January 3, 2022 CAPE Storm Obs/Nowcast

[Kleimax]

10 minutes ago, Roger Smith said:

Fast 1-3 inches and out by lunch time? 

Just going too fast to do very much. Might be heavy snow for a few minutes though.

I was expecting another 24 inch prediction from you like last year. Gotta be a good thing he thinks we won’t get much

[yuki neko]

5 minutes ago, 87storms said:

seeing some returns showing up on cod.  not sure if that's virga, but it's a good sign.  interesting system, that's for sure.

Plain rain in Bethesda.

Maybe this band of precip is where the jack will set up

[WEATHER53]

12 midnight ob

pretty special because 44.5 but some  sleet is mixed in with rain shower. Impressive cold up top 

[Kleimax]

Just now, CntrTim85 said:

I'm in Corolla til' next week. Chesapeake should get an inch or so. Will sure look nice for them! Chesapeake has almost gotten more snow than you over recent years! Good luck! LOL

Coastal flood warning for Chesapeake. Hope you don’t live near any low lying areas 

[IUsedToHateCold]

Radar made a fool of my last post. Rain already moving in. 

 

[Cobalt]

1 minute ago, CntrTim85 said:

I'm in Corolla til' next week. Chesapeake should get an inch or so. Will sure look nice for them! Chesapeake has almost gotten more snow than you over recent years! Good luck! LOL

lol i'm sure they have. Thank you for making snow measuring a competitive sport!

[matzacski]

Going with the inverse Roger Smith rule here I’d say there’s a good chance of at least 8 inches for the cities tomorrow!

[pazzo83]

some light rain downtown - 45/36

[MillvilleWx]

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

[hstorm]

42/35 with a 50/50 RA/IP mix in Great Falls 

[Brianonymous]

My security cams have started picking up some very very light rain. 45/36

[KAOS]

Pasadena. Just started. I hear sleet. Temp/Dewpoint DGAF.

[Kleimax]

3 minutes ago, CntrTim85 said:

Nope! Only a small portion of Chesapeake lies within flood prone areas. Mainly areas along the Elizabeth River. I'm high and dry. Thank you for the concern though. I see you are in Owings Mills. Ew, been a rough few days I'm sure. There is always next week! Good luck! 

Thanks! I don’t think that sled you bought will work very well in the sand! Lol

[nj2va]

45/35. A few rain drops. 

[KAOS]

Just now, MillvilleWx said:

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

That is one hell of an analysis. The best part is this...

Sorry... not sorry.

[wawarriors4]

43/34 down here NW of FXBG. It’s cooled down faster than I anticipated, still 11 to go tho.

[BTRWx's Thanks Giving]

6 minutes ago, MillvilleWx said:

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

Best post I have ever read on these forums!

[psuhoffman]

10 minutes ago, MillvilleWx said:

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

We have got to get you back into the area! 

[Jebman]

10 minutes ago, MillvilleWx said:

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

This is without a doubt one of the most helpful posts I have EVER read in this sub.

[TowsonWeather]

Just now, CntrTim85 said:

We just take the fins off our surfboards! Works 10x better. Did you guys really only get 20" of snow last year? That's dismal! Not a whole lot else to look forward to up there except some flakes. Good luck! 

How is this obvious troll still posting?

[BTRWx's Thanks Giving]

Would the current radar depiction be a good indication of the northern edge tomorrow?

[KingJWx]

Looks like IAD and DCA both reporting light rain at the midnight obs.

[KAOS]

Please get rid of troll.

[WxMan1]

04Z continues the string of crush jobs across the sub forum from the HRRR. Not concerned about absolute values here with the snow totals (I'd be happy with 75% TBH), but the location (and trends) with the max snow axes. HRRR continues to be not as far south.

04Z HRRR snow thorough 17Z, and still snowing.

[KAOS]

Bye...

[caviman2201]

OK ok people...

[matzacski]

6 hours from now it will be snowing!

[BTRWx's Thanks Giving]

4 minutes ago, CntrTim85 said:

Again, I am not trolling and have done nothing to violate the rules of this forum. Please stick to the weather and topic at hand. Are you concerned about dry air on the back side? Or current temps and mixing? I've seen it many times with these setups. 

You're posting way too frequently in a region you don't live in.

[Solution Man]

39/33 light sleet

[Roger Smith]

By the way my 1-3" fast in and out was meant for the I-95 corridor, probably 3-6" in a few spots just south of that, but still with the ground fairly warm and the fast motion, mid-day clearing trend, can't see this amounting to a big dump of snow for very many. Rates may be good for about 1-2 hours. May do better in central VA too. Better than nothing, anyway.