Jack Wales

Chill out, just because my opinion doesn't tie in with yours doesn't mean I'm not entitled to express it. I'm not trying to wipe the event away, just saying that in my opinion it won't be anything like as severe as has been forecast. And yes, forecasters and weather models can get it wrong from time to time.

Yes temps are falling but there is still some way to go. I agree that between 2am and 4am is when the cold undercutting will really start to take place.

I use this one which is also in our neck of the woods... http://www.wunderground.com/cgi-bin/findweather/getForecast?query=51.58000183,-3.45700002&sp=IRCTPORT2

Heavy rain here now, and up in Giflach at over 200m asl, this is going to need a remarkable turnaround if the forecasts are to manifest. Current temp 3C DP 2C

Toatally agree, I'm surprised my noose joke was removed, humour is obviously not allowed when it comes to snow as even the mods are snow biased!!! Anyway back on topic, the frontal band is edging ever closer with snow flurries reported in Aberdare and Llantrisant, rain edging into Swansea and Port Talbot. I should go to bed but this is riveting. No widespread change in temps as yet with air temps around 4-5C and dew points 0-2C around the coasts but lower inland.

I don't mean to be a doom merchant but I speak from experience and interpreting the charts the best way I can. i hope I'm wrong though :-)

Air temp and dewpoint now at 2C here in Tonyrefail, wind also just started to pick up, this is going to be an intense band as you can see a strong convergence developing over the thermal gradient. Interesting times but i fear some will be disappointed. Upper south wales valleys could get a pounding, Swansea & Cardiff most probably rain, sleet or wet snow.

Heavy rain now into Rhosilli, Gower. Need the cold feed to start digging in soon, front starting to slow down which is a good sign, uppers still marginal at -4C 850hpa.... need a cold surface feed but not happening as yet...

I think a lot of people will be disappointed, this is looking to be a very marginal event. It appears that the snow will be reserved for locations chiefly above 250m and away from the coast. Current temp here up from 2c to 3c in the last hour. Elsewhere, Swansea 6, Barry 5, Cardiff 5, Cwmbran 2. It's just too mild in the populated areas. However some spots are looking more favourable e.g. Brynmawr 0, Brecon 1. Rain already into west gower and dyfed.

This chart nicely shows the SSW now taking place through all layers of the stratosphere... To me the jet seems too amplified for the easterly to manifest itself this weekend. I suspect a downgrade and the real cold will stay the other side of the north sea a la December just gone. Having said that, due to the nature of this SSW event, I believe there is scope for a cold spell although it may take a few attempts. It certainly looks as if the rampant jet / mild pattern should be disrupted for the second half of winter.

Bartlett high to dominate, the much vaunted ssw will not sufficiently curb the jet stream. Mild... 5.1°C

This cold spell looks less and less likely as time goes by. We have seen continuous downgrades in all models/ensembles of late, particularly regarding the heights over scandi and the location of the Euro low. The bottom line is that the jet stream is too amplified rendering the blocking to take up a more eastern position. If you look at the trend so far this winter, the severe cold has always been a week away (sound familiar?) and this could be the story of our winter. Don't get me wrong, I take my hat off to GP et al as their winter forecast is panning out according to plan regarding the northern hemisphere analogues, however for our tiny islands, the smallest divergence is proving to have a dramatic effect. Therefore, I expect a brief cold/dry spell until Tue/Wed next week followed by a more traditional mild zonal pattern.

