Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
333 PM EST Friday Dec 26 2014
high pressure centered over the Carolinas will drift slowly out to
sea through Saturday. A cold front will cross the area on Sunday,
then stall just to our south as low pressure rides along it Sunday
night into Monday. A strong Canadian high pressure system is then
expected to gradually build east Tuesday through Friday of next
Near term /until 6 am Saturday morning/...
some high clouds will move over the region tonight, but otherwise
should see mostly clear skies. Winds will again be light, but
generally out of the southwest. So once again should see some good
radiational cooling. However, with the relatively warm air mass in
place, temperatures should still be slightly above normal, generally
ranging from the middle 20s to middle 30s.
Short term /6 am Saturday morning through 6 PM Saturday/...
by tomorrow, the center of the surface high will be along the NC
coast, while the developing surface low will have lifted over
northern Michigan. As a result, our region will be in between these
systems leading to warm, albeit still rather weak, southwesterly
flow. Thus, highs tomorrow should be a few degrees higher than
Long term /Saturday night through Friday/...
clouds will be on the increase Saturday night has high pressure
continues to slip off the East Coast and a cold front approaches
from the west, with some light precipitation expected in our
northern and western sections before sunrise. The temperature
profile expected at that time suggests mainly rain showers at the
onset of precipitation, except perhaps in the higher elevations of
the southern Poconos and northwest New Jersey where some light snow
is possible, with no significant accumulation. Then mainly light
rain or rain showers expected for most of the day on Sunday as the
front continues to move southeast. As colder air moves in on the
back side of this front Sunday night, light snow is expected
basically north and west of the I-95 corridor, but even more
likely north of I-78. With limited qpf, any snow accumulations
should be limited to an inch or less. There could be some travel
impacts on untreated roads during the Monday morning commute, but
by then heaviest precipitation should be ending in the north. The
highest storm total precipitation from this system should fall
south and east of the I-95 corridor, but the temperatures in this
area favor rain vs. Snow, so winter impacts are not anticipated.
GFS is suggesting an additional round of light precipition across
the Delmarva, southeast PA and southern New Jersey Monday night into
Tuesday associated with a convergence zone setting up between two
different jet stream sources setting itself up over the middle-
Atlantic region during that time frame. The European model (ecmwf) is not, so the
weather grids were not populated for that time period with this
Then a sprawling high pressure system from Canada begins it/S slow
progression eastward, building over the region from Tuesday night
through Friday, along with parallel period of benign weather.
Temperatures for the extended portion of the forecast period will
start out above normal Sunday into Monday...then dip below normal
Tuesday into Thursday...then return to near normal for the end of the
workweek. It appears the bitter cold air will remain locked in
Canada for the foreseeable future, with no major snowstorms on the
horizon just yet.
Aviation /20z Friday through Wednesday/...
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
VFR conditions are expected through taf period. Only few to scattered high
clouds are expected through the period. Winds will slowly shift from
southwesterly to southerly through the period.
Saturday night...some MVFR ceilings possible northwest airports, VFR ceilings
Sunday into Monday...MVFR, possibly IFR, conditions possible at
times as waves of precipitation move from north to south across the
area with the cold front. The northern part of the precipitation
shield could be light snow.
Monday night through Tuesday...VFR in the north, MVFR, possibly IFR,
in the south.
Tuesday night and Wednesday...VFR.
winds and seas should stay below Small Craft Advisory criteria tonight and tomorrow.
Wind direction will gradually shift from westerly to southerly
through the period. A few gusts near 20kt are possible late tonight.
Saturday night into Sunday morning...a slightly stronger southwest
flow preceding a cold front will bring wind gusts closer to Small
Craft Advisory criteria on the ocean.
Sunday afternoon and night...sub Small Craft Advisory conditions
Monday through Tuesday...sub Small Craft Advisory conditions expected.
Lower confidence as a wave of low pressure is predicted to form
south of the area waters on the mentioned front. Its possible that
Small Craft Advisory conditions might occur if this low intensifies
faster than we are currently forecasting.
Tuesday night through Wednesday...sub Small Craft Advisory