Low topped squall line Friday/strong winds

[weatherwiz]

Looks like we will kick off November with a very mild start as a storm system off to our west will allow for heights to rise across the east and for a warm front to lift northward bringing in unseasonably warm/moist air into the region.  This will allow for some weak instability to work into the region as well.  With a deep trough/cold front sliding eastward, lift as well as jet dynamics will increase over the region and forcing may be strong enough to generate a low topped squall line which would slide east.

 

Both the NAM/GFS are showing very impressive jet dynamics associated with the system, although some of the winds, especially with regards to the LLJ may be a bit overdone.  Regardless, winds above the surface will be very strong and even outside of any convective elements winds will be very gusty during the afternoon.  Especially if we can truly warm sector eroding any inversion.  

 

As the front approaches, we may see a low topped squall line associated with the front sliding east.  Depending on the degree of low level instability and low level lapse rates (depends on whether or not we can squeeze any sun) the line may become strong enough to tap into some of the stronger winds aloft.  Helicity levels will be elevated too so if any updrafts can become strong enough they will certainly have to be watched.

 

Friday may actually be enough to warrant wind advisory criteria as well as winds will be very strong just above the surface, so it will be quite windy regardless of any convective elements.  

 

 

[Ginx snewx]

Looks like we will kick off November with a very mild start as a storm system off to our west will allow for heights to rise across the east and for a warm front to lift northward bringing in unseasonably warm/moist air into the region.  This will allow for some weak instability to work into the region as well.  With a deep trough/cold front sliding eastward, lift as well as jet dynamics will increase over the region and forcing may be strong enough to generate a low topped squall line which would slide east.

 

Both the NAM/GFS are showing very impressive jet dynamics associated with the system, although some of the winds, especially with regards to the LLJ may be a bit overdone.  Regardless, winds above the surface will be very strong and even outside of any convective elements winds will be very gusty during the afternoon.  Especially if we can truly warm sector eroding any inversion.  

 

As the front approaches, we may see a low topped squall line associated with the front sliding east.  Depending on the degree of low level instability and low level lapse rates (depends on whether or not we can squeeze any sun) the line may become strong enough to tap into some of the stronger winds aloft.  Helicity levels will be elevated too so if any updrafts can become strong enough they will certainly have to be watched.

 

Friday may actually be enough to warrant wind advisory criteria as well as winds will be very strong just above the surface, so it will be quite windy regardless of any convective elements.  

inversion 

[weatherwiz]

inversion 

 

Unfortunately it's quite difficult to get setups like this without some sort of inversion.  However, judging by that, even below the inversion winds look pretty decent...should make for some gusts into the 30's or so even w/o convective elements around.  It's also very difficult to get breaks of sun but that could happen locally.  

 

Just have to watch and see if any convection can fire ahead of the front.

[OceanStWx]

Unfortunately it's quite difficult to get setups like this without some sort of inversion.  However, judging by that, even below the inversion winds look pretty decent...should make for some gusts into the 30's or so even w/o convective elements around.  It's also very difficult to get breaks of sun but that could happen locally.  

 

Just have to watch and see if any convection can fire ahead of the front.

 

As modeled that's a strong LLJ. GEFS pushes it to +3 SD southerly anomaly, while the op GFS and NAM both go above +4 for a time.

[forkyfork]

as soon as i see any sort of inversion near the surface my interest falls off a cliff. lapse rates matter... see sandy

[Typhoon Tip]

As modeled that's a strong LLJ. GEFS pushes it to +3 SD southerly anomaly, while the op GFS and NAM both go above +4 for a time.

 

 

The FRH grid has sustained 41mph mid BL wind...  Considering we are in the warm sector and it's over 70F in the machine guidance, that suggest for me a well enough mixed layer to suggest momentum transfer downward should any convection occur, at all.   There may in fact be strong gusts anyway, if the typical takes place, which is better sky condition than modeled for a SW flow.  Typically there will be too many clouds modeled with unilaterally SWerlies.   Obviously the sun doesn't do a whole helluva lot at this time of year; still, having just a little diabatic contribution would only add to the concern..  it would run out inversion.

 

Whether a ribbon echo squall wends its way through the area or not, I'm liking the wind signal in general. 

[forkyfork]

all models are showing clouds/rain during the day and a low level jet that peaks around 15z... too early

[Ginx snewx]

Box has all of SNE 45-50 gusts

[OceanStWx]

The FRH grid has sustained 41mph mid BL wind...  Considering we are in the warm sector and it's over 70F in the machine guidance, that suggest for me a well enough mixed layer to suggest momentum transfer downward should any convection occur, at all.   There may in fact be strong gusts anyway, if the typical takes place, which is better sky condition than modeled for a SW flow.  Typically there will be too many clouds modeled with unilaterally SWerlies.   Obviously the sun doesn't do a whole helluva lot at this time of year; still, having just a little diabatic contribution would only add to the concern..  it would run out inversion.

