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georgiedre

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Posts posted by georgiedre

    Model output discussion - Closing in on Christmas

    in Forecast Model Discussion

    Posted

    6 minutes ago, terrier said:

    So looking at the gfs & ecm this morning we have a 2 to 3 day cold spell  with a few frost. How desperate it shows we have become in the U.K.. Then the high looks to topple and we are getting milder air moving in. Ala the met office long range updates. So it seems like we are then hoping a ssw to do us a favour. But as we all know even a ssw doesn’t guarantee us cold. Call me pessimistic but haven’t we been here before hoping for a ssw event. 

    Met office says the West will be driest and East wettest so that wouldn't mean mild air would it? 

    • Like 3

    Model Output Discussion - Colder spell ending, what's to follow?

    in Forecast Model Discussion

    Posted

    14 minutes ago, Tamara said:

    This analysis is geared towards fitting a bias preference into a diagnostic framework which doesn't exist to support singular ice sculptured solutions.

    No theory (in the true sense of the word) has been turned on its head in respect of La Nina. What has happened, as has occurred in some previous late autumns and early winter, is that a relatively active intra-seasonal high frequency tropical signal has created a rossby wave feedback that has resulted in a higher amplified downstream tropospheric pattern than would be seen in a more typical -ve frictional/mountain torque regime that represents a La Nina feedback. However, that doesn't on its own mean anything for the weeks and months to come - especially when pivotal wavelength changes will couple the NAO and AO much more closely, one way or the other, as deeper winter arrives in a few weeks

    Intrinsic coupling of the Annular Mode heading into deeper winter requires more exacting forcing than seen so far - and, with a w/QBO likely to influence, once again, the most important layers of atmosphere through the winter the chances increase that a more organised westerly gyre takes over once present intra-seasonal factors diminish and the tropics cease propagating rossby wave eddies poleward to sustain the imbalance between the pole and the mid latitude. .

    So, in this way, the tropospheric/stratospheric relationship can quickly can become much more stable (i.e through a much more stable GSDM relationship to the oceanic base state) This comes about by less eastward propagation of tropical forcing and greater additions of easterly wind inertia to re-configure the upstream pattern and send greater polar jet energy further downstream. This, in the absence of a top-down forcing to loop that polar jet, rather than across the mid latitudes, instead around the arctic and sustain and/or intensify an unstable profile across the polar field.

    At present, while there is indication that the African/Indian Ocean low frequency standing wave present for quite some time through the summer and into the autumn is relocating/propagating east towards the Maritimes, much more evidence is required to see whether a more specific tropical convergence can set up even further east into the western/central Pacific. This, essentially, leading to a more east based La Nina pattern. Much as happened for example  in 2017/18. This cycle meant that a more unstable GSDM profile persisted into the New Year and which ultimately led to the SSW in February 2018. At present, there is no clear indication, either way, what is going to happen - and angular momentum trends during the remainder of December will be pivotal in this respect.

    From my point of view at 39N, where I will be residing in the next couple of weeks, it is immaterial in terms of any high impact cold weather repercussions this winter - but for those looking for winter wonderlands at latitudes further north - its always worth being aware that there is never any x+y= equation when it comes to fitting given diagnostic parameters to weather patterns

    It is necessary to look at periodicity of high frequency tropical signals (the recurrence timeline) and not assume that the tropical cycle behaves like a time-clock which replicates the same on its subsequent 'mini ENSO cycle' within the next circa 30 days.  These periodicity timelines extend up to circa 60 to 90 day  lengths. Unlike a winter such as 2017/18 the likely persistence of a westerly QBO gyre at the most important levels of the atmosphere means that the tropospheric/stratospheric relationship is going to be also be dependant on solar assistance to de-couple ( ramifications for Brewer Dobson Circulation transport between the tropical and polar stratosphere). Equally, in tandem with US and Asian torque mechanisms getting in on the act to trigger poleward momentum transport  - but then as the complexities of even the last two winters have shown where contravailing forces have mitigated the propagation of these poleward eddies, staring at stratospheric forecasts at *insert time-period* does not not inextricably make it snow even if they move forward in time.

    What does this mean in normal meteorological terms for us no brainers hahaha it sounds really complicated and even the best of us are struggling with all the changes this winter 

    • Like 3

    Model output discussion - Winter approaches

    in Forecast Model Discussion

    Posted

    2 minutes ago, ICE COLD said:

    The models are very poor for a cold and snowy outlook or even frosty . The meto update has changed for the worse . I see N America goes fully into the freezer in FI . Seems to happen every winter now while we just stay mild , wet , windy and a few cool days now and then yawn . Same year in year out now . 

    901DD27D-B1E4-4842-9910-1919508EACA9.png

    It looks like a plume pushing up the west coast of greenland.. would this not result in higher pressure in the greenland-iceland area???

    Earthquake Activity Thread

    in Space, Science & nature

    Posted · Edited by georgiedre

    IMG_20191216_182652.jpg

    6554b6be8c0d829a8bf63ae0c82cf121_link.pn *Earthquake watch* A powerful earthquake swarm has occured under the volcanic mountain Fagradalsfjall in Iceland. Over 900 earthquakes were detected in less then 36 hours. » Severe Weather Europe

    WWW.SEVERE-WEATHER.EU
    -spread the word- Iceland is a land of fire and ice. It is also a land of volcanoes and earthquakes, and they usually come in abundance. A...

    Another swarm in Iceland

    • Like 1

    Stratosphere and Polar Vortex Watch

    in Spring Weather Discussion

    Posted

    15 minutes ago, Mike Poole said:

    Today in the strat, according to GFS 0z, has the split between strat and trop vortex again right through he run, here the NAM plot from stratobserve, blues in the trop strong and stubborn:

    image.thumb.jpg.1e287ad7415b58c4248c36717bdfa7ba.jpg

    And the decline in the reds in the upper part of this plot reflective of the weakening of the strat vortex anyway.  Here's the zonal wind plot:

    image.thumb.jpg.f8814d931d6868a7787611386430465b.jpg

    So given a few days ahead is the peak, if the disturbed trop situation persists it gets less encouragement from the strat to couple after that...this disconnect could easily run into December now in my opinion...

    What would this mean?

     

    Cold hunt - models and chat

    in Spring Weather Discussion

    Posted

    19 minutes ago, bluearmy said:

    Not for the first time , the gfs run at day 9 looks like the previous gfsp ......

    oh, forgot to post earlier ........after the noon suites, I reckon that Leeds snowline (relating to the day 6 system, not the first half of next week) is probably adjusted south to Sheffield/n Derbyshire 

    So does this stop on the Welsh border??? ☀️

    Stratosphere and Polar Vortex Watch

    in Spring Weather Discussion

    Posted

    5 minutes ago, Glacier Point said:

    Here's the importance of the wave 2 attack that is happening right now. That is opening the channel and the low frequency forcing that will manifest itself during the early and middle part of December will keep that (Scandinavian) channel open. 

    So when the next phase of vortex disruption takes place, the response time will be a whole lot faster than the strat warming which was associated with the strong MJO last middle February.

    What impacts do you reckon this is likely to be for the UK gp?? What your thoughts on next month

    • Like 1

    Model output discussion - The Hunt For Cold

    in Forecast Model Discussion

    Posted

    Hahahaha the posts of panic from posters these last couple of days is unbelievable. People need to calm down and reflect what is actually happening. Not often you get high pressure in charge of proceedings around our neck of the woods at this time of the year.. let's see what happens next but I believe that this won't be the last we've seen of the wintery charts. Let's wait and see what happens in December

    • Like 7
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