Jack Wales

Hi, As i see it the stratospheric profile is becoming less conducive for cold, I hasten to add I'm no expert in this field so feel free to clarify my understanding. The current NH stratospheric profile currently shows a cold anomoly, though this is undercut by downwelling from the warming event in mid January... Due to the time lag of warming events affecting the troposphere, is it correct to assume that the upcoming cold spell is the result of the January warming event? Conversely, does that mean that the current cold anomoly will have the opposite effect towards mid/end of feb and facilitate a return to synoptics observed in early January? With regard to the forecast SSW event, I fail to see this on the CPC forecast charts although a gradual warming appears to be in process, especially at lower levels. Having said that, the warming seems to be centred over N America / Asia... The persistent cold anomoly around the UK / N Atlantic would appear to be a straspheric vortex which to my lesser trained eye would encourage troughing in the region at the surface. Feel free to interpret or explain the charts as you see them........... Cheers JW

Tricky month to forecast; needless to say I doubt we'll see the positive anomoly of 2011! The cold is pretty much nailed on for week 1, possibly cool dry inversion type synoptics for week 2. Weeks 3&4 should follow a milder more zonal pattern although there is some signal for the cold pattern to reset... Therefore I'm going for a conservative 2.7°C

It's not a cold snap, maybe cool in eastern areas for a day or so. I doubt I'll see frost in my locale with daytime highs across the UK of around 5C to 10C. Look at the 850hp uppers, the -5C isotherm only skirts the eastern side of the UK for a few hours...

Yet again we are being teased in FI with the GFS control run destroying the PV over Greenland. Interestingly, if you look at the whole NH run, this is facilitated by strong heights progged to develop over the Canadian Rockies (SLP 1056mb+) advecting warm air polewards. Therefore it will be interesting to observe the upcoming runs to see if this key building block is a prominent feature over the next few days. One word of caution though is that according to the 18z ensembles, FI starts at T+96hrs!!

The current pattern appears well and truly 'locked-in' at least until the end of January. Therefore largely mild with occasional cold zonality... 4.8°C

Still a very zonal pattern however I note that a developing feature on a few of the gfs runs for cut of lows to run through the channel around next weekend. That's still in FI at the moment as nearly all the models have been poor in the medium range lately, but with with uppers around -5 there this could be something to follow over the next few days!!

Cheers SB, it's nice to come top although I think sticking my neck out in February and April undoubtedly helped me. I can't remember how I did last year but seem to remember doing OK.

Mild.... 6.0°C

There is a signal for a scandi/ arctic high but I think the jet stream is more amplified this year than in 2010 to allow a similar outcome.

I believe any cold signal for later in the month will be overridden by the highly amplified jet stream driven by the La~Nina based atmospheric state. Therefore I'm going for a predominantly mild month with only transient cold spells...... My prediction: 7.9C°

A very very tricky month to predict. High pressure will never be far away in the first half of the month but after this weekend the devil is in the detail with regards to the exact position of the HP cell. After that my guess is that any northerly incursions will be transient and that we'll slide into a more zonal second half of the month. therefore I'm going for a warm 11.6°C.

98L seems to be getting it's act together, NHC give it a 60% of becoming a TC within the next 48hrs... http://www.nhc.noaa.gov/gtwo/gtwo_atl_sub.shtml?area1#contents From looking at the satellite image, there's no closed circulation as yet and the system appears to be impacted by light southwesterly sheer.

Summer (if you can call it that) has been very poor here. Very cool, often windy / wet and I cannot recall a settled period lasting more than two days. I'm not sure about elsewhere in the UK but the most summery months in these parts were March and April.

