033 
fxus61 kphi 061411 
afdphi 


Area forecast discussion 
National Weather Service Mount Holly New Jersey 
1012 am EDT sun Jul 6 2008 


Synopsis... 
a weak frontal bounndary across the region will tend to dissipate 
over the next couple of days as the Bermuda high becomes re- 
established over the middle-Atlantic region. A cold front will cross 
the area around middle-week, followed by high pressure on Thursday and 
Friday. 


&& 


Near term /until 6 PM this evening/... 
the scattered early morning convection over parts of Delaware-Maryland-Virginia managed to 
maintain themseleves to some degree as one of what may become an 
annoyingly regular series of impulses kicking out of the upper level 
low to our west acts on the moist and mrgnly unstable air over our 
area. The decision to keep a chance of rain showers/thunderstorms in the morning forecast was 
a good one. Better chance for rain showers/thunderstorms and rain should be this afternoon with 
daytime heating and abundant low level moisture resulting in more instability. 
Also, the upper low closing off over the Ohio Valley will provide more 
southerly flow and increasing moisture for today. Thus we are expecting more 
widesprd thunderstorm activity than yesterday and the moist env will allow for 
locally heavy downpours. We do not expect any significant flooding as 
overall conds are rather dry, however if multiple storms train across a 
particular area there could be some problems so this bears watching. 


&& 


Short term /6 PM this evening through 6 PM Monday/... 
the upper trough remains to our west during this period and the 
airmass will remain quite moist and somewhat unstable. Rain showers/thunderstorm 
activity from sun will likely persist into the evening but gradly weaken 
overnight. The weak q-stationary frontal boundary across the middle-Atlantic 
region is forecast to move north and/or dissipate by Monday so there may 
be less of a low- level focusing mech for convection. Still...the airmass 
and overall synoptic pattern should support scattered afternoon/evening thunderstorms. 


&& 


Long term /Monday night through Saturday/... 
the upper trough is forecast to move eastward off the coast and weaken on 
Tuesday with the flow aloft becoming more zonal across the middle- 
Atlantic region. With the upper pattern less favorable for convection but the 
same airmass in place we have kept basically a minimal chance for 
afternoon/evening thunderstorms across roughly the northwest half of the forecast area. 
Daytime maximum temperatures should show a gradual warming trend Monday and Tuesday 
as somewhat warmer air at 850mb moves in from the west. 


For Wednesday...an upper trough and associated surface cold front are forecast to approach 
from the northwest. The cold front is expected to cross the area Wednesday evening but 
should be preceded by afternoon thunderstorms...also aided by Lee trough forecast 
over eastern PA. Dynamics may be suff to support some severe thunderstorms at 
that time. After the frontal passage the remainder of the week 
looks mostly dry although with continued warm temperatures. 


&& 


Aviation /14z Sunday through Thursday/... 
nearly stationary frontal zone over our forecast area will continue 
to be a focus for convective activity for the next 48 hours. Some 
drier air to our north is trying to push south but having a difficult 
time doing so. With very light winds, only some middle and high clouds, 
and plenty of low level moisture, fog and haze will prevail this 
morning. Conditions are currently MVFR/IFR. This will persist until 
late morning when conditions are expected to improve to VFR/MVFR. 
Not much in the way of low level flow, so visibility in many areas may 
remain MVFR in haze. Difficult to pinpoint where convection will 
fire up and like yesterday, and storms will move quite slowly. 
Expect most convective activity to occur in the afternoon and 
evening, with only scattered to isolated showers/thunderstorms at other 
times. Once the convection tapers off later this evening, we'll 
start the cycle all over again. 


Outlook... 
the frontal zone will gradually weaken as a large Bermuda high 
pressure system takes over the circulation. This will bring an 
increasingly warm and humid flow to our area and continue the 
threat of showers and thunderstorms through midweek. A cold 
front approaching from the northwest may work its way into the 
forecast area Wednesday night. 


&& 


Marine... 
the quasi-stationary front over our waters is forecast to weaken 
gradually or lift north as a Bermuda high to the southeast and 
associated middle level ridge gradually build. Since the front seems to 
have sunk south overnight over most of our area, we generally start 
with an east to southeast flow today, and it will take a little time 
for that to change. Still, even the models furthest south with the 
front are forecasting a southerly flow to be increasingly dominant 
over all the waters with time. Eventually, what is left of the middle 
level low to the west and an associated cold front should move 
across our area and cause winds to shift to the west. This probably 
will happen late in the forecast period, either Wednesday night or 
Thursday. Winds through the forecast are prognosticated to be light to 
moderate and seas are capped below the advisory criteria. Scattered 
showers and thunderstorms remain in the forecast given the middle level low to 
the west and the warm and humid air mass. Because of the rising dew 
points and the relatively cool water temperatures, some fog may 
occur, especially in the overnight and morning periods. 


&& 


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


&& 


$$ 


Synopsis...amc 
near term...amc/delisi 
short term...amc 
long term...amc 
aviation...rpw/delisi 
marine...rpw/delisi