Scientific Forecaster Discussion
fxus61 kokx 262059
Area forecast discussion
National Weather Service New York New York
359 PM EST sun Feb 26 2017
high pressure off the mid-Atlantic coast will bring mild, but
unsettled weather for Tuesday and Wednesday. A strong cold
frontal passage Wednesday evening returns cold, but seasonable
weather for the end of the week with the chance for light snow
for early Friday. It's a dry weekend and warming up on Sunday.
Near term /until 6 am Monday morning/...
any remaining stratocumulus dissipates towards sunset, then
just sky clear. Winds also diminish and back to SW as the high builds
Lows in the 20s with 30s in the New York Metro as still a few degrees
Short term /6 am Monday morning through Monday night/...
with the high having moved off the coast - that sets up the
start of a prolonged warm advection period. Clouds increase
through the day and it's mostly cloudy in the afternoon - this
keeps temps in the lower 50s.
Long term /Tuesday through Sunday/...
nwp appears fairly clustered and consistent with the overall
pattern, but not without lots of local forecast problems this
1. Tuesday - Wednesday. Warm air advection advection pattern will likely bring
light rain by late afternoon Tuesday there persists on and off into Wednesday
afternoon. We have likely pops, but expect these to go to categorical
as timing of precipitation becomes clearer.
There's lots of spread in the temperature guidance for Tuesday
and have gone with the cooler side (gfs) due to the onset of
precipitation and the extensive cloud cover. That being said, temps
should get well into the 60s by Wednesday away from the coast - of
course with a strong gradient at the coast. Advection fog also
becomes a forecast problem and can see repeat of a few days ago.
2. Wednesday aftn/eve. Instability is once again present along
with very strong shear in excess of 60 knots. Li's of -2 c and
total totals in the lower 50s are not to be ignored this time
of year as we saw Saturday night. Thus have included ts in the
forecast. No enhanced wording, but that may come as we get
3. Thursday. Windy with steady or slowly falling temps. Think
40 mph should do it for the winds, but we could get close to
Wind Advisory criteria.
4. Friday. Clipper system passes the region. Looking at the
gefs suggest much of the energy passes across up state and
across New England. Thus, keeping just a 30 pop for light snow.
The operation GFS is on the higher end of the quantitative precipitation forecast across the
okx forecast area.
On the other hand, the operational European model (ecmwf) is south of the area.
Temps are forecast slight below normal for Saturday, but rebound to
the lower 50s for Sunday.
Aviation /20z Sunday through Friday/...
high pressure moves southeast of Long Island through the taf
period. VFR conditions are expected to continue. Stratocumulus
mostly few-scattered with broken near kswf with diminishing clouds this
evening. Winds generally left of 310 magnetic and gusting 20-25
kt into early evening. By mid to late evening and into
overnight, winds will gradually diminish and back to west-southwest-SW
direction. The flow becomes gusty once again late Monday morning
into Monday afternoon with gusts near 20 kt.
Outlook for 20z Monday through Friday...
Monday-Monday night...VFR. SW winds g15-20kt Monday afternoon,
subsiding at night.
Tuesday...chance of MVFR in light rain.
Tuesday night-Wednesday morning...areas of fog with light rain
continuing. MVFR/IFR and possibly lower. Low level wind shear possible with SW
winds 45-55 kt at 2kft. SW winds g15-20kt Wednesday morning.
Wednesday afternoon-Wednesday night...showers and a chance of
thunderstorms. MVFR or lower possible. SW winds g20-30kt. Winds
become westerly late Wednesday night.
Thursday...VFR. West-west-northwest winds g20-25kt.
Friday...MVFR/IFR possible with a chance of light snow. West-northwest
lingering Small Craft Advisory conditions will persist on the forecast waters
into this evening and remain overnight for much of the ocean
mainly due to seas east of Fire Island Inlet. For the ocean
east of Fire Island Inlet, the Small Craft Advisory conditions will extend
through Monday with other waters being more marginal and likely
falling a little below Small Craft Advisory criteria. The Small Craft Advisory conditions on the
eastern ocean zones could extend into Monday night, but the
forecast has the wave heights in these zones at 5ft so this is
marginal for Small Craft Advisory and so am not highly confident in this as winds
decrease with the high moving farther offshore and becoming
For the rest of the forecast, Tuesday will have increasing southerly
flow but will still be below Small Craft Advisory levels. The region will be in
between the high pressure well offshore and a low pressure area
moving into the Midwest. The pressure gradient gradually tightens
through midweek with a strong cold front eventually approaching from
the west. The resulting increasing SW flow will build seas to Small Craft Advisory
range beginning Tuesday night and continuing through midweek. Ahead
and just behind the cold front will be potentially the highest of
winds, when gales will be possible for the eastern waters and the
ocean Wednesday through Wednesday evening with otherwise Small Craft Advisory winds
for all waters. After this cold front moves across Wednesday night,
there will be gusty northwest flow and cold air advection. The ocean will
likely remain at Small Craft Advisory levels through the rest of the marine forecast
period through Friday. Small Craft Advisory level winds will persist Wednesday night
through Thursday and come to a brief lull below Small Craft Advisory Thursday night
before returning to around Small Craft Advisory levels Friday.
no hydrologic impacts are anticipated over the next 7 days.
Rainfall in the Tuesday afternoon to Wednesday evening should
average around 0.5" with local amounts up to 1'.
Releases from Spring snow melt is occurring down the
Connecticut and Housatonic rivers.
Marine...Small Craft Advisory until midnight EST tonight for anz335-338-
Small Craft Advisory until 6 am EST Monday for anz330-340-350-