March 13/14th Storm Thread (Storm Mode)

[Cobalt]

NWS Calling for 7" In DC and 9" In Fairfax. Anyone think this is realistic?

[high risk]

16 minutes ago, Always in Zugzwang said:

Surprising looking snow map for the I-95 and DC areas.  I would have expected much less looking at the precip type and thermals, it looked like nearly all rain through sometime after 03Z, then the DC metro looks on the border of heavy snow/rain around 06Z, then the precip blows by and is gone shortly thereafter (by 09Z).  Must drop all that in literally a 3 hour period or so, if that map is even close to realistic.  2-m temperatures are just above freezing through about 06Z, though they're crashing by that point it appears.  850 temperatures mirror that, crashing below 0C around 06Z after the zero line is well north and west of DC metro before then.

 

       2 critical points:

   1)    that's snow + sleet

   2)    if the NAM has 1" of liquid, and it's 50% rain and 50% mangled snowflakes, the tally comes up with .5" liquid equiv of snow.   Slap on a 10:1 ratio, and you get a 5" prediction even though the model doesn't really show that at all.

 

  

[clskinsfan]

1 minute ago, TowsonWeather said:

You think the WPC is discounting the Euro and rolling with the NAM - the only model I've seen that shows this solution?

wut?

Well if you look at the probabilities map just posted. They clearly are discounting the Euro on it. 8-12 for my area????

[WinterWxLuvr]

Just now, TowsonWeather said:

You think the WPC is discounting the Euro and rolling with the NAM - the only model I've seen that shows this solution?

wut?

Tell ya what pal, call those pros over at WPC and tell them you disagree.

Here is their map

[EastCoast NPZ]

49 minutes ago, dailylurker said:

I had 14" on 11/11/87 during the day. Anything is possible. 

Not saying you're wrong, obviously; however, that sun-angle is equivalent to late January.

[BTRWx]

Wpc guidance actually improved! I'm surprised...http://origin.wpc.ncep.noaa.gov/wwd/day3_psnow_gt_08.gif

[WinterWxLuvr]

The para NAM which was dry as a bone here earlier is now very wet.

At a glance it appears an earlier storm formation as the whole precipitation panel seems to have shifted south.

[Scarlet Pimpernel]

Just now, high risk said:

 

       2 critical points:

   1)    that's snow + sleet

   2)    if the NAM has 1" of liquid, and it's 50% rain and 50% mangled snowflakes, the tally comes up with .5" liquid equiv of snow.   Slap on a 10:1 ratio, and you get a 5" prediction even though the model doesn't really show that at all.

 

  

Thanks...I kind of thought that might be the case (at least the counting sleet part; didn't realize it considered just 50% snow as "all snow" for those accumulation plots).  It did look unrealistic compared to what the other parameters were indicating...and like I said, if (big if!) that were even all snow around 06Z, the amounts shown in the snow map would literally have to fall in about a 3 hour period!

[WinterWxLuvr]

Just now, EastCoast NPZ said:

Not saying you're wrong, obviously; however, that snow-angle is equivalent to late January.

Exactly.  Started to post the same thing.  Sure, snow at night and all that, but as the sun comes up it's a different story.  Need that overnight precipitation to do its work.

[aldie 22]

1 minute ago, WinterWxLuvr said:

The para NAM which was dry as a bone here earlier is now very wet.

At a glance it appears an earlier storm formation as the whole precipitation panel seems to have shifted south.

All I cared about on the nam was how wet...that's why I asked EJ

[EastCoast NPZ]

Just now, WinterWxLuvr said:

Exactly.  Started to post the same thing.  Sure, snow at night and all that, but as the sun comes up it's a different story.  Need that overnight precipitation to do its work.

Yep, or heavy rates.

[PDIII]

1 minute ago, DCAlexandria said:

Feels a lot like sequester repeat. Set your expectations guys.


Sent from my iPhone using Tapatalk

This is a completely different set up.  That was a bowling ball/ vigorous upper level low that was supposed to produce its own cold air... and It did a good job of it in the favored elevation areas.  This is a coastal low that is developing just to our south east.  This is a thread the needle type event.  Sequester relied on dynamics and it just wasnt enough for the cities.  

[WinterWxLuvr]

Just now, leesburg 04 said:

All I cared about on the nam was how wet...that's why I asked EJ

Supposedly that para is the new NAM so one would think it possibly a better model.

[TowsonWeather]

10 minutes ago, WinterWxLuvr said:

Tell ya what pal, call those pros over at WPC and tell them you disagree.

Here is their map

Did you read the WPC discussion from a few hours ago?

