Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
743 PM EDT Tuesday Mar 11 2014
an intensifying low pressure system will pass across the region
Wednesday evening. An Arctic blast of cold air moves over the
region for Thursday with high pressure building in. A cold front
will pass through late on Saturday...with more cold high pressure
for Sunday. Low pressure tracks south of region early next week.
Near term /through Wednesday/...
following a day with warmest highs of the year so far...middle 60s
to upper 50s...as downslope flow compressed and shot temperatures up - a
return to winter is coming.
A sea breeze developed late this afternoon and was moving through
central Long Island early this evening. Temperatures in the middle
60s this afternoon have fallen to the lower and middle 50s with the
sea breeze passage...with tough hourly temperatures and dew
Anyway...with temperatures in the 40s sitting over the ocean and the
flow backing to east overnight...expecting a drop off over eastern
Long Island first. Lows in the 30s...except middle 40s for the the
NYC metropolitan are a MOS blend which demonstrated little spread.
Dry overnight with increasing/thickening clouds.
Short term /Wednesday night/...
while there are some minor variation in the nwp in terms of the synoptic
feature...spread is rather low and feel confident with a low
tracking directly over NYC/Long Island Wednesday evening.
Precipitation start time is delayed until afternoon with just a low chance
in the am for northern areas. This based on a consensus of the nwp
with the operational GFS being the exception. The GFS had quantitative precipitation forecast out
of clear skies in WV today...so feel it is over doing the over-
running in the am.
Regardless...probability of precipitation still increase to 100 in the afternoon. Strong
inverted boundary layer profile prevents 60-70 knots low level jet at 2 kft above ground level
from translating to surface.
Frontal passage looks to be in the 03-06z time frame from west to east with
plummeting temperatures in the wake of the front. Middle teens north to middle 20s
on eastern Li by morning.
The question is how much precipitation will be on the backside. Based on
latest nwp and the transient nature of the low...only expected
light precipitation on the the backside. Snow totals of less than an inch
except far north. Coastal areas look closer to a coating.
Regardless...the rapid drop of temperatures results in moderate
confidence for a flash freeze event in the predawn hours of
Long term /Thursday through Tuesday/...
two systems of interest in the long term...the first the departing
coastal low Thursday-Friday and the second a possible coastal low
for early next week.
For the first systems...appears to be good agreement that
likely see Wind Advisory criteria winds across at least NYC/Long
Island/coastal CT and southern/eastern portions of NE New Jersey/lower
Hudson Valley...with a possibility of advisory level winds across
interior/western lower Hudson Valley and NE New Jersey zones. At this
time...with only the European model (ecmwf) having 850 winds of 50 knots...probability
of reaching High Wind Warning criteria is low. The strongest winds
should be during the morning hours...then diminishing through the
Thursday afternoon into Friday. Any winds to advisory criteria
should come to an end during Thursday afternoon from west to east.
With the strong northwest winds advecting in a very cold airmass for this
time of year...do not expect temperatures to rise much...if at all
during the day on Thursday. Used a blend of mav/met guidance with
NAM 2-meter temperatures and a mix down from 875 hpa for highs
Thursday...with readings struggling to reach the upper teens to
around 20 across the interior and the lower to middle 20s elsewhere.
These cold temperatures coupled with the aforementioned strong
winds will allow for wind chills at best in the single digits
Thursday...and possibly in the single digits below zero across
Also in the wake of the departing low...have the chance for mainly
scattered -shsn Thursday morning...tapering off by early afternoon from
SW to NE.
Thursday night will have clearing with slowly diminishing
winds...and will continue to be very cold. For lows used the
lowest of NAM 2-meter temperatures and mav and met
guidance...with values approaching record levels by early Friday
morning. Coupled with brisk northwest winds...will see wind chills as 0
to -5 across the interior and 0 to 5 above across coastal areas
overnight Thursday night.
Weak ridging transits across the area Friday...keeping things
dry. For highs Friday used a blend of mixing down from 925 hpa per
BUFKIT soundings...NAM 2-meter temperatures and a blend of
mex/men/ekd/ece/ecm/wpc guidance - with values around 10 degrees
Some differences in timing and strength of northern stream
shortwaves forecast to track to the north/west of the area Friday night
and Saturday. Given uncertainty and with core of energy passing
well to the N/W...have limited any probability of precipitation to slight chance in this
time frame. The last of these shortwaves brings another polar
cold front through late Saturday...with Canadian high pressure
building in behind it. This low level cold air and the exact
strength and location of this high will be a key player in whether
another coastal low impacts the region early next week.
For now it appears Saturday night and Sunday should be dry with
the region under confluent flow aloft.
