Scientific Forecaster Discussion
fxus62 kffc 301136
Area forecast discussion
National Weather Service Peachtree City Georgia
736 am EDT Thu Mar 30 2017
Previous discussion... /issued 352 am EDT Thu Mar 30 2017/
.Severe storms likely this evening into tonight...
Short term /today through Friday/...
Latest surface analysis shows high pressure over the New England
states beginning to bridge southward along the Atlantic coast and
wedge into the Carolinas. The leading edge of this will move into
eastern sections of the forecast area later this morning allowing
for an increase in low level clouds and perhaps even a little
drizzle. Not your typical cool season cad though as this one will
have a little more convective punch later this afternoon as low
clouds lift and instability increases. Cape values on the order of
1500 j/kg are possible along eastern sections this afternoon and
will plenty of low level moisture in place and a focus along The
Wedge front...scattered showers and storms will develop.
Meanwhile...strong system will be moving into the mid Mississippi
Valley with embedded strong shortwaves ahead of main upper low to
impact the area. Should see a healthy amount of precip coverage
for northwest sections prior to 00z as moisture and lift increase.
Definitely a split jet pattern with one jet streak across the Tennessee
Valley and the other over the northern Gulf. Concern with this
would be a split in precip as well with far north Georgia getting good
coverage as well as southern sections but areas in the middle
Thinking right now is this will be more tied to severe
potential and less to do with overall coverage and will continue
with categorical pops areawide. So speaking of the severe
potential...models still not all that bullish with the instability
and keep it in the two distinct north and south axis referenced
above. Did go however 2 to 3 degrees above guidance for highs
today and by the time all is said and done...would expect higher
instability values than what models currently project. Shear
certainly wont be an issue with 40 to 50 kts of 850mb flow to aid
in strong wind potential. Temps aloft remain on the cold aide as
well with a continued hail threat with the stronger storms. So
weighing the marginal instability with the strong shear and would
expect scattered strong to severe storms..especially across the NW
portions...but not nearly as meaningful a threat as areas west of
Depending upon which model you go with...activity could be well
west of the area by mid morning Fri. This would keep the secondary
threat for severe storms over central Georgia Fri afternoon to a
minimum. For now have gone low end sct over the these areas giving
a nod to slower moving NAM but could be that Fri afternoon is
clearer than grids currently reflect.
Long term /Friday night through Wednesday/...
Warm and sunny weather returns just in time for the weekend with
upper ridging in control. Temperatures will be well above average
both Saturday and Sunday with highs by Sunday nearing 80 in north
Georgia and well into the mid 80s in central Georgia.
The tranquil weather comes to a quick end as the active pattern revs
back up. By late Sunday clouds will begin increasing ahead of the
next storm system with rain close behind. This next system will
follow a more southerly track than previous systems. The GFS brings
the surface low across southern Tennessee into North Carolina on
Monday while the European model (ecmwf) is a bit slower and farther north with the
center of the low. Regardless, expect widespread rain and
thunderstorms to overspread the area on Monday. The potential for
strong thunderstorms as well as heavy rainfall will also be a
concern during the Monday time. As the upper low passes overhead or
just north of the County Warning Area Monday night into Tuesday morning, wraparound
rainfall can be expected into at least part of the day Tuesday.
Wednesday looks largely dry at this time, but the break in
storminess will again be brief as the progressive pattern continues.
The next storm system will already be knocking on the door of the
area, though there are model discrepancies with the timing.
Nonetheless, showers and thunderstorms will returning by the
Wednesday night into Thursday timeframe.
VFR cigs for most of today at the taf sites in advance of a storm
system expected move through late this afternoon into the evening
and overnight hours. Timing will be difficult to pinpoint with
this system but for now have gone 04z for atl and added some wind
gusts to the prob30 group. This prob30 group will eventually
transition to a tempo later today.
//Atl confidence...06z update...
medium on thunderstorms and rain timing.
High on remaining elements.
Preliminary point temps/pops...
Athens 83 59 76 51 / 40 80 60 5
Atlanta 83 58 74 52 / 30 90 40 5
Blairsville 75 54 67 46 / 40 100 50 5
Cartersville 82 56 72 49 / 40 100 30 5
Columbus 85 60 77 54 / 20 90 40 5
Gainesville 80 57 72 51 / 40 100 50 5
Macon 86 61 78 53 / 20 70 60 5
Rome 82 55 72 48 / 60 100 30 5
Peachtree City 83 57 75 50 / 30 90 40 5
Vidalia 87 64 82 57 / 40 50 40 5