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Jonathan Lang

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Posts posted by Jonathan Lang

    Model Output Discussion; into 2015

    in Forecast Model Discussion

    Posted

    GFS op continues the theme from the last couple of days with FI potential:  attachicon.gifgfs-0-372.png

     

    At that range details are not a concern. The pattern change continuing is the main upbeat theme.

     

    For those of you who criticized what I said yesterday regarding the high linkup. The chart IDO posted clearly shows what would happen if the high wins. The fact the charts are showing this (and have been for a fair few runs now) shows it isn't impossible. Still unlikely to happen but relatively speaking the chances have increased drastically for it to in my opinion.

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    Model Output Discussion; into 2015

    in Forecast Model Discussion

    Posted

    Even if the surface low and 500mb heights were weaker, and at this close range - only could be slightly weaker, the positive tilt of the upper torugh pushing east (i.e. SW to NE aligned) the high over the UK will be unable to riddge NW against the west to east movement of this upper trough which has a strong upper flow pushing behind it.

     

    If the chart you posted was date-stamped a week later, then there would be more scope for the models perhaps overestimating the strong flow and hence the flow would perhaps be more weaker and more amplified and prone to undercutting this ridge over the UK. In fact a a few days or more ago I'm sure we were discussing the potential for the ridge perhaps rasing heights over Scandi.

     

    But at only 2 days away, it's very unlikely to pan out any different from what's shown given the very low Shannon Entropy with the predictable strong zonal flow.

     

    But if you see my second post, this is not the only attempt the high makes of this. It happens more than once and we may prove lucky eventually. Low chance of happening but I think its something to watch.

    Model Output Discussion; into 2015

    in Forecast Model Discussion

    Posted · Edited by Jonathan Lang

    The flow at 500mb (roughly 16,000ft up) generally determines where surface lows and highs end up - the 500mb heights contours roughly show the direction of the 500mb flow and are shown by the colours on the chart below. Surface  Lows like the one near Greenland will generally follow the 500mb contour so will drift NE in this case. Also worth noting the upper trough above the surface low near Greenland will also push east sinking the high over the UK.

     

    attachicon.gifh500_su18z.png

     

    But if the low was weaker, with weaker heights, wouldn't the high simply break through and cut off the aforementioned low? Also the amplification evident in the chart you showed means the high should have an easier time breaking through? Please bear with me as I am no expert and still learning.

    Model Output Discussion; into 2015

    in Forecast Model Discussion

    Posted · Edited by Jonathan Lang

    Yeah, i was thinking we could be looking for a nice little surprise into early next week but It looks like the Atlantic is just too strong this time round Hope i'm wrong though 

    I think it's also worth noting it nearly succeeds in FI on the GFSP. Wouldn't take much to make that succeed I think and I believe it may do on future runs.

     

    airpressure.png

    Model Output Discussion; into 2015

    in Forecast Model Discussion

    Posted

    I think this deep low just to the south of Greenland is important if we are going to get cold and snow. If it develops just a bit further south than shown or even just weaker, I think the high pressure cell by the UK could then ridge into Greenland and latch onto the high already there. The low would then be forced to track much further south.

     

    airpressure.png

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