Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
640 am EST Friday Feb 27 2015
Previous discussion... /issued 312 am EST Friday Feb 27 2015/
Short term /today through Saturday/...
latest surface analysis shows strong high pressure over the
Central Plains with ridging noted through the Tennessee Valley and
north Georgia. Continued cold air advection pattern in place
across the local area but to a lesser extent than the previous 24
hours. Temperatures over the northern sections will be a battle
between radiational cooling enhanced by snow cover and approaching
low level moisture bringing a broken cloud deck. Looks like we will
be far enough removed time wise form approaching low clouds that
much of this area will realize middle 20s prior to daybreak.
For the remainder of today...have gone below guidance for highs
for areas north of the metropolitan as increased cloud cover should have
an impact through the afternoon hours. Elsewhere...a much needed
fair weather day in store with highs across the southern tier
approaching the 60 degree mark.
Tonight into Saturday will feature a developing wedge over the
Carolinas into west central Georgia. Low levels saturated with
this feature per cross sections and should see good influx of low
clouds into the area into Friday night. South to southwest flow
aloft through 6k feet should allow for some moderate isentropic
upglide by Saturday with southern sections seeing patches of light
rain or drizzle developing. Once again went slightly below
guidance as clouds look to hang in for most of the day over the
area while guidance is decidedly more optimistic.
Long term /Saturday night through Thursday/...
nearly zonal upper flow over the region at the start of the extended
forecast period. Still relatively cool across the forecast area but
better cold air remains well north of the state. Medium range models
continue to build a fairly strong wedge from the middle-Atlantic coast
into north Georgia. Upper flow is not the best for keeping this
feature locked in for too long...and the source region is not
particularly cold...however some residual snow cover in the wake of
the Appalachians from the recent winter storm helps to provide at
least some re-enforcement. Still some uncertainty as to whether or
not we will see enough moisture over-riding The Wedge for some
patchy drizzle by early Sunday...however most of the models show the
potential increasing through the day. If we see any light
precipitation developing early Sunday...surface temperatures will
likely be cool enough for some light icing in northeast Georgia.
Progressive nature of the upper flow moves the surface ridge off the
east by later in the day Sunday through Sunday night so the threat
for icing appears to be limited to early Sunday morning. Confidence
is low to medium at best right now. Upper-level flow is beginning to
amplify by early next week and this trend continues through the
remainder of the extended forecast period. Fortunately Georgia
remains on the warmer...southwest flow...side of the amplifying
pattern. Weak front drops into the vicinity Monday/Tuesday but
washes out with little to no upper support. Instability looks
marginal at best for thunder. Much better chances for thunder
Wednesday and Wednesday night associated with an approaching cold
front and strong short wave. Cooler and drier airmass builds in for
the end of the week in the wake of this system.
12z update... VFR conditions expected for most of this taf cycle.
Low cloud deck continues over portions of Tennessee and is moving
southward into the Georgia portion. Expect this to approach the
northern most taf sites this morning but expect to come up just
short at this time. Surge of easterly low level moisture in store
for Friday evening into the overnight period and will introduce
MVFR deck by 09z for atl.
//Atl confidence...09z update...
medium on MVFR cloud potential Sat morning.
High on remaining elements.
Preliminary point temps/pops...
Athens 49 32 44 33 / 5 5 5 20
Atlanta 45 33 48 35 / 5 5 5 20
Blairsville 37 26 42 30 / 5 5 5 20
Cartersville 39 26 46 34 / 5 5 5 20
Columbus 55 37 53 40 / 5 5 20 20
Gainesville 45 31 42 32 / 5 5 5 20
Macon 56 34 49 38 / 5 5 20 20
Rome 39 26 50 34 / 0 5 5 10
Peachtree City 49 31 50 36 / 5 5 5 20
Vidalia 58 37 49 40 / 5 5 20 20