474 
fxus61 kphi 192330 
afdphi 


Area forecast discussion 
National Weather Service Mount Holly New Jersey 
730 PM EDT Friday Mar 19 2010 


Synopsis... 
high pressure over the Gulf Coast states will ease eastward tonight 
and Saturday morning and move gradually off the East Coast later 
Saturday. A weakening cold front will drop down from the north 
Saturday and move into our area Saturday night into Sunday. Low 
pressure will organize over the lower Mississippi Valley and head 
toward our region later in the weekend. The low will move just 
south of our region Monday night and head off to the east Tuesday. 
High pressure will settle over the area Tuesday night into Thursday 
before a cold front moves in late Thursday or Thursday night. 


&& 


Near term /until 6 am Saturday morning/... 
high pressure will control our weather tonight giving US mostly 
clear skies, light winds, and relatively mild temperatures. 
Overnight lows will range from the upper 30s to the middle 40s. 


&& 


Short term /6 am Saturday morning through Monday/... 
the high pressure system will begin moving off to the east 
Saturday, but continue to control our weather. May not be quite 
as much sun as we've seen today, but temperatures will still 
climb into the middle 60s to low and middle 70s. A weakening backdoor 
cold front will drop into our area Saturday night into Sunday. 
Don't expect much, if any, shower activity from this system. 
What it will do is bring some clouds and swing our winds around 
to the south southeast. Since the front will be weakening as it 
crosses our region and we won't get very deep into the cooler air 
behind it, temperatures will remain on the mild side Saturday 
night through Sunday night. Lows Saturday night will be mainly 
in the 40s. Highs Sunday will range from the upper 50s north, 
where there will be more clouds and possibly even a late day 
shower, to the lower 70s south, where there will be more sunshine. 
Cloudiness will be increasing ahead of the approaching low pressure 
system Sunday night, and the threat of showers will be increasing. 
Monday looks to be a mostly cloudy day with showers likely. There 
could even be a few afternoon thunderstorms. Highs Monday will 
range from the low and middle 50s north to the low and middle 60s south. 
Rainfall amounts through Monday should average 1/4 to around 
1/2 inch. But with convection possible, there could be isolated 
higher amounts. And if this falls in an area that had recent 
flooding, additional flood problems could be encountered. If this 
does occur, it will more than likely happen in the first 12 to 24 
hours of the long term forecast period. 


&& 


Long term /Monday night through Friday/... 
the GFS is fairly similar to yesterday/S long term projections... 
with a deep closed low moving slowly eastward through the 
southeastern states (sounds familiar this winter / early spring) 
at the start of the long term period. The associated surface low 
still seems to be exiting our stage early Tuesday or during Tuesday. 
So...likely probabilities will continue for Monday night into 
Tuesday, and unfortunately with rather decent rain amounts for the 
already saturated northern and central New Jersey river basins. 
Also, a slight chance of thunderstorms was added to Monday night/S 
weather grids as well, based on GFS vorticity and upper diffluence. 


Then, another quiet interlude is forecast to follow before the next 
system intrudes Thursday into Friday. The models seem to slow down 
this event as well...as they have been lately...so rain chances were 
lagged into Friday for now. 


A trend to a more zonal flow during next week would seem to indicate 
a tendency toward more normal temperatures...albeit under the 
influence of a strong late March sun where clouds will be minimal... 
later in the long term period. HPC temperatures were followed. 


&& 


Aviation /23z Friday through Wednesday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, 
kilg, kmiv, kacy and surrounding areas. 


VFR conditions will continue through the taf period, with only some 
cirrus overhead at times. 


For all of our taf sites, the wind should be light and either 
variable or from the west-southwest for tonight and early 
Saturday morning, with a west-southwest wind around 8 or 10 knots 
developing late Saturday morning. Another sea breeze is expected 
for Saturday afternoon. However, slightly stronger westerly winds 
aloft may keep it from progressing as far inland as today/S 
boundary. 


Outlook... 
dry weather conditions should continue for Saturday night into 
Sunday. As low pressure approaches from the southwest, showers are 
likely Monday along with a chance of afternoon thunderstorms. The 
low is expected to pass off the middle Atlantic coast Monday 
night...with a chance of showers lingering into Tuesday. High 
pressure should build into our region from the west Wednesday. 


&& 


Marine... 
high pressure is forecast to continue influencing our region into 
Sunday with tranquil marine weather conditions anticipated. 


Low pressure is expected to approach from the southwest late in the 
weekend and should pass off the middle Atlantic coast Monday night. 
We may see Small Craft Advisory conditions for a time early in the 
new week. 


High pressure should build into our region from the west for the 
middle of the coming week. 


&& 


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


&& 


$$ 


Synopsis... / rpw 
near term...rpw 
short term...rpw 
long term.../ 
aviation... / iovino 
marine... / iovino