Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 201538
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
1038 AM EST Mon Nov 20 2017


.UPDATE...

Temps/dewpts largely on track for near term so no changes made
with a mostly clear and dry ridge dominated Monday on tap.
Previous discussion follows...

Baker

&&

.PREV DISCUSSION... /Issued 637 AM EST Mon Nov 20 2017/

.SHORT TERM /Today through Tuesday/...

Mid and upper level flow pattern will noticeably amplify during the
short term forecast period as several strong shortwaves dig into the
middle US from the Pacific NW and southwestern Canada.

After a cold start /Freeze Warning in effect thru 9am for much of
the area...see NPWFFC for details/ Monday will be a rather
pleasant day as weak NW flow in the mid levels takes its time
shifting to the SW. A broad area of high pressure will rule the
lower levels. Expect nothing more than some passing cirrus
clouds...gradually increasing as the day progresses. High temps
upper 50s north to middle 60s central.

Conditions begin to change Monday night as a strong speed max slides
down the front range of the Rockies. This shortwave...along with
another digging vort max across the Upper Great Lakes...will help
amplify a broad area of cyclonic mid level flow into the Southern US
and Gulf of Mexico. The lower level response to this will be to push
the sfc high into the western Atlantic. This will quickly lead to an
increase in Atlantic moisture to the easterly lower level flow
regime. This will result in decent WAA advection and a rapid
increase in low level cloud cover from the south by Tuesday morning.
This also combined with emerging disturbances within mid level
cyclonic flow should allow for some sporadic light precip across the
area on Tuesday. Right now NAM12Bufr soundings /which is preferred
over the GFS given better lower level resolution/ indicate potential
for drizzle Tuesday morning before becoming more showers through the
day. Overall have kept just slight chance over the area given weak
lift and weak lower level ridge influence.

Kovacik

&&

.LONG TERM /Tuesday Night through Sunday/...

The long term period begins with another frontal boundary moving
toward the area from the Tennessee Valley. This looks to be a dry
front with very limited moisture associated with it. Precipitable
water across the northern tier is only around a half an inch so no
pop inclusion for the far NW. Further south there is a slightly
better moisture profile but definitely nothing to write home
about. Southern stream energy is quite strong as it rotates
through the lower Mississippi Valley and warrants slight chance to
low end chance pops despite the limited moisture.

Trough scours moisture south of the area for the remainder of
Wednesday with dry northerly cool advective flow. Another light
freeze will be possible across the far northern tier for early
Thanksgiving morning. An additional strong shortwave moves through
the Tennessee Valley and Mississippi Valley with GFS quicker with
the progression than the ECMWF. Moisture does surge ahead of this
feature as a surface low forms over the Gulf. Looks as though it
will only be the SE corner affected by this activity if at all and
will limit chances to 30 percent.

Deese

&&

.AVIATION...
12Z Update...
VFR conditions expected through today as cirrus gradually increase
from the west. The main concern in terms of ceilings will be
overnight tonight into Tuesday. Low clouds are expected to
rapidly increase from the south and a quick lowering to MVFR and
possibly IFR is expected. Patchy drizzle and light showers may
accompany the low clouds but confidence is not high enough on
coverage to mention in TAFs yet. NW winds this morning should
shift to the NE in next hour or so then to the SE this afternoon
and remain there at under 10kts.

//ATL Confidence...12Z Update...
Medium on ceiling trends/timing into Tuesday morning.
High on all other elements.

Kovacik

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          59  39  57  44 /   0  20  20  20
Atlanta         60  44  59  45 /   0  20  20  20
Blairsville     58  36  56  38 /   0  20  20  10
Cartersville    59  38  58  41 /   0  10  20  10
Columbus        63  47  65  49 /   0  10  20  20
Gainesville     58  39  55  44 /   0  20  20  20
Macon           63  45  65  47 /   0  10  20  20
Rome            58  37  60  40 /   0  10  10  10
Peachtree City  61  38  61  44 /   0  20  20  20
Vidalia         65  47  68  52 /   0   5  40  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Kovacik/Baker
LONG TERM....Deese
AVIATION...Kovacik


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