Spring discussion

Warm or Cold?


Seems the models are hinting a change towards milder conditions. Can't say I'm fully convinced yet. March is looking interesting. There's going to be a lot of northern blocking around given the current events in the stratosphere! This leading a disrupted polar vortex.

www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1" target="_blank" rel="nofollow">http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

Where this sets up will depend on the weather we get. I think there's every possibility of a cold start to spring. Both the AO and the NAO are set to remain negative

http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

The current problem is the west based NAO. This means we have to low just sat over or to the west of us with the coldest air missing us. We need this NAO to transfer East with the lows shifting east. That would allow the all the colder air bottled to the North East of us to transfer west over us.

If the NAO remains west based then slow turn to milder conditions from the south west remains a possibility. The jet stream remains to the south though so it may be a slow process. Beforehand further risks of snow with lows passing to the South. Will be interesting to see what happens in the long term, cold or mild!

I have put together a post about NAO,AO and the stratospheric conditions. This can be viewed in the learners area.

Models don't seem to want to shift the pattern eastwards. Blocking will still be feature however might not deliver us cold. A gradual warm up as lows from the south west gradually push further north introducing milder air. Snow events beforehand. One starting tomorrow for the Midlands, Wales and parts of Northern England

Thanks for the updates Mark interesting looks like March may come in like a lion!

Yep thanks for the updates.

Thanks

If we was to use the GFS 18z run Northern England would be favoured for the heaviest snow. Further south would see snow at times. But only back edge and front edge stuff due to the track of lows. Mild weather does seem distant still. Still looks rather cool on the whole going by the 18z. There's a lot of uncertainty regarding the track of the lows. So its one to watch over the coming days.

I dont mind winter carrying on for a bit but i hope Summer will be a good one even if it means less Thunderstorms because the last 3 summers have been so dreadful tbh.

Want a good summer!

Models now agree on milder slowly pushing north during Wednesday and Thursday. Models not in total agreement for the medium range. There is however little to suggest anything particularly mild. Cold air flooding south as the lows exit only for mild air to push north again as another low comes in from the South West. So wet and windy in the South with wintry weather continuing in the North (Northern England and Scotland) seems the general theme. Perhaps something wintry for a time in the Midlands from front and back edge stuff.

Long term and the ECM looks interesting. Recently the models want to try and build something to the North East. One to watch perhaps. Until the models come into agreement in the short and medium there is little point looking at the longer range. The teleconnections do not indicate mild.

Will do an update looking at the AO,NAO,MJO and the current stratospheric profile in the coming days.

Tbh im fed up of Winter now and want warmer weather to hurry up but looks like im going to have to wait sometime.

Can't see much in the teleconnections that support an big turn towards milder conditions. IMO its going to be a slow process.

The AO does show signs of turning positive so that could indicate the reformation of the polar vortex with lower heights over the arctic.
http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

The warming forecasts show the 30hpa level continue above average with the 10hpa close to average.
www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1" target="_blank" rel="nofollow">http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

Zonal winds seem to be trending westerly (however only slightly), they are currently easterly. This will help aid lower heights and PV over the arctic. But not by much.
www.met.fu-berlin.de/cgi-bin/times?plot=fluxes&alert=1" target="_blank" rel="nofollow">http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=fluxes&alert=1

This to me shows that the polar vortex is going to try and regain some strength. Going by the warming forecasts i think it will remain pretty much disrupted, for the time being. The jet stream may slowly start to trend further North as we head through March.

Will have a proper look tomorrow as I'm just having a brief look at them

Decided not to do an in depth look as it don't really have time. Nothing to suggest mild continues to be the theme. Looks cool and unsettled with wintriness continuing in the north. It will be milder at times in the South.

Looking further ahead and there is continued signs of height rises to our North/North East. The ECM T216 chart bringing wintry showers and sunshine with uppers of -10 850hpa. Its one to watch!

The teleconnections continue to show a -AO (however it is rising) The stratospheric profiles continue to support a disrupted PV and -AO, for now.

Mark wrote:

This to me shows that the polar vortex is going to try and regain some strength. Going by the warming forecasts i think it will remain pretty much disrupted, for the time being. The jet stream may slowly start to trend further North as we head through March.

Mark wrote:

Looking further ahead and there is continued signs of height rises to our North/North East. The ECM T216 chart bringing wintry showers and sunshine with uppers of -10 850hpa. Its one to watch!

I broadly agree with the above. It now seems the height rises to the North East then quickly moving North West seems likely. This bringing us a cold spell from the East/North East. This is shown on the GFS and ECM operational's this morning. Its also supported by the ensembles. The GEM supports something similar. Both the GEM and the GFS having quite a strong easterly flow. All the models giving a good spell of snow for many. Something which would not melt during the day given the conditions (if it had a reasonable depth). No point looking at specifics however a cold start from the North East/East looks likely for the first half of March.

