Spring/ Summer 2014 Convection Discussion

[moneypitmike]

MBY time.  How are things up this way?  Seems perhaps too far north?

 

Maybe I can finagle something tonight.

 

Gross running weather out there.

 

74.4/68

[Tornadomachine]

Taunton said spin ups.  That means its totally happening.

 

TOMORROW...

FIRST WAVE OF HEAVY RAINFALL SHOULD EXIT THE REGION EARLY MONDAY
MORNING BEFORE ANOTHER ROUND APPROACHES BY THE LATE AFTERNOON. THERE
COULD BE A BREAK IN PRECIP DURING THE DAY AND IN FACT CROSS SECTIONS
ARE SHOWING A BRIEF BREAK IN MOISTURE/RH AT THE MID-LEVELS WHICH MAY
ALLOW FOR BREAKS IN THE CLOUD COVER. THIS WILL HELP INCREASE DIURNAL
HEATING AND SUCH THE POTENTIAL FOR STRONG/SEVERE THUNDERSTORMS.

ASIDE...ANOMALOUS LOW WILL SET UP OVER THE GREAT LAKES PUSHING THE
TROUGH AXIS OVER THE MIDWEST KEEPING SNE IN THE SOUTHWEST FLOW. THIS
WILL CONTINUE TO INCREASE THE MOISTURE PROFILES AS DEWPOINTS REACH
ABOVE 70F. ANOTHER SHORTWAVE WILL RIDE THROUGH THE FLOW ON MONDAY
SPARKING OFF ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS. BELIEVE
AREAL COVERAGE WILL BE MORE THEN SUNDAY...ALTHOUGH A FEW OF THE HI-
RES GUIDANCE SHOWS MORE OF AN ISOLATED COVERAGE. HOWEVER MANY OF THE
SYNOPTIC MODELS SHOW QPF AND WITH THE AMOUNT OF LIFT AND MOISTURE IN
THE PROFILE BELIEVE COVERAGE WILL BE MORE SCT/WIDESPREAD. CAPE
VALUES WILL INCREASE BETWEEN 1500-2000 J/KG AND WITH 0-6 KM BULK
SHEAR VALUES REACHING 45 KTS...COULD SEE STRONG AND PERHAPS SEVERE
WEATHER WITH DAMAGING WINDS AND HEAVY RAINFALL BEING THE MAIN
THREATS. AS DEWPOINTS WILL REACH INTO THE 70S...CANNOT RULE OUT THE
POTENTIAL FOR A QUICK SPIN-UP IN THIS SOMEWHAT TROPICAL AIRMASS AS
WELL AS 0-1 KM SHEAR VALUES NEAR 20-25KTS. KEEP AN EYE TO THE SKY
AND STAY TUNED FOR UPDATES TO THE FORECAST AS THE SEVERE WEATHER
POTENTIAL CAN CHANGE.

 

IMHO, it sounds like this will be much like the events of last year's tropical firehoses.  Lots of rain, a couple mini-supercells, a few tobacco nets flying around somewhere in CT.  

[CoastalWx]

But I guess what I'm wondering is because this isn't your typical summer setup and it's more anomolous does that have bearing on potential outcomes or should we not even include that in our evaluations?

 

A deep and anomalous trough allows for a deep tropical fetch of moisture and strong winds aloft, but I would say that there isn't a linear relationship to something like "the more anomalous a trough, the more severe you'll get.." There are just too many variables that go into severe wx that supercede how anomalous a trough is.  

[CT Rain]

But I guess what I'm wondering is because this isn't your typical summer setup and it's more anomolous does that have bearing on potential outcomes or should we not even include that in our evaluations?

 

But just because it's anomalous doesn't mean it's going to be huge. All of our "big weather" comes from anomalous things whether it's a big blocking high or a deep cut-off low. We get these a couple times a summer... nothing crazy about this one. 

[CT Rain]

12z NAM looks good for severe both Monday and Tuesday. Pretty impressive setup for both days. As Scooter said when you start seeing 30-40 knots at 850mb and some surface based CAPE you remain interested. 

[CoastalWx]

Ryan and I were kind of saying to watch BDL into western MA tomorrow.

[Damage In Tolland]

Is this a valley setup more so than anywhere else with the backed winds?

[weatherwiz]

Agreed we may not see widespread severe or widespread sig severe.

