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Pattern The Great December Dump

Ridge to the west definitely moving in the right direction the last several runs of the American. moving west and trying to get steep ? ?A311F461-0BB3-49CE-A198-FDAEE2A09074.png
 
I mean since there’s nothing else to talk about. I know it’s out there, but let’s see what it do
22EE044B-A52B-4269-80F6-02F0EFC8C1A9.gif
 
Lotta source region cold on the GFS.. can't complain about that, however the geo potentials shimmy..
 
GEFS regarding the storm on the 21-22nd
I find interesting that even though the GEFS trended much lower with the Snow. The pattern still looks very favorable for a Miller A storm taking verbatim.

Composites using Webb’s Maps
View attachment 27829View attachment 27830View attachment 27831View attachment 27832

Thank goodness the King is there to keep us in line with reality! King is putting his robe and crown on now and will be sitting in his thrown starting in less than 10. Giddy up!
 
@Arcc and company are going to love the move toward a stronger +PNA and in the general direction of the stubborn GEFS on the new EPS for 12/15-20 with the result being a colder SE 12/20-23 (below normal vs the near normal on the 12Z run) to get folks more into the Christmas spirit! Hopefully this isn't a fake gift from Santa. This change being on the well respected EPS makes it quite believable to me.
 
GEFS regarding the storm on the 21-22nd
I find interesting that even though the GEFS trended much lower with the Snow. The pattern still looks very favorable for a Miller A storm taking verbatim.

Composites using Webb’s Maps
View attachment 27829View attachment 27830View attachment 27831View attachment 27832

Yeah, that pattern is a few adjustments away from being verbatim what you'd expect to see in a Miller A event. The positively tilted trough axis on the east coast would suggest a weaker storm and more progressive pattern overall >>> low more likely to scoot OTS faster vs the composite. Plenty of time for the pattern to change on the model tho.
 
The GEFS continues to get consistently better around the solstice pattern-wise. We're throwing more cold air into the pattern w/ successive runs thanks to the stronger 50-50 low & SE Canada trough. Note the higher MSLP anomalies (in red) over the midwest & southern Canada, our surface highs are getting stronger which confirms the previous statement regarding extra cold air being fluxed into the US on later GEFS runs. We're also trending towards a stronger west-based -NAO, +PNA, & -EPO.

There's lots to like about where this period may be potentially headed.

gfs-ens_z500trend_namer_19.png

gfs-ens_mslptrend_namer_19 (1).png
 
The GEFS seems to lack support of the 21st storm except a few members still. I do like the improving look on the EPS though. A couple more runs of the same westward trend and it'll be the same as the GEFS at H5 for the US. In fact, it's not too far off from the GEFS at all other than a weaker Aleutian high, but all the features are there and within less than 1000 miles of each other.
gfs-ens_z500a_namer_41.png
ecmwf-ens_z500a_namer_11.png
 
I am not sure if anyone has mentioned this recently but some sites have overly simplified algorithms behind their snow (clown) maps. This is one of them. So something falling from the sky with surface temps close to freezing = snow but they don't take mid level temps into account. This does show areas that have a chance of freezing rain overnight Thursday night into Friday AM though that is likely too broad of an area too. There is a separate thread for the potential ice event.
 
Remember when people were freaking out about this warm pattern on the EPS?

Instead, stronger cyclonic wave breaking over Atlantic Canada creates a stronger west-based -NAO and thus we're trending towards a pattern that's capable of producing a winter storm around the solstice.

View attachment 27836

What on earth is a west based -NAO? That must be before my time.
 
Meanwhile something to watch from DOC
DISCUSSION...
Medium-range guidance remains in relatively good agreement that a
shortwave trough will move from the Great Basin into the
southern/central Plains on D4/Sunday, continuing through the mid MS
Valley and into the Upper Great Lakes on D5/Monday. Guidance differs
on the location of the surface low associated with this shortwave
trough, with current forecasts of its position at 12Z D5/Monday
ranging from the KS/OK/MO border intersection to central TX. Even
with these differences, consensus is good for a moist and moderately
unstable environment from the Lower MS Valley through the TN Valley
on D5/Monday ahead of the approaching shortwave. Strong vertical
shear will extend across this region, supporting long hodographs and
supercell wind profiles. Consequently, there is a threat for severe
thunderstorms D5/Monday afternoon and evening from the Mid-South
into the Lower OH Valley as the shortwave trough and associated cold
front move through. Forecast confidence is high enough to introduce
severe probabilities. Refinements to this area are likely in
subsequent forecast as mesoscale details become more apparent.day5prob.gif
 
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