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FXUS62 KFFC 230600
AFDFFC

Area Forecast Discussion...Updated for Aviation
National Weather Service Peachtree City GA
100 AM EST Wed Jan 23 2019



.UPDATE...

Near term looks mostly on track with some slight adjustments to
have some initial lower dewpts in parts of the north with wedge in
place. Still thinking will have some isentropically enhanced light
shower or drizzle begin late this evening which in combination
with some higher elevations in far NE GA expected to be close to
freezing, would still warrant the Winter Weather Advisory for a
light glaze of freezing rain. Previous discussion follows...

Baker

&&

.PREV DISCUSSION... /Issued 708 PM EST Tue Jan 22 2019/

UPDATE...

00z Aviation update below.

Baker

PREV DISCUSSION... /Issued 256 PM EST Tue Jan 22 2019/

SHORT TERM /Tonight through Wednesday Night/...

The rest of the afternoon should be dry and cool with high
temperatures this afternoon in the 40s and 50s across much of the
area, with some areas in the mountains remaining in the 30s. As we
progress through the day, moisture will start to increase ahead of
the next frontal system progged to cross the area. Chances for
showers will start to increase late this evening and continue to
increase through the overnight hours across the whole area, but
especially across the mountains by early morning. As precipitation
starts across northeastern Georgia, the potential to see a mix of
freezing rain and rain continues, especially across northeast
Georgia. As such, a Winter Weather Advisory is still in effect from
7 PM this evening through 4 AM Wednesday morning for light freezing
rain in the higher elevations. Totals are expected to be fairly
light, less than a tenth of ice, so minor accumulations would be
most likely be on elevated surfaces.

The heaviest of the precipitation should be pushing into the area by
Wednesday late afternoon and will continue through early Thursday
morning, before precipitation start to push out of the area.
Overall, total precipitation for this system through Thursday
morning is at least an inch and a half for most of the area, with
the highest totals around 2 to 2.5 inches across northern Georgia.
Moderate to heavy rain will also be possible with this system, so
there is the potential for some flooding issues in portions of
northeastern Georgia, especially in the mountains where the highest
rainfall totals are.

On the backside of this system, cold temperatures will start to push
into the area bringing the potential for some wintry precipitation
early Thursday morning. At this point the moisture looks to push out
of the area very quickly, so the chances aren't very high. The best
time frame to see a mix of rain and snow would be around midnight
through early Thursday morning. The best location looks to be far
northwest Georgia. Current totals are expected to be light with
little to no accumulations expected outside of far northwest
Georgia, where current totals are around a tenth or less of snow.

Reaves

&&

.LONG TERM /Thursday through Tuesday/...

At the onset of the long-term forecast period, precipitation will be
quickly ending from west to east as a cold front sweeps through the
area. Brief rain/snow mix or light snow showers will be possible in
far north Georgia as the precipitation exits Thursday morning, but
moisture will quickly diminish and no accumulations are expected.

High pressure will build into the region behind the cold front,
bringing dry and cool conditions. As alluded to in the morning
discussion, models are coming into much better agreement in
eliminating any impactful weekend precipitation. A weak shortwave
could muster a light rain or snow shower in far north Georgia
Sunday, but even this potential looks increasingly unlikely.

Otherwise, the next cold front looks to arrive on Tuesday. The ECMWF
is currently more bullish with QPF as compared to the GFS. Thermal
profiles would be supportive of some snow potential; however, this
remains a week out, so there is plenty of time to refine details
over the coming days.

Temperatures will be several degrees below normal for late week
before moderating back toward normal by Sunday into Monday.

Previous discussion follows.

RW

PREVIOUS LONG TERM Discussion /Wednesday Night through Monday/...

A line of moderate to heavy showers ahead of cold front will be
moving through the area Wednesday Night with 1-2" of rain expected
for the forecast area (with the highest amounts expected for far
North Georgia, per usual). An occasional rumble of thunder isn't out
of the question with some weak upper-level instability, but with no
surface-based instability overnight, the threat of any severe
weather with this line seems improbable at this time. There is a
chance that the colder air from behind the front could just catch up
with some of the precip on the backside of the line in which case
some light snow flurries could be possible for NW GA. But the
probability is small and no real accumulations are expected.

A weaker, secondary "cold front" is then expected Thursday overnight
into Friday morning, more of the result of a strong, Canadian high
pressure forcing its way into the area. The front is expected to be
dry. There will be an outside shot of some very light snow flurries
to the far north but the chances of that have waned with each
passing day.

Speaking of that surface high pressure system, it is now expected to
be much stronger in the overnight deterministic model runs than
previously expected. Yesterday, the GFS and Euro had a low-pressure
system developing along the Gulf coast on Sunday, but this beefier
high pressure system is now expected to help push that system much
further off shore that originally expected (Hooray!). But just when
you think we might be out of the woods, Mother Nature comes around
again (I told you last night that we can't have nice things).

At the far end of the forecast period, the GFS is now indicating a
strong cold front pushing through the area once again thanks to the
active pattern we're expected to have with a upper-level longwave
trough center over nearly all the lower 48. The GFS is also
indicating line of showers turning to snow for a large portion of
the forecast area. The Euro is lagging behind with this system, but
is also starting to come in line. However, hold off on buying bread
and milk for the moment. Recent model solutions have been very
inconsistent with Day 6-7 shortwaves rolling through the broader
longwave trough. At a certain point, models can only predict so many
systems in the future as small changes grow exponentially with
time. Therefore, there is little confidence of this coming to
fruition just yet, however, we will continue (as always) to
monitor the situation going forward.

Thiem

&&

.AVIATION...
06Z Update...
Ceilings lowering to IFR by around 10z and then possibly LIFR
for northern sites. IFR lingering into the morning with a slight
improvement by 18/21z. Precip chances for VCSH or -DZ until
after 21z today when more widespread SHRA expected with a
frontal passage. This evening could have lowering of cigs again
with MVFR/IFR. Winds initially east to SE near 10-12 kts
gusting up to 18 kts...then shifting more SSE by afternoon before
a shift to the SW/west expected late (after 01z for KATL).

//ATL Confidence...06Z Update...
Medium on potential for LIFR cigs (vs. IFR) this morning at
northern sites.
High on all else.

41

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens 36 59 42 50 / 50 60 100 20
Atlanta 40 60 38 48 / 50 80 100 10
Blairsville 32 51 34 43 / 50 90 100 20
Cartersville 39 58 35 45 / 50 90 100 10
Columbus 48 67 41 51 / 40 80 100 10
Gainesville 35 54 38 47 / 60 80 100 20
Macon 45 68 45 54 / 40 50 100 20
Rome 40 57 34 45 / 50 100 100 10
Peachtree City 42 62 39 48 / 40 80 100 10
Vidalia 48 71 54 60 / 50 40 100 40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 4 AM EST Wednesday for the
following zones: Lumpkin...Towns...Union...White.

&&

$$

SHORT TERM...Reaves/Baker
LONG TERM....RW
AVIATION...41
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