Scientific Forecaster Discussion
fxus62 kffc 271150
Area forecast discussion
National Weather Service Peachtree City Georgia
650 am EST Mon Feb 27 2017
Previous discussion... /issued 416 am EST Mon Feb 27 2017/
Short term /today through Tuesday/...
fcst period will be characterized by Gulf moisture return and
slightly amplified upper flow to the west with several relatively
weak perturbations traversing along the main longwave energy
generally oriented from the arklatex to the Tennessee Valley. The first of
which should ramp up pops for north Georgia late this afternoon into
evening for mainly showers. Trended chance to brief likely pops
given the NAM isentropic forcing for onset and on best consensus
among hi-res solutions. Progged instability axis looks a bit more
limited and confined farther south but still going for slight chance
thunder mention mainly south of LaGrange to Macon this afternoon.
Zone of precip should propagate into portions of central Georgia by this
evening before diminishing/shifting east of the County Warning Area.
No clear period for at least north Georgia to budge from chance pops
through overnight and again likely mention Tuesday with another one
or two weak impulses possible. Increased thunder mention to general
chance as well given a bit greater instability able to advect
northward across the area from the continued S/SW fetch off the Gulf
source. The real action should be later Wednesday with a strong
frontal passage - see long term below for more details on growing
concern for severe threat.
Given this regime the latest guidance blend looks reasonable with
temps about 5 deg above norms (aside for the far north due to
aforementioned precip likelihood). By Tuesday we should be back into
the oddly so familiar 10-15 deg above norm zone with 70s across most
areas and even low 80s southeast.
Long term /Tuesday night through Sunday/...
main concern this long term period will be a strong cold front
forecast to move across the County Warning Area starting late Wednesday but
most so Wednesday night. Some timing differences with the front
are seen in the models with the GFS a fair bit faster than the NAM
or European. The Storm Prediction Center has included an enhanced
risk area for severe storms over the far northwest including the counties
of Floyd...Gordon Murray and counties to the northwest. A slight risk area is
indicated into central Georgia with a marginal risk area for the farther
southern portions of the cwa S and east of wrb. See spc's day 3 outlook.
Potential for 35-45 kts of low level shear along with a 50 kt 850mb
jet along and 500-1000 of cape and a mid level short wave. The main
hazard with be damaging winds. Tornadoes will also be possible close
to the enhanced risk area. Highest pops and storm potential will be
later Wednesday and Wednesday evening.
Storms end most so Wednesday evening and night with a mostly dry
forecast thereafter. Temperatures will be well above normal until
the front moves through.
VFR conditions for start of fcst period with gradual building in
of Alto deck from west ahead of next disturbance. Cu/stratocu
field in 3-5 kft range should develop around 18-22z today along
with increased shower chances (slight timing differences among
sites). Lull in precip should occur after 03-06z into early
Tuesday...though cigs should start trending lower in MVFR and
possible IFR levels along with MVFR vsbys. Winds initially light
southeast increasing later today but less than 10 kts.
//Atl confidence...12z update...
medium on precip timing and late period cigs.
High on all else.
Preliminary point temps/pops...
Athens 67 50 74 58 / 30 40 30 20
Atlanta 65 53 73 59 / 40 50 40 20
Blairsville 57 46 65 55 / 50 40 60 50
Cartersville 61 51 72 58 / 50 40 50 20
Columbus 71 56 78 62 / 30 30 20 10
Gainesville 61 50 68 58 / 40 30 50 20
Macon 73 54 80 57 / 30 40 20 5
Rome 59 51 72 59 / 80 40 60 30
Peachtree City 66 51 75 57 / 40 50 20 20
Vidalia 77 61 82 62 / 30 30 20 5