Just given the ingredients we have storms certainly need to be watched b/c they can take off very quickly.

12z NAM is very interesting...just have to see how much cape we can develop.

[CT Rain]

Agreed we may not see widespread severe or widespread sig severe.

Just given the ingredients we have storms certainly need to be watched b/c they can take off very quickly.

12z NAM is very interesting...just have to see how much cape we can develop.

 

9z SREF mean is like 1000 j/kg of MLCAPE tomorrow at BDL. That's a pretty decent signal. 

[Damage In Tolland]

Seems like we lost any shot at storms today/ tonight

[moneypitmike]

It's cooled down with the overcast. 

 

73.3/68,  breezy with a shawl.

[REDMK6GLI]

Its a morgue in the NYC subforum. Hows the SVR threat looking for NYC-LI this evening through tuesday? Thanks alot guys

[weatherwiz]

9z SREF mean is like 1000 j/kg of MLCAPE tomorrow at BDL. That's a pretty decent signal. 

 

That's not bad at all for a SREF mean...would be more than enough given the shear profiles we will have

[weatherwiz]

The 9z SPC SREF does have a SIG torn area depicted both tomorrow and on Tuesday as well.  

[weatherwiz]

Nice hodo

 

[moneypitmike]

Precip shield is making pretty rapid progress.  COC Sunday, fail. 

[Quincy]

The 9z SPC SREF does have a SIG torn area depicted both tomorrow and on Tuesday as well.

A little blip shows up in the climo favored area from lower/mid-Hudson Valley into far western CT/Mass. The NAM sounding for DXR at 21z shows good backing in the lowest 2-3km with adequate SRH and elevated SBCAPE. The profile is fairly saturated and given the respective hodograph, as from previous posts, we're most likely looking at a brief spin-up threat, as opposed to something more like 2008. (which has plenty of clear differences from this setup)

[CoastalWx]

Looks like a weak low moves into NNE Tuesday on the GFS with backed flow and strong flow out of the SW at H5. Might be something to watch up there.

[CT Rain]

A little blip shows up in the climo favored area from lower/mid-Hudson Valley into far western CT/Mass. The NAM sounding for DXR at 21z shows good backing in the lowest 2-3km with adequate SRH and elevated SBCAPE. The profile is fairly saturated and given the respective hodograph, as from previous posts, we're most likely looking at a brief spin-up threat, as opposed to something more like 2008. (which has plenty of clear differences from this setup)

 

What's the big difference between this and the 2008 NH setup? Just curious.. synoptically they're fairly similar IMO. 

[ct_yankee]

Nice hodo

 

I was just this second looking at that exact hodo on COD when you posted it, I mean it's still open in another browser tab...  Needless to say, I like it too.

[weatherwiz]

The GFS isn't nearly as backed with the llvl fow, however, it generates fairly similar instability for tomorrow.  Going to be an interesting afternoon.  

 

Really going to have to watch storms that move into the valley area...especially if we see the higher end of the instability potential develop.  

[Weathergun]

12z NAM Bufkit hodos look best with decent CAPE over Lower Hudson Valley tomorrow evening. I think we could see an isolated spinup.

 

[andyhb]

This or bust: http://www.spc.noaa.gov/exper/archive/events/20140616/soundings/14061619_SNDG/last.gif

 

 

[Quincy]

What's the big difference between this and the 2008 NH setup? Just curious.. synoptically they're fairly similar IMO.

7/24/08 had the closed low over ROC at 15z with a vortmax swinging through central NY. The GFS projection for Tuesday has the ULL further NW over Ontario with the vortmax a couple of hundred miles displaced from 08, as the surface front is moving into New England. This go around just seems to have the best forcing displaced from the best wind fields and instability. Not ruling out severe and even a few spinups, but not to the level of 2008.

Not to mention the magnitude of the upper level flow for 2008 was much more impressive. The 12z ALY sounding had 55-80kt flow aloft, about 15-30kt stronger than the projections coming up.

[CT Rain]

7/24/08 had the closed low over ROC at 15z with a vortmax swinging through central NY. The GFS projection for Tuesday has the ULL further NW over Ontario with the vortmax a couple of hundred miles displaced from 08, as the surface front is moving into New England. This go around just seems to have the best forcing displaced from the best wind fields and instability. Not ruling out severe and even a few spinups, but not to the level of 2008.

