Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Peachtree City Georgia
633 PM EST sun Feb 7 2016
no major changes anticipated through the evening as current forecast
looks on track with a slight chance of mainly light showers moving
into far northwest Georgia toward morning ahead of an approaching cold front. /39
Previous discussions... /issued at 339 PM EST sun Feb 7 2016/
..Winter Weather Advisory for accumulating snow in higher
elevations of NE Georgia Monday morning through Tuesday and possible
black ice at lower elevations in the advisory area Monday night into
Short term /tonight through Tuesday/...
Main focus on accumulating snow potential for portions of north
Georgia beginning Monday morning through Tuesday with initial
frontal forcing then transitioning to a more scattered cold air
advective forcing near the center of the deep upper trough. Very
tricky forecast to gain any confidence for snow amounts other than the
higher elevations in NE Georgia where profiles support enough low
level saturation and potential instability to get convective
support. Surface temperatures also make it tricky since soundings all support
rain to snow transition for p-type though many areas outside of far
NE Georgia are too warm Monday for any snow to stick. Even latest
guidance struggles to saturate below 850/900 mb so difficult to say
how far south any snow would be of impact. The good news is that
overall quantitative precipitation forecast extent has been trending lower than before so focus has
shifted mainly to the far NE. Still cannot rule out a light band of
snow showers or flurries that could result in a light accumulation
anywhere else in north Georgia by Tuesday but confidence is too low
to even weigh in on that with late period probability of precipitation.
All in all have issued a Winter Weather Advisory for 1-2 inches in
the far NE with isolated higher amounts possible...especially on the northwest
facing slopes due to the persistent prognosticated fetch around the
aforementioned low mainly Monday morning through Tuesday afternoon.
Areas of black ice at lower elevations are possible Monday night
into Tuesday due to likely refreezing of previous rain or melted
snow earlier in the period.
Long term /Tuesday night through Sunday/...
no big changes to the extended. Broad upper trough rotating over
the eastern states...with moisture pushing down into the Tennessee
Valley should start to move east of the area by the beginning of
the period. Low probability of precipitation continue for the northeast into Tuesday
evening but precipitation should pull out of the forecast area
Tuesday night. Some rain/snow mix expected with little additional
accumulation expected. High pressure building into the southeast
for the remainder of the period. Have added a slight chance north
for Friday and Friday evening even though models differ on the
amount of moisture involved in a short wave that moves across the
southeast. Previous discussion is included below.
/issued 321 am EST sun Feb 7 2016/...
the middle levels will remain very active early next week...while
temperatures remain below normal for this time of year. A warm up
to near normal values is expected by the latter half of the
week...with dry conditions.
At the beginning of the period...a strong upper level
disturbance/trough associated with a coastal low will begin to push
up the eastern Seaboard. A secondary longwave trough will dig
southward through Sunday...and remain over the Gulf states through
the middle to late part of the week. A temporary decrease in middle
level forcing will allow for a transition to more orographically
induced precipitation across the mountains overnight Sunday with northwest surface
However...with the strong trough and shortwave energy digging south
on Monday...the orographically produced precipitation will be enhanced by
some middle level forcing later Monday into Tuesday. The trough will
begin to shift offshore on Wednesday.
Atmospheric profiles will be cold enough aloft for snow...and icing
or widespread sleet is not expected. Rain may mix with snow outside
the higher elevations that have probability of precipitation early Monday evening...but
should transition to all snow before 10pm. Precipitation chances continue
into Tuesday...with all snow continuing across northern Georgia...with a
rain snow mix possible outside the higher elevations during the
The latest quantitative precipitation forecast forecasts have no measurable precipitation across the atl metropolitan
for Monday night through Wednesday. This is not unreasonable since
the atmos will be pretty dry. The best accumulation values will
remain across the higher elevations...but even then...values are an
inch or less through 36 hours. Total accumulations through late
Tuesday/early Wednesday across the western facing slopes of the
highest elevations are averaging one to two inches.
Even though snow and or a snow/rain mix is in the forecast for
Monday night through early Wednesday.... snowfall accumulations will
remain on the low side. Precipitable waters will decrease to around a quarter of
an inch (or less) through Wednesday. So...even though we have the
forcing...there won't be much moisture in the atmospheric column.
The best chances for accumulating snow will remain across northern
Georgia...with the greatest potential across the northeast mountains
The potential for black ice will be high...especially from the metropolitan
Atlanta area northward through Wednesday. Any lingering moisture on
the roads is expected to re-freeze overnight and possibly cause
slick spots on roadways...especially bridges and overpasses.
The remainder of the extended forecast remains fairly quiet. There
is some potential for light precipitation on Friday. However...chances
remain too small to mention at this time. However...the system will
need to be watched.
VFR conditions will prevail tonight...but an approaching cold front
will spread MVFR ceilings into Atlanta taf sites between 12-14z Monday.
Expect these ceilings to improve to VFR middle level ceilings by 18z Monday along
the a chance of spotty -shra through the afternoon. VFR middle level ceilings
persist until around 00z Tuesday when MVFR ceilings spread back in along
with a slight chance for isolated -shsn. Current northwest winds around 5-
7kts will back more west by 06-09z Monday... and remain mainly westerly
on Monday with speeds increasing to around 10-15kts by 18z with occasional
higher gusts through Monday afternoon.
//Atl confidence...00z update...
medium on Monday afternoon VFR ceiling.
Low on precipitation chance/type late in period.
High on all else.
Preliminary point temps/pops...
Athens 35 52 28 39 / 5 40 40 10
Atlanta 37 50 29 36 / 10 30 30 20
Blairsville 31 43 23 30 / 20 60 60 50
Cartersville 34 49 27 35 / 20 40 40 20
Columbus 35 54 31 42 / 5 20 20 5
Gainesville 36 49 27 34 / 10 50 50 20
Macon 34 56 30 43 / 5 30 30 5
Rome 34 48 27 35 / 20 40 40 20
Peachtree City 34 51 28 37 / 10 30 30 10
Vidalia 36 58 33 46 / 0 20 20 5
Winter Weather Advisory from 7 am Monday to 7 PM EST Tuesday for
the following zones: Dawson...Fannin...Gilmer...Lumpkin...