 

Whether a ribbon echo squall wends its way through the area or not, I'm liking the wind signal in general. 

 

I can certainly see one of those scenarios where winds howl above the tree line, followed by a strong gust, then eerily calm again. These usually aren't those wall to wall strong gradient winds at the surface.

[Typhoon Tip]

I can certainly see one of those scenarios where winds howl above the tree line, followed by a strong gust, then eerily calm again. These usually aren't those wall to wall strong gradient winds at the surface.

 

Right the cfront passes and it's suddenly benign.  

[Typhoon Tip]

all models are showing clouds/rain during the day and a low level jet that peaks around 15z... too early

 

If it stays clouds and rain much of the time, that would certainly contribute to some kind of inversion and deflection of momentum transfer.

 

It's just that there is a known bias to have overly pessimistic sky cover in warm sectors up this way.  It'll be interesting to see how this plays out.   

 

Blue Hill could be a good target for a fire-hosing      

 

18z NAM is even a little stronger with the winds in the BL    37knots sustained.

[TalcottWx]

Bump

[Typhoon Tip]

Savage squall line containing embedded discrete spinners down in lower Ill.  Synoptics would suggest that region of the sounding transports up this way tomorrow.   Just sayin'

[OceanStWx]

Savage squall line containing embedded discrete spinners down in lower Ill.  Synoptics would suggest that region of the sounding transports up this way tomorrow.   Just sayin'

 

Tornadoes aside, if we can get some convection with even marginal height to it a significant LLJ will be available for tapping into. Locally significant wind gust (as the MCDs mention tonight) would certainly not be out of the question.

[Typhoon Tip]

Tornadoes aside, if we can get some convection with even marginal height to it a significant LLJ will be available for tapping into. Locally significant wind gust (as the MCDs mention tonight) would certainly not be out of the question.

 

Yeah I'm thinking tomorrow has some chance for general wind concern coming along.  I noticed the machine guidance on high temps has been elevating every cycle... 12z MAV had 76F at BOS!  

[Wx4cast]

inversion 

 

Yes but its low and shallow and a forced low top convective line casn easily breech it.

Unfortunately it's quite difficult to get setups like this without some sort of inversion.  However, judging by that, even below the inversion winds look pretty decent...should make for some gusts into the 30's or so even w/o convective elements around.  It's also very difficult to get breaks of sun but that could happen locally.  

 

Just have to watch and see if any convection can fire ahead of the front.

Totally right.  Will get decent GUSTS even w/out any sun. NCFRB will do the magic.Think outside of the box on these features. You don't always need or get sun to enhance the instability.

 

as soon as i see any sort of inversion near the surface my interest falls off a cliff. lapse rates matter... see sandy

 

Ummm all due respect two totally different beasts, FF.

I can certainly see one of those scenarios where winds howl above the tree line, followed by a strong gust, then eerily calm again. These usually aren't those wall to wall strong gradient winds at the surface.

True but the GUST potential tomorrow is huge

 

Right the cfront passes and it's suddenly benign.  

Haven't really looked at SNE/SENE/ENE too closely but WNE and ENY IMO will have the higher gust potential post-frontal in partial clearing, strong DNVA/DVM around 18z in the afternoon. Also wind speed shear increases with height these areas while directional shear is not much up thru 5K-8K feet

 

==== Add: Theta-E lapse rates are quite impressive right near the frontal boundary.

[Typhoon Tip]

Yes but its low and shallow and a forced low top convective line casn easily breech it.

Totally right.  Will get decent GUSTS even w/out any sun. NCFRB will do the magic.Think outside of the box on these features. You don't always need or get sun to enhance the instability.

 

 

Ummm all due respect two totally different beasts, FF.

True but the GUST potential tomorrow is huge

 

Haven't really looked at SNE/SENE/ENE too closely but WNE and ENY IMO will have the higher gust potential post-frontal in partial clearing, strong DNVA/DVM around 18z in the afternoon. Also wind speed shear increases with height these areas while directional shear is not much up thru 5K-8K feet

 

==== Add: Theta-E lapse rates are quite impressive right near the frontal boundary.

 

Perhaps if you can get an isollobaric type wind pulse but I don't see a lot of that's comparative to the lead PGF and LLJ combined, in that region. Looks like more of a gust to 35mph for the hill tops sort of deal to me.   CAA can have lapse rates -- as you mentioned, and can help with momentum transfer, but the WCB and convection mix potential in warm sector seems to be the bigger play here, Ryan. 

 

We'll see. It's an interesting dynamic system.  Lots of convection and snowing up in Canada.  Love this transition season stuff. 

[weatherwiz]

Yeah I'm thinking tomorrow has some chance for general wind concern coming along.  I noticed the machine guidance on high temps has been elevating every cycle... 12z MAV had 76F at BOS!  

 

If temps like that were to verify there would be serious issues.  

