Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
1025 am EDT Friday Jul 29 2016
Latest model trends seem to be all pointing to enhanced pops
across the northern tier today given one big caveat and that is
will clouds clear enough to realize sufficient instability.
Looking at the latest satellite imagery...my first inclination is
that although clouds will be entrenched across the north...we
should see enough breaks eventually to see 1500 j/kg by mid
afternoon. Combine this with precipitable water values of close to
2.20 inches from Cedartown to Cleveland and points northward as
well as the coldest mid level temps (although still relatively
warm)...we should have no problem in generating good pop coverage
down to the northern atl Metro today.
Current grids have a great handle on this distribution but may
raise the highest pops to high end chance based on aforementioned
parameters. Could actually end up being likely depending on how
clouds evolve today and will monitor for additional changes
Previous discussion... /issued 730 am EDT Friday Jul 29 2016/
Short term /today through Saturday/...
short term forecast period sees persistent weak upper troughiness
over the region as the western Atlantic upper ridge weakens and
continues to get suppressed south and east. Medium range models
indicating that the weak short wave that has kept some active
weak convection across Tennessee overnight will remain over the
region but weaken further through the day today while weak surface
trough remains across north Georgia. This all points to a
continuation of the scattered...mainly diurnal...pattern of
convection. Instability should remain moderate at best so although
a few strong storms are possible...severe chances remain minimal.
Temperatures will remain highly dependent on the amount of cloud
cover and precipitation that materializes...but should show a
decidedly northwest to southeast gradient as will pops.
Long term /Saturday night through Thursday/...
Long range begins with with a persistent but weak long wave
trough that stretches from the Great Lakes southward into Tennessee
Valley. This feature and the associated subtle disturbances
traversing through the upper flow should help enhance our chances
of mainly diurnally driven convection through the weekend. Weak
wind shear and moderate instabilities suggest most afternoon and
evening storms should remain below severe limits... but with
added upper support... cannot rule out a few strong or isolated
severe storms across mainly parts of north Georgia over the weekend. By
early next week it appears the upper trough meanders slightly
eastward as an upper ridge over Texas builds east. Although this may
lesson our convective chances a bit... still expect sufficient
moisture and instability to support at least a 30-40 percent pop
each afternoon and evening... with 20-30 percent warranted
The expected increase in clouds and precip chances should help
hold temps closer to seasonal norms over the weekend... then
expect another gradual warm up into mid next week with increasing
high pressure influence from the west.
Area of MVFR ceilings across northwest Georgia currently is expected
to continue slowly spreading southeast through 16z. Have included
MVFR ceilings 12-15z in the Metro Atlanta tafs but do not currently
expect these ceilings to reach kahn...kmcn or kcsg. Otherwise...
mainly VFR conditions expected outside of convection. Will see some
local MVFR or lower visibilities developing through 14z but do not
expect any impacts at the taf sites. Winds will remain southwest to
west 6kt or less through 14z increasing to 7-10kt after. Scattered
convection developing after 16z then diminishing after 00z.
//Atl confidence...12z update...
Medium concerning extent of the MVFR ceilings in the morning and on
the coverage of convection this afternoon. High otherwise.
Preliminary point temps/pops...
Athens 92 72 93 74 / 40 30 30 30
Atlanta 90 73 90 75 / 40 40 40 30
Blairsville 86 69 88 68 / 50 40 40 40
Cartersville 89 72 91 72 / 50 40 40 30
Columbus 94 75 95 75 / 30 30 30 30
Gainesville 88 73 91 73 / 50 40 40 30
Macon 96 73 96 74 / 30 20 30 30
Rome 90 72 91 72 / 50 40 40 30
Peachtree City 90 72 92 72 / 40 40 40 30
Vidalia 98 75 98 75 / 20 20 30 20