Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
345 PM EDT Friday Jul 31 2015
Short term /tonight through Saturday night/...
largely a persistence forecast on tap as little change to current
regime is expected. Surface high remains northwest of the area despite some
weak inverted ridging east of the Appalachians impinging more east
flow into the NE County Warning Area. Greatest instability gradient remains across
central Georgia along with a stalled frontal boundary draped from near
Columbus to Macon. This feature along with the more enhanced
moisture gradient should have little change in location /perhaps a
bit farther south/ for Saturday. Have included chance probability of precipitation again for
showers/thunderstorms in the afternoon to evening. Bufr soundings in
the southeast /moreso the NAM/ with decent low level lapse rates
again for Saturday and as recent radar trends have indicated thus
far...could see some strong storms with gusty winds and frequent
lightning and an isolated severe cannot be ruled out. Could be
dealing with some patchy morning fog in areas that receive precipitation
this evening so will need to monitor for future updates.
Temperatures should stay near climatology norms through the period. Have gone
slightly higher on dewpoints as what has trended recently behind
Long term /Sunday through Friday/...
overall long term trends look to be on track so have avoided
making any wholescale changes to the forecast. Have made minor
adjustments to temperatures and dew points for better neighbor
consistency and to use the latest model guidance data. The
previous forecast discussion follows...
/issued 341 am EDT Friday Jul 31 2015/
models are showing good agreement on a weak cold front stalled
across parts of central Georgia Saturday night... sagging further
south and into south Georgia on Sunday...then into North Florida
on Monday. This should lesson thunderstorm chances across the area
through the first part of next week as a drier air mass settles
over the region. The combination of a moist southerly surface to
middle level flow and subtle upper disturbances from the west will
bring a chance of showers and thunderstorms back to the forecast
area for Wednesday and Thursday. Modest instability and weak deep
layer wind shear continues to suggest any afternoon/evening storms
should remain below severe limits.
Behind the front... a drier air mass will help hold heat indices
below the 100 degree mark for most areas for Sunday through
Tuesday. Then as Gulf moisture begins to creep northward... near
critically high heat indices are likely to return to much of the
area by middle week.
mostly VFR conditions through period across area with
afternoon/evening rain showers/thunderstorms and rain potential greatest for southern sites
along with possible reduced visibilities. Depending on where precipitation
occurs today...may need to include MVFR visibilities for early morning
tomorrow. Ceilings in 4-6 kft range with cumulus field then mostly clear
overnight and similar trend again for Saturday afternoon. Precipitation
chances again staying in southern tier for Saturday. Winds have
been tricky this afternoon into evening as katl and nearby sites
may have some wavering between east and north-northwest but should mainly
stay east of north and close to north overnight before NE again
//Atl confidence...18z update...
medium to low on afternoon/evening winds today.
Medium on precipitation chance this afternoon near katl.
High on all else.
Preliminary point temps/pops...
Athens 70 94 69 94 / 10 10 10 10
Atlanta 72 93 72 93 / 10 10 10 10
Blairsville 59 88 60 88 / 10 5 10 10
Cartersville 64 93 64 94 / 5 5 10 10
Columbus 75 94 73 95 / 30 40 20 20
Gainesville 69 92 69 92 / 10 5 10 10
Macon 73 92 71 95 / 30 40 20 20
Rome 62 94 63 93 / 0 5 5 10
Peachtree City 68 92 67 93 / 20 10 10 10
Vidalia 74 91 73 93 / 40 50 30 30