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Winter Storm Threat February 3-5


Grothar

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fwiw the 18z gfs ens phase in the northern stream moreso and dont cut off the low in the mid west. Thus resulting in a big jump further north extent of the precip field compared to the op. Looks like 7 of the 12 get .1 up to phl. The gfs ens mean brings .25 up to phl and .5 from central del to just south of cape may

accum precip

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Not surprised the GGEM shows the solution given the Sunday disturbance pushes out much faster than the GFS and is a bit more amplified out of the gate. It's the exception to the rest of the models that matter though.

if you compare the ggem and the ukie they are pretty close in low placement with tracking along va/nc border. Both of them phase in the northern stream disturbance and don't cut off the low in the plains like the 18z gfs did, thus a more amplified solution.

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I added pictures of what im talking about. You can see on the ggem and ukie the solid black line where the models are trying to phase in the northern stream with the storm coming out of the plains. The ukie phases them but to a lesser extent as the ggem. While you look at the gfs it keeps the systems separate and shears them apart.

ggem

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ukie

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gfs

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The GFS ensemble members are run at a courser resolution, so maybe that's why they are quicker to phase. But.......the resolution of the op can ggem and ukmet are not exactly coarse in themselves. Ironically the can ggem ensemble members support the op gfs more while the 18z gfs ensemble members are more inclined toward the op can ggem. The NAEFS pops jumped upward, with a tightening of the pop gradient. Without sounding too optimistic, I think you have to leave the door open on this one yet. Pretty complicated with rex blocks and phasing (or lack thereof), kind of smacks of the modeling issues that occurred with boxing day, don't have to slow streams down too much without getting a plethora of different solutions. We may not know a definitive answer til the 00z run on Saturday.

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Placement of the northern stream energy may be key. GGEM and some of the GEFS members dig it further SW.

Part of this is evolution also (and we saw how the 12z gfs run on 12/24 was right after a poor initialization), but the can ggem 500mb 12hr forecast is not verifying well over Eastern Alaska and northern Canada off the 00z raobs, I see a 10m and a pair of 30m height errors meanwhile the gfs is spot on with two and a 20m error with the third. Based on those errors, that northern stream trof is not as sharp as depicted by the canadian forecast. The problem though is what happens to the kicker and that is still in the Pacific south of Alaska. On the Canadian, the forecast closed low by sunday morning is 100 meters deeper than the gfs and that is what drives the ridging in front of it and then permits the not so well initialized lead short wave to phase more. That kicker comes inland 00z sat.

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The GFS ensemble members are run at a courser resolution, so maybe that's why they are quicker to phase. But.......the resolution of the op can ggem and ukmet are not exactly coarse in themselves. Ironically the can ggem ensemble members support the op gfs more while the 18z gfs ensemble members are more inclined toward the op can ggem. The NAEFS pops jumped upward, with a tightening of the pop gradient. Without sounding too optimistic, I think you have to leave the door open on this one yet. Pretty complicated with rex blocks and phasing (or lack thereof), kind of smacks of the modeling issues that occurred with boxing day, don't have to slow streams down too much without getting a plethora of different solutions. We may not know a definitive answer til the 00z run on Saturday.

That right there is why i don't really worry what models, ensembles or weeklies say about the weather 2-4 weeks from now.

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