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Pattern February Discussion part 3. Don's Winter Storm Hunt

Lol, what in the world... This isn't likely to transpire but its probably worth making a point here (for those who aren't familiar w/ this concept) regarding potential vorticity, that will be useful later in the hurricane season, particularly when tropical cyclones are undergoing extratropical transition. Lol yeah that's a hybrid/shallow warm-core subtropical cyclone off the Carolina coast on the GFS, lol... You can tell this is at least a hybrid warm core because there's little-no temperature gradient &/or fronts across this disturbance, it's equatorward of the subtropical jet, and potential vorticity actually decreases as this storm intensifies off the Carolinas. Oth, note the higher potential vorticity in association with the trough over the midwest... In fact, potential vorticity is often utilized to distinguish between tropical and extratropical cyclones, extratropical cyclones derive potential vorticity from the stratospheric reservoir and bring it towards the mid-upper levels of the troposphere, while tropical cyclones derive it from the surface and carry it upwards into the low-mid levels of the troposphere, and thus tropical cyclones are usually characterized by lead to negative potential vorticity anomalies (denoted in the deeper blue and white colors below) at least on potential vorticity surfaces that are normally closer to the upper troposphere like the one depicted here. In general the 330K potential vorticity surface is found near 250mb or so (the upper troposphere)..

144 HR GFS forecast...
gfs_pv330K_us_25.png


192 HR GFS forecast. Note again the low off the SE US intensified while potential vorticity actually decreased, indicative that this system is at least partially warm core in the model.
gfs_pv330K_us_33.png
 
1. 2/15/2017's MJO was at am amplitude of 3.46 in phase 8, making it the 2nd strongest MJO phase 8 in Feb on record! The only stronger phase 8 Feb day was the 3.58 of 2/25/1988.


2. 2/15/17's PNA peaked at +2.04, making it the first met winter PNA day to reach +2.00 since 2/1983, when one day hit +2.08! The only other ones were on two days in 2/1968. As is often the case, the GEFS was slightly too low with its forecasts although it forecasted this very well.
 
Webberweather53 said:
Lol, what in the world... This isn't likely to transpire but its probably worth making a point here (for those who aren't familiar w/ this concept) regarding potential vorticity, that will be useful later in the hurricane season, particularly when tropical cyclones are undergoing extratropical transition. Lol yeah that's a hybrid/shallow warm-core subtropical cyclone off the Carolina coast on the GFS, lol... You can tell this is at least a hybrid warm core because there's little-no temperature gradient &/or fronts across this disturbance, it's equatorward of the subtropical jet, and potential vorticity actually decreases as this storm intensifies off the Carolinas. Oth, note the higher potential vorticity in association with the trough over the midwest... In fact, potential vorticity is often utilized to distinguish between tropical and extratropical cyclones, extratropical cyclones derive potential vorticity from the stratospheric reservoir and bring it towards the mid-upper levels of the troposphere, while tropical cyclones derive it from the surface and carry it upwards into the low-mid levels of the troposphere, and thus tropical cyclones are usually characterized by lead to negative potential vorticity anomalies (denoted in the deeper blue and white colors below) at least on potential vorticity surfaces that are normally closer to the upper troposphere like the one depicted here. In general the 330K potential vorticity surface is found near 250mb or so (the upper troposphere)..

144 HR GFS forecast...
View attachment 183


192 HR GFS forecast. Note again the low off the SE US intensified while potential vorticity actually decreased, indicative that this system is at least partially warm core in the model.
View attachment 182
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I see class is in session again... great stuff man, informative as always.

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metwannabe said:
I see class is in session again... great stuff man, informative as always.

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Sure, I'm glad you liked it! Yea, I honestly wished people would have explained potential vorticity to me like this, lol would have made life a lot easier... I don't think this has a legitimate chance of verifying atm, just thought this was a really good opportunity to give everyone here a bit more background knowledge on this topic going forward into the upcoming hurricane season... We usually see several extratropical transitions over the course of a hurricane season, so this is liable show up again before you know it.
 
SD said:
I also really wouldn't be too shocked to get a pretty significant system the first couple days of the month that is probably to our NW

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I agree with you
 
SD said:
Good to see Canada filling with cold air in late Feb. Still might eek something out during the first week of March the Alaskan ridge might be enough

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GFS is showing a possibility - cold coming down and moisture not too far away (sure - it's out there's a way and moisture and cold have not consummated a marriage yet, but they are holding hands and kissing) - FWIW

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Just sayin' ...
 
tennessee storm said:
wouldn't rule out a severe wx outreak right just before any cold takes place... with this big warmup taking place out ahead...
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The ones around the 24th and the 1st both have potential. I'm not sure about the 24th with the low well removed and the 1st might lack good moisture return either way though they are worth keeping an eye on

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This look is getting close but you need a little more western ridge and the vortex south of baffin Bay to help keep from having a weak ridge in the SE...that said I'm not disappointed in the look
3f49c867dec5ad7e20f87e1ec06a07ee.jpg


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SD said:
This look is getting close but you need a little more western ridge and the vortex south of baffin Bay but at this lead time at least it's not horrific

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if i might - it's better than anything for a while ... fluke or a start? here's to "start"!

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pcbjr said:
if i might - it's better than anything for a while ... fluke or a start? here's to "start"!

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Hopefully a start but I worry in this look there is going to be too much energy dropping too far West and we see areas like the OV and lakes do well while we torch

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SD said:
Hopefully a start but I worry in this look there is going to be too much energy dropping too far West and we see areas like the OV and lakes do well while we torch

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"Worry" is our middle name down here - o_O
 
GaWx said:
Phil,
My temporary time in Gainesvile taught me one thing that I'll never forget and that also gave me my fondest memory: Gainesville, FL, is the radiation capital of the SE! I'd put them right up against most any major SE city in any radiation cooling contest. On a sunny day with low dewpoints and light winds, I just know that the temperatures will be taking a nosedive there starting in the last hour before sunset. I took many an evening walk last winter/spring and loved how it cooled so much on days like these.

At 4 PM Gainesville was a sunny and beautiful 67 with a dewpoint of 27 along with light westerly winds. It wouldn't shock me if they went down to 32 tonight! Regardless expect a beautiful frost in the morning. Get ready for the big plunge!
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You might well be right - they've dropped the official to 35º and it is dead calm out - no wind to stir heat. I'll be dadgummed ...

and remember, the airport is east and close to 3 big lakes that do tend to throw up some warmth (Lochlossa, Newnan's and Orange) - plus the Prairie ... NW Hogtown should be colder - it always is ....
 
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With such a warm winter we've been having, I really do feel that if a storm could "bomb" out and give us a good snowstorm. The reason why I think of this, is becuase after this warm episode and cold air coming down, this can trigger some strong storm systems. With more storms coming along the southern stream late this month and with cold air coming down excites me. I do think it will remain active in the southern stream mid month in March.

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pcbjr said:
You might well be right - they've dropped the official to 35º and it is dead calm out - no wind to stir heat. I'll be dadgummed ...
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35? My forecasted low is only 39 tonight so you are doing really good. Unfortunately it looks like last night was my last night of below freezing temps for at least a week or more.
 
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