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Good morning!

A busy weather day in store today, so let's jump right in. A meandering warm front lies just to the south of most of us this morning, but that should be working its way northward today, and with it comes the rain and some of that will be heavy. If you thought yesterday was rainy... hold on to that umbrella. 

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First let's hear from the Atlanta NWS

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...Flash Flood Watch For Far North GA...

A challenging forecast with a myriad of hazard concerns starting with dense fog. No slam dunk by any means on this one but considering it was in the metro, did not get too cute with it and just ran through the morning hours. Entirely possible that increased lift and rain chances will allow visibility to increase prior to hazard end time, but hazard can be cancelled if that ends up being the case. Embedded shortwaves in zonal flow are increasing lift across the area in vicinity of warm front. This has already allowed for the development of showers and coverage and intensity should increase through the morning hours very rapidly.

Models continue to increase QPF with not only this feature but multiple rounds as second more vigorous shortwave moves through the Tennessee Valley this evening. Now have storm total in excess of 3 inches across portions of North GA, north of the metro in general. Based on the latest QPF and area now being in moderate risk of Excessive Rainfall, have chosen to go with a Flash Flood Watch for areas that line up with high QPF axis.

Instability will be primarily elevated early on, but will need to watch for potential severe storms by afternoon across the Northwest portions. SPC has slight risk for this area which looks to be on target with frontal position. Low level helicity will be off the charts with STP approaching 4 on the NAM. Pretty much an all included with potential hazards of damaging winds, hail  and even isolated tornadoes.

Finally some clearing for tonight and especially into Wed to help dry things out. A very nice day in store for Wed with a drying northerly flow and temperatures in the lower 70's north to lower 80's for portions of Central GA.

 

Next up, the WPC Excessive Rainfall Discussion:
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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Tue Mar 24 2020

Day 1
Valid 12Z Tue Mar 24 2020 - 12Z Wed Mar 25 2020

  • ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL TODAY IN THE SOUTHEAST U.S...

...Moderate Risk affecting TN, MS, AL, GA, NC...
It has been a gradual build up, and now suddenly the flash flood risk looks very pronounced today over the Southeast. The environmental parameters and expected rain rates are not especially strong, but they are sufficient, and the main problem is repeated rounds of convective rainfall and increasing confidence that the heaviest swaths will tend to overlap. On Monday a weather system laid down at least one inch of rain from
northern Louisiana to southern Tennessee and northern Georgia. Amounts of two inches were more common in the middle of this swath, especially northern Mississippi and Alabama. When added to long-term wetness over the past few months, HRRR soil moisture products and the National Water Model indicate near-surface soil moisture ranging from 60 percent to near 100 percent. Additionally, the models are unanimous in producing a swath of rain over this region this morning - forced by warm advection and including convectively-enhanced rainfall - followed by a vigorous shortwave trough producing another round of storms in the evening/overnight hours. It is a setup unique to spring in which the deep layer flow and low level response to the shortwave are strong enough to pump unstable air back into the same areas that see the morning rainfall.

Model QPFs have shown a marked upward trend over recent runs, and the 00Z runs are relatively unanimous as to location, with a broad swath of 2 to 3 inch rainfall from central/southern Tennessee south and eastward. We crafted the Moderate Risk area to include the heaviest Day 1 QPF, with emphasis on areas near and west of the Smoky Mountains and northern Atlanta metro, where RFC gridded flash flood guidance values are particularly low... with only 1"/hour or 1.5"/3-hour rainfall needed to produce flash flooding. Per coordination with local offices, areas farther east into the Carolina's were kept out of the Moderate Risk, as they have less antecedent wetness in the soils.

 

NWS Atlanta has issued a Flash Flood Watch, and that could be expanded a little. 
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THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* FLASH FLOOD WATCH FOR PORTIONS OF NORTH CENTRAL GEORGIA... NORTHEAST GEORGIA AND NORTHWEST GEORGIA...
INCLUDING THE  FOLLOWING AREAS...
IN NORTH CENTRAL GEORGIA... DAWSON... FANNIN... GILMER... LUMPKIN... PICKENS AND UNION.
IN NORTHEAST GEORGIA...  TOWNS AND WHITE.
IN NORTHWEST GEORGIA... CATOOSA... CHATTOOGA...  DADE... GORDON... MURRAY... WALKER AND WHITFIELD. 

* THROUGH LATE TONIGHT

* TWO WAVES OF SHOWERS AND STORMS ARE EXPECTED TODAY AND TONIGHT.
  WILL SEE MODERATE TO HEAVY RAIN AT TIMES WITH LOCALIZED FLOODING
  POSSIBLE. PORTIONS OF NORTH GEORGIA WILL RECEIVE 1 TO 3 INCHES
  OF RAINFALL WITH LOCALLY HIGHER AMOUNTS.
WITH ONGOING HIGH
  STREAMFLOWS AND ALREADY-SATURATED SOILS, RUNOFF FROM THIS
  ADDITIONAL RAIN WILL LEAD TO A GREATER THREAT OF FLASH FLOODING. 