Cold zonality to be the theme for December, my estimate... 3.3°C

Although the chart below depicts the Northern Hemisphere above 60N, the 1hpa warming episode was not that significant according to this as any warming episode is not easily discernable at that level... Indeed if anything the Polar Stratosphere is anomaolsly cool against an anomolously warm Tropical stratosphere, which (as I understand it) helps underpin an active Polar jet stream and a zonal pattern across the N Atlantic. The stratospheric forecasts don't offer any inducation of SSW into December, if anything it's quite the opposite with the upper stratosphere forecast to cool, here is the T+240 forecast at 1 hpa... At 30 hpa, there is a slight warming trend, albeit in the wrong location for W Europe... It's only at the lower levels of the stratosphere where we see a slight warming trend across the polar regions... What's confusing for me is that atmospheric profile in the Northern Hemisphere is giving conflicting signals e.g. the current stratospheric profile v the glaam spikes. I'd be grateful for any analyses / explanations as to what the possible outcome at the surface could be :-)

The cold spell keeps getting downgraded in the more reliable time frame, the main reason seemingly being the tilt / angle of the HP Cell to the west of the UK. Now we see a more North-to South elongated HP cell, (rather than the SW to NE tilt linking into Scandi), the upshot of this being a shortwave trough / cut-off low forming to the north of the uk and restricting the westward advection of the cold past Norway, here is Tuesdays chart (T+24)... The second attempt for the real cold to move in is at the weekend, but here is the GFS chart for Saturday (T+102) which shows the shortwave being the spoiler again. I can't help but think that GFS have over-egged the jet on this run but as we move nearer to the reliable timeframe, the forthcoming cold spell does appear to be somewhat less of event than expected a week or so ago.

6.6 for me.

There could be a warm up next weekend, especially with the large trough progged for the N Atlantic drawing a warm s'ly flow. There is also a growing signal for heights over Europe and the mid latitudes so I'm not convinced of a stormy month coming up. After next week, I wouldn't be surprised to see an anticyclonic spell...which could be cold or warm depeding on the exact synoptics.

Now up to 80mph, quite remarkable given the shear and marginal sst's Here's the latest from the NHC... 000 WTNT44 KNHC 292037 TCDAT4 HURRICANE NADINE DISCUSSION NUMBER 69 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 500 PM AST SAT SEP 29 2012 ALTHOUGH ANALYSES FROM UW-CIMSS AND THE SHIPS MODEL CONTINUE TO SHOW 20 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR...NADINE HAS CONTINUED TO BECOME BETTER ORGANIZED. THE EYE HAS BECOME MORE APPARENT IN VISIBLE AND INFRARED IMAGERY...AND THERE HAS BEEN AN INCREASE IN BANDING AROUND THE EYE. A RECENT SSM/IS OVERPASS SHOWS THAT THE EYE IS TILTED TOWARD THE NORTH...BUT THE TILT IS LESS THAN THIS TIME YESTERDAY. WHILE SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM TAFB AND SAB...THE CIMSS ADT ESTIMATE IS NEAR 80 KT...THE LATEST AMSU ESTIMATES FROM CIMSS AND CIRA ARE IN THE 70-80 KT RANGE...AND THE LATEST CIMSS SATCON ESTIMATE IS 78 KT. BASED ON THIS...THE INITIAL INTENSITY IS INCREASED TO 70 KT...AND THIS COULD BE A LITTLE CONSERVATIVE. THE INITIAL MOTION IS 345/13. NADINE IS BETWEEN A DEEP-LAYER RIDGE TO THE EAST AND A MID-/UPPER-LEVEL LOW TO THE WEST. THE GLOBAL MODELS FORECAST THE CYCLONE TO MERGE WITH THE LOW BETWEEN 24-72 HR...WITH THE SYSTEM THEN CAUGHT IN AN AREA OF LIGHT STEERING CURRENTS. THE DYNAMICAL MODELS ARE IN GOOD AGREEMENT THAT NADINE WILL SLOW DOWN AND MAKE A CYCLONIC LOOP DURING THE NEXT 96 HR. THE CANADIAN MODEL FORECASTS THE LARGEST LOOP...WITH THE CENTER OF NADINE MOVING SOUTHWARD TO 30N BEFORE TURNING EASTWARD. THE NEW FORECAST TRACK SHOWS MORE SOUTHWARD MOTION DURING THE LOOP THAN THE PREVIOUS FORECAST...BUT STILL NOT AS MUCH AS FORECAST BY THE DYNAMICAL MODELS. AFTER 96 HR...THE GLOBAL MODELS FORECAST A LARGE BAROCLINIC CYCLONE TO DEVELOP OVER THE NORTHEASTERN ATLANTIC WITH THE ASSOCIATED WESTERLY WINDS EXTENDING SOUTHWARD TO AT LEAST 30N. THIS SYSTEM SHOULD STEER NADINE TO THE EAST OR NORTHEAST NEAR THE END OF THE FORECAST PERIOD. NADINE DOES NOT APPEAR AS SHEARED AS THE CIMSS/SHIPS-ANALYZED SHEAR SUGGESTS...AND IT MAY BE THAT A MID-/UPPER-LEVEL TROUGH SHORTWAVE TROUGH JUST SOUTH OF THE SYSTEM IS PARTIALLY SHELTERING IT. THIS TROUGH COULD ALSO PROVIDE SOME FAVORABLE UPPER-LEVEL DIVERGENCE... AND THE INTENSITY FORECAST THUS CALLS FOR A LITTLE MORE STRENGTHENING DURING THE FIRST 12 HR. FROM 24-72 HR...NADINE COULD ENCOUNTER DECREASING SHEAR AS IT MERGES WITH THE MID-/UPPER-LEVEL LOW. HOWEVER...THIS MERGER IS LIKELY TO AT LEAST SOMEWHAT DISRUPT THE STRUCTURE...AND THE NEW INTENSITY FORECAST FOLLOWS THE PREVIOUS FORECAST IN CALLING FOR WEAKENING DURING THIS TIME. LATE IN THE FORECAST PERIOD...INTERACTION BETWEEN NADINE AND THE BAROCLINIC CYCLONE SHOULD LEAD TO EXTRATROPICAL TRANSITION. THE FORECAST CALLS FOR THIS AT 120 HR...ALTHOUGH IT COULD BE DELAYED IF NADINE IS SOUTH OF THE CURRENT FORECAST TRACK. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 34.4N 36.7W 70 KT 80 MPH 12H 30/0600Z 35.8N 37.4W 75 KT 85 MPH 24H 30/1800Z 36.7N 38.2W 70 KT 80 MPH 36H 01/0600Z 36.5N 38.7W 65 KT 75 MPH 48H 01/1800Z 35.9N 39.0W 60 KT 70 MPH 72H 02/1800Z 35.0N 39.0W 55 KT 65 MPH 96H 03/1800Z 35.0N 37.0W 50 KT 60 MPH 120H 04/1800Z 38.5N 32.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ FORECASTER BEVEN