12z European model (ecmwf) has trended towards 12z CMC solution of a low developing
over the southeast states Sunday...then tracking NE off the middle-Atlantic
and NE coasts Sunday night-Monday. The GFS however does not show
as much interaction with a southern protuberance of the polar
vortex and a southern stream shortwave...keeping the storm well
to the S and east. Given the overall Superior performance of both the
CMC and European model (ecmwf) in the extended over the GFS so far this year in the
long term...have favored a blend of the European model (ecmwf)/CMC from Sunday
Based on this bring in chance probability of precipitation for mainly snow...possibly
mixed with rain to start across NYC and maybe Long Island late
Sunday evening...then have a chance of snow for all zones from
late Sunday night through Monday...with only slight chance probability of precipitation
Monday night as the storm pulls away...and a potential secondary
low likely tracks well to the S and east. Given the uncertainty...it
is too early to speculate on amounts or potential impact.
Remember...there is still the potential that the GFS could end up
being correct...and the area remain dry early next week.
On Tuesday went dry...with weak ridging forecast over the region.
For temperatures Friday night-Tuesday used a blend of
mex/men/ekd/ece/ecm/wpc guidance...mixing in European model (ecmwf) 2-meter
temperatures Monday-Tuesday to weigh in expected impact of
precipitation induced evaporative cooling and then snow cover.
Expect temperatures to be near to slightly above normal Friday
night and Saturday. Then near to slightly below normal Saturday
night...followed by below normal Sunday-Tuesday.
Aviation /00z Wednesday through Sunday/...
low pressure over the Midwest will force a warm front through from the S
early Wednesday...and pass directly over the region late Wednesday afternoon into Wednesday
The development of ceilings around 1000 feet can be expected in vicinity of the
warm front tonight into Wednesday morning. After the front passes...a quick
transition to VFR is possible.
IFR likely as the low tracks over the region. In addition...isolated to
scattered thunderstorm development possible.
Low level wind shear around 2kft of 40-50 knots develops Wednesday afternoon into Wednesday evening.
Light and vrb winds this evening...then southeast flow Wednesday morning veers to the S
behind the warm front. Winds shift to the northwest behind the low Wednesday
night...and continue to increase even beyond 6z.
A changeover to snow is most likely at kswf Wednesday evening before 6z.
New York metropolitan enhanced aviation weather support...
Detailed information...including hourly taf wind component forecasts can
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)
Kewr fcster comments: no unscheduled amendments expected through 6z.
Kjfk fcster comments: no unscheduled amendments expected through 6z.
Klga fcster comments: no unscheduled amendments expected through 6z.
Kteb fcster comments: no unscheduled amendments expected through 6z.
Khpn fcster comments: no unscheduled amendments expected through 6z.
Kisp fcster comments: no unscheduled amendments expected through 6z.
Outlook for 00z Thursday through sun...
Wednesday night...MVFR or below in rain showers with snow showers
developing northwest-southeast later Wednesday night. Slight chance of thunderstorms and rain in evening. Low level wind shear
2kft of SW winds 40-50 knots early evening. Southeast-S winds around 10-15 knots
gusting up to around 20 knots into early evening then west-northwest winds around
20-25 knots gusting up to around 35 knots late Wednesday night.
Thursday...residual snow showers with MVFR or below in
morning...improving to VFR in afternoon. Northwest winds g30-40kt.
Sat...MVFR possible in showers.
wind generally light and variable across the forecast waters. With
a southerly component along the northern New Jersey coast.
Winds and seas increase on Wednesday with southerly flow. Small Craft Advisory criteria
are likely to be reached by late afternoon.
Gale Warning for Wednesday night as low pressure pass across Long
Island and deepens. Winds in the wake of the low will quickly
increase from west to east around and after midnight.
Gale conditions should continue into Thursday evening...then
subside to small craft levels late Thursday night. Small Craft Advisory conditions
could linger into Friday on the coastal ocean and eastern waters.
Winds increase ahead of an approaching frontal system Friday
night...so Small Craft Advisory level seas and winds possible on coastal ocean and
eastern waters again Friday night.
Sub-Small Craft Advisory conditions should move into all waters...except for
possibly seas on the eastern coastal ocean waters from late
Saturday into Sunday.
a low pressure system will pass of the region Wednesday evening.
Quantitative precipitation forecast of around 1/3 of an inch along the coast to 3/4 of an inch inland
is expected. Only minor to moderate rises are expected on rivers.
There is the possibility of significant precipitation over the
area from Sunday night through Monday. At this time it appears it
will be mainly in the form of snow at this time. However...there
is still quite a bit of uncertainty with this system...so it is
too early to specify exact amounts or any potential impact.
record low temperatures are likely to be tied or broken at most local
climate sites Friday morning.
Record and forecast low temperatures for Friday morning (mar 14)...
Newark.........17 in 1980 16
Bridgeport.....16 in 1980 13
Central Park... 8 in 1896 18
LaGuardia......18 in 1980 20
Kennedy........19 in 1980 18
Islip..........17 in 1989 13
the National oceanic and atmospheric administration weather radio transmitter that serves the New York City
metropolitan area remains out of service due to radio frequency
interference with the U.S Coast Guard transmitter.
For more information see the following public information
statement (all lower case):
Marine...Gale Warning from 11 PM Wednesday to 2 am EDT Friday for