Area Forecast Discussion
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FXUS62 KFFC 270608
Area Forecast Discussion
National Weather Service Peachtree City GA
108 AM EST Mon Feb 27 2017
.PREV DISCUSSION... /Issued 1031 PM EST Sun Feb 26 2017/
Current temps already approaching overnight lows so have therefore
made adjustments to min temps tonight. Cirrus will overspread the
CWA after midnight which should slow down the temp drop keeping
temps from bottoming out. No other changes planned.
PREV DISCUSSION... /Issued 224 PM EST Sun Feb 26 2017/
.SHORT TERM /Tonight through Monday Night/...
Latest RAP analysis of the eastern half of the US shows high
pressure centered right along the spine of the Appalachians
providing for a very light wind flow over the local area. Right
around normal for the temps thus far which for this year is
seasonably cool with mostly upper 50s and lower 60s. Building high
clouds to the west but for the local area it is high and dry.
Speaking of dry...dewpoints remain in the single digits and teens
across a vast majority of the area driving the RH values in the
teens as well with current Fire Danger Statement certainly on
Moisture will be on the increase through tonight and especially
into Monday as high pressure quickly shifts offshore in zonal flow
aloft allowing for good return flow off the gulf. A warm front
should setup across the deep south in response and act as the
focus along with embedded shortwaves in mid level flow for shower
development west of the area initially.
This activity will eventually translate east to affect NW GA Mon
afternoon although instability axis will remain outside these
areas such that only SHRA are expected at onset. Instability does
build through the late afternoon and into the overnight and have
included slight chance thunder for primarily the southern and
western zones. Confident in categorical pops for NW zones but much
uncertainty with models on if and how quickly this activity
translates east and south through the overnight period. Have
favored a more progressive solution for now.
.LONG TERM /Tuesday through Sunday/...
Start of the long-term forecast period brings us to the last day of
February...where the synoptic pattern in the mid levels will feature
long-wave trough over the Western US/Intermountain West...with a
subtropical ridge parked over the Caribbean. This would leave the
eastern two-thirds of the US in a quasi-zonal/weakly anticyclonic
flow regime. Down at the sfc...strong high pressure centered well
offshore of the Atlantic coast will still have enough ridge
influence over the Mid-Atlantic and SE states...while low
pressure will get spun up over the Central Plains as perturbations
within long wave trough induce cyclogenesis.
Sensible weather will be somewhat disturbed on Tuesday as moist
southerly flow regime promotes persistent WAA pattern in the wake of
a warm frontal passage from Monday. GFS/Euro backing off on
QPF...but still looks like north Georgia will see at least scattered
showers during the day. Moist boundary layer looks to allow for
enough destabilization for thunderstorms /sub-severe/. Temps will
once again be well-above normal with highs 70s north 80s central
Tuesday afternoon and near 60 Tuesday night.
Wednesday and Wednesday night will be the most interesting periods
of the long-term as a cold front approaches. SPC more aggressive
with 15-30% severe weather outlook across the SE US/state of
Georgia. Will have to fine tune things the next few days...but
GFS/ECMWF consistent in bringing a strong shortwave across the
Southern Plains into the OH Valley...with associated 90kt+ mid level
jet streak spreading across this area and right entrance region open
to the SE. At the sfc...continued promotion of high theta-e air from
Gulf from southerly flow in the warm sector should allow enough
instability develop...despite cooler mid level air displaced to our
northwest. Strong SW flow aloft atop weaker S/SW surface flow should
promote strong deep layer shear /at least 40-70kts/...albeit
unidirectional. All this undoubtedly raises concern for severe
weather...but will have to wait to see if dynamics will actually
line up...which never really seems to be the true case. Strongest
forcing already seems to be displaced a little too far north and
west...but still warrants attention at this point.
Rest of extended remains dry Thursday-Saturday night under sfc high
pressure and weak NW flow aloft. Temps should be more "seasonal" in
the 60s during this time. Still evidence of moisture return just
outside of this forecast period as models continue to hint at a
southern stream trough over northern Mexico. Looks like another warm
up as well.
VFR conditions for majority of fcst period with gradual building
in of alto deck from west ahead of next disturbance. Cu/stratocu
field in 3-5 kft range should develop around 18-22z today along
with increased shower chances (slight timing differences among
sites). Lull in precip should occur after 03-06z into early
Tuesday...though cigs should start trending lower in MVFR and
possible IFR levels along with MVFR VSBYs. Winds initially light
SE to calm increasing later today but less than 10 kts.
//ATL Confidence...06Z Update...
Medium on late period precip timing and cigs.
High on all else.
.PRELIMINARY POINT TEMPS/POPS...
Athens 67 52 75 59 / 30 40 40 20
Atlanta 65 55 74 61 / 70 50 40 20
Blairsville 57 47 66 54 / 30 50 60 50
Cartersville 61 53 72 59 / 70 40 50 40
Columbus 72 57 80 62 / 30 30 20 10
Gainesville 62 51 70 59 / 70 50 50 40
Macon 74 56 82 59 / 30 40 20 10
Rome 60 52 73 59 / 70 50 60 40
Peachtree City 67 53 76 59 / 50 50 30 20
Vidalia 78 61 84 63 / 30 30 20 10