Area forecast discussion...updated
National Weather Service Peachtree City Georgia
735 am EDT Tuesday may 21 2013
Short term /today through Wednesday/...
upper ridge continues building over the southeast today with an
upper low near southeast Georgia/northeast Florida. The air mass remains
unstable however water vapor shows some drier air has worked into
northwest Georgia. Have kept a slight chance/low chance probability of precipitation mainly over
the eastern half of the County Warning Area this afternoon and evening...closer to
the upper low and better moisture. Tonight looks like a lull between
systems and have only included slight chance probability of precipitation across the extreme
north. The GFS hints at a short wave crossing the Tennessee Valley
overnight. A closed upper low moving into the Great Lakes region by
Wednesday should push a front into the lower Mississippi Valley
toward Georgia. The models want to keep the front west of the County Warning Area
during the day...but an increase in moisture and instability should
support better chances of thunderstorms across the County Warning Area by Wednesday
afternoon. Mav/met temperatures are close and have taken a
compromise.
41
Long term /Wednesday night through Monday/...
weak cold front approaching with an upper level trough/short wave
forecast to move into the area Wednesday night and with associated
moisture and instability...scattered showers and thunderstorms
are reasonable...most so for the evening hours. The weak cold
front moves into the area on Thursday. It is unclear how much
convection will be associated with the front. The best instability
is forecast over central Georgia with the best upper support over north Georgia.
At this time it seems reasonable that there will be a chance of
showers and thunderstorms...most so in the afternoon. The main
upper trough moves east for Friday with a drier airmass moving over
the area behind the front as surface high pressure builds along
with a much drier northwest flow. Dry conditions continue Saturday as
high pressure moves across the eastern states. Sunday looks to be
mainly dry as well except the northwest flow aloft begins to become more
active to the north with some moisture skirting by the area. Moisture
continues to skirt by Monday and Tuesday with a sharp gradient of
significant moisture at the Georgia/SC line. For now will leave a dry
forecast for Monday/Tuesday and continue to monitor the progress
of the northwest flow. Temperatures generally running within 5 degrees of
normal through the period except Saturday and Sunday morning lows
running 5-10 degrees below normal.
Bdl
&&
Aviation...
12z update...
expecting VFR today with scattered to broken clouds at or above 040. IFR
visibilities will improve quickly this morning as most areas of fog
are shallow. Widely scattered convection possible this afternoon and
evening. Probability of having a thunderstorm affect the taf sites
is low so have left thunder out of forecast for now. Winds expected
to become southwest later this morning around 5 to 8kt. Winds will
gradually Switch Back around to the south-southeast again by 00z this evening
but will be generally less than 5kt. .
//atl confidence...12z update...
medium confidence on timing of SW winds. High confidence on all
other elements.
41
&&
Preliminary point temps/pops...
Athens 87 64 86 64 / 30 30 40 40
Atlanta 86 67 84 66 / 10 10 50 40
Blairsville 82 60 81 60 / 30 30 50 50
Cartersville 86 64 85 63 / 10 10 50 40
Columbus 90 68 88 68 / 10 10 30 30
Gainesville 85 66 84 64 / 30 30 50 40
Macon 89 64 88 65 / 20 20 30 30
Rome 86 63 85 62 / 10 20 50 40
Peachtree City 87 61 86 63 / 10 10 50 30
Vidalia 88 69 88 68 / 30 30 30 30
&&
Ffc watches/warnings/advisories...
none.
&&
$$
Short term...41
long term....bdl
aviation...41
