Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
1103 am EDT Sat Jul 4 2015
mosaic radar shows an area of widespread rain and a few
thunderstorms extended from eastern Texas into central Georgia. Over
the last hour or two...have noticed a few holes develop in the
coverage across central Alabama and central MS. Do think the first
break in the precipitation may reach US sometime during the middle
afternoon...and the hrrr seems to have a decent handle on this.
The hrrr also shows rain re-developing in the west by 7-8pm. This
is what is already in the grids...so see no reason to change this
now and will stick with persistence.
Have also bumped high temperatures down under the rain shield.
Previous discussion... /issued 850 am EDT Sat Jul 4 2015/
the start of Independence day has been pretty soggy for portions
of north and central Georgia. Middle level flow continues favorable
for training of showers and a few thunderstorms mainly along and
north of Interstate 20.
Instability is limited...so have pulled back on the thunderstorm
coverage for today. Think the main issue will be heavy rainfall
due to storms repeatedly moving across the same areas. Will have
to take a look at high temperatures again towards middle morning.
No changes to the Flood Watch.
Previous discussion... /issued 743 am EDT Sat Jul 4 2015/
Previous discussion... /issued 414 am EDT Sat Jul 4 2015/
Short term /today through Sunday/...
current radar loop shows showers and isolated thunderstorm across
most of north and central Georgia with more precipitation moving
in from Alabama. All in all we are in a very moist near zonal flow
pattern which continues to send one wave after another across the
southeast. This will continue to support multiple rounds of
showers/thunderstorms that should persist through at least Sunday
night. Have broad brushed occasional to chance probability of precipitation across the
entire area through the weekend as timing and intensity of each
wave will be difficult to get a handle on. This is a very rapidly
changing environment with the only constant being north and
central Georgia getting more and more precipitation every hour. The
forecast models are in good over all agreement but they are also
showing some differences in timing and intensity. One good thing
is the models are showing a bit less instability developing this
afternoon so should mainly see just general thunderstorms across
the area today. Given moist environment and limited heating due to
clouds and rain...severe potential will generally be low.
However...we can not rule out a severe storm or two moving in out
of Alabama later this afternoon. If we see any they should be
isolated and short lived. The same should be the case for Sunday
as well. Have also extended the Flash Flood Watch until Sunday
evening for continued precipitation through the weekend. Looking
for 1 to 3 inch totals across north Georgia through Sunday.
Long term /Sunday night through Friday/...
by Monday...upper level trough axis is over the eastern two thirds
of the area with some middle level drier air noted for the northern
County Warning Area with precipitable water dropping to 1.4 inches. Overall would
expect this to result in a reduction in coverage of storms over
previous days and plan to continue lowering probability of precipitation through the end
of the forecast. Drier air continues for Tuesday before eroding
away and giving way to a bit of increased moisture for the
remainder of the long term. With middle and upper level ridge
building in however...upper level energy is much reduced through
the period and diurnally favored chance probability of precipitation look suffice for the
grids. Remainder of the forecast is on track and no major changes
showers and thunderstorms continuing across the area through the
day. Regional radar loop shows showers lining up all the way back
through Arkansas. There are some lightning strikes moving in from
Alabama but its mainly showers for now. The atl area taf sites will
see precipitation off and on through the taf period. Winds expected to
stay mainly out of the west in the 6-16kt range. Will see higher
gust with convective activity later this afternoon. Ceilings will
be up and down through the taf period ranging from VFR to MVFR.
//Atl confidence...12z update...
confidence medium on all elements
Preliminary point temps/pops...
Athens 84 70 85 69 / 100 60 60 40
Atlanta 83 71 84 70 / 100 70 70 40
Blairsville 75 64 78 63 / 100 70 70 50
Cartersville 81 68 83 67 / 100 70 70 40
Columbus 87 72 87 71 / 60 60 70 40
Gainesville 79 69 82 68 / 100 70 70 50
Macon 90 71 89 70 / 50 60 70 40
Rome 82 69 83 68 / 100 70 70 40
Peachtree City 84 70 84 69 / 100 70 70 40
Vidalia 93 71 91 72 / 40 40 70 40
Flash Flood Watch through Sunday evening for the following