Area Forecast Discussion
Issued by NWS Atlanta, GA
FXUS62 KFFC 282313
Area Forecast Discussion
National Weather Service Peachtree City GA
713 PM EDT Fri Apr 28 2017
Updated for the 00Z Aviation Discussion.
.PREV DISCUSSION... /Issued 331 PM EDT Fri Apr 28 2017/
SHORT TERM /Tonight through Saturday Night/...
After this morning`s low clouds burned off, today has been
characterized by warm and dry conditions. The potential for any
precipitation is very limited for the remainder of the day.
Overnight low temperatures will be quite warm for this
time of year, only dropping to the upper 60s to near 70 by
Saturday morning. These values are about 10 to 15 degrees above
normal for late April.
The very warm trend continues on Saturday with forecast high
temperatures within a degree or two of record values at area climate
sites. Our area will be on the western periphery of a surface high
off the Atlantic coast, which will allow for some moisture
return. This moisture combined with plenty of heat and instability
will likely yield isolated to widely scattered thunderstorm activity
by Saturday afternoon, especially of the upslope variety in the
north Georgia mountains, though some isolated activity is possible
farther to the south as well. While overall thunderstorm coverage
should remain relatively limited, a few strong or severe
thunderstorms will be possible given ample forecast instability
around 3000 J/kg in north Georgia as well as relatively steep lapse
rates of 6.5 - 7 C/km. Strong winds and hail would be the primary
threats in these pulse thunderstorms Saturday afternoon.
Thunderstorm activity should begin to diminish after
sunset Saturday with continuing above average temperatures Saturday
LONG TERM /Sunday through Friday/...
Models are still in fairly good agreement in the long term.
Sunday will be warm across much of north/central GA. Anticipate the
typical diurnal thunderstorms Sunday afternoon with the best
coverage across the higher elevations.
The next storm system looks to approach the NW tier of GA just prior
to sunrise and slowly move east across the area through Monday
afternoon. The overall extent of severe weather looks somewhat
marginal across north GA and possibly a bit better organized
further south. While the upper level support is displaced to the
north, the better instability collocated with low/mid level shear
and high values of helicity is noted further across central GA.
Given the timing of fropa and cloud coverage ahead of this system,
not sure how much instability will be realized. But for locations
that are not observing as much cloud coverage during the morning
hours (perhaps those across central and eastern GA), this area may
see a bit more activity, especially during the afternoon hours.
The shear and helicity are the best ingredients with this system
at this point, so anticipate a HSLC possible QLCS scenario for
Monday. Given we are within the spring months and models tend to
downplay instability, we will have to keep a close eye on this
storm system and see how it evolves through the weekend.
Anticipate a reprieve after the aforementioned front exits late
Monday through Wednesday with the typical diurnal thunderstorms
during the Wednesday afternoon. The next system may be long-
winded as we tap into moisture riding the southern stream starting
Wednesday night. Meanwhile a deepening trough will dip south and
pivot through the area with a closed low slowly tracking northeast
Friday into Saturday. This may mean a prolonged rain event with
instability in question. The severe potential during this period
will ultimately depend on the surface low placement and upper
level dynamics. At this point, it is too hard to narrow down the
fine details. However, it is safe to say that the end of the
work-week into the weekend looks anomalously wet.
PREV DISCUSSION... /Issued 348 AM EDT Fri Apr 28 2017/
LONG TERM /Saturday Night through Thursday/...
Medium range models in relatively good agreement through the period,
at least with respect to the large-scale patterns. Two main focal
points for organized, widespread, beneficial precipitation centered
on late Sunday/early Monday and again late in the work week.
System moving in late Sunday still showing some potential for strong
to severe thunderstorms. Models continue to weaken the instability as
the system moves across, but also continue to show a decent shot of
low-level and deeper-layer shear. These elements still not aligning
all that great but they do merit watching closely. Timing is a little
later than previous runs with best forcing/instability/shear not
pushing into the far west until closer to 12Z Monday.
Late week system also showing up currently as somewhat lacking in
instability, but this is quite a ways out in the model run and the
surface and upper-level forcing are showing enough potential to keep
an eye on this system as well.
Time periods between these systems show a general flow pattern
supporting some isolated to scattered, mainly diurnal, convection
Records for 04-29
Max Temperature Min Temperature
Station High Low High Low
------- ---------- ---------- ---------- ----------
KAHN 90 1915 50 1999 66 1975 38 1973
KATL 88 1894 47 1934 67 2014 39 1992
KCSG 92 1943 57 1934 71 1970 39 1928
KMCN 92 2012 50 1934 68 1970 37 1992
No major changes from the previous forecast. Mostly VFR conditions
through the forecast. With mostly clear skies tonight and light
winds, patchy fog could develop and have added that to most of the
TAFs. Winds will become southeast 5 to 10kts with a few gusts.
Other concern is the smoke from the southeast GA fires. As the
winds turn southeast late tonight/Saturday, some of the smoke
could spread into the MCN and ATL area. At this time will leave it
out of the TAF due to uncertainty but this will need to be
//ATL Confidence...00Z Update...
Medium on fog development tonight.
High on remaining elements.
.PRELIMINARY POINT TEMPS/POPS...
Athens 67 89 66 85 / 5 20 20 10
Atlanta 69 87 69 85 / 5 20 10 10
Blairsville 63 84 63 78 / 10 30 30 20
Cartersville 67 88 67 85 / 10 20 10 10
Columbus 70 89 69 87 / 5 20 10 5
Gainesville 66 86 66 82 / 10 30 20 20
Macon 67 90 67 89 / 5 10 5 5
Rome 67 89 67 86 / 10 20 10 10
Peachtree City 66 87 66 85 / 5 20 10 10
Vidalia 70 91 68 89 / 5 10 0 5