Not to mention the magnitude of the upper level flow for 2008 was much more impressive. The 12z ALY sounding had 55-80kt flow aloft, about 15-30kt stronger than the projections coming up.

 

Here's the 18z GYX sounding during the tornado.

 

 

The specifics regarding the setup aren't identical but there's a lot that's similar. 

 

Per the NARR the 2008 case had a 570dm 500 mb closed low... this case is substantially deeper (sub 560dm). Additionally, the flow is more out of the SSW in this case which makes it a bit different. 

 

At the end of the time it will come down to subtle s/w timing (which we can't resolve now) and mesoscale details that we won't really be able to resolve until Tuesday morning. 

 

Certainly can't "expect" something like the 2008 tornado but if you're looking at both setups side by side one doesn't jump out at me as substantially different or better than the other. 

[weatherwiz]

12z NAM Bufkit hodos look best with decent CAPE over Lower Hudson Valley tomorrow evening. I think we could see an isolated spinup.

 

12zNAMkswfhodo.png

 

Holy crap...that's actually quite impressive...especially the shear of 26 m/s.  Would certainly have to watch out for even more than just a brief weak spinup

[Quincy]

Per the NARR the 2008 case had a 570dm 500 mb closed low... this case is substantially deeper (sub 560dm). Additionally, the flow is more out of the SSW in this case which makes it a bit different.

Let's look at some sub 560dm cases then with the closest 500mb match to Tuesday's NAM forecast.

8/12/04: 558dm right over Ontario/Quebec. 0 tornado reports in the Northeast, only a few isolated wind/hail in SW New England.

7/27/94: Sub 558dm ULL, scattered severe reports across western Mass. and northern New England, just one lone tornado report in northeastern NJ.

7/7/84: (meh) 552dm in about the same spot as above, but zero severe reports region-wide.

Here are the tornado reports for all the top analogs combined:

Give me greater deep layer shear, stronger flow aloft and better forcing across NY/New England and then I'll start comparing this setup to big historical dates.

[Typhoon Tip]

While this Tuesday's (circa) convection ship hasn't completely set sailed, the dock hands are certainly removing the mooring cables... 

 

This has no where near the same look as it did 4 days ago, when the most guilty Euro was doing what it always does ...erroneously drilling lowering heights through the OV/NE regions.  Then, it had a stripe of hybridized continental/EML air in place, well timed diabatic heating, and strong vorticity advection entering the area, ...along with veered lower 200mb wind field.  It was tornado Tuesday on those runs back when. Even driving SPC to through up a D5/6 outlooks for the NE corridor.  

 

Now that the Euro bias has completed yet another demonstration of being a POS in that time range, the interest shifts toward the higher SBCAPE ... which is in the MA.  

 

Doesn't mean there won't be anything in the area..  We should pool theta-e in our own rite, and together with oreographic forcing and/or frontalysis convergent vectors, there's likely to be pulse strong storms, and invariable when those occur there are an isolated incident of severe or two or three.   Just probably less organized at this point.  Guess you call that a See TXT.  

[CT Rain]

Let's look at some sub 560dm cases then with the closest 500mb match to Tuesday's NAM forecast.

8/12/04: 558dm right over Ontario/Quebec. 0 tornado reports in the Northeast, only a few isolated wind/hail in SW New England.

7/27/94: Sub 558dm ULL, scattered severe reports across western Mass. and northern New England, just one lone tornado report in northeastern NJ.

7/7/84: (meh) 552dm in about the same spot as above, but zero severe reports region-wide.

Here are the tornado reports for all the top analogs combined:

image.jpg

Give me greater deep layer shear, stronger flow aloft and better forcing across NY/New England and then I'll start comparing this setup to big historical dates.

 

lol ok... I think you've really missed the point. 

[Quincy]

lol ok... I think you've really missed the point.

The point is that while this threat has some low-end potential, unless there's a major shift in the model guidance with a number of factors, this will probably be a See Text event, as Tip mentioned. I wouldn't even rule out a brief rain-wrapped spinner, for the record. When asked for ULL cases that support a "notable" severe event, all that's given is a cherry pick of 7/24/08 and no consideration is given to the numerous top analogs/setups that produced little to no severe weather across SNE.