Kirkcaldy Weather

You change your mind as often as FI changes with each run feb

Some more info on Alaska First a record-high temperature, then record-breaking snowfall hit Anchorage on Saturday WWW.ADN.COM Eagle River had over a foot of snow by Sunday morning, while areas in Anchorage saw up to 10 inches.

Part of Upper Peninsula approaching 10 feet of snow already; Snowbanks tower over sidewalks WWW.MLIVE.COM An incredible amount of snow has already fallen over much of the U.P.

Think that is for a completely different type of weather "model" Mike ?

but the possible development of the higher pressure is still out in FI feb so not sure how you can write it off? Also not been 3 downgrades from what I can see? Lets just wait and see how things develop as we head through the Christmas period toward the new year and see where we are.

Plenty of interest in the GEFS and this one for fun... A 1060mb Russian / Siberian high joining forces with higher pressure across Scandi

Just as I was beginning to think that people in here were starting to have a glass half full approach yesterday / last night and suddenly one less cold run and its back to square one with the negativity. Some points I will throw out there. As I have mentioned before how many times over the years have the models handled higher pressure / blocking higher pressure (during winter) well especially out in FI? - Very rarely (one occasion that springs to mind was the GFS performance before the 2010 cold spell which given the time frame was good going but very much an exception since then) Just out of interest given we are now 7 days from Christmas lets see how close the models are from 7 days out ( I will revisit with the actual chart for comparison after Christmas) GFS CPTEC NCMRWF FIM NASA/GEOS5 NAVGEM GEM ICON/DWD JMA Many differences between them but key areas to me look to be Atlantic / UK and possibly most interesting the differences / struggles with the higher pressure toward Russia / Siberia. As I said yesterday the key thing will be trying to pinpoint the timeframe for the possible higher pressure development, some firming up that it will be after Christmas possibly some time around 28th December? Lets see what this afternoons/ evening runs show but still very much an interesting outlook from my POV

I mentioned earlier about a jackpot outcome - Until / if / when we reach the stage of higher pressure / wedges developing those kinds of charts are very much just for fun although I would rather see those kinds of runs appearing rather than them not.

Has been further snowfall in areas of the UK (see my recent posts in the Scotland thread and also the snow and ice twitter thread) mainly on high ground although some lower areas in the north of Scotland saw some snowfall yesterday, Overall a good example of what a cool / cold zonality setup can deliver albeit just a bit unlucky not to get the best setup to include more lower areas. Well after a 10 day period in phase 2 the MJO has now moved into phase 3 so moving forward this is where my attention is focusing (will need to keep monitoring as it may be a brief spell in phase 3 before entering COD and then uncertainty about the next phase(s) ) again the GEM ensembles highlight the options that may arise (questions will be how quickly phase 3 feedback is seen) something akin to this would be the jackpot outcome other option(s) looks to be higher pressure through UK up toward Scandinavia certainly could be an interesting spell of model watching coming up.