I'm sure Nadine has formed an eye which you can see on this live feed... don't be surprised if she is reinstated as a hurricane at the next NHC update. It looks like she will last until around next Tuesday after which she will almost certainly be engulfed by a deep layer trough / front and whisked eastwards across the Atlantic

Looks like the polar vortex is becoming established over greenland which will contribute to their low temps.

11.5 for me

A very warm start and average end to the month should take us over a degree above the norm... My estimate: 15.8C

Have a feeling August could be an action replay of July, changeable start with a warm spell towards the end of the month.... my guess 16.1ºC

The pressure anomaly often sits along the boundary between warm and cold sea surface temperature anomolies as referred to by SB. Therefore, in the northern hemisphere (generally speaking), where you have a warm anomaly situated to the north of a cold anomaly, the thermal gradient is slacker which can support a high pressure build. The opposite is true where you have a cold-over-warm anomaly which increases the oceanographic thermal gradient thus stimulating the formation of cyclogenisis (low pressure). I must add that SST’s are only one player in long term forecasting and it’s worth remembering that they can change fairly rapidly and be over-ridden by other telconnectors. The current Atlantic SST profile now appears to indicate a more negative NAO and neutral/negative AO type pattern, which is typical of a low angular momentum (La Nina) atmospheric base state. This is a little surprising since the ENSO has now transitioned to a more neutral phase so I’ll have a more detailed look at this before posting again on here tonight. However my gut instinct is that this pattern could persist for some weeks, should it evolve.

Not looking great for next month. I'll go for 16.5C