Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
352 am EDT Thursday Jul 2 2015
Short term /today through Friday/...
short term period continues to be marked by active pattern as a
series of upper level disturbances in a dirty northwest flow funnel
into the southeast. The interaction of these disturbances with a
moist...unstable atmosphere will continue to produce widespread
showers and thunderstorms. Hi-res short term models continue to have
difficulty resolving convection trends...with none of the models
really having a good handle on the situation. Expect best coverage
and highest severe potential to be this afternoon and evening...and
generally north of a La Grange to Macon to Swainsboro line.
However...isolated severe storms are still possible outside of this
The main threats continue to be strong...damaging winds and frequent
lightning. Hail up to 1 inch is also possible. Anomalous modeled
precipitable water values continue to suggest that locally heavy
rainfall may pose a flash flood risk...particularly of low lying and
flood prone areas. Storm Prediction Center does have much of north and central Georgia
in a marginal risk for severe storms for today...with a small sliver
of northwest Georgia in the higher slight risk area.
On a side note...ncar ensemble forecast 1 km reflectivity seemed to
do well with overall convection trends Wednesday and Wednesday
night. The 00z run seems to parallel current forecast thinking with
best probability of precipitation staying across the far northern zones. Have under-utilized
this product in the past and can not speak to its overall skill in
this environment yet.
Storms are expected to diminish somewhat overnight...and have scaled
back daytime/evening likely probability of precipitation to likely in the far north...and
then just good chance early Friday morning. Active pattern continues
Friday...though storm coverage seems less impressive as of now. Have
opted to continue with slightly less probability of precipitation for Friday...but still in
the good chance to likely categories.
Overall...near normal temperatures are expected through the short
term...and have gone with a blend of guidance for both highs and
Long term /Friday night through Wednesday/...
no major changes were made to the extended periods. The middle and
long range models continue to show an active pattern through the
weekend as disturbances move through the base of a long wave
trough parked over the area. Moderate cape values of 2000-2500
j/kg continue to support scattered to numerous showers and
thunderstorms each afternoon and evening over the weekend... and
with added forcing from outflows and upper disturbances... a few
severe storms cannot be ruled out. However... deep layer shear
values of 15-20kts remain rather modest... suggesting most storms
should hold below severe limits for the most part. The best chance
for a few strong to severe storms will be from middle afternoon
through early evening when cape and shear values are expected to
peek. Isolated to scattered convection will likely linger
overnight as disturbances continue to traverse the area... but any
strong to severe storm threat should end by middle to late evening
with loss of daytime heating.
Both GFS and European model (ecmwf) are showing the upper trough weakening and
shearing eastward by Monday... with weak ridging possibly
settling over the deep south for Monday through Wednesday. Will
remain optimistic... and just show a low chance of probability of precipitation each day
as the typical summertime isolated to low scattered coverage of
afternoon storms are still expected.
/issued at 319 am EDT Thursday Jul 2 2015/
showers continue to diminish across central Georgia as area of
showers and thunderstorms push into far north Georgia. Expecting
generally MVFR to low VFR conditions across the area through
14z...though local areas of IFR are possible. SW-west winds at 6-10kt
today with higher gusts will remain 4-8kt into the overnight
period. Vrb winds with gusts to 25kt possible in/near convection.
//Atl confidence...06z update...
medium to high confidence on all elements.
Preliminary point temps/pops...
Athens 86 69 87 70 / 60 40 50 40
Atlanta 85 70 85 71 / 60 50 50 40
Blairsville 78 66 78 64 / 70 70 60 60
Cartersville 84 70 84 68 / 70 70 60 50
Columbus 88 73 91 72 / 60 30 40 40
Gainesville 82 68 83 69 / 60 60 60 40
Macon 89 72 90 71 / 50 30 40 40
Rome 84 70 85 69 / 70 70 60 50
Peachtree City 86 70 86 70 / 60 50 50 40
Vidalia 92 74 92 73 / 40 30 40 30