Scientific Forecaster Discussion
fxus62 kffc 232323
Area forecast discussion
National Weather Service Peachtree City Georgia
623 PM EST Thu Nov 23 2017
updated for the 00z aviation discussion.
Previous discussion... /issued 223 PM EST Thu Nov 23 2017/
Short term /tonight through Friday night/...
very pleasant Thanksgiving afternoon across north and central
Georgia, with just a few clouds drifting across the area.
Temperatures are running about 5 degrees cooler than this time
yesterday, largely due to influence of upr trough and northeasterly
flow advecting low lvl cooler/drier air across the forecast area.
Broad area of low pressure moving across central Florida is
responsible for the thicker cloud-cover across much of southeast
Georgia. Outside of some spotty drizzle or very light rain across
parts of our far southeast counties (telfair to Emanuel county) this
afternoon, dry conditions prevail and will persist into this weekend.
Light winds, clearing skies and dry conditions will result in chilly
conditions overnight. Expect widespread 30s with some lower 40s
extreme southern counties. Temps rebound a few degrees on Friday
(and Friday night) as low lvl winds shift around to west-southwest
and slightly higher dewpts move back across the area.
A safe and Happy Thanksgiving to everyone!
Long term /Saturday through Thursday/...
the long term forecast period begins 12z Saturday with a fairly
amplified flow pattern in the mid and upper levels across the Continental U.S.
As a ridge builds over the western US and a trough develops across
the east. Within this amplified regime...a shortwave embedded within
the cyclonic flow in the east will have lifted into the upper
Great Lakes region...while a more subtle speed Max races into
Missouri. At the sfc...associated Great Lakes reflection will
merge with a stronger area of low pressure from a shortwave in
Canada and push a cold front into the Ohio/Tennessee valleys. This front
will hardly contain any moisture...with the most notable effect
being increased relative humidity between the 700-500mb layers. Think the main
effect from the front will be increased mid/high cloud cover
during its passage thru the day from northwest to southeast on Saturday. That
being said...see some increased /altho light/ precip being
generated in the latest guidance. With the shortwave from Missouri
accompanying the front as it moves towards our area...will have
to monitor potential for isolated light showers...mainly north
Saturday fropa will allow for slightly cooler temps on Sunday under
clear and dry conditions. Altho high pressure will be building in at
the sfc..weak northwest flow in the mid levels is an open invitation for
shortwave energy riding over the western US ridge and into our
region. A wave is expected to move across the area late Sunday into
Monday...but at best would just be associated with some cirrus. Sfc
high pressure to continue the dry spell thru Monday.
By Monday afternoon..upper pattern transitions to more of a central
US ridge and western US trough as a cyclone enters the West Coast of
Oregon. As this trough digs into the intermountain US...the ridge
will be forced east & dampen and start pushing the sfc high
offshore. Tuesday will continue dry with increasing moisture but the
reminder of the forecast then becomes fuzzy. Both operational ec and
GFS have the northern stream energy associated with trough
outrunning the southern stream energy which would help develop a
closed low across the 4 corners vicinity. This not really seen in
eps/gefs/Gem ensemble data so think more of a broad positively
tilted trough will push the the region Wed/thurs. Will likely have
some moisture move through near this time as the upper energy
creates a sfc frontal boundary.
a few MVFR clouds around mcn, but this will push to the southeast
this evening. Otherwise VFR through the forecast. Winds will
remain light northeast to east, becoming light south southwest
//Atl confidence...00z update...
high on all elements.
Preliminary point temps/pops...
Athens 36 62 41 65 / 0 0 0 0
Atlanta 39 62 45 63 / 0 0 0 0
Blairsville 32 60 37 59 / 0 0 0 10
Cartersville 32 62 41 63 / 0 0 0 5
Columbus 40 66 44 68 / 0 0 0 0
Gainesville 38 60 43 62 / 0 0 0 0
Macon 39 65 40 68 / 0 0 0 0
Rome 33 62 40 61 / 0 0 0 10
Peachtree City 35 64 40 65 / 0 0 0 0
Vidalia 44 65 44 70 / 10 5 0 0