Another brilliant in depth blog by Judah Cohen, here are some bits that may be relevant for UK. "I spent last week in San Francisco attending the Fall AGU and one thing that I was trying to understand was the quasi-biennial oscillation (QBO). I was under the impression that the QBO was in its easterly phase this winter that favors disruptions of the stratospheric polar vortex (PV) in early winter. The winds along the equator are indeed easterly in the mid to upper stratosphere but are still westerly in the lower stratosphere (see Figure i). Therefore, the QBO influence on the PV is more consistent with a westerly QBO that does not favor a PV disruption in the early part of the winter. I raise this because our statistical model (which I have acknowledged suffers from too many false positives) and the dynamical weather prediction models all predicted a significant if not major disruption of the PV that failed to verify for early to mid-December. I think categorizing the QBO this winter as westerly and not easterly helps to place those poor forecasts in context. It reminds me of early winter 2016/17 when a weakening PV was predicted by the dynamical models to achieve major warming status (reversal of the zonal mean zonal wind from westerly or positive to easterly or negative at 60°N and 10 hPa) but never did and instead the PV quickly spun up contributing to a mild pattern across the Northern Hemisphere (NH) for an extended period. Westerly QBO favors a strong PV as atmospheric vertical energy transfer is directed towards the tropics and away from the North Pole that favors a strong PV. Still if a major warming is to occur during a westerly QBO winter, it is preferred mid to late winter. The QBO phase this winter seems similar to me as in 2017/18 when a major warming occurred in February. Whether the QBO is easterly or westerly does not change our temperature forecast as it is not currently used as a predictor, though there are studies that argue easterly QBO favors colder winters relative to westerly QBOs. Still in our analysis on reflective PV disruptions (Kretschmer et al. 2018), it did seem that they are more common in westerly QBO winters, which does favor colder winters in central and eastern North America and has been the pattern so far this winter. The GFS is predicting a return of blocking in the Barents-Kara Seas so I expect perturbations to the PV to continue into the New Year. I tweeted out yesterday that the models are predicting colder temperatures to become more widespread across Siberia and wherever you live in the NH mid-latitudes this is something that you should pay attention to, if you are interested in knowing the weather. On the simplest level cold air that builds in Siberia often discharges to the southeast towards East Asia or west towards Europe. But even for North America, relatively cold temperatures in Siberia are favorable for more active atmospheric vertical energy transfer that disrupt the stratospheric PV. The largest PV disruptions can unleash severe winter weather in favored locations for an extended period but especially the more minor PV disruptions that I refer to as “reflective” events that are of shorter duration - favor cold temperatures focused in central and eastern North America. It does look like such an event is possible the end of December with the surface impacts felt in early January. So, as I have been saying for years, “Siberia is the refrigerator for the NH” and if Siberia turns cold that increases the risk of cold air outbreaks in East Asia, Europe and even eastern North America. But that is not the main point that I want to make. In my mind the best support that the Arctic influences mid-latitude weather is if Siberia experiences a cold winter. And if high Eurasian snow cover/low Arctic sea ice can contribute to a cold winter in Siberia, then high Eurasian snow cover/low Arctic sea ice can contribute to cold winters elsewhere including East Asia, Europe and the US. This idea was the main focus of my two talks at Fall AGU. Most of the critics of the idea that Arctic change (warmer temperatures, less sea ice and I include heavier snowfall) can contribute to colder temperatures in the mid-latitudes argue that any observed cold winters over the past two decades are due to chance (or maybe due to tropical variability) and therefore cannot be attributed to the Arctic. The main tool to support this argument are the dynamical models that when forced with low Arctic sea ice they do not simulate cold temperatures across the continents. Therefore, if we observe cold temperatures it is not forced but rather is attributable to randomness in the atmosphere or natural variability. However, I believe that the warm models and colder observations are not symptomatic of randomness but rather due to systemic errors in the models. To me the most compelling support of this position is juxtaposing the model forecasts with the observations. In Figure ii, I show the winter (Dec-Jan-Feb) surface temperature anomaly forecasts from the North American Multi-Model Ensemble (see NMME website) from 2011/12 through 2018/19 on the left and the observed winter surface temperature anomalies on the right. The forecast temperatures are always warmer than the observed temperatures for the NH. But sometimes the models do predict cold temperatures across North America but never for Northern Eurasia. I am assuming this is because in the models, tropical variability (mostly ENSO) can force cold temperatures in North America but not Eurasia. In the models the only truly important forcing for Eurasia is increasing greenhouse gases (which may include the warming influence of Arctic sea ice loss). Yet despite the model forecasts Eurasia is always observed to be colder than the forecasts, with the one possible exception of winter 2014/15, where any observed cold was regional. If we can predict that the model forecast will be universally warm for Siberia and that the observations will be colder, then this is less consistent with randomness and more with systemic model errors i.e., the models incorrectly simulate the influence of Arctic forcing on mid-latitude temperatures, or at least Arctic influence is incorrectly overwhelmed by tropical influence and/or global warming. What about this winter? In Figure iii, I present from the C3S (the ensemble of European models – ECMWF, UK MetOffice and Meteo-France made available at Copernicus) forecast for both sea level pressure and temperature anomalies for Nov-Dec-Jan 2020. I show these three months because we already have a fairly good idea how the forecasts are verifying. All the models predicted a strong signal for relatively low pressure across the entire Arctic basin and the predictable universal relative warmth across the NH. I thought the forecasts were especially notable since as I argue all the time in the blog, low sea ice and warm temperatures in the Arctic favor high pressure and not low pressure. For example, the daily trend of geopotential heights shows increasing pressures in the Arctic troposphere throughout the winter (see Figure iv).I include in Figure iii the observations for Nov-Dec-Jan 2020 through today and so far, the Arctic is not completely dominated by low pressure and the NH continents are not universally warm. In fact the regions of cold are downstream of the two regions that are warmest in the Arctic - in eastern North America downstream of the warm bullseye in the Chukchi Sea region (presumably aided by below normal sea ice extent) and in Siberia downstream of the warm bullseye in the Barents-Kara Seas region. This warm Arctic cold-continent relationship was shown by Kug et al. (2015) and others. I would argue that if the temperature variability across the NH resembles previous analysis related to Arctic warming that is not a random but supportive for a previously constructed argument. That is why I was excited to see the cold forecasts for Siberia because in my opinion it is consistent with Arctic influence favoring colder temperatures. Despite the stratospheric PV being displaced, strong and circular circulation exists around the PV center with relatively low heights (Figure 13). The largest negative temperature departures in the polar stratosphere are over Central and Eastern Siberia, likely supporting the cold temperatures in that region. Had the strong PV returned to the North Pole in this current configuration, it would likely contribute to a relatively mild pattern across the NH. For now this is not the forecast but a scenario worth considering.The forecast for the troposphere is ridging across Southwestern Europe, much of the Arctic, East Asia, Alaska and the Gulf of Alaska with troughs over the eastern Mediterranean, Central Asia, Eastern Siberia, the Dateline, and central North America (Figure 14). This pattern favors relatively mild temperatures for Eastern Europe, Western Asia and western North America with seasonable to relatively cold temperatures for Western Europe. Siberia, Northeast Asia, Eastern Canada and the Northeastern US (Figure 15). The CFS forecast for January has returned to predicting a circulation pattern prediction that projects on to the pattern of variability associated with a negative AO." AO Blog Update | AER | Weather Risk Assessment WWW.AER.COM December 16, 2019 - Dr. Judah Cohen from Atmospheric and Environmental Research (AER) embarked on an experimental...