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Area forecast discussion
National Weather Service Peachtree City Georgia
635 PM EST Sat Feb 25 2017




Update...
updated for the 00z aviation discussion.

&&

Previous discussion... /issued 221 PM EST Sat Feb 25 2017/

Short term /tonight through Sunday night/...
cold front is all but through the entire forecast already and will
be into south Georgia by this evening. Already seeing extremely low
dew points spreading across the area. Although upper flow remains
west to southwesterly and cold advection is not strong, however with
very dry air mass in place, clear skies and diminishing winds we
should see temperatures drop quite well tonight. Dry and mild
tomorrow as the surface ridge transits the region with low-level
flow back on the return side of the ridge by tomorrow night.
Increasingly southwesterly orientation to the upper-level flow
Sunday night with some short wave energy approaching by late in the
period, but medium range and hi-res models keep precipitation north
and west of the state through the overnight hours.

20

Long term /Monday through Saturday/...
a blocking pattern over the northern Pacific Ocean will begin to
break down at the start of the long term period...with a quasi-zonal
southern stream flow and slightly amplified northern stream. Main
notable features in the mid levels will be larger scale trough over
Pacific northwest and a deamplifying southern stream shortwave
trough /phasing with a weak northern stream shortwave trough/
pushing across Tennessee Valley. At the surface...high pressure centered
well east of Delaware-Maryland-Virginia will still promote ridge influence across the
southeast...while weak sfc low over Red River area of Texas/OK will have
associated warm front draped east/southeast across Gulf states.

Will see increasing rain chances on Monday as weak shortwave trough
approaches the area from the west. Associated 850 mb sfc low across Tennessee
and southerly low level flow will promote impressive warm air advection regime
across the southeast. Upglide atop sfc ridge will promote necessary lift
/along with DCVA from shortwave/ for rather widespread rain. Some
elevated instability will develop in the afternoon and allow for
chance of thunder. This disturbed pattern will persist through Tuesday
as higher Theta-E air infiltrates the area in continued southern
flow regime. Quantitative precipitation forecast looks highest across north Georgia with totals
between .50-1.00 inch / minus any convective influence/. Temps
will warm back into the 70s by Tuesday.

May see a brief lull in wider-spread activity going into Wednesday.
However...next cold frontal system is progged to move through the
area Wednesday into Thursday. Forecast is too far out to go into
more finer detail...but the potential may exist for strong to severe
thunderstorms along and ahead of the front Wednesday and
Wednesday night. Right now...GFS and European model (ecmwf) both show strong mid
level jet streak across the Tennessee Valley...with right entrance region
over the southeast. Lower level airmass should be plenty moist for
instability /despite warm mid level temps and perhaps abundant
cloud cover/ as dewpoint rise into the 60s and co-exist with
50-60kts deep layer shear given enhanced flow. Will have to
monitor system evolution the next few days. Storm Prediction Center already outlining
areas to our west in severe outlook for day 5.

After fropa by Thursday morning...remainder of extended will be
dry under sfc high pressure influence and dry northwest flow
pattern aloft. Temps will become more "seasonal" with highs in the
upper 50s north to 60s central /much like this
weekend...actually/. Hints at moisture return just outside of the
extended as longer-range models try to develop a trough across
northern Mexico.

Kovacik

Fire weather...
very dry airmass in place across north and central Georgia Sunday
results in relative humidity values at or below 25 percent through
most if not all of the afternoon. A fire danger statement will
likely be needed for Sunday afternoon into the early evening. Will
let the evening shift monitor the trends in 10-hour fuel moisture
levels before making any final decisions.

20



&&

Aviation...
00z update...
VFR conditions will continue through the forecast. Skies will be
clear through Sunday afternoon with some cirrus moving across the
region late Sunday afternoon. Winds will diminish rapidly early
this evening...go near calm in some areas late tonight. Winds will
becoming variable Sunday afternoon with a general trend to the
northeast or southeast late Sunday afternoon with speeds less than
5 kts.

//Atl confidence...00z update...
high on all elements.

17

&&

Preliminary point temps/pops...
Athens 34 62 40 66 / 0 0 5 60
Atlanta 33 60 42 63 / 0 0 5 70
Blairsville 27 57 34 55 / 0 0 5 80
Cartersville 31 59 39 59 / 0 0 5 80
Columbus 35 64 42 68 / 0 0 5 50
Gainesville 32 59 40 60 / 0 0 5 80
Macon 34 64 39 71 / 0 0 0 50
Rome 30 59 38 59 / 0 0 10 80
Peachtree City 32 61 39 65 / 0 0 5 60
Vidalia 39 67 44 75 / 0 0 0 30

&&

Ffc watches/warnings/advisories...
none.
&&

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