Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Mount Holly New Jersey
921 PM EST Thursday Feb 26 2015
high pressure will build across the region tonight and into the
weekend. A weak upper air disturbance will cross the area Friday. A
weak low pressure system and its fronts will affect the area Sunday
night into Monday. More high pressure will arrive for Monday night
and early Tuesday. Another storm will affect the area for the middle
of next week.
Near term /until 6 am Friday morning/...
this update mainly to time the snow showers/flurries. At least
over the next couple of hours, its the Poconos first and then as
the short wave moves closer, it should spread deeper into our County Warning Area.
Based on the radar and obs, the wetter (the ones that have some
measurable) model solutions are looking better. We did up min
temperatures about 1 to 3 degrees, less in Delaware-Maryland-Virginia where it snowed
heavier this morning.
The low pressure which brought snow to the southern half of the
region Thursday has moved offshore. Skies will remain partly to
mostly cloudy as another shortwave approaches the region from the
west. The time of the low temperature may be variable, from the
evening west till toward daybreak further east. Clouds and the
approaching shortwave may also lead to slightly rising
temperatures west of phl overnight. Scattered snow showers with
the shortwave should enter the region after midnight, with the
highest chance probability of precipitation around Philadelphia by sunrise.
Short term /6 am Friday morning through 6 PM Friday/...
any clouds and flurries from the shortwave should clear
out during the morning. Total accumulation will be under 1/2 inch in
the areas that do see snow primarily from Philadelphia to the
northwest closer to the shortwave. Areas across the Delaware-Maryland-Virginia and
Jersey Shore may not see anything as the shortwave weakens during
the morning. Modeled two meter temperatures looked a few degrees to
chilly while the met/mav perhaps a degree to warm overall. Temperatures
only in the 20's to low 30's across the region for highs with cold air advection
throughout the day.
Long term /Friday night through Thursday/...
high pressure will settle across the area between Friday night and
Sunday morning. A dry period is expected with temperatures mostly
below normal through the period. Skies will be partly to mostly
clear through the period. There will be increasing clouds Sunday
morning with the next system approaching.
An approaching upper 500 mb trough and a weak surface low...along with its
associated fronts...will arrive Sunday afternoon and it will
affect the weather into early Monday. P-type will be mostly snow
with the system...however significant amounts are not expected at
this time. A brief mix with some sleet or perhaps some freezing
rain is possible...but these details will be looked at over the
next few days as the details become clearer. Temperatures still mostly
below normal sun/Mon.
More high pressure with dry weather later Monday into Tuesday.
Temperatures rising back to near normal levels.
Another low...a bit stronger than the previous one...will track
from the plains to the Great Lakes. Moisture will arrive later Tuesday
and remain into Thursday. Temperatures will be back near normal Tuesday and
probably above normal Wed/Thu. Looks like mostly rain S/east and snow
changing to rain north/west for this system.
Aviation /02z Friday through Tuesday/...
the following discussion is for kphl, kpne, kttn, kabe,
krdg, kilg, kmiv, kacy and surrounding areas.
00z tafs predicting some MVFR conditions toward morning mainly in
for terminals and airports in the northwest half of our forecast
For this evening...VFR with mainly a middle level VFR ceiling. At kacy
and kmiv, they will start with no ceiling before the middle level clouds
move back over the area. Light north winds.
Overnight...VFR ceilings lowering with light north winds. Late at krdg
and kabe some MVFR conditions due to snow showers are possible.
Friday morning...primarily VFR stratocu based ceilings. The chance
for MVFR conditions due to snow showers shifts early to the kphl
metropolitan area, i95 corridor airports. We have lower confidence of
this occurring than at farther upstream airports in the overnight.
North to northwest winds increase to 5 to 10 knots. Winds at kacy
and kmiv are an average for the entire daytime period.
Friday afternoon...VFR with a stratocu based ceiling continuing.
North to northwest winds should average close to 10 knots. Not
much gustiness is anticipated. Late we are predicting the VFR ceiling
Friday night through sun...VFR expected. Increasing clouds sun.
