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November Weather Discussion

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Here's an excerpt from Larry Cosgrove's medium range discussion:

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I have a suspicion that things are about to get awfully ugly from Texas into the Great Plains and Mississippi Valley on Week 2. There seems to be good agreement among the various global forecast models of a broad, cold 500MB trough taking shape through the middle third of the U.S., with a possible closed low in central Texas. This second feature has all the marking of a synoptic scale heavy rain and severe weather event that will linger for some well into the longer term period. Colder temperatures are probable over the Rocky Mountains and High Plains, but the eastern third of the nation will be under south/southwest flow. Hence warmer temperatures are probable to the right of the Mississippi River. California and the Southwest, as per usual, look warm and dry.

 

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And here is his extended (11-15 day) discussion:

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If I had to sum up my thoughts for November in terms of temperature, I would say "warm West, cool Central. warm East". The numerical models still have a semizonal flow through North America, with no evidence of high latitude blocking signatures, and occasional formation of a full-latitude trough north to south across the Great Plains into Oklahoma and Texas. This is the same basic alignment that took shape in later September and will continue into the first week of November. And no description of a forecast would be complete without mentioning the subtropical jet stream, which looks to be finding a semi-permanent home from the equatorial Pacific Ocean through Mexico into TX and AR.
 
This is a critical point, as in a "typical" El Nino the "Pineapple Express" sets up from the central portions of the Pacific Basin into California, bringing the Golden State the precipitation needed to sustain agricultural and urban areas. No such luck so far this autumn, with the central/southern Mexican shoreline seeing inputs from tropical cyclones, which is then driven into already soaked areas north and east of the Rio Grande. Try as I might, I do not see a break in this pattern through November. While not a normal +ENSO scenario, it will be very tough to develop Arctic values and deliver that chill into lower latitudes. Polar type air (cP, cPk) may occupy the space between the Rocky Mountains and Appalachia from time to time, but even that importation of lower temperatures may give way to a flatter, milder flow after Thanksgiving.
 
Strong surface low pressure areas are apparent in this period around November 6 - 8, and again November 9 - 11. Severe weather threats may arise due to unseasonably warm, moist and unstable values brought up from the Gulf of Mexico with both storms. But snowfall threats look quite limited. You need blocking in Alaska/and/or Greenland, along with a thicker, more extensive snowpack, to build up a chill worthy of November. Instead, you will have to wait until the last week of December, and possibly beyond, before you get get yourself into winter mode in U.S. locations. That said, it certainly looks stormy.
 
Prepared by Meteorologist LARRY COSGROVE on 
Saturday, October 27, 2018 at 10:45 P.M. CT

 

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You've seen several of these types of post today, chances are increasing that the first 10 days of the month will be stormy for the eastern US

 

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Thank you Steve!   Ol Men have trouble with new tricks evidently!   So reading what is above we are looking at the same weather pattern holding into early December as has been all this year?  I mean this is what i gleaned from Larry's writing.  Not the normal severe outbreaks we see with the temp difference on both sides of the fronts, but a more rainy system with flooding possibility across Texas, La and Arkansas especially -- till we can get a big weather pattern shift.

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17 minutes ago, RickyD said:

Thank you Steve!   Ol Men have trouble with new tricks evidently!   So reading what is above we are looking at the same weather pattern holding into early December as has been all this year?  I mean this is what i gleaned from Larry's writing.  Not the normal severe outbreaks we see with the temp difference on both sides of the fronts, but a more rainy system with flooding possibility across Texas, La and Arkansas especially -- till we can get a big weather pattern shift.

Larry sees more of a zonal type flow in November, I'm not so sure he's correct, at least in a general sense. We are starting to see some signs that the early November period may be quite active, and we "may" see a chance for a little severe this week. We are entering our "fall" tornado season, so a few severe weather chances are certainly not out of the question.

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44 minutes ago, Armystrong88 said:

So how does this affect our severe Wx for Wed/Thu?

We could potentially see some severe weather this week, but not anything major. 

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James Spann was showing the parameters for Thursday and there really wasn't anything there at the moment.  Of course things could change within 48 hours of the event....

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So what's your feeling on nov and dec? Sounds like he thinks mild but that's not what most are saying.

 

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There are some that believe that December may be mild and then the bottom drops out in January, and I'm not one of those. We could see some mild weather in November, but it doesn't appear to be long very long lasting at the moment.

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I had a tornado go through my backyard on Nov 30th of 16, I believe. EF-1 (110 mph) winds. Missed my house by about 75 yards or so. When I hear fall severe, I pay attention! Lost 7 out of 9 trees in my backyard, 10 houses were completely destroyed, had to be rebuilt from the ground up

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Just now, SNOW said:

I had a tornado go through my backyard on Nov 30th of 16, I believe. EF-1 (110 mph) winds. Missed my house by about 75 yards or so. When I hear fall severe, I pay attention! Lost 7 out of 9 trees in my backyard, 10 houses were completely destroyed, had to be rebuilt from the ground up

Where? 

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2 hours ago, NorthGeorgiaWX said:

Where? 

 

2 hours ago, NorthGeorgiaWX said:

Where? 

Simpsonville, SC.

It wasn’t a big outbreak, I think that was the only one, it was embedded in a squall line. I can’t figure out how to insert pics, I still have quite a few

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2 minutes ago, SNOW said:

 

Simpsonville, SC.

