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Area forecast discussion...updated 
National Weather Service Peachtree City Georgia
728 am EDT Thursday Jul 28 2016




Previous discussion... /issued 417 am EDT Thursday Jul 28 2016/

Short term /today through Friday/...
should be fairly quiet this morning with some low/mid level
stratus across the north and west eventually mixing with cumulus field
development by mid/late morning around 5kft.

The sub-tropical high anchored off the southeast coast, that has
seemingly dominated our sensible weather, will become somewhat
shunted to the southeast as a mid-level impulse moves through the
Tennessee Valley today. This disturbance will act as a mechanism for
better convective organization, especially across the
north/northwestern tier. With sufficient cape values, shear and
marginal mid-level lapse rates, feel today may be the better day
of the work week to see thunderstorm activity, mainly across the
north half of the County Warning Area. Due to higher shear and the mid-level
impulse crossing to the north, convection could also be a bit
better organized with straight-line winds being the main impact.
Lower than normal confidence on the overall coverage of
convection, but feel the timing will be later in the afternoon
through early evening. Apart from this main forecast challenge,
should be fairly quiet elsewhere with gusty SW winds given the
tighter pressure gradient in place. Highs in the upper 80s to
upper 90s from northwest to southeast respectively; low/mid 80s across the
higher terrain.

Anticipate some lingering cloud cover from convective debris
overnight with light southwest winds. Lows in the low/mid 70s.
Although we start to get on the Lee side of the mid level trough
across to the west, there is no real vort Max in the low/mid
levels to aid in convective initiation. Therefore, feel
shower/thunderstorm activity will be limited Friday, perhaps
initiating on any linger outflow boundaries from the previous day.
SW winds will continue, although albeit not as gusty. Highs in the
upper 80s to the northwest to upper 90s across the southeast tier.

26

Long term /Friday night through Wednesday/...

Primary concern in the long term period is increasing chance for
diurnal convection compared with last few days. While overall
pattern of zonal flow along northern Continental U.S. (Latitudes north of
40deg n) and ridging further south will persist, broad troughing
to persist and deepen a little over Midwest states through this
weekend before upper ridging over the central US builds north and
east next week. With weak southwest flow aloft across the
southeast ahead of broad troughing to the north, should see
increased moisture and increased convection, both in coverage and
intensity, as a result. No one day to focus on for heavier
rainfall or more widespread convection. Guidance blend of 30-50pct
pop looks good for most afternoon and evenings, but particularly
on sun thru tues.

Fortunately, with more clouds and precip, temps will drop closer
to seasonal norms or just above instead of more recent streak of
near or above 100f in parts of County Warning Area. Unless we get a lot of rain,
temps may creep back up to these levels by middle of next week
though.

Another concern, though not a direct threat at this time, is more
active tropical development in the Atlantic Basin. Last few
deterministic GFS/European model (ecmwf) runs have become consistent in developing
a weak tropical low/wave that moves into Caribbean and possibly
South Florida early next week. Ggem even more aggressive with tropical
development both in South Atlantic and in Caribbean Sea. Of
course can't pin down anything specific yet. Just pointing out
that Atlantic Basin becoming more active and needs to be watched
more closely.

Snelson

&&

Aviation...
12z update...
expect VFR conditions for most of the taf period. Observing stratus
across the northwest tier of Georgia this morning, likely to bypass most
Metro taf sites to the north. Did place a tempo at ryy/atl to
denote lower cigs through 14z. Anticipate SW flow with gusts
around 18-20kts. Overall convective coverage looks limited this
afternoon. However, some model guidance hinting at scattered thunderstorms and rain
nearing the Metro taf sites between 21-01z. May need to add a
tempo to illustrate this potential. Activity should erode through
the evening hours with convective debris lingering thereafter.

//Atl confidence...12z update...
low to moderate confidence in convective coverage. High
confidence on all other elements.

26

&&

Preliminary point temps/pops...
Athens 94 74 92 74 / 20 20 20 10
Atlanta 91 74 89 74 / 30 20 30 20
Blairsville 85 69 84 68 / 40 40 40 20
Cartersville 90 73 88 72 / 40 30 30 20
Columbus 95 75 94 75 / 20 20 20 20
Gainesville 90 73 88 73 / 30 20 30 20
Macon 98 75 95 74 / 10 5 10 10
Rome 89 72 89 71 / 50 40 30 20
Peachtree City 92 73 90 73 / 30 20 20 20
Vidalia 100 76 98 76 / 5 5 10 10

&&

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

$$

Short term...26
long term....snelson
aviation...26

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