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Good morning!

Laura continues her journey across the southeast this morning and her counter-clockwise rotation continues to pump thick Gulf moisture across Georgia. 

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This morning we have a nice thunderstorm around White and Towns counties and scattered showers elsewhere. This coverage will continue to expand as the day goes on.

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Looking at the Columbus AFB radar in MS, you can see several areas of showers and thunderstorms. One over Alabama embedded in the comma tail of Laura, and further west over Memphis where the core of Laura is still located. 

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Ridging will remain in control of the region today with the remnants of Hurricane Laura impacting portions of north Georgia on Saturday. Deep moisture available across the area with deep southerly flow and PWAT's near 2 inches through the period. Moderate instability and ample moisture in place will lead to convective development. Isolated showers developing across portions of west and north Georgia will increase mainly along and north of I-85 this morning will increase throughout the day as the remnants of Laura moves through with the highest POPs across north Georgia this afternoon and evening, where QPF values of 1-2 inches rainfall is expected through the forecast period. Will again start the day with clouds across the area with scattered low clouds this morning lifting this afternoon, but good cloud cover remaining across the area. South to southwest flow will keep temperatures at or just above normal throughout the forecast period.

Saturday Night through Next Thursday
The long term will be somewhat characterized by unsettled weather due to a rather active westerly upper flow pattern to start allowing for ample moisture and short waves to enhance shower and thunderstorm activity. A weak cold front is forecast to move into the area on Sunday and  stall across the area by Monday, then move north and east and exit the area on Tuesday. An upper level ridge is forecast to build Tuesday into Thursday. Showers and thunderstorms will have the potential to develop most days and maximize with the heating of the day.

Forecast temperatures will favor near to above normal through the long term. Heat indices of 100 to 105 will be possible over central and portions of N GA as well.

 

Here's a look at the precipitable water values from the NAM 3km for the next 60 hours. Lot's of moisture hanging around and then we dry out a little late Saturday and into Sunday. 

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We are still on a slow cool down believe it or not. All of this extra moisture might hide that fact for now, but once we get a cold front, it will be readily apparent. As it is our temperatures will be running just a little bit above normal but the heat index will be the big factor in how it feels. 

Here's a look at the 10 day Euro ensembles for a few cities and towns across north Georgia, and you will notice that the highs dip toward the 70's toward the end of the period. 

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The next 48 rainfall forecast looks like this. Again, you can see more if you get in one of these training lines.

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And the 7 day totals.

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That's it for now! I hope everyone has a wonderful Friday!

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54 minutes ago, Tanith said:

Everything seems to be scooting past us to the northwest so far.

It's muggy as all get-out in NE GA this morning. Good day for a slow cooker meal.

I think it will be closer to evening before we see much rain. I was telling my wife this morning that it's amazing how sometimes when we are covered in tropical moisture we get no rain, and other times it pours. It all has to do with the mechanisms that help to create lift. This morning I took a few snapshots of the upper level winds. The first image is over my house (early this AM) and you can see that the winds are light at all levels and pretty much from the same general direction.

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Looking at the winds over Memphis at the same time, we see much higher winds that also change directions a little with height. That aids in the chances for rain.

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The main story for this afternoon and evening will be the increased
moisture across the local forecast area as the remains of Laura get
swept up into an upper level trough and continue moving north of
the area. Most notable as of now, showers and thunderstorms across
northwest Georgia entering from Alabama are in a more favorable
environment with a combination of shear and instability that could
lead to severe weather. SPC has included a Marginal Risk of severe
storms across portions of northwest Georgia with a small area of
Slight Risk across the far northwest for this afternoon into the
overnight hours. In addition, WPC has included a Marginal Risk of
excessive rainfall across portions of northern and western Georgia
with a Slight Risk across far northwestern Georgia for this
afternoon and evening. Overall, some strong to isolated severe
storms will be possible with the main hazards being damaging wind
gusts, potential for a tornado, and heavy rain that could lead to
some localized flooding issues. Additional showers and thunderstorms
are expected later this evening and into the morning hours as
moisture continues to increase, especially across north Georgia, as
the remnants of Laura pass north of the area.

 

 

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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1223 PM EDT Fri Aug 28 2020
 
Day 1
Valid 16Z Fri Aug 28 2020 - 12Z Sat Aug 29 2020 

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER SIZABLE 
PORTIONS OF THE EASTERN U.S...
...EXPANSION OF SLIGHT RISK OVER PORTIONS OF THE MID ATLANTIC AND 
IN MISSISSIPPI/ALABAMA...

...Tennessee Valley down to the Central Gulf Coast...
Tropical moisture around the center of Laura and extending back 
along a trailing trough structure will provide impetus for a 
scattered flash flood risk through today. The rains around the 
core of Laura had really diminished in intensity, but at the 
leading edge of the strongest height falls we had seen some south 
to north training across TN this morning, producing perhaps 1.50 
inch rainfall amounts in only a couple of hours. This mainly falls 
a bit below the roughly 2 inch per hour flash flood guidance 
values, but the region has had a decent amount of rain over the 
past week to keep soils moist and resistant to infiltration, and a 
slight boost to diurnal instability could yield some heavier short 
term rain rates this afternoon, leading to flash flooding. The 
models that best represented the rain rates and spatial structure 
of precipitation over the Tennessee Valley, and more generally 
over the eastern U.S. were the NAM Nest, WRF-ARW2, and early 
morning HRRR runs. Based on these we adjusted the Slight Risk area 
to focus near and southward from the track of Laura, whereas HREF 
probabilities of rainfall exceeding FFG (i.e., 2 inches in 3 
hours) were quite low across eastern KY/TN owing to greater 
stability there. The environment along the trailing trough lacked 
focus, but broadly convergent low level flow had led to an uptick 
in convective coverage over sensitive areas in southern Louisiana 
and southeast Texas, and with some training up into Mississippi.

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SPC Images

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I am more saying this to comfort myself, but I also wanna make sure I remember, that 2% for tornadoes means there is a 98% chance there WON'T be a tornado within 25 miles of any given point?

Edited by Asperman1
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Sorry for the second post, I would habe edited the first again if I could. Anyways, when a special weatber statement says chance of a brief tornado, how brief do they mean, and how strong? It isn't a severe storm, just strong, so I am a bit confused...

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