It wasn’t a big outbreak, I think that was the only one, it was embedded in a squall line. I can’t figure out how to insert pics, I still have quite a few

Fixed it so you can now upload images. Just refresh the page.

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Has been a old wives tale , what ever Halloween weather is Thanksgiving will copy., hummmm 

have to see if this holds true .,

 Ive been tracking and so far over past several years it seems to hold up..

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57 minutes ago, MNW said:

Has been a old wives tale , what ever Halloween weather is Thanksgiving will copy., hummmm 

have to see if this holds true .,

 Ive been tracking and so far over past several years it seems to hold up..

You never know! We'll see!

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From Atlanta

 

General Overview:
Forecast is gaining confidence for a fall severe weather event Thursday as a cold front pushes through the state. At this time, models are signalling this will be one of the stronger systems we've seen in a while. Although instability is limited, there should be enough shear and forcing to produce isolated strong to severe thunderstorms.

Threats
Main concerns will be winds greater than 60 MPH and possible tornadoes. Given the environment, the possibility of seeing some embedded rotations within a line of storms is increasing. Highest rainfall amounts could be 1.5 to 2 inches.

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"Looks like the bulk of the activity should move across north/central GA between 15z/Thu-00z/Fri. With respect to low-lvl instability, an area of low to mid 60s dewpoints should work north across much of the area ahead of the front, but resultant CAPE values seem to remain relatively low 200-600 J/KG (according to 12z/Mon GFS and NAM -- the 00z/Mon ECMWF is a bit higher and stronger with deepening sfc low to NW). Despite the not so impressive CAPE values, pronounced low-lvl wind shear and syntopic-scale forcing is beginning to increase forecaster confidence that a few strong to severe storms will exist Thursday. Uncertain about the tornado threat at this time, but would not be surprised to see some embedded rotating showers/storms within linear (QLCS) features."

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And this from the SPC

Quote

Day 4-8 Convective Outlook '

NWS Storm Prediction Center Norman OK

0311 AM CDT Mon Oct 29 2018 Valid 011200Z - 061200Z

...DISCUSSION...

Medium-range guidance continues to struggle with the evolution of the shortwave trough pivoting through the base of the large upper trough expected to cover much of the CONUS on D4/Thursday. Thunderstorms are likely across the Southeast on D4/Thursday but the strength of these storms will be tied to downstream destabilization and speed of the cold front, both of which are highly uncertain at this point. A severe threat may evolve on D4/Thursday (primarily across southern AL and the western FL Panhandle) but uncertainty is too high to delineate any areas with this outlook.

After D4/Thursday, forecast confidence decreases further as model solutions diverge. Depending on frontal timing, some thunderstorms may occur on D5/Friday along the Mid-Atlantic coast. Stable conditions look to prevail during the weekend.

 

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8 hours ago, NorthGeorgiaWX said:

Where? 

This can happen in November! The fall severe threat is real!

B9445A89-6ABC-4649-BD77-BAF4B5E51E24.jpeg

C13F6B04-9460-4A54-A3CE-C7CF76C423C3.png

671DCA4F-D487-4C7F-BA4F-AA7BC89F9B8A.png

AF9EFADB-CBBE-42CB-87E0-7B2FF7F04FA7.jpeg

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Here's the latest from the Storm Prediction Center for Thursday. The greatest threat for any severe weather will be from central Georgia southward.

Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0207 AM CDT Tue Oct 30 2018

   Valid 011200Z - 021200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE CENTRAL GULF COAST STATES...FLORIDA PANHANDLE AND SOUTHWESTERN
   GEORGIA...

   ...SUMMARY...
   A line of thunderstorms associated with wind damage, hail and
   possibly a tornado or two will be possible on Thursday from parts of
   southeast Louisiana and southern Mississippi eastward across parts
   of Alabama, the Florida Panhandle and southwestern Georgia.

   ...Gulf Coast States/Carolinas...
   An upper-level trough and an associated cold front will move
   eastward across the eastern portion of the southern Plains and into
   the lower Mississippi Valley on Thursday. A moist airmass,
   potentially with moderate instability, should be in place ahead of
   the front along the central Gulf Coast. A line of thunderstorms is
   forecast to be ongoing along the front at the start of the period
   from southeast Louisiana into central Mississippi. This line is
   forecast to move eastward across Alabama, western Florida and into
   southwest Georgia during the morning and afternoon. Although weak
   instability is forecast northeastward across the Carolinas, some
   convection will also be possible along the front aided by strong
   large-scale ascent during the evening and overnight period.

   Forecast soundings across the warm sector show the strongest
   instability Thursday morning from New Orleans eastward to Mobile.
   The NAM and GFS are forecasting MLCAPE values along this corridor in
   the 1000 to 1500 J/kg range. In addition, moderate deep-layer shear
   should be in place with 30 to 40 kt of south-southwest flow in the
   lowest 2 km AGL. This should be favorable for wind damage as a line
   of storms moves eastward across the central Gulf Coast States during
   the day. A tornado or two will also be possible with rotating cells
   embedded in the line due to strong low-level shear. In spite of
   instability weakening with northward extent, an isolated wind-damage
   threat will be possible across parts of south-central Alabama and
   southwestern Georgia where low-level flow is forecast to be
   maximized.

 

30-day3otlk.gif

30-day3prob.gif

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Here is the NAM simulated radar for 2pm Thursday, which is the 60 hour limit for this model. You can see the worst of the activity stays to our south.

 

30-NAM-WRF 3-km Southeast US Simulated Radar 60.png

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