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November 15 Snow/Ice Chance


showmethesnow

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Here is the snowfall mean from the overnight run of the model that shall not be named.

epssnowmean.thumb.gif.c93862b3d075382779fa4131a13b6ad9.gif

We are seeing a continuous uptick with snow especially north and west of the cities. The individual members have shown vast improvement from where many are now seeing snow in the region especially NW of the cities. If I have the time I will try to explain in a little bit why I think we are seeing an improvement

 

 

 

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Thought I would give a quick run down of why I believe we are seeing the Euro moving towards a snowier/icier solution that the GFS has been showing us.

What it pretty much is coming down to is the timing on the onset pf precip within the region. GFS has been much quicker with allowing the southern energy to move north vs. the Euro. At one point we were seeing a 24-30 hr difference. Later arrival and the odds decrease for a more wintry storm as we lose CAD (Cold air damming) through our region. Below we have the run from Sat 12z where the onset of precip is later (Fri 8 am). Notice we see low pressure in the central lakes and a high that is located in the Atlantic. The high is now so far south and off shore that the return flow around the back side is actually helping to scour the cold we have in place through our region. Not to help matters we are also seeing low pressure in the lakes which is now also helping to scour out the cold with a southwesterly flow. Notice the circled area through our region? Typically at 500 mb you would see the higher pressures hook down on the east side of the mountains which would be a good indicator of CAD. In this case we are seeing very little if any of this signature.

 

EuroNov1012z.gif.7647ca40e73a468c13041b37b8efe5df.gif

 

Now compare the above map to the latest run. We are now seeing an onset of precip occurring at 8 pm Thur night. This 12 hr difference is actually not allowing the high to escape quickly enough to the east thus we have an easterly flow around it. Though not optimal (we would really prefer a NE flow to really hold in the cold) it is still helping to lock in the cold somewhat so we are seeing a somewhat modest CAD signature. Notice also that the low in the lakes is farther west so we are not seeing the SW flow around it affecting our area as of yet to start scouring out the cold. Want to mention something else that is a positive on the latest run. We are seeing both the Great Lakes low and the East coast High coming in farther north. These are both good things as the GL low has less chances to influence our region during the storm and the farther north high will give a better component of the flow around it to lock in the cold (more northerly component to the easterly flow). eta: (Also meant to mention that we are seeing the High come in stronger which is a good thing as well)

 

 

EuroNov1200z.gif.9e6daf8c14001c4a0f3cc36b4b77d231.gif

 

ETA: WxUSAF made me aware that I pulled the wrong time frame for the bottom map. Should have been the 18z instead of the 00Z so it makes the onset of precip roughly 2pm and the difference in timing 18 hrs from the previous map. You can definitely see the difference in the CAD signature on this time frame (map below) vs the other map.

EuroNov1200zredo.gif.f4ec57324d80854c8ca12d05e82cc2ae.gif

 

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5 minutes ago, WxUSAF said:

Euro is still that much slower than the GFS? GFS has precip across the area before 12z Thursday.

Still running a 6 hr difference I believe. GFS has moved a little towards the Euro but the Euro has been jumping towards the GFS. I think we really need the precip to move in as early as possible if the cities are to have any chance of seeing anything more then a stray snowflake/sleet pellet. 

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11 minutes ago, Wonderdog said:

Looking at the 500 EURO maps, can someone tell if the upper level LP jumps to the coast at some point on Thursday? Looking at the GFS regular maps, it appears that there is a reorg. going on off the delmarva? Or is the LP just being  blocked?

No, we are not seeing the closed low jump to the coast. But we are seeing a stronger initial closed low which looks to make it through our region intact.  A little better timing and a little farther southward/eastward swing and things could maybe get very interesting.

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1 minute ago, showmethesnow said:

No, we are not seeing the closed low jump to the coast. But we are seeing a stronger initial closed low which looks to make it through our region intact.  A little better timing and a little farther southward/eastward swing and things could maybe get very interesting.

I'm concerned about the temps. I agree with you about the needed track because we need the winds to come from the north or northeast to cool us down.

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Just now, Wonderdog said:

I'm concerned about the temps. I agree with you about the needed track because we need the winds to come from the north or northeast to cool us down.

Dewpoints on the GFS are in the low 20's and the upper teens on the NAM at the onset of precip with actual temps in the low to mid 30's.  I haven't looked at any temp profiles, but at least in the beginning, temps support frozen precip of some form.  

I'm looking at it out here of course.

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2 minutes ago, osfan24 said:

NAM not buying the wintry precipitation at all, though outside of its useful range, if it has one.

The late afternoon/evening arrival time would be a killer. Solar heating of the lower levels throughout the day plus the withdrawing NE high and possible approaching GL low/lower pressures would probably be the final nail in the coffin for our snow/frozen chances even out in the favorable areas. But the NAM at range, so toss.

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9 minutes ago, Kmlwx said:

Yeah - I love the graphics - don't love the navigation. Page is also slow for me to load a bit. 

dont expect it to be any better during model run times. you'll find information here faster than you will in real time on the website. 

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22 minutes ago, mappy said:

dont expect it to be any better during model run times. you'll find information here faster than you will in real time on the website. 

If it's that slow and tough to navigate - I may bail on the subscription and just go back to getting PBP here...it isn't terrible so far but it's definitely not what I'd expect from a pay site. 

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GFS verbatim may be a very brief period of some mix precip for the cities but quickly transitioning over to rain.  Would be a prolonged frozen event for the 81 corridor.  

Even with an all rain scenario for MBY, its good to see this setup as he head into more favorable snow climo for the corridor.  Love to see a parade of coastals.  

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3 minutes ago, nj2va said:

GFS verbatim may be a very brief period of some mix precip for the cities but quickly transitioning over to rain.  Would be a prolonged frozen event for the 81 corridor.  

Even with an all rain scenario for MBY, its good to see this setup as he head into more favorable snow climo for the corridor.  Love to see a parade of coastals.  

I think the only hope is to get the ULL to go south of us for more than what you stated above.  So far is has it going through WVa and north of the region.  But, lets keep these looks going forward.  

 

Edit:  I think the ICON showed this yesterday with the change back over to snow through the region.

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2 minutes ago, Kmlwx said:

If it's that slow and tough to navigate - I may bail on the subscription and just go back to getting PBP here...it isn't terrible so far but it's definitely not what I'd expect from a pay site. 

you get used to the navigation, the slowness bothers me. i continue to use it though because i don't mind looking at outputs at my own pace. 

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6 minutes ago, nj2va said:

GFS verbatim may be a very brief period of some mix precip for the cities but quickly transitioning over to rain.  Would be a prolonged frozen event for the 81 corridor.  

Even with an all rain scenario for MBY, its good to see this setup as he head into more favorable snow climo for the corridor.  Love to see a parade of coastals.  

same as 06z, warm layer from 700-850. sleety

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20 minutes ago, mappy said:

same as 06z, warm layer from 700-850. sleety

GFS is probably a sleet/snow/snow grains mix to start with the dry air aloft, but goes over to rain fairly quickly. Probably stays rain/sleet mix for you through 18z.

I’m pleased looks like a solid chance of first frozen for most of the subforum.

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