998 
fxus61 kphi 021828 
afdphi 


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


Synopsis... 
high pressure will build over the region tonight into Thursday night. 
The winds in the upper atmosphere remain from the west and very fast. 
As a result, the fast flow will push a cold front to the east and 
approach our forecast area Thursday morning, and sweep to the coast 
by the evening. High pressure will build back over the area through 
Friday. 


&& 


Near term /through Wednesday/... 
the cloudiness moving north from the Carolinas is moisture between 14 
and 19,000 feet as earlier forecast. The 500 mb moisture field shows it 
clearing the region just before Sundown. Other clouds are diurnal in 
nature and will be dissipating during the evening hours. Rather uneventful 
period next couple of days. Upper trough departs the coast as another 
Canadian trough digs down through the northern plains. The return flow 
around the departing coastal high pressure and the gradient ahead of 
the northern front will bring warm air back into the region during the 
day on Wednesday. 


Skies should be clearing all areas with lows ranging from 17 in the 
higher zones to 29 Delaware-Maryland-Virginia zones. Skies during the day tomorrow will 
generally be clear with lows 41 to 50 degrees and light south 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 /18z 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 Wednesday. 


An upper air trough has allowed stratocu around 4 thousand feet to develop 
in response to sunshine and mixing at Abe and ridge. However, farther 
south at phl/pne/Acy/ilg/miv/ttn...cirrus and some middle clouds 
spread in from the south. These middle and high clouds will continue 
to limit any stratocu develop this afternoon. The upper trough will shift 
to the east this evening allowing the middle and high clouds to move 
out to sea. Meanwhile, any stratocu from this afternoon will 
dissipate and skies should go clear during the evening hours. Winds 
were west around 10 knots this afternoon and these winds will also go light 
and variable after dark. Mostly clear skies should then continue 
through Wednesday. 


Outlook...the next threat of precipitation is with a cold front that 
will move through from the west 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... 
although we have some long period swells of 5-6 feet well offshore, 
winds and seas remain below Small Craft Advisory criteria. Relatively tranquil 
conditions are forecast to continue through Wednesday as high 
pressure will move by to the south. 


On Thursday, we have a cold front moving east from the Ohio Valley 
that will move through the area in the afternoon. 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. I anticipate 
the need for Small Craft Advisory on the ocean and Delaware by for 
Thursday. 


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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