Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service New York New York
1249 am EST sun Nov 23 2014
high pressure passes southeast of the area tonight. A warm front
approaches from the southwest Sunday. This warm front lifts to
our north Monday morning. A cold front then follows behind it
Monday night. High pressure briefly builds into the the region
Tuesday. A coastal low pressure may impact the region Wednesday
into Wednesday night. A trough of low pressure then lingers near
the area into Friday.
Near term /until 6 am this morning/...
no significant changes made to the forecast. Will adjust hourly
temperatures/dew points based on latest surface observation...which seem to be a bit
warmer than forecast. Will follow this trend for a few hours...and
will raise overnight lows by a degree or so.
Otherwise...weak shortwave pass across New England overnight in
zonal flow...with a few sprinkles or light rain showers overnight.
Thermal profiles support liquid precipitation. Cloud cover and warm air advection SW
flow should only allow surface temperatures to remain steady or only
slowly drop overnight. Potential for interior valleys of lower
Hudson Valley and CT to drop to around freezing in a few
spots...but overall expect temperatures to hold above freezing there.
Forecast temperatures may be a degree or so too cold. Freezing rain
threat looks to be low and sparse at worst across interior
valleys...but will be monitored.
Short term /today and tonight/...
ridging Sunday occurs ahead of digging middle west trough. Models
remain in general agreement on overall features.
Surface high pressure departs over the western Atlantic as low pressure
organizes and deepens over the middle portion of the country. This
deepening low marches northeast toward the Great Lakes region Sunday
night...with a warm front approaching from the southwest late at
For Sunday...any morning clouds give way to partly to mostly sunny
skies. SW winds gradually turn toward the south late in the day.
Temperatures rise into the lower 50s most locales...close to a MOS blend.
Then temperatures remain steady in the evening before rising overnight
Sunday night as clouds move in and southerly winds increase.
Rain out ahead of the warm front will quickly move in from southwest
to northeast Sunday night.
Long term /Monday through Saturday/...
models in general agreement with upper flow for early week...with
phasing southern stream/northern stream and Pacific energy over the
upper Great Lakes on Monday lifting into Ontario/Quebec Monday
night/Tue. The result will be a bombing low over the Great Lakes
taking a similar path as the upper energy. Ahead of it...deep S/SW
flow...with 70-75 knots low level jet...will bring a moist airmass (pw 3-4 Standard
above normal) into the region up and over an approaching warm
front. The result should be a period of moderate to heavy rain
sliding east across the region late Sun night through Monday morning. A
bit of elevated instability and strong forcing indicate slight
potential for thunder...mainly eastern portions of tri-state. Rain
should taper off by midday Monday as warm front passes north...with
region warm sectored in its wake.
Unseasonably mild temperatures...15-20 degree above seasonable...possible
across interior Monday after. A tight SW gradient and continued healthy
low level jet of 40-45 knots at 950 mb should result in windy conditions on
Monday...15 to 25 miles per hour with gusts 25 to 35 miles per hour. There is a low
probability for gusts of 40-45 miles per hour...particularly across higher
elevations and areas n&w of NYC Monday with any breaks of sun and
resultant deeper mixed layer. Cold front pushes through Monday
night...with some accompanying light shower activity
possible...and then cold air advection in its wake late.
Tranquil and near seasonable temperatures on Tuesday as high pressure builds
Then potential increasing for a coastal storm impacting the
region Wednesday/Wednesday night...but uncertainty on exact track of this
system. The driver for this system appear to be phasing northern
stream and Pacific energy diving down the back side of deep central US
troughing early this week...with the energy pivoting up the coast
midweek as it phases with yet another piece of northern stream
shortwave energy. Differences exist more so with the degree of
this second interaction...affecting how negatively tilted answer
strong the trough becomes. The result is some timing...but mainly
track differences with how close to the coast low pressure
developing in the Gulf tracks to the region Wednesday night. For now
have played a middle of the Road track between operational and
ensemble means...which would track low pressure near the 40/70
latitude/Lon benchmark Wednesday night. This would bring potential for a
rain/snow coast...snow interior on Wednesday...changing to all snow Wednesday
night for most if not all of the region as the low deepens and
track north. Too much uncertainty to talk about snow amounts and
location...but at this point a low potential exists for several
inches of snow for a portion of the tri-state.
