showmethesnow Posted January 28, 2019 Share Posted January 28, 2019 3 minutes ago, Ralph Wiggum said: Didnt the models have a finger of heaviest snows extending SW from Eastern PA down into DC yesterday? Looks opposite now unless that secondary max is the finger and shifted E? Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 28, 2019 Share Posted January 28, 2019 2 minutes ago, showmethesnow said: Overall the run doesn’t look that different to me, so not sure why the snowmap looks so different. Did it cut back QPF or is it because of temps? Link to comment Share on other sites More sharing options...
arlwx Posted January 28, 2019 Share Posted January 28, 2019 The latest from LWX: .NEAR TERM /THROUGH TONIGHT/... High clouds will be exiting the area later today giving way to abundant sunshine with high pressure building over the area. Clouds will start increasing again this evening ahead of next low pressure moving through Michigan and its associated cold front. Expecting light snow to break out after 07Z across far west and nrn MD counties. Any accumulation through 12Z Tue will be less than half inch. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Models have been indicating a secondary low pressure center forming along the front as it moves across the area Tue afternoon. Overall, guidance has trended wetter and colder across the north with this system. Through midday Tue, expect snow north of I-70 and west of Rt 15 with rain east and south of there, then rain gradually changing to wet snow as colder air filters in. Over the I-95 corridor, the changeover may not occur until closer to sunset with a 3-6 hr period of moderate wet snow falling at sfc temps likely around freezing before ending by midnight Tue night. QPF is generally 0.1 to 0.5 inches with highest amts along the I-95 corridor, but most of that would be falling as rain or rain/snow mix. This translates to about 1-3 inches of snow with highest accumulations north of I-70. Rapid clearing is expected Tue night after midnight, then Arctic front will follow on Wed with rapdily falling temps during the afternoon. Winds could gust up to 45 mph Wed creating dangerous low wind chills. Snow showers or snow squalls may accompany the front as it crosses the area or develop behind the front on the strong NW flow. Link to comment Share on other sites More sharing options...
showmethesnow Posted January 28, 2019 Share Posted January 28, 2019 12 minutes ago, DCTeacherman said: Overall the run doesn’t look that different to me, so not sure why the snowmap looks so different. Did it cut back QPF or is it because of temps? Cut back a touch on the precip. Didn't really dive into the temps. Euro doesn't have the maps (at least that I can find) but going by the GFS the differences we are seeing with placement and amount of snow fall on the different models is probably due to how they are handling the intensity and the placement of the lift at both 850 and 700mb as they run through the region. The interaction between the two is important to get moisture into the colder air moving in. And the GFS has been somewhat erratic with those features. Probably should start focusing more on the Meso's at this point because the GFS will probably have a hard time nailing down those features. Wish I could find Euro maps for it because of its higher resolution as well. Link to comment Share on other sites More sharing options...
LP08 Posted January 28, 2019 Share Posted January 28, 2019 12 minutes ago, DCTeacherman said: Overall the run doesn’t look that different to me, so not sure why the snowmap looks so different. Did it cut back QPF or is it because of temps? Not much change in precip and thermals seemed like noise to me. Razor thin here. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 28, 2019 Share Posted January 28, 2019 23 minutes ago, LP08 said: Not much change in precip and thermals seemed like noise to me. Razor thin here. Thanks for the map. I guess it’s really gonna be all about the boundary layer. Seems like most models agree on 0.25-0.5 QPF. If we can get a quick flip we can score 3-5, if it’s 37 degrees with white rain at 00z wed we’re in trouble. Link to comment Share on other sites More sharing options...
PDIII Posted January 28, 2019 Share Posted January 28, 2019 All the models are showing the precip max in eastern pa. I am sad about that. Why can't the blue be over me? Link to comment Share on other sites More sharing options...
psuhoffman Posted January 28, 2019 Share Posted January 28, 2019 54 minutes ago, DCTeacherman said: Overall the run doesn’t look that different to me, so not sure why the snowmap looks so different. Did it cut back QPF or is it because of temps? Qpf decreases about .1 but it was also temps were slightly warmer. Bad combo when it’s a marginal setup. Can’t afford any bleeding when your on your deathbed already with marginal temps and modest qpf. Link to comment Share on other sites More sharing options...
heavy_wx Posted January 28, 2019 Share Posted January 28, 2019 There's some convective instability in the mid-levels (~600-700 mb) at BWI on the GFS for Tuesday afternoon ahead of the first cold front; lapse rates in this layer are about 7C/km. Additionally, there is some moderate frontogenesis associated with the strengthening boundary just below this layer. This forcing in the convectively unstable region would allow for the some mid-level convection to be realized. The location of the unstable region is also within the dendritic growth layer, favoring more efficient ice crystal growth; isothermal temperatures near 0C below 850 mb would also support very large, wet aggregates. Of course, these temperatures may also turn out to be marginal for precipitation staying all snow. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 28, 2019 Share Posted January 28, 2019 6z Euro cuts back again. Now looks to be in line with other models with coating to 2 inches for most of the immediate DC area. Link to comment Share on other sites More sharing options...
