Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
345 am EST sun Nov 29 2015
Short term /today through Monday/...
Surface front vicinity of the Tennessee Valley should stay north and west
of the forecast area as a couple of short waves travel along it.
However...a constant southwest flow aloft will bring deep moisture
into the southern Appalachians through the period. The best moisture
supply should affect mainly north Georgia. The air mass is stable with
positive lifted index values and little cape expected. So no thunder
has been included. Likely or categorical probability of precipitation are forecast for the
northern third...with probability of precipitation diminishing toward central. A portion of
south central Georgia may not see any rain at all through the short term.
Temperatures should generally remain warm even with clouds and rain.
Highs may be a few degrees cooler northeast on Monday as a weak wedge
Long term /Monday night through Saturday/...
Still noticeable differences between the main medium range models
through the latter half of the extended forecast period...although
not as marked as some previous cycles. Monday night through Wednesday
remain potentially very wet across the far north...with both the GFS
and European model (ecmwf) finally pushing the front through the state Wednesday into
Wednesday night ushering in drier air. There will likely be a very
tight gradient in the rainfall totals today through Wednesday from
north to south. The GFS continues to be less progressive with the
following system for late in the week and into the weekend...actually
closing off a weak upper low over the region while the European model (ecmwf) sweeps a
quick open trough and associated short wave through the southeastern
U.S. Both models keep a large surface ridge in place over the region
but the GFS pulls substantially more moisture over the ridge across
the area while the European model (ecmwf) keeps the region fairly dry. For now I have
chosen to not stray from the blend we have been using that favors the
drier European model (ecmwf) trends we have been following over the past few days.
We are looking at an extended period of rain that will affect mainly
north Georgia. Latest quantitative precipitation forecast forecast gives totals of about 3.00 to 4.00
inches through Wednesday for the area from Rome to Helen and north.
Lesser amounts into central Georgia. There does exist the possibility of
some localized flooding. However we are not confident enough at this
time that we will see those amounts...or if the rain will be spread
out long enough to minimize the effects. So no Flood Watch has been
issued on this shift.
Aviation... /issued 1235 am EST sun Nov 29 2015/
VFR expected until middle morning with some MVFR starting to develop
mainly northern taf sites after 15z. Most of the rain should stay
north of the taf sites until around sunset today. MVFR becoming
more widespread just ahead of the rain. Light and variable winds
becoming light southwest after 14z.
//Atl confidence...06z update...
medium confidence in timing of weather.
Medium to high confidence all other elements.
Preliminary point temps/pops...
Athens 69 54 64 53 / 30 60 60 40
Atlanta 70 57 69 55 / 30 50 50 30
Blairsville 62 54 60 51 / 70 80 80 70
Cartersville 66 56 68 54 / 60 70 70 50
Columbus 74 56 74 57 / 10 10 20 10
Gainesville 66 55 62 52 / 50 70 70 50
Macon 73 53 74 55 / 5 10 10 20
Rome 65 56 68 55 / 70 80 80 50
Peachtree City 70 55 71 54 / 20 40 40 30
Vidalia 74 54 75 57 / 5 5 10 10