 

Here are the WPC rainfall amounts through 8 AM Wednesday.
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Now, last but not least, the Storm Prediction Center
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   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1233 AM CDT Tue Mar 24 2020

   Valid 241200Z - 251200Z

  •    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MID-SOUTH TO THE SOUTHERN APPALACHIANS...

   ...SUMMARY...
 Scattered severe storms -- including potential for hail/wind damage,  and a few tornadoes -- will be possible over the Mid South/Tennessee Valley/Southern Appalachians vicinity.

   ...Discussion...

   Strong mid-level speed max over the southern Plains is forecast to
   translate into AR by the start of the period, then into the TN
   Valley during the day, before stronger flow digs into central MS by
   25/00z. In response to this feature, a weak surface low will shift
   into AR by early afternoon as the frontal zone that is currently
   draped across the central Gulf States begins to lift north to near
   the TN border. This boundary should advance another 100mi or so
   before stalling across the TN Valley. Aforementioned surface low
   will then track along the wind shift into middle TN by early
   evening.

   Early this morning, scattered thunderstorms were spreading across KS
   in association with the mid-level speed max. This activity should
   propagate into southeast KS/northwest AR by sunrise but new
   thunderstorm clusters are expected to evolve along/north of the
   advancing warm front downstream into western TN during the morning.
   Some of this activity could generate hail early in the convective
   cycle when updrafts will be primarily rooted atop the cooler
   boundary layer. However, diurnal heating will be maximized ahead of
   the surface low across AR where low-level flow should veer and
   surface temperatures should reach convective temperatures by mid
   afternoon. At that time surface-based supercells are expected to
   evolve across the warm sector and near the warm front. This activity
   will develop within strong deep-layer shear, but low-level shear is
   not forecast to be particularly strong given the southwesterly
   surface winds (although locally stronger in the vicinity of the warm
   front). Given these conditions, supercells are expected across the
   warm sector, especially along a corridor from northern MS into
   northern AL and adjacent regions of southern TN. Surface-based
   nature of these storms suggests all hazards are possible, including
   a few tornadoes
. Hail will be the primary risk north of the
   boundary.

 

I am following all of this closely today, so please keep checking back throughout the day. 

The music today is one I'm sure you've all heard. To me, this is one of the most powerful, emotionally stirring songs I've ever heard. I've watched voice coaches on YouTube listen in tears the first time they hear it. When I play it here, I throw it up on the big screen and listen through the stereo. The voices are full and powerful through good speakers. If I could have everyone over to see and hear it I would, but since I can't, here you go. 
I hope everyone has a great day! Stay dry and safe!

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Just heard a rumble of thunder here in western Lumpkin county. I guess the good news is that many of us are already safely at home...

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53 minutes ago, Tanith said:

Just heard a rumble of thunder here in western Lumpkin county. I guess the good news is that many of us are already safely at home...

Yep, nothing bad though.

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Steve are we looking at another round of storms later? These i believe gotta be it. Its too cold for more.

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45 minutes ago, Jeff9702 said:

Steve are we looking at another round of storms later? These i believe gotta be it. Its too cold for more.

According to the TV weatherman, we're to get another round tonight. You're right, though; it seems too chilly.

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44 minutes ago, Tanith said:

According to the TV weatherman, we're to get another round tonight. You're right, though; it seems too chilly.

 

1 hour ago, Jeff9702 said:

Steve are we looking at another round of storms later? These i believe gotta be it. Its too cold for more.

Oh yes. The sun is getting ready to come out and warm us up.

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2 minutes ago, NorthGeorgiaWX said:

 

Oh yes. The sun is getting ready to come out and warm us up.

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Excellent I need the round 2.

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9 minutes ago, NorthGeorgiaWX said:

 

Oh yes. The sun is getting ready to come out and warm us up.

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About to watch this wedge get kicked out in Gwinnett!

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Now an "Enhanced Risk" for TN and parts of AL.

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Quote

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1115 AM CDT Tue Mar 24 2020

   Valid 241630Z - 251200Z

  •    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR SOUTHERN MIDDLE TN AND NORTHERN AL...

..SUMMARY...
The threat for tornadoes, large hail, and damaging winds will be focused this afternoon and evening across the Tennessee Valley.

...TN Valley this afternoon/evening...
A midlevel shortwave trough over AR/MO this morning will move eastward to the TN Valley by this evening, as an associated surface cyclone in OK develops eastward along a rain-reinforced boundary near the southern TN border.  Along and south of this surface boundary, dewpoint's will remain in the mid 60's through the afternoon, beneath mid-level lapse rates of 7-8 C/km per 12z soundings.  The net result with daytime heating in cloud breaks will be moderate buoyancy (MLCAPE 1000-1500 J/kg) within the warm sector, in advance of the surface cyclone/mid-level trough.