MD Snow Posted January 28, 2019 Share Posted January 28, 2019 It’s hard to not invision this being a pretty simple frontal passage with rain turning to snow. An inch tops in the metro areas. 2 inches tops along the md/pa line. Two things that could provide a slight boom scenario would be 1) temps going in not being as high which would allow for an immediate change over. Or 2) some light snow early tomorrow morning as dipicted by some models that could be a surprise dusting .5” especially north and west. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted January 28, 2019 Share Posted January 28, 2019 Literally every model decreased snow a little on the 6z suite. My bar here in east Baltimore is 1” Link to comment Share on other sites More sharing options...
LP08 Posted January 28, 2019 Share Posted January 28, 2019 3 minutes ago, MD Snow said: It’s hard to not invision this being a pretty simple frontal passage with rain turning to snow. An inch tops in the metro areas. 2 inches tops along the md/pa line. Two things that could provide a slight boom scenario would be 1) temps going in not being as high which would allow for an immediate change over. Or 2) some light snow early tomorrow morning as dipicted by some models that could be a surprise dusting .5” especially north and west. Yeah. Clicking through soundings on the 3k NAM showed around the DC area show the temps never getting below freezing until after precip pulls out. I still think that if someone can get the .25 QPF over a 3 hour window, you can dynamically cool to <32 and accumulate, but I don't think that will be widespread and we will have lots of varying reports and conditions come tomorrow night. Link to comment Share on other sites More sharing options...
MD Snow Posted January 28, 2019 Share Posted January 28, 2019 5 minutes ago, LP08 said: Yeah. Clicking through soundings on the 3k NAM showed around the DC area show the temps never getting below freezing until after precip pulls out. I still think that if someone can get the .25 QPF over a 3 hour window, you can dynamically cool to <32 and accumulate, but I don't think that will be widespread and we will have lots of varying reports and conditions come tomorrow night. The idea of just a simple, yet figorious frontal passage is becoming more likely especially as the meso’s come into range. Given their dispiction, it’s hard to see there being an extended period of heavy snow. Which is what you would need Still could be a fun and dynamic event. I’m looking forward to it. This still has a chance to be one of the more wintery weeks of winter. Arctic front tomorrow, snow squalls on Wednesday, clipper on Friday, and deep cold Wednesday- Saturday. Sign me up! Link to comment Share on other sites More sharing options...
frd Posted January 28, 2019 Share Posted January 28, 2019 1 hour ago, DCTeacherman said: 6z Euro cuts back again. Now looks to be in line with other models with coating to 2 inches for most of the immediate DC area. Wondering if the outcome for tomorrow plays a hand in the potential snow squalls for Weds. PM. ? Link to comment Share on other sites More sharing options...
psuhoffman Posted January 28, 2019 Share Posted January 28, 2019 44 minutes ago, MD Snow said: It’s hard to not invision this being a pretty simple frontal passage with rain turning to snow. An inch tops in the metro areas. 2 inches tops along the md/pa line. Two things that could provide a slight boom scenario would be 1) temps going in not being as high which would allow for an immediate change over. Or 2) some light snow early tomorrow morning as dipicted by some models that could be a surprise dusting .5” especially north and west. The trough is going negative tilt with a lot of cross boundary flow and some pretty good forcing. This isn’t a typical front. But the waves impacts will be narrow. Somewhere is getting a 3-5” thump from this. But it could be north or northeast of us. That doesn’t mean it failed because it was a “typical front”. This is anything but. Link to comment Share on other sites More sharing options...
MD Snow Posted January 28, 2019 Share Posted January 28, 2019 2 minutes ago, psuhoffman said: The trough is going negative tilt with a lot of cross boundary flow and some pretty good forcing. This isn’t a typical front. But the waves impacts will be narrow. Somewhere is getting a 3-5” thump from this. But it could be north or northeast of us. That doesn’t mean it failed because it was a “typical front”. This is anything but. But it isn’t as negative as it was 24hrs ago. What I mean by “typical” is surface depiction/precip field for our area. It’s pretty vigorous otherwise. Most arctic fronts are. 12z NAM looks interesting for maybe some secondary development east of 95 tomorrow night. It also has a nice little slug of moisture up your way before the front goes through tomorrow morning. Would think maybe you could capitalize on that given your elevation? Link to comment Share on other sites More sharing options...
psuhoffman Posted January 28, 2019 Share Posted January 28, 2019 NAM is developing the wave well northeast of us. The trend in the globals has been east for 48 hours now. This was bullseying WV to central PA 3 days ago. Hope the good looks yesterday weren’t just a temporary pit stop as the guidance continues to shift northeast. Not thrilled with how it’s heading. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted January 28, 2019 Share Posted January 28, 2019 5 minutes ago, psuhoffman said: NAM is developing the wave well northeast of us. The trend in the globals has been east for 48 hours now. This was bullseying WV to central PA 3 days ago. Hope the good looks yesterday weren’t just a temporary pit stop as the guidance continues to shift northeast. Not thrilled with how it’s heading. The old north trend inside 48 hours. Link to comment Share on other sites More sharing options...
