287 
fxus62 kchs 191513 
afdchs 


Area forecast discussion 
National Weather Service Charleston SC 
1013 am EST Wednesday Nov 19 2008 


Synopsis... 
cold high pressure will remain over the region into Thursday. A 
dry reinforcing cold front will move across the area Thursday 
night...followed by high pressure through Monday. Another cold 
front should move through the area Monday night into Tuesday. 


&& 


Near term /until 6 PM this evening/... 
currently at the surface...high pressure ridge axis stretches from 
the southern Middle-Atlantic States into the Southern Plains. Visible 
satellite imagery shows clear skies in place across the forecast 
area...with some scattered/broken altocumulus upstream over the 
southern end of the Appalachians. Main near term concern for this 
afternoon revolves around maximum temperatures. 


This afternoon... 
high pressure will remain in firm control of the areas 
weather...resulting in sunny/mostly sunny skies across the area. 
Expect that upstream scattered/broken altocumulus will continue 
to break up as it crosses the higher terrain...with nothing more 
than a middle level clouds brushing the forecast area. Low level 
thickness values support highs ranging from the upper 40s/around 
50 north to the lower 50s south in line with the going forecast. 
Update already sent cancelling the freeze warning...otherwise only 
minor initialization tweaks made. 


&& 


Short term /6 PM this evening through 6 PM Thursday/... 
the temporary intrusion of the upper ridge will retrograde tonight 
while a weak shortwave drops southeast through the Carolinas. 
Although winds may drop to nearly calm early this evening with the 
loss of daytime heating...winds will probably pick back up after 
midnight with the increasing geostrophic winds. Overnight lows 
across far inland areas may be similar to...perhaps a few degrees 
warmer than...this morning. However along the coast the threat for 
a freeze is significantly lower due to 5-10 knots of wind for much of 
the night. 


A thermal ridge will build east on Thursday and downslope warming 
will continue as well. Highs will rebound significantly into the 
lower to middle 60s. 


&& 


Long term /Thursday night through Tuesday/... 
a dry westerly flow will be in place early Thursday night... 
preceding the passage of a cold front. The reinforcing cold front 
appears to move across the area later in the night...but given the 
dry air in place will not be capable of producing any precipitation. 
High pressure will build in behind the front...with strong cold air 
causing temperatures to fall further below normal. Highs on Friday 
and Saturday will generally be in the 50s...while lows Friday night 
and Saturday night should be in the 20s across most locations away 
from the immediate coast. 


Expansive high pressure at the surface will move to the 
mid-Atlantic/Carolina coast on Sunday...before shifting offshore 
Monday. As the high shifts farther from the coast...a southerly flow 
will become established. This will result in a brief return to near 
normal temperatures...but also allow moisture to increase slightly. 
The medium range guidance is in good agreement showing the next cold 
front moving across the area Monday night into Tuesday. Both the 00z 
GFS and 00z European model (ecmwf) now show some showers in association with the 
front...and this needs to be accounted for in the forecast as 
precipitable water values do appear to increase as Gulf of Mexico 
moisture is tapped. Therefore...a slight chance of showers is now 
forecast for Monday night into Tuesday. 


&& 


Aviation /15z Wednesday through Sunday/... 
VFR conditions will continue under dry high pressure. 


Extended aviation outlook...VFR conditions will prevail. 


&& 


Marine... 
high pressure continues to build into the region this 
morning...allowing low level wind fields to diminish. Winds and 
seas have dropped below small craft thresholds across the 
nearshore waters within 20 nm of the coast...therefore have 
cancelled the small craft advisories. Across the outer Georgia 
waters...favorable northerly trajectory and slightly higher wind 
speeds continue to favor seas in the small craft range...so will 
continue to keep the Small Craft Advisory going through the 
afternoon. A continued downward trend in wind speed and seas is 
expect through the remainder of the day. Update already out. 


A wind surge is expected tonight through early Thursday morning as 
a shortwave drops through the waters...however conditions expected 
to remain just below Small Craft Advisory criteria. 


A cold front will move offshore Thursday night. Despite strong cold 
air advection in wake of the front...conditions are expected to 
remain just below Small Craft Advisory criteria through Friday. The 
flow will shift more northerly Friday night with seas...and to a 
lesser extent winds...expected to reach Small Craft Advisory 
criteria over the outer Georgia waters and possibly across portions 
of the near shore waters as well. Conditions will slowly improve as 
the weekend progresses with high pressure settling over the eastern 
United States. 


&& 


Climate... 
record lows for today... 


Chs...27/1949 
chl...32/1951 
sav...27/1951 


&& 


Chs watches/warnings/advisories... 
Georgia...none. 
SC...none. 
Marine...Small Craft Advisory until 4 PM EST this afternoon for amz374. 


&& 


$$ 


Jrj