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Mitchg

12/8-9 Ana-frontal wave First flakes of the year?

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Probabilities are ticking up!  00z GEFS:

snowprobf120.png.90f25aadd76f487d6c186aab2f4f1ad6.png

50-60% chance of snow falling at 00z Fri in SNJ, ~45% for PHL attm.  (Starting with the next cycle I added a contour label to 50% and 90% to make it easier to read.)

Pushing 40% chance of >0.1" snow liq equiv now too in SNJ:

snowliq10probf120.png.419ac3a583bb7abfc21a5bfdba682cd7.png

And chances of >0.25" aren't all that much worse:

snowliq25probf132.png.68bbca09091761286114466f49328ca3.png

 

(Should I stop posting these???)

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Euro was a whiff for most of the CWA, sans coastal kings and Delmarva. 

6z GFS was a miss. Trough not as sharp, lower height rises along the coast to bring her up close enough. 

 

Fwiw, EPS mean is 3" for philly, but there  still are a considerable amount of whiffs. 

This is the type of set up that we could be smoke cirrus, and watching beaches get some white stuff. Little room for error for the 95 crowd. 

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13 minutes ago, irishbri74 said:

I mean, that's our wiggle room.... 

IMG_7850.GIF

Eps has 1-3 inches for the coast with the control having slightly more.

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Between coastal event later friday into Saturday morning and then follow clipper, snowfall breakdown is like this

LV/pocs 1.5-2"

nw burbs 2-2.5"

philly and immediate burbs to 295 2.5-3"

295 to the coast 3-3.5

southern and central de to interior south jersey 3.5-4"

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qpf for phl on the mean is .35

22 members with 2" or more, 12 of them having 6" or more

Looks like 14 whiffs

so that would make 15 members of <2"

 

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Granted the trough is positive tilted. But still, I saw this at h5 and then looked at the surface reflection and was like

ecmwf_z500_anom_conus_138.png

Image result for baffled gif

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1 hour ago, irishbri74 said:

Euro was a whiff for most of the CWA, sans coastal kings and Delmarva. 

6z GFS was a miss. Trough not as sharp, lower height rises along the coast to bring her up close enough. 

 

Fwiw, EPS mean is 3" for philly, but there  still are a considerable amount of whiffs. 

This is the type of set up that we could be smoke cirrus, and watching beaches get some white stuff. Little room for error for the 95 crowd. 

Yea, I think this can only come so far west. To many s/w's messing around with the flow to really amplify it. I think we are in a great spot though 4.5/5 days away to have a storm just offshore. About all you can ask for really. Areas to the south and east of philly definitely have higher odds right now. I feel like I'm reliving the jan 7th nightmare storm right now. 

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Despite the op going east, the 6z gefs increased from 0z

 

gefs_snow_mean_ma_25.png

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06z GEFS e-wall individuals: 2 good hits and several scrapers.

gefswave.gif

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5 minutes ago, Chubbs said:

06z GEFS e-wall individuals: 2 good hits and several scrapers.

 

full 20 members. So the higher totals are skewing the mean

 

gefs_snow_ens_neng_25.png

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1 hour ago, irishbri74 said:

I mean, that's our wiggle room.... 

 

Can see more amplified ridge out west allows everything to sharpen up. Good demonstration of that there.

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10 minutes ago, tombo82685 said:

Can see more amplified ridge out west allows everything to sharpen up. Good demonstration of that there.

This time of year to keep the ocean at bay,  better off with a flatish wave.  There comes a point where too much amplification would become a negative.

Would be nice to have the Ukmet on board.

That is a very nice 180kt 250mb jet.

index.gif.513dae7b1e7a112d8f82043daf0c3844.gif

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21 minutes ago, tombo82685 said:

Can see more amplified ridge out west allows everything to sharpen up. Good demonstration of that there.

 

22 minutes ago, Rainshadow said:

This time of year to keep the ocean at bay,  better off with a flatish wave.  There comes a point where too much amplification would become a negative.

Would be nice to have the Ukmet on board.

That is a very nice 180kt 250mb jet.

Per GEFS, the orientation of the WC ridge is getting more favorable allowing energy to drop due south and lowering heights in the maritimes as it pushes the PV east.

gfs-ens_z500trend_namer_8.png

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7 minutes ago, Chubbs said:

 

Per GEFS, the orientation of the WC ridge is getting more favorable allowing energy to drop due south and lowering heights in the maritimes as it pushes the PV east.

gfs-ens_z500trend_namer_8.png

It is rare for modeling to not increase ridging as we get closer to t00.

This is the 75% percentile off the CIPs analogs.  #1 analog was a whiff to the east.  #2 analog was nearly all rain, but would have been 4" of snow.   I don't want say (some) rain is out of the question this far out.  The antecedent air mass giving max temps in the low 40s in December is not cold, but the predicted dew points are pretty low. While I have much greater confidence in temps than dews, the dews are predicted so low, they'd be in pretty big bust territory right now to be that wrong.

Capture.JPG.fe32c22afc045bc257eb9202a1519bf0.JPG

 

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1 hour ago, Rainshadow said:

This time of year to keep the ocean at bay,  better off with a flatish wave.  There comes a point where too much amplification would become a negative.

Would be nice to have the Ukmet on board.

That is a very nice 180kt 250mb jet.

 

It's a catch 22, need to sharpen the trough which would pull everything west. Like you said, still have warm oceans so you can only go so far west. Honestly, I don't see this coming to the point where it's 50/100 miles off shore. Just to much in the flow allowing for a huge amplification. That back side energy is helping to deamplify the trough too and punt. If we had a robust -nao signal, then we can start talking, but even though the  h5 look is amplified, it's progressive too.

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25 minutes ago, tombo82685 said:

It's a catch 22, need to sharpen the trough which would pull everything west. Like you said, still have warm oceans so you can only go so far west. Honestly, I don't see this coming to the point where it's 50/100 miles off shore. Just to much in the flow allowing for a huge amplification. That back side energy is helping to deamplify the trough too and punt. If we had a robust -nao signal, then we can start talking, but even though the  h5 look is amplified, it's progressive too.

Well the nao outlook trend for latter half of this week is to go slightly more negative.  This is with the caveat (shocking result) that the bias has been to over sell -nao.  On the other side, the pna has been verifying more positive than outlooked.

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30 minutes ago, tombo82685 said:

It's a catch 22, need to sharpen the trough which would pull everything west. Like you said, still have warm oceans so you can only go so far west. Honestly, I don't see this coming to the point where it's 50/100 miles off shore. Just to much in the flow allowing for a huge amplification. That back side energy is helping to deamplify the trough too and punt. If we had a robust -nao signal, then we can start talking, but even though the  h5 look is amplified, it's progressive too.

We can stand some amplification so it is not a bad set-up right out of the gate.

 

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1 hour ago, Chubbs said:

We can stand some amplification so it is not a bad set-up right out of the gate.

 

Or system could de-amplify as per the 12z gfs

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42 minutes ago, Chubbs said:

Or system could de-amplify as per the 12z gfs

Yea that wasnt't a good run at all. The lower hgts associated with the pv being further east is flattening the flow. Need that thing back west so you can get return flow

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