Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Peachtree City Georgia
115 am EDT Monday Aug 31 2015
Previous discussion... /issued 804 PM EDT sun Aug 30 2015/
updated grids a couple times to better reflect radar and observed
near-term trends. Dry slot convection has dissipated and appears
window of opportunity for additional development is closing. Will
keep probability of precipitation low through the night and Monday morning. With dry slot
clearing aloft and residual low level and ground moisture...potential
for areas of radiational fog high late tonight. Have added fog to
most areas 2am-10am.
Previous discussion... /issued 333 PM EDT sun Aug 30 2015/
Short term /tonight through Monday night/...
current radar loop shows showers and isolated thunderstorms
rotating around main low pressure center along the Alabama/Georgia border.
This low is expected to continue moving north to northeast and
will weaken as it does. The models also show the main area of
moisture over north Georgia and the Carolinas moving northeast overnight.
This will help to end the precipitation over the area by midnight.
There may be a few left over showers across north Georgia but thats it.
The models are showing the upper ridge over the northern Gulf
building slightly northward Monday and the moisture remains of
Erika remaining south and east of the forecast area. There will
still be some moisture over the area Monday but it will be a lot
less than today. Going with low chance probability of precipitation across north and
central Georgia Monday. Instabilities expected to be fairly weak for
this time of year so only going with a slight chance of thunder
Monday as well. This fits well with Storm Prediction Center as they currently have US
in just a general thunderstorm risk for Monday. Temperatures will be in
the 60s and 70s for lows...and mainly in the 80s for highs with
some 70s in the north Georgia mountains.
Long term /Tuesday through Sunday/...
unsettled weather will continue into the extended portion of the
forecast. No major changes needed.
The unsettled weather will come in two forms for the extended...an
upper low that pretty much stays parked across the Gulf
states/northern Gomex and the remnants of Erika.
Models have continued the trend of shifting the deepest tropical
moisture associated with erikas remnants eastward. So...the highest
quantitative precipitation forecast should remain across the far eastern zones. As far as the upper
low GOES...the feature could help keep convective precipitation more
scattered/isolated in the west. Either feature will have abundant low level
moisture to work with.
Another by-product of the upper low will be that temperatures will struggle
to get out of the 80s for much of the period.
MVFR ceilings in place with IFR ceilings developing. Some MVFR
visibilities and possibly IFR visibilities can be expected as well due to fog
and possibly some drizzle. Conditions expected to improve from
15z on to scattered-broken 3500-4500 feet in the afternoon. Surface winds
east-northeast less than 10 kts and could become variable during the day
Monday. Confidence for thunderstorms Monday is too low to include
in the tafs.
//Atl confidence...06z update...
low to medium confidence for visibilities.
High confidence for ceilings and winds to start.
Medium confidence for ceiling improvement and wind direction
during the day Monday.
Preliminary point temps/pops...
Athens 84 69 88 71 / 30 20 30 20
Atlanta 85 70 88 72 / 30 10 20 10
Blairsville 81 63 83 65 / 30 20 30 20
Cartersville 85 67 88 69 / 30 10 20 10
Columbus 89 71 90 73 / 20 10 20 10
Gainesville 82 69 86 71 / 30 20 30 20
Macon 87 70 89 71 / 20 10 20 10
Rome 85 67 89 69 / 30 10 20 5
Peachtree City 85 68 88 70 / 30 10 20 10
Vidalia 86 73 89 73 / 20 20 30 20