In the wake of the elevated convection this morning, additional thunderstorm development is expected by mid afternoon in the vicinity of southwestern TN/northern MS, south of the ongoing elevated storms in the left-exit region of the mid-level jet over northeast AR.  Storms will subsequently spread eastward across northern AL and southern middle TN through the evening. Strong deep-layer vertical shear with long hodographs and effective bulk shear of 50-60 kt, as well as low-level hodograph curvature with 0-1 km SRH near 200 m2/s2, will favor supercells.  Low-level shear could be enhanced some along the residual rain-cooled boundary that will likely shift northward into southern middle TN by mid afternoon. 

Farther south, some vertical mixing of moisture could introduce somewhat larger (15-20 F) temperature-dewpoint spreads from central MS into central AL this afternoon.  Thus, the most favorable corridor for tornadic storms will be in the zone of greater low-level shear and retained low-level moisture near the rain-cooled boundary, closer to the TN border this afternoon/evening.  The favorable near-storm environment, in combination with an expected discrete/cluster storm mode, may support a strong tornado or two.

 

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Do you think that enhanced risk will move over here to Georgia? 
 

Also, how do chances of Tornado look for me?

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The wedge has won today but is finally giving in Buford. Finally went from 54.5 degrees to 57 degrees and it is getting brighter outside. should be interesting how the storms later interact with the wedge front.

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ww0061_radar.gif.f1b3e7a0f36be7174a0e742adf421bd0.gif

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URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 61
   NWS Storm Prediction Center Norman OK
   305 PM CDT Tue Mar 24 2020

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Northern Alabama
     Northeastern Mississippi
     The southern half of western and middle Tennessee

   * Effective this Tuesday afternoon and evening from 305 PM until
     1000 PM CDT.

   * Primary threats include...
     A few tornadoes likely with a couple intense tornadoes possible
     Scattered damaging wind gusts to 70 mph likely
     Scattered large hail events to 1.5 inches in diameter possible

   SUMMARY...
   Scattered supercell development is expected in the next
   couple of hours from western Tennessee and northeastern Mississippi
   into northern Alabama and southern middle Tennessee.  The storm
   environment will be favorable for tornadoes, including a strong
   tornado or two, in addition to damaging winds and large hail. 
   Storms will spread eastward through late evening.

   The tornado watch area is approximately along and 95 statute miles
   east and west of a line from 85 miles north of Huntsville AL to 55
   miles south southwest of Muscle Shoals AL. For a complete depiction
   of the watch see the associated watch outline update (WOUS64 KWNS
   WOU1).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...
   A Tornado Watch means conditions are favorable for
   tornadoes and severe thunderstorms in and close to the watch
   area. Persons in these areas should be on the lookout for
   threatening weather conditions and listen for later statements
   and possible warnings.

 

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NWS Atlanta

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Main focus of forcast will largely be the strong to severe storm threat in the near term and tonight period. An upper shortwave looks to amplify some across the area late this afternoon into overnight. While a lingering wedge has persisted in the northeast, mainly from northern half of the Atlanta Metro over to Athens and northward, the other portion of the CWA has had more destabilization with some scattering of stratocu and increased daytime heating. The RAP even has an axis of progged SBCAPE getting up to near 1500 J/kg going into this evening ahead of the trough. With ample low and deep layer shear expected, the Slight to Marginal severe outlook looks well justified for damaging winds with any bowing segments, along with hail and isolated tornado threats. The HREF probs for STP greater than 1 do get above 90 percent for late afternoon into evening across mainly western portions of the CWA, though any localized interaction with the aforementioned wedge front could focus an increased risk for stronger rotating convection and will need to be monitored.

 

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15 minutes ago, NorthGeorgiaWX said:

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Will this Tornado watch go to us this evening, do you think?

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If you remember yesterday when I showed all of the severe parameters, I mentioned the wedge and how that would take away some of the severe threat in those areas. The fringe of those areas needs to be watched for rotating storms later as per the NWS discussion above.

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4 minutes ago, Asperman1 said:

Will this Tornado watch go to us this evening, do you think?

It is possible, but no talk about it right now.

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22 minutes ago, Asperman1 said:

How does timing look?

It will be much later this evening, and I suspect many will be sleeping. According to the HRRR, it starts to enter the state around 10 PM and pushes through by 3-4 AM. The images in this loop are hourly.

 

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Quote

Mesoscale Discussion 0229
NWS Storm Prediction Center Norman OK
0535 PM CDT Tue Mar 24 2020

Areas affected...northern AL and southern middle TN

Concerning...Tornado Watch 61...

Valid 242235Z - 250000Z

The severe weather threat for Tornado Watch 61 continues.

SUMMARY...
Tornado potential will likely maximize through 8pm CDT
near the AL/TN border.  A strong tornado is possible.

DISCUSSION...
Trends in KHTX VAD data show a strengthening of the
wind field in the 2-3km layer during the past 1-2 hours.  This trend
seemed to be necessary in order for more organized low-level
mesocyclone development.  The intensification of flow is resulting
in around 300 m2/s2 0-1km SRH per observed storm motions.  Surface
observations show temperature/dewpoint spreads around 10 deg F and
reduced mixing compared to areas farther south.  It continues to
appear that the corridor for greatest tornado risk will focus near
the AL/TN border with the stronger updrafts/supercells through the
early evening.

 

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