What about further ahead (mid month onwards). On previous posts i warned about the PV gaining some strength and reorganising. It seems this is now the case. For the time being its situated in a position that will still give us a chance at cold. Currently it will be located over the pacific side of the arctic (hence the +PNA). It would only take a small shift for the high retrogressing north westwards to then sink. Which is why i favour a milder second half of March (at current times)

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=1&map=1&archive=0

(Note were the deepest cold (PV) is)

Looking at the teleconnections they support a first cold half to March. They also indicate the PV gaining strength.

AO
This continues to rise towards positive however stays negative through the forecast (overall). This to me indicates the polar vortex is gaining strength over the arctic.
http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

NAO
Remaining negative. This suggests that the PV is going to be placed in an ideal position, for now. It supports the idea of the high retrogressing north westwards and the idea of cold through the first half of March
http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

Stratospheric Warming

10hpa returning to more neutral slightly negative values. This supports the PV gaining a little more organisation and strength. The 30hpa remains above average. These suggest that although the PV is going to gain strength. It won't however be a very strong +AO. Perhaps around Neutral.
www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1" target="_blank" rel="nofollow">http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=temps&alert=1

Zonal winds
Turning westerly which will add strength to the reforming PV over the arctic. Nothing to significant though. An AO around neutral to slightly positive perhaps.
www.met.fu-berlin.de/cgi-bin/times?plot=fluxes&alert=1" target="_blank" rel="nofollow">http://strat-www.met.fu-berlin.de/cgi-bin/times?plot=fluxes&alert=1

If i was to make a forecast it would be for a cold start to March before turning milder in the second half. This would be due to the PV changing position and forcing the high to sink from the North West. I suppose that's speculation from me as I'm not knowledable enough to known were and how its going to move about. The PNA turning negative would be a good indication of us losing the
-NAO as the lower heights transfer across from the pacific side.

PNA: Is a measure of heights over the pacific side of the arctic
http://www.cpc.noaa.gov/products/precip/CWlink/pna/pna.sprd2.gif

GFS 12z's a little progressive! Does highlight the uncertainty in detail (which is obvious at that time frame) Shows the PV really gaining some strength and forcing the high to sink as we head into FI. I think that will happen in the long run (around mid month). At the moment i feel its being far to progressive in doing it. I would be more inclined to go with the ECM 0z. We shall have to see how the models handle the situation over the coming days. A cold start is still odds on

Thanks for the update. Yes, something cold looms but again nothing too bad i dont think. Will it ever warm up!

Nothing to change my thoughts. Cold spell from the East to start with (not that snowy going by the GFS/ECM) before the high retrogresses northwards leaving us i a weak northerly flow. That's the general pattern I'm expecting for the first half of March. I think the ECM and GFS may be right with the high further south reducing the snow risk. There's always time for change though. The UKMO for example being much better!

Stunning day today. Non stop sunshine and very pleasant/warm in the sun. Best day of the year so far by miles!

Lovely.

There is uncertainty regarding if it will turn cloudier by the end of the week or not. Seems like here will see more Sunshine than the East anyway and if the whole GFS 12z was to come off (obviously it wont) we would see very little precipitation- Barely above 3mm.

Short update

The easterly is still on however not a snowy easterly. Some wintry showers possible further South. The high is struggling to retrogress North Westwards with to much low pressure around Greenland. The PV is also getting its act to together across the pole. The high is likely to sit just to the north west of the UK brining settled conditions across the Uk. Still some uncertainty about what the high is going to do. Could finally progress north west westward into greenland providing a week northerly flow like on the ECM 0z (something which in mentioned the other day) or it could sit over us (ECM 12z). I still favour a milder second half the month (compared to the average)

Im really glad nothing cold is on the way now. A day like today or yesterday again and i will be very happy!

I would still favour a cold showery flow from the North. Can lead to snow into May. Northerlies are great during March and April. Especially as the sun is stronger increasing convection. When compared to the average nothing particularly mild is shown on the models! Would probably be like today with overnight frosts and cold (but feeling pleasant in the sun) days.

One spring in my bed popped.

Lol.

Cloudy and cool this morning but sunny intervals and mild this afternoon. Only seems to be mild down here tbh although the sun is out for many this week.

Not mild here, felt warmish in the sun however the max temp was 5.4c. No change from the settled conditions for the reliable future. Remaining on the cool side.

The settled conditions will do a lot of good for the muddy woodland near here. Would be nice if i cam back without muddy shoes and trousers for once and a clean dog! Lol.