794 
fxus61 kphi 131540 
afdphi 


Area forecast discussion 
National Weather Service Mount Holly New Jersey 
1140 am EDT Monday Oct 13 2008 


Synopsis... 
high pressure will remain over the region today. A back-door cold 
front will cross the region later today as the high shifts 
southward. A cold front will cross the area Thursday followed by a 
return of high pressure for the weekend. 


&& 


Near term /through tonight/... 
public products have been updated to remove the morning fog, 
include partly cloudy wording for all areas, and make minor 
adjustments to temperatures and dew points. Maximum temperatures 
have been lowered several degrees with the milky cirrus/cs clouds 
expected for most of the afternoon. 


A back-door cold front will move into the region late this afternoon 
and cross sometime this evening, shifting the winds around from 
the west to the east or northeast. The 00z NAM/GFS and 12z European model (ecmwf) 
are in agreement with the timing of this feature. Also, there is 
an indication that the middle level trough will be more amplified as 
the front is expected to move further south than in previous 
forecasts. The front is expected to remain dry, as indicated in 
all the models, and we have kept precipitation out of the forecast 
through tonight. 


Temperatures should remain warm today as we remain in the same 
airmass. While highs reached into the low to middle 70s across most of 
the region yesterday, todays highs should be able to reach around 
80, as 850mb temperatures continue to be around +14-16c over our area. 


&& 


Short term /Tuesday through Tuesday night/... 
high pressure aloft and at the surface begins to break down as it 
shifts to the south. The airmass will be slightly cooler behind 
the front but not enough to make a big difference. Daytime temperatures 
will be about a degree or two cooler on Tuesday than they will be 
today as we get a little influence from the easterly winds, 
especially closer to the coast, and a few extra clouds overhead. 
However, nighttime temperatures are expected to be slightly warmer than 
the past couple of nights. Fog may once again form in areas of our 
County Warning Area but it was left out of the forecast due to low confidence. 


&& 


Long term /Wednesday through Sunday/... 
the upper ridge axis should shift off to the east by late Wednesday. 
A cold front is forecast to cross the region Thursday ushering in a 
much cooler airmass behind it. High pressure will build in behind 
the cold front and persist through early next week. 


Precipitation-wise, it looks like Thursday will be the best bet 
for showers across the region. However, there is a decent amount 
of uncertainty the farther you head into the extended period. We 
have included some slight chance probability of precipitation in the grids but these probability of precipitation 
will not show up in the zone forecast product. 


Temperatures will start off 5-10 degrees cooler on Thursday than 
they were on Wednesday and cool even more so that by the time we 
reach Saturday we will be seeing temperatures in the middle to upper 
50s for highs. This is roughly a 20-25 degree drop over the course 
of the extended period. Low temperatures won't have quite so drastic 
a drop but should get back into the lower 40s by the weeks end. 


We went with a blend of the new 00z MOS guidance and continuity for 
the temperatures to make sure some newer data was ingested into the 
forecast. 


&& 


Aviation /16z Monday through Friday/... 
VFR conditions will continue through the afternoon with a broken-overcast 
layer of CI/cs. A period of ac clouds possible too. Winds 
generally west to northwest around 10 knots. 


Outlook...the high pressure system will continue to supply US with 
great flying weather through middle week. A cold front is expected to 
cross the region Thursday, possibly bringing showers with MVFR/IFR 
conditions. 


&& 


Marine... 
a large high pressure system will keep winds and seas below Small 
Craft Advisory criteria through middle week. A cold front is expected 
to cross the area Thursday. As high pressure pushes in from the 
west behind the front and low pressure develops on the front off 
the South Atlantic coast, the pressure gradient will begin to 
tighten in the north to northeast flow and may bring Small Craft 
Advisory conditions by the weekend. 


&& 


Phi watches/warnings/advisories... 
PA...none. 
New Jersey...none. 
Delaware...none. 
Maryland...none. 
Marine...none. 


&& 


$$ 
Synopsis...meola 
near term...meola/O'Hara 
short term...meola 
long term...meola 
aviation...O'Hara/rpw 
marine...rpw