Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
630 PM EST Thursday Nov 26 2015
high pressure east of Nova Scotia slowly gives way to an
approaching cold front over the Midwest this evening. The front
will pass through the area around daybreak Saturday...then stalls
just south of the region through the weekend. High pressure builds
into the area early next week. Another storm system is expected to
impact the region during the middle of the week.
Near term /until 6 am Friday morning/...
forecast generally on track with some minor adjustments to
temperatures. Temperatures have dropped a bit quicker than
forecast...especially north and west of NYC. Therefore...have
made some adjustments to account for this.
Otherwise...anomalously warm heights aloft across the eastern
Seaboard will gradually give way to an upper trough moving across
the upper Midwest. The latter of which will send a cold front
through the area around daybreak Sat.
High pressure east of Nova Scotia will be slow to retreat into
the North Atlantic. This will allow for a weak onshore flow to
continue tonight. The forecast dilemma is whether or not
sufficient low-level moisture can pool beneath a strong
subsidence inversion and form low clouds. Guidance is varying.
Based on recent performance...prefer to go with partly to mostly
cloudy skies and patchy fog after midnight. There is even some
weak low-level lift likely driven by wind shear at the top of the
mixed layer. There is low confidence of sprinkles or drizzle so
for the time will leave mention out of the forecast.
For overnight lows...readings will be mainly in the 40s to around
50. This is well above normal.
Short term /6 am Friday morning through Friday night/...
another warm day across the region with highs getting into the
low to middle 60s most locations as SW flow develops ahead of the
approaching cold front over the Great Lakes.
Clouds will increase Friday night with the cold frontal passage
prior to daybreak most locations. Limited moisture and weak lift
should keep this a mainly dry frontal passage. There is some weak
overrunning behind the front that could result in widely scattered
Lows Sat night will remain mild in the 40s.
Long term /Saturday through Thursday/...
much of the forecast based on blended model/MOS data.
A cold front associated with a middle and upper level trough will move
across the region Saturday...and stall just south of the County Warning Area
Saturday night and Sunday. The 12z forecast guidance has little
precipitation associated with the frontal passage...so will keep
just slight chance or chance probability of precipitation in the forecast. The 12z
European model (ecmwf)...is hinting at a surface wave developing along this
front...and moving across the region Saturday night into Sunday.
So...will keep the chance probability of precipitation in the forecast for this time period
As the upper trough moves east...weak ridging temporarily builds
into the region Monday. Expect mostly sunny skies and dry
Another area of low pressure approaches for Tuesday and Tuesday
night. There are some timing and positional differences...but with
retreating high pressure...will ramp up probability of precipitation through the day
and into Tuesday night.
High pressure returns late in the week.
Temperatures will remain at or slightly below normal through the
long term period. Followed blended models data which was reasonably
close to wpc guidance.
Aviation /00z Friday through Tuesday/...
high pressure east of New England will move slowly east as a cold
front approaches late Friday.
With onshore flow and increasing low level moisture across area
terminals...MVFR ceilings and visibility in fog should develop between 07z and
15z Friday. There is a low chance for IFR/LIFR in ceilings and visibility/fog
during this time.
Winds are forecast to remain 10 knots or less through at least 16z
Friday then increase from the SW at 10-15 knots after 16z Friday.
Outlook for 00z Saturday through Tuesday...
Friday night-Saturday night. MVFR or lower possible...with a chance
of showers. North-NE winds g15-20kt possible Saturday afternoon/evening.
Sunday-Sunday night...VFR likely. Low chance of MVFR.
Tuesday...VFR possibly becoming IFR in rain and fog by afternoon.
a Small Craft Advisory for hazardous seas has been issued for the ocean for Friday
into Friday night as a long period swell approaches from the southeast.
Seas will top out around 6 feet Friday night. Elsewhere...sub-sca
conditions will persist with a weak S/SW flow.
Seas will remain around 5 feet through Saturday night for the coastal
ocean waters...due to a swell and winds. It appears seas diminish on
Sunday...however a few left over 5 feet seas may remain across the
Sub-Small Craft Advisory conditions are then expected through Tuesday morning. Winds
and seas will increase Tuesday afternoon through Wednesday as a low
pressure system passes near the area waters.
there is the potential for a widespread rainfall event midweek
as a storm system impacts the region.
Marine...Small Craft Advisory for hazardous seas from 11 am Friday to 6
am EST Saturday for anz350-353-355.
long term...British Columbia