LP08 Posted January 28, 2019 Share Posted January 28, 2019 3k Looks to change DC ~19z tomorrow. 90% of this is snow with temps hovering around 32-34 in the immediate burbs. Link to comment Share on other sites More sharing options...
mattb65 Posted January 28, 2019 Share Posted January 28, 2019 Assuming the timing on the NAM is correct, it seems there is a first wave favoring areas closer to the MD/pa line around 0900 with temps in the whole column supporting snow and supporting sleet mix closer to DC. Then the main chunk of snow comes in closer to 1300 which seems to be a speed up on terms of onset time and could cause pretty significant impacts on traffic assuming I'm reading the timing correctly. Boundary layer temps are 33 according to the 3k NAM in the DC metro so impact will depend on rates. Soundings clearly support snow as the ptype. Link to comment Share on other sites More sharing options...
nj2va Posted January 28, 2019 Share Posted January 28, 2019 1 minute ago, LP08 said: 3k Looks to change DC ~19z tomorrow. 90% of this is snow with temps hovering around 32-34 in the immediate burbs. Thanks for posting this. LWX forecast of 1-2" looks good for DC/immediate burbs. Link to comment Share on other sites More sharing options...
clskinsfan Posted January 28, 2019 Share Posted January 28, 2019 16 minutes ago, psuhoffman said: NAM is developing the wave well northeast of us. The trend in the globals has been east for 48 hours now. This was bullseying WV to central PA 3 days ago. Hope the good looks yesterday weren’t just a temporary pit stop as the guidance continues to shift northeast. Not thrilled with how it’s heading. Same thing the ICON has been doing for days. Gets its act together too late for us. Link to comment Share on other sites More sharing options...
osfan24 Posted January 28, 2019 Share Posted January 28, 2019 I would take the 3K and run at this point, especially with the way latest guidance is tredning. Not as good for DC, but most of Maryland picks up 2-4 with that. Link to comment Share on other sites More sharing options...
clskinsfan Posted January 28, 2019 Share Posted January 28, 2019 I am gonna pull a Ji and say the NAM just took away all of my snow. I get zip. NOTHING. Link to comment Share on other sites More sharing options...
MD Snow Posted January 28, 2019 Share Posted January 28, 2019 3 minutes ago, LP08 said: 3k Looks to change DC ~19z tomorrow. 90% of this is snow with temps hovering around 32-34 in the immediate burbs. This would be best case scenario imo. Areas north of DC have potential to capitalize in the morning and areas east have potential to capitalize in the afternoon. Link to comment Share on other sites More sharing options...
psuhoffman Posted January 28, 2019 Share Posted January 28, 2019 1 minute ago, osfan24 said: I would take the 3K and run at this point, especially with the way latest guidance is tredning. Not as good for DC, but most of Maryland picks up 2-4 with that. Yea I guess...but that back edge of decent qpf keeps creeping east every run. Those of us west of 95 are running out of room on the cliffs edge. 95 east the problem is temps. Link to comment Share on other sites More sharing options...
psuhoffman Posted January 28, 2019 Share Posted January 28, 2019 1 minute ago, MD Snow said: This would be best case scenario imo. Areas north of DC have potential to capitalize in the morning and areas east have potential to capitalize in the afternoon. I doubt that morning band is much. Temps are really questionable even up here. And even if it dropped a quick 1-2” it probably would melt during the lull then the afternoon drops another 1” and the numbers say we got 3” but only 1” otg. I hate that crap. Link to comment Share on other sites More sharing options...
LP08 Posted January 28, 2019 Share Posted January 28, 2019 Just now, psuhoffman said: Yea I guess...but that back edge of decent qpf keeps creeping east every run. Those of us west of 95 are running out of room on the cliffs edge. 95 east the problem is temps. <blah blah DC to bmore jackpot blah blah> haha Link to comment Share on other sites More sharing options...
NorthArlington101 Posted January 28, 2019 Share Posted January 28, 2019 I am gonna pull a Ji and say the NAM just took away all of my snow. I get zip. NOTHING.Yeah, western areas look pretty out of this without a miracle. Just hoping to see some flakes. Link to comment Share on other sites More sharing options...
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