They are clearly not dismissing the Euro. Far from it. 

http://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd

[dallen7908]

Its the last update of the NAM, which is expected to be retired in FY19? in deference to a non-hydrostatic finite volume model that will hopefully work well at regional and global scales. 

[WxUSAF]

20 minutes ago, Cobalt said:

NWS Calling for 7" In DC and 9" In Fairfax. Anyone think this is realistic?

That looks quite reasonable to me.  Maybe high in DC, because DC, but otherwise pretty good. 

[cae]

The 12z Euro snow map is out on windytv.  I'm not sure what algorithm they use to determin the p-type, but it's based on 10:1 ratios.  You can see where they think the rain/snow line will set up. 

Edit:  They say it's the 12z map, but it looks like it could be the 00z map to me.  So take with a grain of salt.

The colors can be hard to read, but you can point-and-click for your backyard here.

https://www.windytv.com/?snowAccu,next6d,39.271,-77.031,8,m:eJYad0L

 

[mattie g]

2 minutes ago, WxUSAF said:

That looks quite reasonable to me.  Maybe high in DC, because DC, but otherwise pretty good. 

Completely agree.

I think it would be reasonable to forecast anything between 4-14" in Fairfax for this thing. There's a realistic chance for a big, hard-hitting event, but just as much for a wet failure.

[Bob Chill]

HP dropping out of Canada a little stronger on 18z vs 12z.  You can see the boost in colder midlevels by hr 24. Good push on top of the vort so tracking further south. 

[Roger Smith]

this could be huge

Evidence of wave formation in western Gulf of Mexico, approximately 100 nm ssw of Galveston. Radar and satellite show development and oil rig in warm sector has seen 50m winds of 35G45 veering rapidly SSE to SW past hour. This seems more developed than models would suggest. Possible seeding of actual energy center more similar to 1993 storm, as this seems headed for FL panhandle in 36h. This in connection to the odd appearance of upper low and warmth-devoid inland low in a rather odd configuration suggest possibility of more dynamic trough developments next 24-36h. I'm thinking this Gulf of Mexico low may capture the Ohio valley low around 36h and form a powerful coastal with a hangback to shadow of upper low, and that the upper low may deepen slightly more and further south than the NAM's most recent effort. 

[AmericanWxFreak]

4 minutes ago, Roger Smith said:

this could be huge

Evidence of wave formation in western Gulf of Mexico, approximately 100 nm ssw of Galveston. Radar and satellite show development and oil rig in warm sector has seen 50m winds of 35G45 veering rapidly SSE to SW past hour. This seems more developed than models would suggest. Possible seeding of actual energy center more similar to 1993 storm, as this seems headed for FL panhandle in 36h. This in connection to the odd appearance of upper low and warmth-devoid inland low in a rather odd configuration suggest possibility of more dynamic trough developments next 24-36h. I'm thinking this Gulf of Mexico low may capture the Ohio valley low around 36h and form a powerful coastal with a hangback to shadow of upper low, and that the upper low may deepen slightly more and further south than the NAM's most recent effort. 

I'm not quite sure what this means for us but I think I like it

[clskinsfan]

3 minutes ago, B-Paq said:

 

According to this, the North end of Easton gets 10.6 inches and the south end gets 1.2 

Ha. I was gonna say it looks like the North bound Bay bridge is rain and the South bound bridge is snow

[yoda]

18z GFS hr 54 1012 SLP south of ILM

hr 57 1008mb SLP NE of ILM

[Joshfsu123]

So far on 18z GFS, SS low is a little stronger and the NS low is a little weaker and slightly SW of 12z... at HR 57

[yoda]

hr 60 1004 SLP HSE

hr 63 998 SLP just offshore NC/VA border 100 miles or so

[clskinsfan]

The GFS definitely has an expanded precip field on the western side of the storm compared to 12Z. 

[WxMan1]

35 minutes ago, WinterWxLuvr said:

Tell ya what pal, call those pros over at WPC and tell them you disagree.

Here is their map

Guys, we tend to follow the same practice with these probs as NHC does with their track forecast -- instead of wild swings W to E or vice-versa from one forecast cycle to the next, you're more likely to see gradual shifts. What if the EC is an anomaly?  I mean, it is east of most EC members and east of the EC mean.  

In situations like these, it's best to not swing from one end of the goalpost to the other..

[Bob Chill]

NS giving up earlier. Should be good for temps. Precip shield look much improved for the western folks. Good run incoming. 

[SomeguyfromTakomaPark]

Looks a lot nicer at 63, more precip on the NW side of the low and 850 line in a good spot. 

[stormtracker]

1 minute ago, DCTeacherman said:

Looks a lot nicer at 63, more precip on the NW side of the low and 850 line in a good spot. 

Yup, i think even the western guys will like this.  We're close once again..but ya know..that's how we roll