ensemble suite last year that left everyone kicking the cat !! At 168 Colder 850hPA temps dialling in on the UK and Europe getting a proper wintry blast, interesting that this is almost a diluted version of some of the rampant GFS control run charts from a couple of weeks back. GFS and ECM Beyond that a couple of control charts from the ECM suite out at 300, to show the easterly flow appearing on the ensembles.

SOHO scientists announced ISON had vaporized at perihelion. Then ISON appeared out of nowhere at around 1145 on the C3 Solar observer. Who knows !!! Looks like it has survived to me.

A clearer image now of the earlier C3, this the raw image file.

TInfoil hat and all that - wonder what the predicted trajectory is ? if part of it sheared off and altered this, it looked like this happened in the earlier C2 Image, ( red one) which shows dust cloud well ahead of the position of what is now potentially the reduced nucleus. Anyone better informed to clarify what was expected?

Still looking very bright, not sure what trajectory this should be on , if this is a remnant or if the nucleus has popped and this is a fragment??

http://198.118.248.97/data/REPROCESSING/Completed/2013/c3/20131128/

NASA tweeting that fate of ISON not yet established. What ? Did it defy Physics pop down to the surface of the sun for a bit, before carrying on it's wonky trajectory. Interesting C3 imagery coming out now. C2 from similar timeframe

Comet Phoenix......???

Gutted ISON didn't survive, would have been a great show during December, wonder how big a Sun Grazer has to be to survive an 800,000 km/h Perihelion??

That LASCO

Comet Ison is an easterly. Has the same nerve jangling anticipation !

Some wise advice there Catch. ECM chart at 216 on the 00z has the pick of the cold air.. Still some way to go yet - good post from Nick F yesterday in the model thread re: the FI period for Northerlies. Question was raised as to whether we can look at FI for Northerlies to be at a longer time frame which I agree with, the models have caught onto these Northerly Blasts well this year, this will be the 3rd when verified. Expect a wee bit of wobbling back and forth on the operational runs yet with respect to the main locale for the blast of cold. East West shifts, GEM whilst a bit like a crazy horse at longer range, did pick up the low at 96 hrs that gave the snow last week, so one to keep note of for the shorter term.