Thereafter...models are still divergent over what happens behind the
storm...but it appears most likely that there could be some
unsettled weather in its wake either due to a lingering trough
behind the low...or another weak storm system crossing the area late
in the week.
Aviation /06z Sunday through Thursday/...
high pressure remains south of the region through the overnight. A warm
front approaches later today.
VFR through around 03z Monday. Low chance for pockets of -fzra
towards daybreak this morning at kswf with MVFR ceilings...but probability
remains too low to include in the tafs.
SW winds will generally average 8-12 knots during the overnight and
into the afternoon. However...with 45-50 knots winds at 2000-3000
feet...will keep low level wind shear in the tafs through around 13z. If these winds
mix down...as appears to be happening at kgon...then SW winds would
range from 15-20 knots with 20-25 knots gusts.
Winds diminish after 13z...and will range from 7-10 knots through the
afternoon. Guidance continues to hint at possible sea breezes at
khpn to kgon with Li sound temperatures in the 40s. This would back winds
to around 170 true after 17z. Winds will otherwise back to the south
Ceilings gradually lower to MVFR/IFR between 03-06z Monday as warm front
approaches from the south.
Outlook for 06z Monday through Thursday...
tonight-Monday...IFR or lower in rain/fog. Low level wind shear possible with 50 knots
winds 1500-2000 feet late tonight through early Monday morning. South
winds around 20 knots with 20-35 knots gusts.
Monday night...improving conds. Winds shift to the west at 10-15
Tuesday...VFR. West winds 15-20 knots with 20-30 knots gusts.
Tuesday night...diminishing winds. Sub-VFR ceilings possible late.
Wednesday-Wednesday night...low confidence forecast with passage of
coastal low. Accumulating snow threat possible for the interior...
but accumulating snow could occur closer to the coast based on track
of low. Strong winds possible depending on track of low as well.
Thursday...low confidence forecast. Lingering rain/snow showers
possible. Strong winds possible as well.
SW winds will remain fairly strong into this evening and overnight
as high pressure passes well to the south and east tonight. Small
Craft Advisory remains up. Marginal conds in western Long Island Sound
and New York Harbor. A few gale gusts are possible over
the ocean waters and eastern Li sound. However...these gale force
winds are expected to be brief...so will not upgrade to gale
warnings at this time.
Winds diminish late tonight and through the day Sunday as the pressure
gradient relaxes somewhat. However...winds turn to the south and
increase once again Sunday night. In fact...gale force winds are
quite possible late at night over the ocean waters...with Small Craft Advisory
criteria elsewhere. Will issue a gale watch beginning late at night
for the ocean waters.
Rough ocean seas will subside Sunday before building yet again late
Winds pick up again Sunday night into Monday as a strong low moves
through the Great Lakes region. A strong low level jet moving
through late at night through Monday bringing the threat of gales.
Better overall chances would be on the ocean waters...but this could
expand to the other zones. Gale watch for ocean waters through Monday.
Small Craft Advisory conditions otherwise prevail Monday night through Tuesday
evening...followed by a relatively brief period of sub-Small Craft Advisory
conditions later Tuesday night through Wednesday morning. Small Craft Advisory conditions
then become more probable later Wednesday through Thursday as a coastal storm
tracks to the southeast of the waters.
rain moves in Sunday night with a quick half an inch to an inch
possible by the morning commute Monday. Total rainfall with this
event from Sunday night through Monday will be around an inch.
Any moderate to briefly heavy rainfall may result in urban/poor drainage
A low potential for 1/2 to 1 inch of precipitation exists Wednesday into
record high temperatures for Monday 24 November...
Location........record/year.....Forecast Monday high temperatures
* also occurred in previous years
Marine...Small Craft Advisory until 6 am EST early this morning for
Gale watch from late tonight through Monday afternoon for
Small Craft Advisory until noon EST today for anz350-353.