680 
fxus61 kphi 030304 
afdphi 


Area forecast discussion 
National Weather Service Mount Holly New Jersey 
1004 PM EST Tuesday Dec 2 2008 


Synopsis... 
high pressure building over the region tonight will move offshore 
Wednesday. An advancing strong cold front will move through the 
region Thursday, allowing high pressure to settle back into our area 
Friday into Saturday. A fast moving low pressure system is likely to 
move southeast from the Great Lakes this weekend. 


&& 


Near term /through Wednesday/... 
the biggest patch of stratocumulus was over our southern zones, with 
one small neck sticking up to about Philadelphia. These clouds 
were moving pretty rapidly eastward in the brisk westerly flow at 5 
to 10 thousand feet. Another small patch was approaching our 
northwestern zones, but this was just starting to diminish according 
to satellite trends. The clouds should move out of the area early in 
the overnight period, so skies will be clearing as high pressure 
builds at the surface. 


A couple of places had to have their hourly temperatures, as well as 
their overnight minimums, adjusted based on current readings, dew 
points, and MOS guidance. 


Skies during the day Wednesday will generally be clear with lows 40 
to 50 degrees, and light south to southwest winds. 


&& 


Short term /Wednesday night through Thursday/... 
cold air will be digging down through the Central Plains behind the 
cold front stretching from James Bay Canada to Brownsville Texas. The 
coldest 80h surge into Missouri late Wednesday night with the surface 
front into western PA around 12z Thursday and offshore after 00z. Upslope 
showers western Appalachians and dissipating showers moving to the 
coast. About .10-.15 hundredths of an inch. As for the type, 
precipitation will begin as rain showers than mix with and change to 
snow showers Thursday afternoon and evening in most areas and all 
snow showers higher elevations. Low Thursday night will be 31 to 
lower 40s in coastal areas. Cold air advection behind the front overspreads the 
entire forecast area during the afternoon and should see snow 
showers from what moisture is available. By 00z see instability 
showers western PA and rain showers offshore. Winds may be an issue 
in the late afternoon and overnight hours. 


Highs for Thursday will come in the late morning hours and be from 
36 to 56 degrees before falling during the afternoon hours. 


&& 


Long term /Thursday night through Tuesday/... 
this part of the forecast will begin to feel like winter. With the 
front offshore a dry wedge has pushed northeast into the area, 
however with -12c at 80h some scattered showers are over western 
PA and there may be some on our northern and western zones 
doorstep at times late Thursday night and Friday. Winds will be a 
big factor brining US to the realization that yes it is winter. 
Wind chills will be down into the teens. We continue to look 
upwards and upstream for our next chance of weather and the fast 
cyclonic flow is not going to disappoint US. With cold in in place 
throughout the air column, high pressure will move through the 
region on Saturday night. What may be the first clipper this year 
will be leaving Alberta province Canada Friday night and take a 
course toward US. However, most clippers tend to move through US a 
little farther to the south than what this one appears to be 
doing. At the onset of any precipitation the temperatures are cold 
and what falls should be in the form of snow and stick. The once 
Alberta clipper moves into New York state but a weak pressure 
trough extends to the southeast off New Jersey and may be just enough of a 
connection to bring some measurable snows even down to our 
Delaware-Maryland-Virginia zones. Wouldn't be surprised to see an inch or two spread 
across our forecast area late Saturday into Sunday. 


Lows Thursday night will be from the middle 20s to middle 30s and highs 
on Friday 40 to 56. Low Friday night 19 to 30 and highs Saturday 28 
to 41. 


The upper trough and related surface low will be out of the picture 
Sunday night but with -16c at at 80h still dealing with some 
instability snow showers through early Monday morning. Low Saturday 
night 20 to 29 and highs 28 to 45 on Sunday. Sunday night lows 16 to 
26. Cold Arctic high over the Ohio Valley will move across the area 
and it will bring a cold sunny day for Monday and a cold clear night 
for Monday night. The upper trough has undergone still another shift 
becoming zonal for Monday night. This time, allowing some warm air 
to creep into our southern zones. And, another low pressure is 
looming on the northwest horizon. Tuesday promises to be a day of 
mixed precipitation across a good part of the region. 


The critical temperatures will be highs Monday 26 to 41, lows Monday 
night 17 to 29 and highs Tuesday 32 to 44. 


&& 


Aviation /03z Tuesday through Saturday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg, 
kmiv, kacy and surrounding areas. 


VFR conditions are forecast to continue through the taf period. 


There are some lingering SC over portions of the region, but all 
ceilings were VFR. Expect SC to dissipate later tonight and most places 
will be sky clear. The mostly clear conditions will continue through 
Wednesday. Otherwise, the wind was light from the west or SW and 
expected to stay that way. 


Outlook...the next threat of precipitation is with a cold front that 
will move through on Thursday. Some rain showers are possible ahead 
of the front and rain or snow showers are possible behind it. Also, 
gusty winds to 30 knots are possible with the front and behind it 
Thursday night. 
&& 


Marine... 
wind and seas are expected to remain below Small Craft Advisory criteria through 
Wednesday, but will begin to increase Wednesday night, as high 
pressure is the dominant weather feature. 


On Thursday, a cold front will move east from the Ohio Valley. The 
gradient increases ahead of the front, so winds are expected to 
increase during the day and gust to 25 or 30 knots by afternoon. Winds 
should start out as SW and shift to west or northwest in the afternoon. Small Craft Advisory 
flags will likely be needed by Thursday for the ocean and Delaware 
Bay. 


Gusty northwest winds should continue Thursday night as colder air moves 
over the region. On Friday, the center of high pressure will 
approach from the west and then move across the area and offshore 
Friday night. This should allow winds to decrease below Small Craft Advisory during 
the day Friday. 


On Saturday night, yet another cold front should move through from 
the west. Gusty winds to 25 knots could again accompany and follow this 
front. 


&& 


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


&& 


$$ 


Synopsis.../ eberwine 
near term.../ eberwine 
short term...eberwine 
long term...eberwine 
aviation...stauber 
marine...stauber 

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