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Extended Range Severe Weather Discussion


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Talk about directional shear with that verbatim and I don't even want to mention what that sfc low/H5 profile mirrors almost exactly in everyway...

Also, favorable height falls stretch all the way to the Gulf Coast (even into the Gulf).

If I was still in a chat with Fred, which we were when the 00z GFS came out...he probably would've fallen out of his chair...

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Talk about directional shear with that verbatim and I don't even want to mention what that sfc low/H5 profile mirrors almost exactly in everyway...

Also, favorable height falls stretch all the way to the Gulf Coast (even into the Gulf).

If I was still in a chat with Fred, which we were when the 00z GFS came out...he probably would've fallen out of his chair...

I hate getting so detailed at this point, but since you mentioned it, there ~45 degree crossover between 850/500 mb across much of the OV/mid south at 00z Sat.

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So possibly in what the Euro is showing, we would get initial development east of a line from Shreveport, LA to Little Rock, AR to Cape Girardeau, MO in the early-to-mid afternoon on Friday, probably in the form of supercells perhaps eventually congealing into an MLCS. By the time 6 PM rolls around the supercells/MLCS would be perhaps from Monroe, LA to Grenada, MS to Lexington, KY?

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So possibly in what the Euro is showing, we would get initial development east of a line from Shreveport, LA to Little Rock, AR to Cape Girardeau, MO in the early-to-mid afternoon on Friday, probably in the form of supercells perhaps eventually congealing into an MLCS. By the time 6 PM rolls around the supercells/MLCS would be perhaps from Monroe, LA to Grenada, MS to Lexington, KY?

Way too early to get into specifics like this.

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Still, it's an interesting setup and it's interesting that the models seem to be holding onto it. I'm looking forward to the Day 4-8 Convective Outlook.

Oh of course, I agree this is quite an interesting setup with a fairly high ceiling, if all the ingredients come together right.

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I posted this on another forum; so, it briefly references a discussion that didn't take place here, but it still fully explains the point....

The Canadian and UKMET are ominously similar to the GFS/Euro blended solution. The GFS ensembles continue to lock on. The NAM at 84 hours is digging the second jet streak into the West Coast at the same angle and intensity. Even the NOGAPS, but it's faster. Like I said before, this is a case where wave #1's energy helps carve out the larger-scale longwave trough that both shortwaves "drive through". Wave #1's height falls just so happened to come onshore in time to be sampled by the 00Z soundings this evening. Now, all of a sudden, everything has converged on one common solution. I'll say it again.... we still have time for "escape routes" to be activated out of this caliber of a risk.... but things like this aren't just model "flukes".

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Predictability still too low for SPC:

IN MID-UPPER LEVELS...PAC JET MAX MOVING INTO GREAT BASIN REGION

SHOULD CONTRIBUTE TO DAY-4/1ST-2ND AMPLIFICATION OF WRN-CONUS

SYNOPTIC-SCALE TROUGHING. THIS WILL YIELD SIGNIFICANT SFC

CYCLOGENESIS OVER CENTRAL HIGH PLAINS. HOWEVER...CONSIDERABLE

DIFFERENCES IN SHORTWAVE DETAILS AMONGST MREF MEMBERS...AND BETWEEN

OPERATIONAL SPECTRAL/UKMET/ECMWF...RESULT IN GREAT VARIATION OF

TIMING/DEPTH/TRACK OF THIS LOW...AND OF RELATED BOUNDARIES. THESE

DISCREPANCIES SPREAD APART EVEN MORE DAY-5/2ND-3RD. POLEWARD EXTENT

OF FAVORABLE MOISTURE RETURN ALSO IS IN QUESTION FOLLOWING PASSAGE

OF COLD FRONT DESCRIBED IN DAY-3 OUTLOOK. SOME SVR IS LIKELY DURING

DAY-4/DAY-5 TIME FRAME...GENERALLY FROM SRN PLAINS TO LOWER/MID MS

VALLEY AND OH VALLEY REGIONS. ATTM...HOWEVER...THERE IS TOO MUCH

UNCERTAINTY TO NAIL DOWN SPECIFIC AREA OF 30% UNCONDITIONAL

PROBABILITIES.

