Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

Storm potential Tuesday 2/17/2015


famartin

Recommended Posts

  • Replies 320
  • Created
  • Last Reply

very nice trend by the NAM, it's still snowing at HR 36 and the snow map already looks good just on 10:1, but with thinking ratio's will be more like 12:1. I don't like relying on 15:1 ratios as they very rarely happen here. will post the 10:1 map after the next frame.

 

The temps will be in the mid to upper teens while it's snowing right?  Shouldn't that be at least 12:1? Especially since a lot of the snow will be falling overnight...

Link to comment
Share on other sites

The temps will be in the mid to upper teens while it's snowing right?  Shouldn't that be at least 12:1? Especially since a lot of the snow will be falling overnight...

cold temps do not equal high ratios. the surface temps have nothing to do with snow growth. if the upper levels are too cold, then you get crappy snow growth and sand like snow that is lucky to get 10:1 on the ratios. I haven't taken a look at those levels but they didn't look  overwhelmingly cold earlier. Also I remember reading somewhere(maybe here?) about how rare it is to get over 15:1 ratios in the philly area. it's a rare event. But I believe you want the upper levels to be -10 to -12C? A met would be able to give a definitive answer, I just know that cold doesn't automatically mean high ratios.

Link to comment
Share on other sites

cold temps do not equal high ratios. the surface temps have nothing to do with snow growth. if the upper levels are too cold, then you get crappy snow growth and sand like snow that is lucky to get 10:1 on the ratios. I haven't taken a look at those levels but they didn't look  overwhelmingly cold earlier. Also I remember reading somewhere(maybe here?) about how rare it is to get over 15:1 ratios in the philly area. it's a rare event. But I believe you want the upper levels to be -10 to -12C? A met would be able to give a definitive answer, I just know that cold doesn't automatically mean high ratios.

 

This is the sounding at hr 33 at PHL, when precip is heaviest. I haven't read much about ratios, but I believe you want a saturated isothermal column between the surface and 700 mb, which this pretty much is. Maybe Ray can provide a better interpretation for us.

 

NAM_218_2015021600_F33_40.0000N_75.0000W

Link to comment
Share on other sites

This is the sounding at hr 33 at PHL, when precip is heaviest. I haven't read much about ratios, but I believe you want a saturated isothermal column between the surface and 700 mb, which this pretty much is. Maybe Ray can provide a better interpretation for us.

 

NAM_218_2015021600_F33_40.0000N_75.0000W

 

Ideally you'd want the best omega (lift/vertical velocities) to coincide with temperatures between -12 and -18C. This sounding is fairly isothermal through about 600mb  which would be good if it were isothermal along ~-15C but this case looks just a little warm for ideal snow growth, but even so 10:1 - 12:1 ratios should be attainable.

Link to comment
Share on other sites

Ideally you'd want the best omega (lift/vertical velocities) to coincide with temperatures between -12 and -18C. This sounding is fairly isothermal through about 600mb  which would be good if it were isothermal along ~-15C but this case looks just a little warm for ideal snow growth, but even so 10:1 - 12:1 ratios should be attainable.

 

Thanks for your input. NYC weenies are getting excited about 20:1 ratios being printed out by some models, which really just isn't feasible on the coastal plain. I'm hoping for 12 or 13:1 ratios here.

Link to comment
Share on other sites

Ideally you'd want the best omega (lift/vertical velocities) to coincide with temperatures between -12 and -18C. This sounding is fairly isothermal through about 600mb  which would be good if it were isothermal along ~-15C but this case looks just a little warm for ideal snow growth, but even so 10:1 - 12:1 ratios should be attainable.

Yes.

Link to comment
Share on other sites

Thanks for your input. NYC weenies are getting excited about 20:1 ratios being printed out by some models, which really just isn't feasible on the coastal plain. I'm hoping for 12 or 13:1 ratios here.

I saw the SREF snow plumes are jacking out some really high ratios, but I wouldn't trust those.

Link to comment
Share on other sites

I trust the RGEM 10000000000000000000000000x more than the NAM, the NAM @ this range likes to have runs like this where it gets wet...the RGEM came in a touch drier...My call for Philly is 1-2" 

 

RGEM hasn't exactly had the hot hand of late. Wanted to give Boston next to nothing today and they ended up with 16.2".

Link to comment
Share on other sites

I trust the RGEM 10000000000000000000000000x more than the NAM, the NAM @ this range likes to have runs like this where it gets wet...the RGEM came in a touch drier...My call for Philly is 1-2" 

seems a little low 2-4 maybe, but pretty much all guidance is giving PHL at least a few inches

Link to comment
Share on other sites

seems a little low 2-4 maybe, but pretty much all guidance is giving PHL at least a few inches

ya the RGEM gives philly 2 inches on a 10:1 scale. 2-4 would be more reasonable and still I think a worst case scenario for the area at this point. I'd be shocked if philly doesn't see 2 inches out of this at this point.

Link to comment
Share on other sites

ya the RGEM gives philly 2 inches on a 10:1 scale. 2-4 would be more reasonable and still I think a worst case scenario for the area at this point. I'd be shocked if philly doesn't see 2 inches out of this at this point.

 

IMO this will definitely be the biggest storm of the year for Philly. I will take Euro/GFS/NAM over RGEM any day of the week.

Link to comment
Share on other sites

IMO this will definitely be the biggest storm of the year for Philly. I will take Euro/GFS/NAM over RGEM any day of the week.

 

Since PHL's biggest is only 1.5, it won't be hard for this to be the biggest.  RGEM's 0.20" QPF is at least 2" and everything else is higher than that.  I would be surprised if they don't break 2.

Link to comment
Share on other sites

GFS QPF

MPO 0.11

ABE 0.16

RDG 0.13

TTN 0.21

PHL 0.24

ILG 0.23

ACY 0.36

GED 0.56

 

NAM QPF

MPO 0.11

ABE 0.17

RDG 0.22

TTN 0.31

PHL 0.41

ILG 0.43

ACY 0.63

GED 0.84

yeah i think 2-4 solid forecast given what we have seen now let's see the euro in a bit.   if euro comes in drier most of the area N of ACY probably ends up with advisory level snow.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...