Scientific Forecaster Discussion
fxus62 kffc 221524
Area forecast discussion
National Weather Service Peachtree City Georgia
1124 am EDT Thu Jun 22 2017
Near term update consisted of adjusting categorical/likely pop
trends in the northwest half of the County Warning Area given actually good hi-res
consensus of progged precip in line with fcst isentropic upglide
zones as we get into the broad warm sector of the Cindy remnants
to the west. Given this, we are still in a highly efficient precip
regime and while no Flood Watch products are out, there still
could be isolated flash flooding especially where any more
convective training could develop given a more likely
destabilizing environment later today into this evening. Have also
mentioned the possibility of an isolated tornado in the far northwest
with a low end sig tor parameter being reached due to the
increased low level helicity. Day 1 Storm Prediction Center outlook still has a
marginal risk out for mainly north and west of the Atlanta Metro.
Also bumped daytime highs down a few degrees for most areas that
has had the persistent low level cloud deck this morning around
the precip shield providing good solar sheltering. Previous
Previous discussion... /issued 728 am EDT Thu Jun 22 2017/
Short term /today through Friday/...
Shear axis/weak boundary that has been plaguing the the County warning forecast area for the
last few days will finally shift northward today. Meanwhile, high
pressure aloft and at the surface will try and get a foothold in the
southeast portion of the County warning forecast area.
With the shear axis/weak boundary shifting northward today, the
focus for any precip will also be shifting northward. Even though
the airmass will remain very moist and tropical, precip should
mostly remain unorganized for most of the outlook area. Since the
boundary will flirt with the Georgia/Tennessee border, extreme northern Georgia
should have the highest amounts of rainfall for the short term
period. Currently, widespread 1" to 2" is possible in this area, but
some locally higher amounts are possible through Friday. For now,
these values shouldn't cause any widespread flooding issues, but
some localized flooding is possible. Will hold off issuing a Flood
Watch for now. The axis should remain mostly north of the County warning forecast area again
on Friday, so the highest chances will remain in that area.
Hi temps today and Friday will creep up a few degrees, but still
average a few degrees below normal. Even a few peeks of sunshine are
possible south of I-20 today. A bit more sunshine is possible on
Long term /Friday night through Wednesday/...
First half of the extended forecast period remains rather damp as we
deal with the approach, passage and remains of Cindy. Still looking
at Friday night as the main severe weather threat as the low/mid-
level shear associated with the remnants of Cindy sweep through the
region. Instability appears to be moderate at best, but sufficient
to support the marginal to slight risk of severe wind gusts with an
isolated tornado threat. General area of interest still looks to be
roughly along/north of the I-85 corridor. Flood threat will be highly
dependent on how much rainfall we get in the next 36 hours leading
up to the passage of the low. Frontal boundary gets stretched out
across the forecast area Saturday with ample moisture remaining. Main
focus for precipitation shifts into central Georgia at that time and
slowly diminishes from north to south through Monday/Tuesday.
End of the extended forecast period is looking dry and quite pleasant
for the middle of Summer. Northwest upper flow and surface high
pressure building over the eastern U.S. Ushers in a dry airmass and
temperatures at or below seasonal normals.
broken IFR cigs should continue for the next several hours, along
with the on/off light rain showers. Do expect cigs to gradually
lift through the morning, and eventually settle around 035. Winds
may flirt with due south later this afternoon, but overall, the
direction should remain on the east side. Models are hinting at
IFR cigs again overnight...but kept at low MVFR for now.
//Atl confidence...12z update...
medium confidence cigs. High confidence remaining elements.
Preliminary point temps/pops...
Athens 81 71 89 72 / 70 60 30 50
Atlanta 80 72 87 73 / 80 60 30 60
Blairsville 74 67 82 68 / 90 70 60 70
Cartersville 79 72 86 72 / 90 60 50 70
Columbus 84 74 90 75 / 70 20 30 40
Gainesville 77 70 86 72 / 90 60 30 60
Macon 87 73 91 74 / 50 30 30 20
Rome 78 72 87 72 / 100 60 60 80
Peachtree City 80 71 88 72 / 80 50 30 50
Vidalia 89 75 92 75 / 50 40 30 20