[OceanStWx]

Haven't really looked at SNE/SENE/ENE too closely but WNE and ENY IMO will have the higher gust potential post-frontal in partial clearing, strong DNVA/DVM around 18z in the afternoon. Also wind speed shear increases with height these areas while directional shear is not much up thru 5K-8K feet

 

==== Add: Theta-E lapse rates are quite impressive right near the frontal boundary.

 

NAM was definitely on board with this. Despite the core of the LLJ moving east, the wind field stays very strong in the vicinity of the front. It mixes the boundary layer out to nearly 4000 feet. That would be tapping 70 knot winds verbatim. Probably overdone, but if you take 75% of that? That's still high wind warning type stuff.

[Typhoon Tip]

NAM was definitely on board with this. Despite the core of the LLJ moving east, the wind field stays very strong in the vicinity of the front. It mixes the boundary layer out to nearly 4000 feet. That would be tapping 70 knot winds verbatim. Probably overdone, but if you take 75% of that? That's still high wind warning type stuff.

 

Wait - but is that "post-frontal"   ? 

 

The PGF combined with LLJ is really along and ahead for the boundary.  I have seen strong S wind events shut like a spigot when the front comes through.  This (NAM) is a smoking gun for that sort of relaxation of wind field.  The FRH grid has been consistently flagging 30Kts (or so...) out around ALB in warm sector, but falling to just 5kts of middle BL flow by 1 or 2am.  

[weatherwiz]

If a line develops it should move through rather early tomorrow as well...then the front clears sometime in the early afternoon or so (later eat obviously) and we get strong wind gusts from CAA

[OceanStWx]

Wait - but is that "post-frontal"   ? 

 

The PGF combined with LLJ is really along and ahead for the boundary.  I have seen strong S wind events shut like a spigot when the front comes through.  This (NAM) is a smoking gun for that sort of relaxation of wind field.  The FRH grid has been consistently flagging 30Kts (or so...) out around ALB in warm sector, but falling to just 5kts of middle BL flow by 1 or 2am.  

 

Bufkit soundings certainly show a pronounced wind shift, yet flow remains 60 knots atop the boundary layer. I think it will be brief, and likely tied to isallobaric forcing as pressures rise sharply behind the front.

[weatherwiz]

Bufkit soundings certainly show a pronounced wind shift, yet flow remains 60 knots atop the boundary layer. I think it will be brief, and likely tied to isallobaric forcing as pressures rise sharply behind the front.

 

That brief period could actually be quite intense...there certainly is a possibility for a small window of wind gusts exceeding 60-65 mph locally...just really tough to gauge that right now b/c the window is so small.  

[OceanStWx]

That brief period could actually be quite intense...there certainly is a possibility for a small window of wind gusts exceeding 60-65 mph locally...just really tough to gauge that right now b/c the window is so small.  

 

My gut would say farther north (close to the low center) where the rise/fall couplet will be greater, but at the same time the wind field is stronger through CNE.

[Wx4cast]

If temps like that were to verify there would be serious issues.  

Those temps would actually happen post frontal in the downslope sw-wsw flow

[Wx4cast]

Perhaps if you can get an isollobaric type wind pulse but I don't see a lot of that's comparative to the lead PGF and LLJ combined, in that region. Looks like more of a gust to 35mph for the hill tops sort of deal to me.   CAA can have lapse rates -- as you mentioned, and can help with momentum transfer, but the WCB and convection mix potential in warm sector seems to be the bigger play here, Ryan. 

 

We'll see. It's an interesting dynamic system.  Lots of convection and snowing up in Canada.  Love this transition season stuff. 

All good point, Tip but the trend on the track from all the models is more south closer to the SLRV. The Delta-P couplet will be moving closer to C/ENY & WNE as a result. Post frontal is when the more widespread gradient wind and strongest wind gust potential will be.

[Typhoon Tip]

Bufkit soundings certainly show a pronounced wind shift, yet flow remains 60 knots atop the boundary layer. I think it will be brief, and likely tied to isallobaric forcing as pressures rise sharply behind the front.

 

Yeah, I mentioned that as possible to Ryan, though I can never remember how to spell "isollobaric"  

 

My hunch is that the front sweeps and the action becomes rather laminar rather quickly.  But isallobaric wind is different than that, so we'll have to see. 

[Wx4cast]

Wait - but is that "post-frontal"   ? 

 

The PGF combined with LLJ is really along and ahead for the boundary.  I have seen strong S wind events shut like a spigot when the front comes through.  This (NAM) is a smoking gun for that sort of relaxation of wind field.  The FRH grid has been consistently flagging 30Kts (or so...) out around ALB in warm sector, but falling to just 5kts of middle BL flow by 1 or 2am.  

Yes.

[weatherwiz]

Those temps would actually happen post frontal in the downslope sw-wsw flow

 

ahh interesting 

[Typhoon Tip]

Yes.

 

Yes I got that, but hmm.   I almost think that CAA is weak here.   Maybe a little more pronounced out your way where that d-p is steeper, and where the sounding supports some chop.