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Thanksgiving Eve Coastal Part Deux


DDweatherman

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Am also in East Columbia. I've noticed a big difference in accums (usually declining) driving from Columbia to BWI area after many storms. Personally, I also don't see much chance of accums on grass, decks, etc. until late afternoon or early evening -- if then -- unless we get some great rates earlier.

Only small elevation changes are needed here. You can drive from dc and start seeing the changeover during storms begin as close as north Bethesda by the 270 split. Go up 270 and once you get past rio towards gaithersburg and montgomery village and you can start seeing legit snow while the city has wet pavement. If i95 can be the rain/snow line Id say from gaithersburg to olney to columbia is often times the accumulation line. It can make a huge difference living out that way. I drove out to germantown for that dec '13 snow and it paid off bigtime. Several inches and pouring snowing there while Bethesda had mostly wet snow of the meh variety.

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Yes, if a Miller A pattern can establish itself from the funky jetstream it gives good odds of snowier Jan and Febs. Temps seem to be pointing to rain events in Dec.

37 winters here and it's really only useful to pay attention from Jan 5 thru March 5, if you like snow.

Agreed though I would say late December snow potentials are worth following. This case is unusual but overall late December to early March with the primetime from early jan to mid/late feb. Just like in the summer we have that 6-8 week period where it can get pretty hot we get the opposite in winter.

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I'm sure to the surprise of no one, but 6z NAM is really, really wet and fairly cold as well.  Also has a warm layer aloft at about 650-700mb early in the morning tomorrow, so maybe some RAPL before changing to SN.  

 

Edit...and precip lasts fairly late into the day as well, maybe 22-23z before shutting off.  Hence the snowier look.  

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I'm sure to the surprise of no one, but 6z NAM is really, really wet and fairly cold as well.  Also has a warm layer aloft at about 650-700mb early in the morning tomorrow, so maybe some RAPL before changing to SN.  

 

Edit...and precip lasts fairly late into the day as well, maybe 22-23z before shutting off.  Hence the snowier look.  

 

I am hoping that 12z NAM continues that trend... would be nice to see if it could happen

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I am hoping that 12z NAM continues that trend... would be nice to see if it could happen

Will (ORH_Wxman) posted the NAM QPF bias in the SNE forum and it shows that it really is a good rule of thumb to only take 2/3rds of NAM precip when it shows these 1-1.5" amounts.  Do that, and it brings it in line well with what the Euro is showing, although maybe even then the Euro is a tad wetter.  

 

GFS continues to look like a hot mess, but I don't particularly care.  I'm more interested in how the GFS brings the trailing vort through closer to us and gives many of us -SHSN Thursday morning.  Maybe even a dusting for DC area?  

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DTs been sticking to the extremely late changeover all along. Problem is if it changes over as late as he says, his forecast accumulation amounts are going to bust hard.

DT is amazing pretty good in the longer range, but I tend to think he has real issues with snow amounts - too high or too low - many many times. That being said, I ain't so great either so I am only sharing my observations. 

 

ETA: Amazing was too flattering - he does well. 

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Will (ORH_Wxman) posted the NAM QPF bias in the SNE forum and it shows that it really is a good rule of thumb to only take 2/3rds of NAM precip when it shows these 1-1.5" amounts.  Do that, and it brings it in line well with what the Euro is showing, although maybe even then the Euro is a tad wetter.  

 

GFS continues to look like a hot mess, but I don't particularly care.  I'm more interested in how the GFS brings the trailing vort through closer to us and gives many of us -SHSN Thursday morning.  Maybe even a dusting for DC area?  

 

Euro last night was 1"+ for all... so NAM has some support

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I'm sure to the surprise of no one, but 6z NAM is really, really wet and fairly cold as well.  Also has a warm layer aloft at about 650-700mb early in the morning tomorrow, so maybe some RAPL before changing to SN.  

 

Edit...and precip lasts fairly late into the day as well, maybe 22-23z before shutting off.  Hence the snowier look.  

I don't trust the NAm QPF, it tends to run high.  I'm on the euro train.  It's sfc temps are pretty warm for DC and me.  I'm not sure how DT gets his 2-4 over me.  He may be right but that seems pretty optimistic unless the temps really crash.

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I don't trust the NAm QPF, it tends to run high.  I'm on the euro train.  It's sfc temps are pretty warm for DC and me.  I'm not sure how DT gets his 2-4 over me.  He may be right but that seems pretty optimistic unless the temps really crash.

Yeah, see my last post, Wes.  Taking 2/3rds of NAM precip when it shows 1-1.5" really is a good rule of thumb apparently.  That would bring it in line with the Euro.  

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