Scientific Forecaster Discussion
fxus62 kffc 231152
Area forecast discussion
National Weather Service Peachtree City Georgia
752 am EDT Wed may 23 2018
Previous discussion... /issued 413 am EDT Wed may 23 2018/
Short term /today through Thursday/...
the mid levels are currently showing a trough centered just along
the Georgia/Alabama border. This feature will help to focus showers and
thunderstorms across our area through the short term period as it
opens and meanders east/northeast.
Activity currently ongoing in west central Georgia will most likely
expand in coverage through the morning before more scattered
activity fills in across the rest of the area. Will continue to
monitor the potential for flash flooding across the area as current
storms are moving very slowly.
Expecting moderate instability this afternoon, so a strong
thunderstorm is not out of the question. We are still stuck in a
very moist environment with very high precipitable waters (currently 1.9 with
forecast values around 1.9-2 inches). As a result, very heavy,
efficient rainfall and high rainfall rates will definitely be
possible this afternoon. Any location that sees slow moving, heavy
rainfall may experience issues with localized flooding. Currently
have likely pops with chance thunder expanding across most of the
area for this afternoon/evening. Activity should diminish some in
the overnight hours, although still could see some thunderstorm
Thursday will be fairly similar to today, with scattered showers and
thunderstorms possible with heavy rain a major threat. Current quantitative precipitation forecast
amounts through Thursday are around 1 to 2 inches with a focus in
central GA, with locally higher amounts possible.
Max temps are generally in the 80s across the area for today and
Thursday. Min temps will remain warm and above average, in the upper
60s across most of the area.
Long term /Thursday night through Tuesday/...
the never-ending unsettled and wet pattern will continue for the
foreseeable future. We now begin the extended period at 00z
Friday /Thursday night/ where evidence of a persistent...nuisance
weak low can still be detected across Georgia underneath a larger
scale /albeit weak/ mid/upper ridge. A glance further to the south
also reveals an enhanced wave of tropical moisture entering the
gom from the western Caribbean. For the local area on Thursday
night...isolated showers and thunderstorms will be possible as
weak low supplies a noticeable swath of enhanced mid level
By Friday and into the weekend...eyes become more focused on a
developing wave of low pressure across the central Gulf. This area
of low pressure will have abundant moisture...absence of land masses
in its vicinity and weakening shear working towards its
advantage...with even some Pacific jet energy being transported
from upstream closed low near the California coast. While this
area of low pressure will not pose any sensible weather effects
/yet/ to the local area on Friday...the threat for scattered
airmass thunderstorms and heavy rain showers will certainly remain
The weekend looks rather gloomy as Gulf low pressure becomes more of
a sensible weather factor. As per latest NHC forecast...this area of
low pressure now has a 50 percent chance of taking on subtropical or
tropical characteristics by the weekend. However...this is rather
unimportant given the impacts expected regardless as to whether it
is any form of tropical cyclone or not. Altho discrepancy between
the 00z runs of the European model (ecmwf) and GFS are still noticeable... ec
continues to favor the ensemble guidance and will continue to lean
towards this solution with placement of the low circulation
across the north Gulf. Note however all guidance places Georgia on
the side of deeper moisture. That being said this system will
essentially remain "hung up" over the Gulf as it becomes the
downstream low of an Omega block over the Continental U.S.. unfortunately
that means an endless train of waves containing very deep tropical
moisture will infiltrate the region into at least early next
week. To make matters worse...troughing can be noted all the way
thru the end of next week...with the potential for any notable
pattern change holding off until June. Needless to say...flooding
concerns will be quickly be on the rise through the extended.
LIFR and IFR conditions present across the taf sites. MVFR
conditions are expected at all sites by 15z, with brief VFR
conditions expected this afternoon ahead of any convection,
18-00z. Cigs should deteriorate to MVFR/IFR conditions overnight.
Winds have been light and vrb, mainly S/SW, and should remain less
than 6 kts through the taf cycle. Expecting katl to shift southeast by
18z, with a shift back SW by 03-04z.
//Atl confidence...12z update...
low to medium confidence on all elements.
Preliminary point temps/pops...
Athens 81 67 81 66 / 60 50 70 40
Atlanta 81 69 81 68 / 70 60 70 40
Blairsville 81 62 80 63 / 60 40 50 40
Cartersville 82 67 83 67 / 60 40 60 40
Columbus 82 70 82 69 / 70 60 60 50
Gainesville 80 67 80 66 / 60 50 70 40
Macon 82 69 81 68 / 70 50 70 50
Rome 84 67 85 67 / 50 30 60 30
Peachtree City 82 68 81 67 / 70 60 70 40
Vidalia 85 71 83 69 / 60 50 70 50