Sun night through Monday...lower conditions possible. Light snow
expected at times. Monday night into Tuesday...mostly VFR.
wavewatch guidance looks to be running several feet below current
levels for the sea height. This trend may continue through the night
and into Friday with north and northeast flow behind the departing
low pressure system. Seas will remain near or five feet likely
through 20z Friday which results in an extension of the Small Craft Advisory on the
ocean waters till 20z Friday. Northeasterly winds in Delaware Bay
have fallen below 25 knots so the Small Craft Advisory will be cancelled in the Bay.
Northerly winds should be below 25 knots Friday with higher gusts
around 25-30 knots tonight.
Friday night - Saturday...sub-sca expected, though persistent
northeast winds may allow for building seas across our southern
Sunday - Monday...possible Small Craft Advisory conditions late on Sunday ahead of an
approaching cold front. Increasing southerly winds and building seas
Tuesday...possible lingering Small Craft Advisory conditions due to seas on the
records for Friday and Saturday. Note records for Friday unlikely
but posted just in case one or 2 are approached at 1159 PM Friday
There is a greater chance of records Saturday.
Por / site / Feb 27 Feb 28
1872 / kphl / 6 1900 9 1934
1874 / kacy / 7 1934* 2 1934
1894 / kilg / 5 1934 -5 1934
1922 / kabe / -2 1963 -10 1934
1869 / krdg / 4 1934* 3 1934
1865 / kttn / 6 1934 1 1934
1948 / kged / 10 1963 8 1950
1901 / kmpo / -9 1993 -15 1907
Kacy rer for 3/1 is 5 in 1980.
Note: * indicate and other years.
Note: por = period of record,the year official climate observation began.
The following is a table of the ***projected*** top 5 coldest
february's on record, based on the current forecast, and thus
subject to change. Each ranking denotes the mean February
temperature /f/ and year of occurrence.
We rereviewed these projections listed below using this Thursday
mornings (26th) mins and the phi forecast as seen on ndfd and sft's. We
see phl/Abe/ilg all very close to yesterdays projections. Kacy
changed to a warmer projection however that could yet revert back to
a colder monthly average due to the potential for radiational
cooling on one or 2 of the mornings.
Por / site / 1st rank / 2nd rank / 3rd rank / 4th rank / 5th rank
1872 / kphl / 22.2(1934) 23.0(1979) 24.3(1885) 24.6(1978) 25.5(2015)
1874 / kacy / 21.6(1979) 23.8(1978/1934) 24.5(2015) 25.5(1875) 25.7
1894 / kilg / 20.2(1934) 22.1(1979) 22.7(1978) 24.5(2015) 24.9(1936)
1922 / kabe / 16.6(1934) 18.9(2015) 20.4(1979) 21.6(1936) 22.0(1963)
Per the above table, Abe is easily on track for the second coldest
February, Atlantic City 3rd coldest followed by the fourth coldest
at ilg, and the fifth coldest at phl.
The following is a table of the ***projected*** mean February 2015
temperatures /f/ and departures from normal. This is also based on
the current forecast, and thus subject to change. January 2015 mean
temperatures are also included for comparison purposes.
Por / site / Feb mean(f) / Feb normal(f) / departure / Jan mean(f)
1872 / kphl / 25.5 / 35.7 / -10.2 / 30.9
1874 / kacy / 24.5 / 35.3 / -10.8 / 30.2
1894 / kilg / 24.5 / 35.1 / -10.6 / 30.3
1922 / kabe / 18.9 / 30.7 / -11.8 / 25.9
In general, mean temperatures at our four major climate sites are on
track to be around 10 to 12 degrees below normal for February 2015.
It's also interesting to note that the projected February 2015 mean
temperatures will be well below the January 2015 mean temperatures.
To put this in perspective, normal mean February temperatures at our
four major climate sites are about 2 to 3 degrees warmer than January.
The opposite is shaping up for February 2015.
Also...of interest...this would also be the second coldest monthly
mean temperature on record at Allentown since records began in
1922; February 1934 being the coldest!
Phl projects around 12th coldest monthly mean since records began in
Atlantic City 7th coldest monthly mean since records began there
Wilmington has missing data in its database (1897-1916) and so we
don't focus as much attention on that record.
Marine...Small Craft Advisory until 4 PM EST Friday for anz450>455.