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Predictability still too low for SPC:

IN MID-UPPER LEVELS...PAC JET MAX MOVING INTO GREAT BASIN REGION

SHOULD CONTRIBUTE TO DAY-4/1ST-2ND AMPLIFICATION OF WRN-CONUS

SYNOPTIC-SCALE TROUGHING. THIS WILL YIELD SIGNIFICANT SFC

CYCLOGENESIS OVER CENTRAL HIGH PLAINS. HOWEVER...CONSIDERABLE

DIFFERENCES IN SHORTWAVE DETAILS AMONGST MREF MEMBERS...AND BETWEEN

OPERATIONAL SPECTRAL/UKMET/ECMWF...RESULT IN GREAT VARIATION OF

TIMING/DEPTH/TRACK OF THIS LOW...AND OF RELATED BOUNDARIES. THESE

DISCREPANCIES SPREAD APART EVEN MORE DAY-5/2ND-3RD. POLEWARD EXTENT

OF FAVORABLE MOISTURE RETURN ALSO IS IN QUESTION FOLLOWING PASSAGE

OF COLD FRONT DESCRIBED IN DAY-3 OUTLOOK. SOME SVR IS LIKELY DURING

DAY-4/DAY-5 TIME FRAME...GENERALLY FROM SRN PLAINS TO LOWER/MID MS

VALLEY AND OH VALLEY REGIONS. ATTM...HOWEVER...THERE IS TOO MUCH

UNCERTAINTY TO NAIL DOWN SPECIFIC AREA OF 30% UNCONDITIONAL

PROBABILITIES.

Yet, if you were to take over 95% of the 00Z guidance tonight for 120 hours out, and print out each image individually on projector transparency sheets, they would overlap almost perfectly.... :whistle:

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Starting to really look like another active tornado/severe weather season.

The switch back to a La Nina global state was very poor timing (or good timing if you are a storm chaser). Pay attention this spring (like last spring) for MJO waves, AAM orbits and when the final warming occurs in the stratosphere. If they tend to produce El Nino-like characteristics on the flow, they will produce a lull in activity.

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you don't what? There is a big difference between looking at the models and taking worst case scenario and hyping it and actually delineating probs for severe DMC, especially in this synoptic scenario.

My mistake for not going more in depth, but I thought the reasons they specified for not issuing an outlook were questionable at best...

i) The point that Fred mentioned stuck out most.

ii) Virtually all of the models showed very little trouble with moisture advection (even quite far north), and they continue to do so.

iii) The 00z suite of models all came out as the data from the first mid/upper jet streak digging on the west coast was being processed, leading to higher confidence on how the second trough would evolve.

iv) The first system it appears, especially now looking at the models, but also evident last night, will not affect the Gulf in a negative way with FROPA.

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My mistake for not going more in depth, but I thought the reasons they specified for not issuing an outlook were questionable at best...

i) The point that Fred mentioned stuck out most.

ii) Virtually all of the models showed very little trouble with moisture advection (even quite far north), and they continue to do so.

iii) The 00z suite of models all came out as the data from the first mid/upper jet streak digging on the west coast was being processed, leading to higher confidence on how the second trough would evolve.

iv) The first system it appears, especially now looking at the models, but also evident last night, will not affect the Gulf in a negative way with FROPA.

There is plenty of time to get the word out should this event unfold as some guidance progs it. But it isn't as simple as looking at MREF/ECENS and noting they all look similar. If they simply did that, they would bust a ton of events since data limitations only allow us to see so "much" w.r.t. the atmosphere. No different than looking at the 16 day GEFS and noting certain patterns it suggests may develop...just because the mean shows us something doesn't mean it will verify! Also worth noting that this setup is partially dependent upon the lead anomaly rapidly deepening, otherwise you get a rather junky warm sector with straight hodos. If you look closer not every ensemble member suggests such a scenario (i.e., a rapidly deepening cyclone ejecting through the OV) even if nearly all prog a negative height anomaly tracking through the OV/SE.

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There is plenty of time to get the word out should this event unfold as some guidance progs it. But it isn't as simple as looking at MREF/ECENS and noting they all look similar. If they simply did that, they would bust a ton of events since data limitations only allow us to see so "much" w.r.t. the atmosphere. No different than looking at the 16 day GEFS and noting certain patterns it suggests may develop...just because the mean shows us something doesn't mean it will verify! Also worth noting that this setup is partially dependent upon the lead anomaly rapidly deepening, otherwise you get a rather junky warm sector with straight hodos. If you look closer not every ensemble member suggests such a scenario even if nearly all prog a negative height anomaly tracking through the OV/SE.

I wasn't just looking at those models...

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