Weather

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Area forecast discussion 
National Weather Service Peachtree City Georgia 
349 PM EDT Sat Oct 11 2008 


Short term /tonight through Monday night/... 
high amplitude pattern remains in place for the immediate short term 
with a deep upper trough in the western U.S. And a high amplitude 
subtropical ridge across the eastern u... over them middle- 
Atlantic region. A large Canadian surface high was located across New 
England and the Quebec province...continuing to shift slowly east 
under the upper ridge. This whole scenario is developing a 
favorable wedge setup for the southeast U.S. Meanwhile...the closed upper 
low...that brought US widespread rain and severe weather middle- 
week...continues to weaken and meander off the Georgia/SC coast. 
Associated rain showers activity is mostly off shore...but some light 
sprinkles/rain showers work their way into our southeast zones. Through Monday...the 
pattern will change little. A strong short wave...now off the 
Pacific northwest coast...will help to Delaware-amplify the pattern by early 
next week...as it moves along the U.S./Canadian border and attempts 
to lift the trough out of the SW U.S. At the same time...this will 
help to squash the high amplitude ridge across the eastern U.S. Further 
south...forming a broad upper ridge anchored over the southeast by Monday. 
The cutoff upper low will be forced S and then west into the Gulf and 
continue to weaken. Consistency among the models and run-to-run 
consistency is good. 


There will be little significant change next 48 hours across the 
County Warning Area. Persistent easterly flow and wedge pattern will keep a 
moist...maritime easterly flow in place. Saturation in the near 
surface/bl will result in continuation of extensive low clouds...most 
noticeable during the late night/early morning hours...with a few 
breaks during maximum daytime heating and subsequent evening hours. As 
the Canadian surface high spreads further east into the more favorable 
wedge position...a reinforcing surge of cooler and drier air will 
begin to spread into the region from the NE. This should take place 
sun...with an increase in NE winds. This coincides with the time 
that the weak closed upper low will move from the Georgia coast into the 
eastern Gulf and its associated deeper middle-level moisture will track 
across the central/S part of the County Warning Area. Thus...-shra 
central/south...and -shra or -dz will be possible NC/NE sun into 
early Monday. Mav/met MOS quantitative precipitation forecast/probability of precipitation advertised in the GFS are way 
overdone...as they have been past several runs. Expecting very 
little measurable precipitation...maybe a few hundredths in our central 
areas sun-early Monday...and little or none in the north. A stable 
marine surface layer...relatively cool surface temperatures...and warm temperatures 
aloft...-4c at 500mb...will create an overall very stable 
environment...so thunderstorms and rain is not expected. Extensive cloud cover will 
result in minimal diurnal temperature variation and near/below normal maximum 
temperatures and above normal min temperatures through the short term. It 
appears that the mav overall has had the best handle on temperatures 
recently...although a bit too cool at night. Mins for tonight were 
adjusted upward based on previous days trends. 


Long term /Tuesday through Saturday/... 
the current high amplitude pattern will continue to break down in 
the extended as aforementioned strong short wave tracks across 
southern Canada/northern U.S. The upper trough will lift northeast 
out of the U.S. As the eastern U.S. Upper ridge Delaware-amplifies and 
broadens across much of the southern U.S. The closed upper low 
will phase out on the south side of the subtropical ridge in the 
central/western Gulf and cease to be a factor in our weather. 
Dry...stable air from the middle-Atlantic will sink south over the 
region for mid-week. Warm temperatures and above normal heights 
aloft along with increasing sunshine will result in above normal 
temperatures well into the 80s for middle week. By the end of the week...the 
upper ridge has sunk far enough South/West into the Gulf to allow 
the westerlies to encroach on the area. This will finally allow a 
long awaited front to drift into the area from the northwest. The 
synoptic pattern with west-northwest flow aloft...stable/dry antecedent surface 
environment/and lack of upper dynamics...which by this point have 
lifted into New England...will likely only allow for a narrow 
band of rain showers...perhaps an isolated thunderstorms and rain. Mex thunderstorms and rain probability of precipitation are less than 
10 percent...and I see no reason to disagree with this. The unknown 
factor in the extended is what effect the remnants of Pacific 
Hurricane Norbert will have? It appears that remnant moisture from 
Norbert will be picked up by the western U.S. Trough. While models 
show this moisture being lifted mostly well north of the County Warning Area as it 
is blocked by the upper ridge...there is still some potential for 
this moisture to be existent along the frontal boundary late in 
the week. Much above normal temperatures are expected through most of the 
extended with the presence of the strong subtropical ridge. Slight 
cooling to more normal temperatures should occur by the weekend behind 
the weak front as weak high pressure moves across the Ohio Valley. 


&& 


Preliminary point temps/pops... 
Athens 62 71 61 76 56 / 20 20 10 10 5 
Atlanta 64 72 61 75 60 / 20 20 20 10 5 
Blairsville 57 69 54 75 51 / 10 10 10 10 5 
Cartersville 60 74 59 76 55 / 10 10 10 10 5 
Columbus 67 76 66 78 63 / 20 20 20 20 5 
Gainesville 61 69 59 74 59 / 10 10 10 10 5 
Macon 67 74 65 79 59 / 30 30 30 20 5 
Rome 62 77 61 77 59 / 10 10 10 10 5 
Peachtree City 65 73 62 75 57 / 20 20 20 20 5 
Vidalia 69 75 65 79 63 / 40 40 40 30 5 


&& 


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


$$ 


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