Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
126 am EDT Wednesday Jul 23 2014
/issued at 940 PM EDT Tuesday Jul 22 2014/
no changes to the forecast. Showers should stay mainly isolated and
probability of precipitation look okay.
short term /tonight through Wednesday night/...
as mentioned in previous updated discussion...large upper low primary
feature with subtle/weaker vorticity center in SC Georgia south of Macon.
Convection could expand a little more in coverage especially in southern
counties where instability higher and north of weak vorticity
center...but not much. Patchy fog and stratus again late tonight.
Upper low will push a little west Wednesday while filling but will
be picked up by weak trough axis aloft. Expect similar coverage and
intensity of storms Wednesday aft/evening. Precipitable water remains high so heavy rain
primary threat. Thursday...larger eastern Continental U.S. Trough digs well
into the state so could see larger precipitation areas and with some more
organized convection. Have bumped probability of precipitation up closer to guidance but
lift ahead of front and trough axis wanes later Thursday. Greatest
coverage of rain showers/thunderstorms and rain may occur late Wednesday night and Thursday morning in
northern counties. Based on MLCAPE around 1500 j/kg and 0-6km bulk
shear of 10-15kts...does not appear that significant severe storms
will occur but much better chance than last several days. Will
continue to monitor.
Long term /Thursday through Tuesday/...
have made minor adjustments to probability of precipitation Thursday night with the
progression of a front. Still differences in guidance on the
strength/progression of upper trough and attendant front
into next week. The European model (ecmwf) continues to be weaker and slower than
the GFS. Have therefore not changed much of forecast...but
adjusted some probability of precipitation and temperatures near next Tuesday where better model
consensus is reached. Previous discussion follows...
Long term /Wednesday night through Monday/...
/issued at 452 am EDT Tuesday Jul 22 2014/
active pattern still expected through the extended period...with
generally above normal rain chances each day. Aforementioned upper
low will keep ample moisture across the area through the work
week. This moisture will combine with a frontal boundary pushing
into the area Thursday to keep rain chances high and have
continued with good chance probability of precipitation or higher Thursday. Weak high
pressure does move in behind the front...and lowest rain chances
look to be Friday and Friday night. The reprieve is short lived as
another upper level disturbance influences the area Saturday night
as longwave trough sets up over the Great Lakes region. Long term
models differ in timing and extent of the precipitation...and
given the uncertainty...have generally gone with good chance probability of precipitation
each afternoon and slight chance probability of precipitation overnight for Sunday through
Modeled instabilities still look to support strong to potentially
brief severe storms each afternoon...but on the whole still expect
the majority to be sub-severe with the main concern being heavy
rainfall. Precipitable waters continue to be high and localized heavy rainfall
amounts can be expected...particularly over areas where storms
have little movement...or where storms may train over the same
In general...near normal temperatures are expected...with a slight
cooling trend into next week with the influence of the second
frontal boundary and longwave trough.
scattered showers continue across north and parts of central Georgia.
These will continue to diminish through the morning. Expect
scattered convection to develop late this morning/afternoon...mainly
across north Georgia. These will also diminish late this evening. VFR
skies currently over the County Warning Area. Scattered-broken IFR/MVFR ceilings will develop
later this morning...increasing to VFR late this morning.
//Atl confidence...06z update...
medium to high on all elements.
Preliminary point temps/pops...
Athens 70 90 71 91 / 30 30 30 50
Atlanta 71 87 72 87 / 30 30 30 50
Blairsville 66 82 65 81 / 30 40 40 50
Cartersville 70 88 70 86 / 30 40 40 50
Columbus 71 89 73 90 / 20 30 20 50
Gainesville 70 86 70 86 / 30 40 30 50
Macon 69 90 71 90 / 30 30 20 40
Rome 70 87 70 87 / 30 40 40 50
Peachtree City 69 88 70 89 / 30 30 20 50
Vidalia 72 92 73 93 / 30 30 20 30