Ik kwam nog deze zeer interessante analyse tegen. Steve Murr is naar mijn beste weten, een prima weeramateur, met vaak goede analyses.
Just to summerise whats happening is the speed of the flow coming off the states & the distribution of energy going into the Northern Arm-
If we cast our mind backs X2 days we were all getting excited at the prospect of a fleeting Easterly ( Mostly going into France) then the large trough coming roaring SW through Scandi introducing that -15c / -20 airmass-
This is the 12z run from the 18th- It should link to the jet stream-
http://91.121.94.83/modeles/gfs/archives/gfs-2009120812-5-144.png?12
Go to the 144 Chart-
NOTE the amplification of the jet- a high pressure is sandwiched in there- Look at the jet flow over the top- it doesnt get right out to the top of greenland- subsequently the shortwave that we were watching traversed east across Greenland & then interacted with the trough coming out of svalbard & they both were picked back up South in the jet flow-
Also look at the jet energy cutting across the UK- the shortwaves will sit on the southern Side hence the lightish easterly flow-
http://91.121.94.83/modeles/gfs/archives/gfs-2009120812-0-150.png?12
Now we move onto todays model run- the energy distribution has changed- obviously T144 is now T96-
look at the jet now on the GFS_
http://91.121.94.83/modeles/gfs/run/gfs-5-96.png?12
A LOT more amplified in terms of loop over greenland- Now remember if the NET energy off the states is ~ the same as X2 days ago then if theres less pulsing North the rest is going into the Southern arm-
When you energise the southern arm the net in this situation is forcing low pressures NE wards- Because there is blocking out of greenland then there is a greater force & SQUEEZE of the isobars along the boundry- in this case Southern England & Northern France- resulting in this-
http://91.121.94.83/modeles/gfs/run/gfs-0-96.png?12
What this also means though is the shortwave that was orginally going to traverse through Greenland is now pushed more poleward & moves slower & doesnt phase with the Svalbard system- as a consequence its delayed & weaker & further North ...........
The ECM on the other hand has taken a step in the other direction by forcing more energy in the northern arm- it has minimal disruption to our 72 chart ( but enough to cause the flow to be to far South & east for a good Easterly to start with- & because of that faster initial flow any subsequent ridging towards greenland from the Upper high to less pronounced & its final local is somewhat tempered - centred more East & South-
To put this into perspective is a SMALL SMALL pterbation between each model- spin this out to t72 & you get minimal difference- throw it to 96 & theres still the same OVERALL hemisphric pattern as is 120 but there are distortions in the shape of the high when comparing model to model-
out to 144/168 & beyond that intial distortion- maybe a difference of only 10 m/s in each arm is enough to show the Greenland high Sinking on the ECM or the GFS block holding strong with undercutting-
incidentally- we had a poor run from the ECM the other day here VV- notice that the jet flow is strong in the northern arm & not amplified- however as we are very very close on this pattern - this run does appear to be quite wrong, & this arguement lends itself to todays similar arguement that the ECM is progging to much Northern Energy-
http://www.ecmwf.int/products/forecasts/d/getchart/catalog/products/forecasts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!144!North%20hemisphere!pop!od!oper!public_plots!2009120712!!chart.gif
We must be cautious though as every time this has happened before the northern arm & the ECM have been correct- HOWEVER the background modality change of the AO & NAO do somewhat mute the previous signals we have seen before & along with it some of the comments put forward by some of our more volatile members-
We have been here before- the GFS looks more believable & this would be a dead cert major easterly if it was yesteryear- but we have to wait as quoted before until the train is visible to confirm its not detouring to Greece or even holland & france in this scenario....
CIAO
Steve
Just to summerise whats happening is the speed of the flow coming off the states & the distribution of energy going into the Northern Arm-
If we cast our mind backs X2 days we were all getting excited at the prospect of a fleeting Easterly ( Mostly going into France) then the large trough coming roaring SW through Scandi introducing that -15c / -20 airmass-
This is the 12z run from the 18th- It should link to the jet stream-
http://91.121.94.83/modeles/gfs/archives/gfs-2009120812-5-144.png?12
Go to the 144 Chart-
NOTE the amplification of the jet- a high pressure is sandwiched in there- Look at the jet flow over the top- it doesnt get right out to the top of greenland- subsequently the shortwave that we were watching traversed east across Greenland & then interacted with the trough coming out of svalbard & they both were picked back up South in the jet flow-
Also look at the jet energy cutting across the UK- the shortwaves will sit on the southern Side hence the lightish easterly flow-
http://91.121.94.83/modeles/gfs/archives/gfs-2009120812-0-150.png?12
Now we move onto todays model run- the energy distribution has changed- obviously T144 is now T96-
look at the jet now on the GFS_
http://91.121.94.83/modeles/gfs/run/gfs-5-96.png?12
A LOT more amplified in terms of loop over greenland- Now remember if the NET energy off the states is ~ the same as X2 days ago then if theres less pulsing North the rest is going into the Southern arm-
When you energise the southern arm the net in this situation is forcing low pressures NE wards- Because there is blocking out of greenland then there is a greater force & SQUEEZE of the isobars along the boundry- in this case Southern England & Northern France- resulting in this-
http://91.121.94.83/modeles/gfs/run/gfs-0-96.png?12
What this also means though is the shortwave that was orginally going to traverse through Greenland is now pushed more poleward & moves slower & doesnt phase with the Svalbard system- as a consequence its delayed & weaker & further North ...........
The ECM on the other hand has taken a step in the other direction by forcing more energy in the northern arm- it has minimal disruption to our 72 chart ( but enough to cause the flow to be to far South & east for a good Easterly to start with- & because of that faster initial flow any subsequent ridging towards greenland from the Upper high to less pronounced & its final local is somewhat tempered - centred more East & South-
To put this into perspective is a SMALL SMALL pterbation between each model- spin this out to t72 & you get minimal difference- throw it to 96 & theres still the same OVERALL hemisphric pattern as is 120 but there are distortions in the shape of the high when comparing model to model-
out to 144/168 & beyond that intial distortion- maybe a difference of only 10 m/s in each arm is enough to show the Greenland high Sinking on the ECM or the GFS block holding strong with undercutting-
incidentally- we had a poor run from the ECM the other day here VV- notice that the jet flow is strong in the northern arm & not amplified- however as we are very very close on this pattern - this run does appear to be quite wrong, & this arguement lends itself to todays similar arguement that the ECM is progging to much Northern Energy-
http://www.ecmwf.int/products/forecasts/d/getchart/catalog/products/forecasts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!144!North%20hemisphere!pop!od!oper!public_plots!2009120712!!chart.gif
We must be cautious though as every time this has happened before the northern arm & the ECM have been correct- HOWEVER the background modality change of the AO & NAO do somewhat mute the previous signals we have seen before & along with it some of the comments put forward by some of our more volatile members-
We have been here before- the GFS looks more believable & this would be a dead cert major easterly if it was yesteryear- but we have to wait as quoted before until the train is visible to confirm its not detouring to Greece or even holland & france in this scenario....
CIAO
Steve
„Et nul ne se connait tant qu'il n'a pas souffert, „C'est une dure loi, mais une loi suprème, „Vieille comme le monde et la fatalité, „Qu'l nous faut du malheur regevoir le baptéme, ~Et qu'a ce triste prix tout doit étre acheté. „Les moissons pour murir out besoin de rosée, „Pour vivre et pour sentir l'homme a besoin de pleura, „La joie a pour symbole une plante brisée, „Humide encore de pluie et couverte de fleurs."
