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Potential Storm 2/17-2/19


Snow_Miser

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The 00z GEFS are indicating one of the most favorable periods we have seen all winter with a nearly ideal ridge axis along the west coast, and positive height anomalies into Greenland and the Davis Straight. Every single operational model has this system, and the potential is there for this to be a pretty large scale system.

 

f180.gif

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I honestly don't see how this DOESN'T happen. Full latitude trough...significant KU signature to it.

Aloft this is better of the 2 systems. The midweek may slide south , but this one has a healthy look to it .

Prob just more of a widespread event not as severe

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It's apples and oranges. The first system is a peice of energy that hangs back after the front slides through the NE. It's a Miller A with marginal temps around. The second system is a full latitude trough and involves the polar and subtrop. jet. Euro tries to hang some of the energy back and hence, it takes forever for the system to evolve (classic issue with the Euro). GFS ensembles were going nuts over the second system.

 

Aloft this is better of the 2 systems. The midweek may slide south , but this one has a healthy look to it .

Prob just more of a widespread event not as severe

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It's apples and oranges. The first system is a peice of energy that hangs back after the front slides through the NE. It's a Miller A with marginal temps around. The second system is a full latitude trough and involves the polar and subtrop. jet. Euro tries to hang some of the energy back and hence, it takes forever for the system to evolve (classic issue with the Euro). GFS ensembles were going nuts over the second system.

Was comparing to the severity of today. Agree widespread. Texas to Maine

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interesting read 

 

 

ECMWF


  • Compared to the other 2 operational models described above, the ECMWF does the best in predicting mid/upper tropospheric heights during the colder part of the year(such as October through April). The ECMWF tends to perform quite well in predicting amplitudes of planetary-scale regimes such as the Pacific/North American teleconnection (PNA). This model can also perform outstandingly during low to high planetary-scale wavenumber transition events, and northern hemispheric-scale regime transitions (Berry et al. 1996, CR TM 111).
  • Outperforms the other medium-range forecast models during shallow cold air situations.
  • Tends to overdevelop mid/upper cyclones across the southwestern U.S. Situations arise where this model will be too slow to predict the movement of cyclones from the southwest deserts.
  • Has a slight tendency to forecast mid/upper tropospheric heights and the resultant thickness calculations too high (i.e.; a warm bias).
  • Sometimes, especially during the warmer portion of the annual cycle, this model has too many closed lows. This bias may be related to its high resolution.
  • Tends to overamplify the long wave pattern, resulting in slower than observed progression of systems through the westerlies. This can result in overly weak and northward displaced short waves and associated surface features lifting into the long wave ridge position.
  • Found to have the smallest overall distance errors with springtime closed low forecasts during days four and five.
  • Westward forecast bias of closed cyclones (related to the issue described above)
  • Often too slow moving short wave features in deamplifying or zonal patterns
  • Of the medium range models, the ECMWF performs best with driving Arctic fronts down the east slopes of the Rockies.
  • The ECMWF too often incorrectly digs closed upper lows SWWD then WWD underneath strong upper ridges over the Eastern Pacific.
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The 12z Euro ENS have a strong signal for this storm with a 1004 mb low just E of LI at hour 192.

 

12zecmwfens850mbTSLPUS192.gif

 

 

The 12z GEFS also have a strong signal for being so far out in the forecast timeframe. 1002 mb low on the Benchmark at hour 180.

That is a pretty big signal...impressive for the ensembles this far out for both models.

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The key to this forecast is the energy coming out of the Southwest in concert with the northern stream. The

Euro ensembles are not hanging back as much energy as the OP sometimes does. This is a good time

to watch for a big amplification especially if the trough can go neutral to negative further west. Very nice

blocking signal at the time as others have mentioned.

 

Euro ens

 

 

OP may be hanging back too much energy

 

 

 

 

 

 

 

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The GFS and Euro are not of much use for this event right now, the GFS cold bias is killing it with 534 thicknesse to Miami and the euro is hanging back stuff in the SW.  The GEM/NOGAPS are most useful at this point since they do not have biases that are not showing the system, should start seeing the GFS/Euro pick it up soon.

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ya GFS looks very cold and the baroclinic zone ends up way east. I think this is a legitimate threat though obviously.  That s/w dropping down behind this trough also has potential. February is looking to get increasingly more stormy and continue with cold, even getting colder relative to normal once we finish off next week.

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