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Area forecast discussion...updated 
National Weather Service Peachtree City Georgia 
545 am EDT Sat Mar 20 2010 


Short term /today through Monday/... 
deep layer ridge still the dominant weather influence...keeping 
subsidence and clear skies over US this morning. Weak shortwave 
crossing north Georgia this afternoon should do little more than 
increase middle/high clouds. An upper level trough deepening over the 
Southern Plains today will advance eastward into the lower 
Mississippi Valley on Sunday becoming a closed low over the 
southern Appalachians by Monday. Models pointing toward significant 
shortwave energy rotating around the upper low into Georgia on 
Sunday beneath a nicely diffluent h2 jet pattern. A 50 knots low level jet 
also brings strong warm advection/isentropic ascent through 
Georgia during the day on Sunday...ahead of a cold front crossing 
the state from west to east between 21z sun and 03z Monday. Rainfall 
amounts of 0.5 to 1 inch still seem likely from this quick moving 
system. Instability lacking...though the considerable dynamics 
should help overcome the 100-200 j/kg convective available potential energy to produce some 
thunder. The cold upper low moving over top north Georgia on 
Monday will lead to extensive cloud cover and light 
showers/drizzle especially north. 800 mb temperatures and thermal profiles 
still very close to being supportive of snow in the mountains... 
though latest models are slightly warmer than previous runs. Will 
continue to keep mention of rain only for Monday. 


Long term /Monday night through Friday/... 
a few light showers or drizzle may linger into early Tuesday in 
the north...mainly over the mountains. A ridge building in from 
the west will quickly bring warmer temperatures and drier air into 
our region by Wednesday. The next low pressure system is poised 
to arrive on Friday bringing our next chance of precipitation as 
indicated by both the European model (ecmwf) and GFS...though by this point the 
model solutions start to diverge with the amplitude of that next 
approaching trough. 


Rrh 


&& 


Aviation... 
only concern in the near term is wind direction affecting east-west 
runway operation decisions. Currently...surface low and front well west 
of the area...located over Arkansas up to the Ohio Valley. Front 
slowly pushing east and south and should push winds to just west of 
south by the time vertical mixing kicks in. Could see some 3 to 6kt 
winds just east of due south this morning before 15z...but should 
not persist. Could see some gusts to 18kts at katl this afternoon. 
Clouds prognosticated to develop near the top of the inversion around 6-7 
kft mainly after 18z. Stuck with scattered based on climatology and 
current pattern even though NAM bufr soundings show relative humidity higher than 
90pct for several hours this afternoon. Cumulus will diminish around 
sunset with high clouds becoming increasingly thick. MVFR to IFR 
conditions likely after 15z Sunday with sustained southeast winds 
increasing to 10-20 kts. 


Snelson 


&& 


Preliminary point temps/pops... 
Athens 76 50 64 42 53 / 5 10 80 60 30 
Atlanta 73 51 63 38 50 / 5 20 80 40 30 
Blairsville 68 45 61 39 47 / 5 10 80 70 30 
Cartersville 73 46 63 38 48 / 5 20 80 50 30 
Columbus 74 50 63 42 53 / 10 30 80 30 20 
Gainesville 73 50 61 41 48 / 5 10 80 60 30 
Macon 76 48 66 44 57 / 5 20 80 40 30 
Rome 74 48 63 39 50 / 5 20 80 50 30 
Peachtree City 73 44 64 39 50 / 5 20 80 40 30 
Vidalia 77 52 68 48 62 / 0 10 80 50 20 


&& 


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


$$