Scientific Forecaster Discussion
fxus62 kffc 210810
Area forecast discussion
National Weather Service Peachtree City Georgia
410 am EDT Sat Jul 21 2018
..Severe Thunderstorm Watch in effect until 10am...
Short term /today through Sunday/...
severe thunderstorm event ongoing this evening as outflow driven
complex moves out of the Tennessee Valley and into the local area.
Impressive cold pool driving this activity with temperatures in
the mid 60s in it's wake, not too bad for this time of year.
Outflow over Tennessee is moving SW which should allow western
tier counties to get in on the act before the night is through and
current Severe Thunderstorm Watch configuration handles this well.
Not a ton of instability to work with but temps aloft continue to
cool with -10c values creeping into far north Georgia at 500 mb. May
prove to be more difficult for mesoscale convective system to maintain itself once it gets
to the Metro and central GA, but given the strength of
aforementioned cold pool and the fact that northwest flow events are over
achievers typically, will continue high pop and svr wording for
most of the area.
This first wave is sure to disrupt the environment for a time this
morning and perhaps into the early afternoon, increasing the
uncertainty for timing of additional storms. Namnest which has had
the best handle on this activity tonight shows a decent break in
activity for the remainder of the day once this initial activity
clears. In fact , it is Sat evening before next wave enters and
Sparks additional strong to severe storm development. Leaned this
way in the grids although keep some form of pops through the
entire day given the uncertainty.
Upper low continues to move southward over the local area through
Sunday with cold temps aloft for this time of year continuing.
Impulses will traverse the overall trough from time to time with
continued timing issues but chances of seeing a cluster move
across most of the area sometime on Sunday looks high.
Long term /Sunday night through Friday/...
the forecast area will be under the influence of an upper level
trough/low pressure system during the long term that is forecast
to hang around through Wednesday before weakening on Thursday with
generally weak west-northwest flow aloft predominating Thursday and Friday.
Plenty of moisture and instability will be associated with the low
pressure/trough system allowing for scattered to numerous showers
Forecast high temperatures will run a few to several degrees below
normal through Wednesday and then close to normal Thursday and Friday.
Forecast low temperatures are running close to normal.
Much of this forecast will depend upon evolution of a series of
storm systems to affect the area over the next 36 hours. The
first of these is moving through NE Georgia currently with a second
moving in from Kentucky. Have inserted a tempo for atl area sites
but recent indications are first system may miss to the east.
Timing is very difficulty with these systems but have inserted a
separate prob30 for late afternoon for possible re-development of
storms. Wind calm currently over atl but should shift to west
with time this morning and remain there for the remainder of this
//Atl confidence...06z update...
Medium on thunderstorms and rain chances and timing.
High on remaining elements.
Preliminary point temps/pops...
Athens 88 70 88 69 / 60 50 30 30
Atlanta 89 72 88 70 / 70 50 40 30
Blairsville 82 64 79 63 / 60 50 60 40
Cartersville 89 69 87 68 / 70 50 50 30
Columbus 92 74 92 72 / 40 40 30 30
Gainesville 86 69 85 68 / 70 50 40 30
Macon 90 72 91 70 / 50 40 30 30
Rome 90 69 87 68 / 70 40 50 30
Peachtree City 90 71 89 69 / 70 40 30 30
Vidalia 91 74 91 73 / 40 40 40 40
Severe Thunderstorm Watch until 10 am EDT this morning for the
following zones: Baldwin...banks...Barrow...Bartow...Bibb...