After extra tropical transition takes place it's no longer under the remit of the NHC to continue public advisories. However they have mentioned the UK in their last few advisories and to me the fact the have singled out the UK Met could mean one of two things... 1, The two bodies have liaised and agreed a warm handover for advisories / weather warnings for Katia. 2, The NHC are concerned at the preperation (or lack of) by the UK Met and authorities so thought they would prod them a little. Either way, in the most recent NHC advisory, they are forecasting 'sustained' winds of between 65-70mph which is just under hurricane strength. I fear that even for Northern Scotland this could be damaging as gusts at higher altitues will almost certainly exceed 100mph. That's Maria and it's way too far ahead to see what track she will take. At the moment she is struggling to retain tropical storm status.

Latest track from the nhc.. .http://www.nhc.noaa.gov/graphics_at2.shtml?5-daynl?large#contents

What's interesting to note is that some of the models retain Katia as a tropical cyclone (warm core intact) up until 20°W. As hurricanes can sometimes strengthen briefly at the point of extra tropical transition, this could pose more of a danger. I don't think too much damage will occur on the current track due to the sparse population however any southward adjustment would be a different story.

GFS has been throwing up those charts in FI since June!! I wouldn't read too much into them as the flow looks very mobile for the forseable future.

For Katia (or any other hurricane)to make landfall on our shores is "almost" impossible the main reasons being... * Low ocean heat content results in tropical cyclones losing their energy source (hurricanes need sst's of 26C+ whereas the UK maxes at around 18C). * Post tropical transition, when tropical cyclones cross about 40 deg north, they get caught up in the upper level westerly flow and merge with atmospheric systems. * High wind shear, again north of approx 40 deg the upper atmosphere is almost always unsuitable for tropical cyclones. However, I say almost impossible as there have been tropical cyclones which have unexpectedly developed or maintained their strength despite the above. A recent example being a tropical storm which made it to within 200nm of the Southern Ireland coast a couple of years ago. Further examples include the late tropical cyclones of the infamous 2005 season (Zeta, Epsilon etc). But perhaps the best example is Hurricane Faith which retained its hurricane status until making landfall in the Faroe islands as a Cat 2 in 1966 before becoming extra tropical!! There is also anecdotal evidence that hurricanes have made landfall in the UK several hundred years ago. Anyway back on topic, Katia appears to have fully closed her eyewall again and mixed out the dry air. Her outflow is superb so the scene is set for further strengthening, I wouldn't be surprised to see an upgrade to Cat 3 later this afternoon.

I agree, Katia now has a definate shot at Cat 5, and conditions appear to favour rapid intensification with increasing ocean heat and low shear. Katia already appears to be a fairly large system so if she does make cat 5 she may not stay at that level for very long. GFS goes for landfall in Nova Scotia / Newfoundland, it'll be interesting to see what track the rest of the models will forecast.

A lovely looking system alreaedy.... A dense CDO forming with cold cloud tops, I think Katia will be a hurricane tomorrow

Fairly dire here. I don't expect a mediterraenean summer but it would have been nice to have a couple of warm spells or heatwaves. 30C seems like a very long time ago here, actually so does 25C!!

Looks like dry air entrainement is also a problem now for Irene, this combined with the shear should reduce intensity to weak cat 1 at the most by landfall IMO. She seems to be weakening rapidy now, especially as the structure of the inner core is not presenting well and is unlikely to regenerate at this stage.

Looks like another thunderstorm is brewing up over Tonyrefail again today. We had one yesterday which I would normally have enjoyed, however as I was out running at the top of a mountain, surrounded by trees and soaking wet, I did feel slightly vulnerable with the thunder cracking directly overhead!!!

Astonishing strenghthening given the system is under 15 - 20 kt of westerly shear!

Agreed Karyo, wouldn't be surprised if this turned out to be another fish spinner, probably as a result of weaker heights over the atlantic the last few years. The latest satellite imagery shows the eye and eyewall emerging from the dense CDO so Irene looks to be strengthening again now she is moving away from Hispaniola. This is becoming a very large hurricane with extended wind radii in all directions. For this reason I think she will only reach Cat 3 as the internal dynamics of large hurricanes make it harder for them to gain and retain Cat 4/5 status.