Area Forecast Discussion
Issued by NWS Atlanta, GA
FXUS62 KFFC 280817
Area Forecast Discussion
National Weather Service Peachtree City GA
417 AM EDT THU JUL 28 2016
.SHORT TERM /Today through Friday/...
Should be fairly quiet this morning with some mid level stratus
across the north and west eventually mixing with CU field
development by mid/late morning around 5Kft.
The sub-tropical high anchored off the SE coast that has seemingly
dominated our sensible weather will become somewhat shunted to the
southeast as a mid-level impulse moves through the TN valley today.
This disturbance will act as a mechanism for better convective
organization, especially across the northern tier. With sufficient
CAPE values, shear and marginal mid-level lapse rates, feel today
may be the better day of the work week to see thunderstorm activity,
mainly across the north half of the CWA. Due to higher shear and the
mid-level impulse crossing to the north, convection could also be a
bit better organized with straight-line winds being the main impact.
Not sure how much of this activity across the higher terrain will
translate southward with outflows possibly initiated
shower/thunderstorm development during the late afternoon across the
Piedmont. Hard to pin-point that aspect, but anticipate
precipitation activity to slowly wind down through the evening
hours. Apart from this main forecast challenge, should be fairly
quiet elsewhere with gusty SW winds given the tighter pressure
gradient in place. Highs in the upper 80s to upper 90s from NW to SE
respectively, apart from the low/mid 80s across the higher terrain.
Anticipate some lingering cloud cover from convective debris
overnight with light southwest winds. Lows in the low/mid 70s.
Although we start to get on the lee side of the trough across the
west, there is no real vort max in the low/mid levels to aid in
convective initiation. Therefore, feel shower/thunderstorm activity
will be limited Friday, perhaps initiating on any linger outflow
boundaries from the previous day. SW winds will continue, although
albeit not as gusty. Highs in the upper 80s to mid-upper 90s across
the SE tier.
.LONG TERM /Friday Night through Wednesday/...
Primary concern in the long term period is increasing chance for
diurnal convection compared with last few days. While overall
pattern of zonal flow along northern CONUS (latitudes north of
40deg N) and ridging further south will persist, broad troughing
to persist and deepen a little over midwest states through this
weekend before upper ridging over the central US builds north and
east next week. With weak southwest flow aloft across the
southeast ahead of broad troughing to the north, should see
increased moisture and increased convection, both in coverage and
intensity, as a result. No one day to focus on for heavier
rainfall or more widespread convection. Guidance blend of 30-50pct
PoP looks good for most afternoon and evenings, but particularly
on Sun thru Tues.
Fortunately, with more clouds and precip, temps will drop closer
to seasonal norms or just above instead of more recent streak of
near or above 100F in parts of CWA. Unless we get a lot of rain,
temps may creep back up to these levels by middle of next week
Another concern, though not a direct threat at this time, is more
active tropical development in the Atlantic basin. Last few
deterministic GFS/ECMWF runs have become consistent in developing
a weak tropical low/wave that moves into Caribbean and possibly
south FL early next week. GGEM even more aggressive with tropical
development both in south Atlantic and in Caribbean Sea. Of
course can`t pin down anything specific yet. Just pointing out
that Atlantic basin becoming more active and needs to be watched
VFR conditions expected through most of the TAF period with mostly
clear skies observed tonight. Do not anticipate widespread low stratus
this morning, but may see BKN mid level deck form by sunrise. CU
development by late morning around 5-6Kft. Southwest winds will
increase through the morning hours topping out in the afternoon
with momentum transport illustrating gusts up to 18-20kt. Convective
coverage will be highest north of the metro TAF sites, so have
kept VCSH in from 18-01Z. Any precip will dwindle after sunset.
//ATL Confidence...06Z Update...
High confidence on all elements.
.PRELIMINARY POINT TEMPS/POPS...
Athens 96 73 93 74 / 20 20 30 20
Atlanta 92 72 89 74 / 20 20 30 20
Blairsville 86 69 84 67 / 40 40 50 40
Cartersville 91 72 88 72 / 30 30 40 30
Columbus 95 74 94 75 / 20 20 20 20
Gainesville 91 72 88 73 / 30 30 40 20
Macon 98 74 97 75 / 10 10 20 20
Rome 91 72 89 71 / 50 40 50 40
Peachtree City 93 73 90 73 / 20 20 30 20
Vidalia 99 74 99 76 / 10 10 20 20