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FXUS62 KFFC 211900

Area Forecast Discussion
National Weather Service Peachtree City GA
300 PM EDT Mon May 21 2018

.SHORT TERM /Tonight through Tuesday Night/...
The persistent unsettled and wet weather pattern will continue
through the short term. A weak upper low currently situated just
off the coast of the Florida panhandle continues to supply
abundant Gulf moisture to the state. The highest shower and
thunderstorm coverage this afternoon remains across southern and
central Georgia closer to this upper low. While shower and
thunderstorm coverage will diminish somewhat overnight, some
shower activity may linger through the overnight hours.

As the upper low drifts northward into eastern Alabama by Tuesday
morning, PWs will increase even more across the entire area with PWs
of 1.7 to near 2 inches expected on Tuesday. With this moisture
surging into the area, expect coverage of showers and thunderstorms
to blossom by midday Tuesday with daytime heating, and widespread
convection is expected through the afternoon hours. Given the
soupy airmass, locally heavy rainfall can be anticipated, and a
few strong thunderstorms with frequent lightning and gusty winds
will also be possible.

High temperatures will be near to slightly below normal Tuesday with
widespread clouds and convection while lows will remain several
degrees above normal Tuesday and Wednesday.


.LONG TERM /Wednesday through Monday/...
Main concerns in the long term are coverage and intensity of
convection each day and the possibility of very heavy rainfall
late in the period given slow-moving tropical/upper low coming
north out of the gulf of Mexico and into southcentral Gulf coast.

At start of the period, remnant of weak upper low gets absorbed into
westerlies over the Carolinas Wednesday, however deep moisture still
trapped under large upper ridge over southcentral CONUS and northern
Gulf of Mexico. Front trying to sag into north GA Wed/Thurs progged
to make little progress into ridge with stronger westerlies well
north and northeast of the area. Upper ridge forecast to build over
the central and eastern CONUS Thurs. Medium range models in good
agreement through this point though 12Z GFS does show a small but
vigorous upper low over over southern AL 00Z Fri. Not seeing this in
other models so somewhat lower confidence in GFS forecast beyond
this point. Either way, bottom line is scattered diurnal convection
likely Wed thru Fri.

By Friday, most medium range models develop circulation over the
southern Gulf and bring it to the northern Gulf coast late this
weekend. 12Z ECMWF and 12Z GFS faster moving inland early Sunday
but EC much further west over LA/MS coast and GFS over FL west
coast. 12Z GGEM slower but also on further west track. Will have
to monitor this low closely. NHC currently indicating 20pct chance
of TS formation but those will likely rise if these model trends

Irregardless of the track or intensity of this low, GA will be on
the wet side of the system with good feed of tropical moisture.
Saturday could be the wettest day in the long term period but with
deep moisture (PW anomalies well above average) and steady
moisture advection, any day could produce very heavy rainfall.



18Z Update...
A mix of lingering borderline MVFR and VFR ceilings are in place
this afternoon, though ceilings should largely lift into the
035-040 range through the evening. The highest coverage of
shra/tsra this afternoon will be in vicinity of CSG/MCN sites.
Shra/isolated tsra is possible at ATL/AHN area sites, but coverage
will be more limited than farther south. IFR ceiling potential
will increase by 08-10z Tues, though there remains uncertainty in
this potential. Showers and tsra will be more widespread on
Tuesday at all sites. Winds remain from the southeast through the
period at 5-10kts.

 //ATL Confidence...18Z Update...
High confidence on winds.
Medium confidence on all other elements.



Athens          66  80  66  84 /  30  60  60  50
Atlanta         67  79  68  83 /  30  70  60  50
Blairsville     62  75  62  80 /  30  70  60  40
Cartersville    66  80  66  84 /  30  70  60  50
Columbus        68  82  69  85 /  50  70  60  60
Gainesville     65  77  66  82 /  30  70  60  50
Macon           68  82  68  85 /  40  70  60  60
Rome            66  81  66  85 /  30  60  50  40
Peachtree City  66  80  66  83 /  40  70  60  60
Vidalia         70  83  69  86 /  40  60  40  60





NWS FFC Office Area Forecast Discussion